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      1 //===-- ProcessMonitor.cpp ------------------------------------ -*- C++ -*-===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 
     10 #include "lldb/lldb-python.h"
     11 
     12 // C Includes
     13 #include <errno.h>
     14 #include <poll.h>
     15 #include <string.h>
     16 #include <stdint.h>
     17 #include <unistd.h>
     18 #include <sys/ptrace.h>
     19 #include <sys/socket.h>
     20 #include <sys/syscall.h>
     21 #include <sys/types.h>
     22 #include <sys/wait.h>
     23 
     24 // C++ Includes
     25 // Other libraries and framework includes
     26 #include "lldb/Core/Debugger.h"
     27 #include "lldb/Core/Error.h"
     28 #include "lldb/Core/RegisterValue.h"
     29 #include "lldb/Core/Scalar.h"
     30 #include "lldb/Host/Host.h"
     31 #include "lldb/Target/Thread.h"
     32 #include "lldb/Target/RegisterContext.h"
     33 #include "lldb/Utility/PseudoTerminal.h"
     34 
     35 #include "POSIXThread.h"
     36 #include "ProcessLinux.h"
     37 #include "ProcessPOSIXLog.h"
     38 #include "ProcessMonitor.h"
     39 
     40 
     41 #define DEBUG_PTRACE_MAXBYTES 20
     42 
     43 // Support ptrace extensions even when compiled without required kernel support
     44 #ifndef PTRACE_GETREGSET
     45   #define PTRACE_GETREGSET 0x4204
     46 #endif
     47 #ifndef PTRACE_SETREGSET
     48   #define PTRACE_SETREGSET 0x4205
     49 #endif
     50 
     51 // Support hardware breakpoints in case it has not been defined
     52 #ifndef TRAP_HWBKPT
     53   #define TRAP_HWBKPT 4
     54 #endif
     55 
     56 // Try to define a macro to encapsulate the tgkill syscall
     57 // fall back on kill() if tgkill isn't available
     58 #define tgkill(pid, tid, sig)  syscall(SYS_tgkill, pid, tid, sig)
     59 
     60 using namespace lldb_private;
     61 
     62 // FIXME: this code is host-dependent with respect to types and
     63 // endianness and needs to be fixed.  For example, lldb::addr_t is
     64 // hard-coded to uint64_t, but on a 32-bit Linux host, ptrace requires
     65 // 32-bit pointer arguments.  This code uses casts to work around the
     66 // problem.
     67 
     68 // We disable the tracing of ptrace calls for integration builds to
     69 // avoid the additional indirection and checks.
     70 #ifndef LLDB_CONFIGURATION_BUILDANDINTEGRATION
     71 
     72 static void
     73 DisplayBytes (lldb_private::StreamString &s, void *bytes, uint32_t count)
     74 {
     75     uint8_t *ptr = (uint8_t *)bytes;
     76     const uint32_t loop_count = std::min<uint32_t>(DEBUG_PTRACE_MAXBYTES, count);
     77     for(uint32_t i=0; i<loop_count; i++)
     78     {
     79         s.Printf ("[%x]", *ptr);
     80         ptr++;
     81     }
     82 }
     83 
     84 static void PtraceDisplayBytes(int &req, void *data, size_t data_size)
     85 {
     86     StreamString buf;
     87     Log *verbose_log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (
     88                                         POSIX_LOG_PTRACE | POSIX_LOG_VERBOSE));
     89 
     90     if (verbose_log)
     91     {
     92         switch(req)
     93         {
     94         case PTRACE_POKETEXT:
     95             {
     96                 DisplayBytes(buf, &data, 8);
     97                 verbose_log->Printf("PTRACE_POKETEXT %s", buf.GetData());
     98                 break;
     99             }
    100         case PTRACE_POKEDATA:
    101             {
    102                 DisplayBytes(buf, &data, 8);
    103                 verbose_log->Printf("PTRACE_POKEDATA %s", buf.GetData());
    104                 break;
    105             }
    106         case PTRACE_POKEUSER:
    107             {
    108                 DisplayBytes(buf, &data, 8);
    109                 verbose_log->Printf("PTRACE_POKEUSER %s", buf.GetData());
    110                 break;
    111             }
    112         case PTRACE_SETREGS:
    113             {
    114                 DisplayBytes(buf, data, data_size);
    115                 verbose_log->Printf("PTRACE_SETREGS %s", buf.GetData());
    116                 break;
    117             }
    118         case PTRACE_SETFPREGS:
    119             {
    120                 DisplayBytes(buf, data, data_size);
    121                 verbose_log->Printf("PTRACE_SETFPREGS %s", buf.GetData());
    122                 break;
    123             }
    124         case PTRACE_SETSIGINFO:
    125             {
    126                 DisplayBytes(buf, data, sizeof(siginfo_t));
    127                 verbose_log->Printf("PTRACE_SETSIGINFO %s", buf.GetData());
    128                 break;
    129             }
    130         case PTRACE_SETREGSET:
    131             {
    132                 // Extract iov_base from data, which is a pointer to the struct IOVEC
    133                 DisplayBytes(buf, *(void **)data, data_size);
    134                 verbose_log->Printf("PTRACE_SETREGSET %s", buf.GetData());
    135                 break;
    136             }
    137         default:
    138             {
    139             }
    140         }
    141     }
    142 }
    143 
    144 // Wrapper for ptrace to catch errors and log calls.
    145 // Note that ptrace sets errno on error because -1 can be a valid result (i.e. for PTRACE_PEEK*)
    146 extern long
    147 PtraceWrapper(int req, lldb::pid_t pid, void *addr, void *data, size_t data_size,
    148               const char* reqName, const char* file, int line)
    149 {
    150     long int result;
    151 
    152     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PTRACE));
    153 
    154     if (log)
    155         log->Printf("ptrace(%s, %lu, %p, %p, %zu) called from file %s line %d",
    156                     reqName, pid, addr, data, data_size, file, line);
    157 
    158     PtraceDisplayBytes(req, data, data_size);
    159 
    160     errno = 0;
    161     if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
    162         result = ptrace(static_cast<__ptrace_request>(req), pid, *(unsigned int *)addr, data);
    163     else
    164         result = ptrace(static_cast<__ptrace_request>(req), pid, addr, data);
    165 
    166     PtraceDisplayBytes(req, data, data_size);
    167 
    168     if (log && errno != 0)
    169     {
    170         const char* str;
    171         switch (errno)
    172         {
    173         case ESRCH:  str = "ESRCH"; break;
    174         case EINVAL: str = "EINVAL"; break;
    175         case EBUSY:  str = "EBUSY"; break;
    176         case EPERM:  str = "EPERM"; break;
    177         default:     str = "<unknown>";
    178         }
    179         log->Printf("ptrace() failed; errno=%d (%s)", errno, str);
    180     }
    181 
    182     return result;
    183 }
    184 
    185 // Wrapper for ptrace when logging is not required.
    186 // Sets errno to 0 prior to calling ptrace.
    187 extern long
    188 PtraceWrapper(int req, pid_t pid, void *addr, void *data, size_t data_size)
    189 {
    190     long result = 0;
    191     errno = 0;
    192     if (req == PTRACE_GETREGSET || req == PTRACE_SETREGSET)
    193         result = ptrace(static_cast<__ptrace_request>(req), pid, *(unsigned int *)addr, data);
    194     else
    195         result = ptrace(static_cast<__ptrace_request>(req), pid, addr, data);
    196     return result;
    197 }
    198 
    199 #define PTRACE(req, pid, addr, data, data_size) \
    200     PtraceWrapper((req), (pid), (addr), (data), (data_size), #req, __FILE__, __LINE__)
    201 #else
    202     PtraceWrapper((req), (pid), (addr), (data), (data_size))
    203 #endif
    204 
    205 //------------------------------------------------------------------------------
    206 // Static implementations of ProcessMonitor::ReadMemory and
    207 // ProcessMonitor::WriteMemory.  This enables mutual recursion between these
    208 // functions without needed to go thru the thread funnel.
    209 
    210 static size_t
    211 DoReadMemory(lldb::pid_t pid,
    212              lldb::addr_t vm_addr, void *buf, size_t size, Error &error)
    213 {
    214     // ptrace word size is determined by the host, not the child
    215     static const unsigned word_size = sizeof(void*);
    216     unsigned char *dst = static_cast<unsigned char*>(buf);
    217     size_t bytes_read;
    218     size_t remainder;
    219     long data;
    220 
    221     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_ALL));
    222     if (log)
    223         ProcessPOSIXLog::IncNestLevel();
    224     if (log && ProcessPOSIXLog::AtTopNestLevel() && log->GetMask().Test(POSIX_LOG_MEMORY))
    225         log->Printf ("ProcessMonitor::%s(%" PRIu64 ", %d, %p, %p, %zd, _)", __FUNCTION__,
    226                      pid, word_size, (void*)vm_addr, buf, size);
    227 
    228     assert(sizeof(data) >= word_size);
    229     for (bytes_read = 0; bytes_read < size; bytes_read += remainder)
    230     {
    231         errno = 0;
    232         data = PTRACE(PTRACE_PEEKDATA, pid, (void*)vm_addr, NULL, 0);
    233         if (errno)
    234         {
    235             error.SetErrorToErrno();
    236             if (log)
    237                 ProcessPOSIXLog::DecNestLevel();
    238             return bytes_read;
    239         }
    240 
    241         remainder = size - bytes_read;
    242         remainder = remainder > word_size ? word_size : remainder;
    243 
    244         // Copy the data into our buffer
    245         for (unsigned i = 0; i < remainder; ++i)
    246             dst[i] = ((data >> i*8) & 0xFF);
    247 
    248         if (log && ProcessPOSIXLog::AtTopNestLevel() &&
    249             (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
    250              (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
    251               size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
    252             {
    253                 uintptr_t print_dst = 0;
    254                 // Format bytes from data by moving into print_dst for log output
    255                 for (unsigned i = 0; i < remainder; ++i)
    256                     print_dst |= (((data >> i*8) & 0xFF) << i*8);
    257                 log->Printf ("ProcessMonitor::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
    258                              (void*)vm_addr, print_dst, (unsigned long)data);
    259             }
    260 
    261         vm_addr += word_size;
    262         dst += word_size;
    263     }
    264 
    265     if (log)
    266         ProcessPOSIXLog::DecNestLevel();
    267     return bytes_read;
    268 }
    269 
    270 static size_t
    271 DoWriteMemory(lldb::pid_t pid,
    272               lldb::addr_t vm_addr, const void *buf, size_t size, Error &error)
    273 {
    274     // ptrace word size is determined by the host, not the child
    275     static const unsigned word_size = sizeof(void*);
    276     const unsigned char *src = static_cast<const unsigned char*>(buf);
    277     size_t bytes_written = 0;
    278     size_t remainder;
    279 
    280     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_ALL));
    281     if (log)
    282         ProcessPOSIXLog::IncNestLevel();
    283     if (log && ProcessPOSIXLog::AtTopNestLevel() && log->GetMask().Test(POSIX_LOG_MEMORY))
    284         log->Printf ("ProcessMonitor::%s(%" PRIu64 ", %d, %p, %p, %zd, _)", __FUNCTION__,
    285                      pid, word_size, (void*)vm_addr, buf, size);
    286 
    287     for (bytes_written = 0; bytes_written < size; bytes_written += remainder)
    288     {
    289         remainder = size - bytes_written;
    290         remainder = remainder > word_size ? word_size : remainder;
    291 
    292         if (remainder == word_size)
    293         {
    294             unsigned long data = 0;
    295             assert(sizeof(data) >= word_size);
    296             for (unsigned i = 0; i < word_size; ++i)
    297                 data |= (unsigned long)src[i] << i*8;
    298 
    299             if (log && ProcessPOSIXLog::AtTopNestLevel() &&
    300                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
    301                  (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
    302                   size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
    303                  log->Printf ("ProcessMonitor::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
    304                               (void*)vm_addr, *(unsigned long*)src, data);
    305 
    306             if (PTRACE(PTRACE_POKEDATA, pid, (void*)vm_addr, (void*)data, 0))
    307             {
    308                 error.SetErrorToErrno();
    309                 if (log)
    310                     ProcessPOSIXLog::DecNestLevel();
    311                 return bytes_written;
    312             }
    313         }
    314         else
    315         {
    316             unsigned char buff[8];
    317             if (DoReadMemory(pid, vm_addr,
    318                              buff, word_size, error) != word_size)
    319             {
    320                 if (log)
    321                     ProcessPOSIXLog::DecNestLevel();
    322                 return bytes_written;
    323             }
    324 
    325             memcpy(buff, src, remainder);
    326 
    327             if (DoWriteMemory(pid, vm_addr,
    328                               buff, word_size, error) != word_size)
    329             {
    330                 if (log)
    331                     ProcessPOSIXLog::DecNestLevel();
    332                 return bytes_written;
    333             }
    334 
    335             if (log && ProcessPOSIXLog::AtTopNestLevel() &&
    336                 (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_LONG) ||
    337                  (log->GetMask().Test(POSIX_LOG_MEMORY_DATA_SHORT) &&
    338                   size <= POSIX_LOG_MEMORY_SHORT_BYTES)))
    339                  log->Printf ("ProcessMonitor::%s() [%p]:0x%lx (0x%lx)", __FUNCTION__,
    340                               (void*)vm_addr, *(unsigned long*)src, *(unsigned long*)buff);
    341         }
    342 
    343         vm_addr += word_size;
    344         src += word_size;
    345     }
    346     if (log)
    347         ProcessPOSIXLog::DecNestLevel();
    348     return bytes_written;
    349 }
    350 
    351 // Simple helper function to ensure flags are enabled on the given file
    352 // descriptor.
    353 static bool
    354 EnsureFDFlags(int fd, int flags, Error &error)
    355 {
    356     int status;
    357 
    358     if ((status = fcntl(fd, F_GETFL)) == -1)
    359     {
    360         error.SetErrorToErrno();
    361         return false;
    362     }
    363 
    364     if (fcntl(fd, F_SETFL, status | flags) == -1)
    365     {
    366         error.SetErrorToErrno();
    367         return false;
    368     }
    369 
    370     return true;
    371 }
    372 
    373 //------------------------------------------------------------------------------
    374 /// @class Operation
    375 /// @brief Represents a ProcessMonitor operation.
    376 ///
    377 /// Under Linux, it is not possible to ptrace() from any other thread but the
    378 /// one that spawned or attached to the process from the start.  Therefore, when
    379 /// a ProcessMonitor is asked to deliver or change the state of an inferior
    380 /// process the operation must be "funneled" to a specific thread to perform the
    381 /// task.  The Operation class provides an abstract base for all services the
    382 /// ProcessMonitor must perform via the single virtual function Execute, thus
    383 /// encapsulating the code that needs to run in the privileged context.
    384 class Operation
    385 {
    386 public:
    387     virtual ~Operation() {}
    388     virtual void Execute(ProcessMonitor *monitor) = 0;
    389 };
    390 
    391 //------------------------------------------------------------------------------
    392 /// @class ReadOperation
    393 /// @brief Implements ProcessMonitor::ReadMemory.
    394 class ReadOperation : public Operation
    395 {
    396 public:
    397     ReadOperation(lldb::addr_t addr, void *buff, size_t size,
    398                   Error &error, size_t &result)
    399         : m_addr(addr), m_buff(buff), m_size(size),
    400           m_error(error), m_result(result)
    401         { }
    402 
    403     void Execute(ProcessMonitor *monitor);
    404 
    405 private:
    406     lldb::addr_t m_addr;
    407     void *m_buff;
    408     size_t m_size;
    409     Error &m_error;
    410     size_t &m_result;
    411 };
    412 
    413 void
    414 ReadOperation::Execute(ProcessMonitor *monitor)
    415 {
    416     lldb::pid_t pid = monitor->GetPID();
    417 
    418     m_result = DoReadMemory(pid, m_addr, m_buff, m_size, m_error);
    419 }
    420 
    421 //------------------------------------------------------------------------------
    422 /// @class WriteOperation
    423 /// @brief Implements ProcessMonitor::WriteMemory.
    424 class WriteOperation : public Operation
    425 {
    426 public:
    427     WriteOperation(lldb::addr_t addr, const void *buff, size_t size,
    428                    Error &error, size_t &result)
    429         : m_addr(addr), m_buff(buff), m_size(size),
    430           m_error(error), m_result(result)
    431         { }
    432 
    433     void Execute(ProcessMonitor *monitor);
    434 
    435 private:
    436     lldb::addr_t m_addr;
    437     const void *m_buff;
    438     size_t m_size;
    439     Error &m_error;
    440     size_t &m_result;
    441 };
    442 
    443 void
    444 WriteOperation::Execute(ProcessMonitor *monitor)
    445 {
    446     lldb::pid_t pid = monitor->GetPID();
    447 
    448     m_result = DoWriteMemory(pid, m_addr, m_buff, m_size, m_error);
    449 }
    450 
    451 
    452 //------------------------------------------------------------------------------
    453 /// @class ReadRegOperation
    454 /// @brief Implements ProcessMonitor::ReadRegisterValue.
    455 class ReadRegOperation : public Operation
    456 {
    457 public:
    458     ReadRegOperation(lldb::tid_t tid, unsigned offset, const char *reg_name,
    459                      RegisterValue &value, bool &result)
    460         : m_tid(tid), m_offset(offset), m_reg_name(reg_name),
    461           m_value(value), m_result(result)
    462         { }
    463 
    464     void Execute(ProcessMonitor *monitor);
    465 
    466 private:
    467     lldb::tid_t m_tid;
    468     uintptr_t m_offset;
    469     const char *m_reg_name;
    470     RegisterValue &m_value;
    471     bool &m_result;
    472 };
    473 
    474 void
    475 ReadRegOperation::Execute(ProcessMonitor *monitor)
    476 {
    477     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
    478 
    479     // Set errno to zero so that we can detect a failed peek.
    480     errno = 0;
    481     lldb::addr_t data = PTRACE(PTRACE_PEEKUSER, m_tid, (void*)m_offset, NULL, 0);
    482     if (errno)
    483         m_result = false;
    484     else
    485     {
    486         m_value = data;
    487         m_result = true;
    488     }
    489     if (log)
    490         log->Printf ("ProcessMonitor::%s() reg %s: 0x%" PRIx64, __FUNCTION__,
    491                      m_reg_name, data);
    492 }
    493 
    494 //------------------------------------------------------------------------------
    495 /// @class WriteRegOperation
    496 /// @brief Implements ProcessMonitor::WriteRegisterValue.
    497 class WriteRegOperation : public Operation
    498 {
    499 public:
    500     WriteRegOperation(lldb::tid_t tid, unsigned offset, const char *reg_name,
    501                       const RegisterValue &value, bool &result)
    502         : m_tid(tid), m_offset(offset), m_reg_name(reg_name),
    503           m_value(value), m_result(result)
    504         { }
    505 
    506     void Execute(ProcessMonitor *monitor);
    507 
    508 private:
    509     lldb::tid_t m_tid;
    510     uintptr_t m_offset;
    511     const char *m_reg_name;
    512     const RegisterValue &m_value;
    513     bool &m_result;
    514 };
    515 
    516 void
    517 WriteRegOperation::Execute(ProcessMonitor *monitor)
    518 {
    519     void* buf;
    520     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_REGISTERS));
    521 
    522 #if __WORDSIZE == 32
    523     buf = (void*) m_value.GetAsUInt32();
    524 #else
    525     buf = (void*) m_value.GetAsUInt64();
    526 #endif
    527 
    528     if (log)
    529         log->Printf ("ProcessMonitor::%s() reg %s: %p", __FUNCTION__, m_reg_name, buf);
    530     if (PTRACE(PTRACE_POKEUSER, m_tid, (void*)m_offset, buf, 0))
    531         m_result = false;
    532     else
    533         m_result = true;
    534 }
    535 
    536 //------------------------------------------------------------------------------
    537 /// @class ReadGPROperation
    538 /// @brief Implements ProcessMonitor::ReadGPR.
    539 class ReadGPROperation : public Operation
    540 {
    541 public:
    542     ReadGPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
    543         : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
    544         { }
    545 
    546     void Execute(ProcessMonitor *monitor);
    547 
    548 private:
    549     lldb::tid_t m_tid;
    550     void *m_buf;
    551     size_t m_buf_size;
    552     bool &m_result;
    553 };
    554 
    555 void
    556 ReadGPROperation::Execute(ProcessMonitor *monitor)
    557 {
    558     if (PTRACE(PTRACE_GETREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
    559         m_result = false;
    560     else
    561         m_result = true;
    562 }
    563 
    564 //------------------------------------------------------------------------------
    565 /// @class ReadFPROperation
    566 /// @brief Implements ProcessMonitor::ReadFPR.
    567 class ReadFPROperation : public Operation
    568 {
    569 public:
    570     ReadFPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
    571         : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
    572         { }
    573 
    574     void Execute(ProcessMonitor *monitor);
    575 
    576 private:
    577     lldb::tid_t m_tid;
    578     void *m_buf;
    579     size_t m_buf_size;
    580     bool &m_result;
    581 };
    582 
    583 void
    584 ReadFPROperation::Execute(ProcessMonitor *monitor)
    585 {
    586     if (PTRACE(PTRACE_GETFPREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
    587         m_result = false;
    588     else
    589         m_result = true;
    590 }
    591 
    592 //------------------------------------------------------------------------------
    593 /// @class ReadRegisterSetOperation
    594 /// @brief Implements ProcessMonitor::ReadRegisterSet.
    595 class ReadRegisterSetOperation : public Operation
    596 {
    597 public:
    598     ReadRegisterSetOperation(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset, bool &result)
    599         : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_regset(regset), m_result(result)
    600         { }
    601 
    602     void Execute(ProcessMonitor *monitor);
    603 
    604 private:
    605     lldb::tid_t m_tid;
    606     void *m_buf;
    607     size_t m_buf_size;
    608     const unsigned int m_regset;
    609     bool &m_result;
    610 };
    611 
    612 void
    613 ReadRegisterSetOperation::Execute(ProcessMonitor *monitor)
    614 {
    615     if (PTRACE(PTRACE_GETREGSET, m_tid, (void *)&m_regset, m_buf, m_buf_size) < 0)
    616         m_result = false;
    617     else
    618         m_result = true;
    619 }
    620 
    621 //------------------------------------------------------------------------------
    622 /// @class WriteGPROperation
    623 /// @brief Implements ProcessMonitor::WriteGPR.
    624 class WriteGPROperation : public Operation
    625 {
    626 public:
    627     WriteGPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
    628         : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
    629         { }
    630 
    631     void Execute(ProcessMonitor *monitor);
    632 
    633 private:
    634     lldb::tid_t m_tid;
    635     void *m_buf;
    636     size_t m_buf_size;
    637     bool &m_result;
    638 };
    639 
    640 void
    641 WriteGPROperation::Execute(ProcessMonitor *monitor)
    642 {
    643     if (PTRACE(PTRACE_SETREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
    644         m_result = false;
    645     else
    646         m_result = true;
    647 }
    648 
    649 //------------------------------------------------------------------------------
    650 /// @class WriteFPROperation
    651 /// @brief Implements ProcessMonitor::WriteFPR.
    652 class WriteFPROperation : public Operation
    653 {
    654 public:
    655     WriteFPROperation(lldb::tid_t tid, void *buf, size_t buf_size, bool &result)
    656         : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_result(result)
    657         { }
    658 
    659     void Execute(ProcessMonitor *monitor);
    660 
    661 private:
    662     lldb::tid_t m_tid;
    663     void *m_buf;
    664     size_t m_buf_size;
    665     bool &m_result;
    666 };
    667 
    668 void
    669 WriteFPROperation::Execute(ProcessMonitor *monitor)
    670 {
    671     if (PTRACE(PTRACE_SETFPREGS, m_tid, NULL, m_buf, m_buf_size) < 0)
    672         m_result = false;
    673     else
    674         m_result = true;
    675 }
    676 
    677 //------------------------------------------------------------------------------
    678 /// @class WriteRegisterSetOperation
    679 /// @brief Implements ProcessMonitor::WriteRegisterSet.
    680 class WriteRegisterSetOperation : public Operation
    681 {
    682 public:
    683     WriteRegisterSetOperation(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset, bool &result)
    684         : m_tid(tid), m_buf(buf), m_buf_size(buf_size), m_regset(regset), m_result(result)
    685         { }
    686 
    687     void Execute(ProcessMonitor *monitor);
    688 
    689 private:
    690     lldb::tid_t m_tid;
    691     void *m_buf;
    692     size_t m_buf_size;
    693     const unsigned int m_regset;
    694     bool &m_result;
    695 };
    696 
    697 void
    698 WriteRegisterSetOperation::Execute(ProcessMonitor *monitor)
    699 {
    700     if (PTRACE(PTRACE_SETREGSET, m_tid, (void *)&m_regset, m_buf, m_buf_size) < 0)
    701         m_result = false;
    702     else
    703         m_result = true;
    704 }
    705 
    706 //------------------------------------------------------------------------------
    707 /// @class ResumeOperation
    708 /// @brief Implements ProcessMonitor::Resume.
    709 class ResumeOperation : public Operation
    710 {
    711 public:
    712     ResumeOperation(lldb::tid_t tid, uint32_t signo, bool &result) :
    713         m_tid(tid), m_signo(signo), m_result(result) { }
    714 
    715     void Execute(ProcessMonitor *monitor);
    716 
    717 private:
    718     lldb::tid_t m_tid;
    719     uint32_t m_signo;
    720     bool &m_result;
    721 };
    722 
    723 void
    724 ResumeOperation::Execute(ProcessMonitor *monitor)
    725 {
    726     intptr_t data = 0;
    727 
    728     if (m_signo != LLDB_INVALID_SIGNAL_NUMBER)
    729         data = m_signo;
    730 
    731     if (PTRACE(PTRACE_CONT, m_tid, NULL, (void*)data, 0))
    732     {
    733         Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
    734 
    735         if (log)
    736             log->Printf ("ResumeOperation (%"  PRIu64 ") failed: %s", m_tid, strerror(errno));
    737         m_result = false;
    738     }
    739     else
    740         m_result = true;
    741 }
    742 
    743 //------------------------------------------------------------------------------
    744 /// @class SingleStepOperation
    745 /// @brief Implements ProcessMonitor::SingleStep.
    746 class SingleStepOperation : public Operation
    747 {
    748 public:
    749     SingleStepOperation(lldb::tid_t tid, uint32_t signo, bool &result)
    750         : m_tid(tid), m_signo(signo), m_result(result) { }
    751 
    752     void Execute(ProcessMonitor *monitor);
    753 
    754 private:
    755     lldb::tid_t m_tid;
    756     uint32_t m_signo;
    757     bool &m_result;
    758 };
    759 
    760 void
    761 SingleStepOperation::Execute(ProcessMonitor *monitor)
    762 {
    763     intptr_t data = 0;
    764 
    765     if (m_signo != LLDB_INVALID_SIGNAL_NUMBER)
    766         data = m_signo;
    767 
    768     if (PTRACE(PTRACE_SINGLESTEP, m_tid, NULL, (void*)data, 0))
    769         m_result = false;
    770     else
    771         m_result = true;
    772 }
    773 
    774 //------------------------------------------------------------------------------
    775 /// @class SiginfoOperation
    776 /// @brief Implements ProcessMonitor::GetSignalInfo.
    777 class SiginfoOperation : public Operation
    778 {
    779 public:
    780     SiginfoOperation(lldb::tid_t tid, void *info, bool &result, int &ptrace_err)
    781         : m_tid(tid), m_info(info), m_result(result), m_err(ptrace_err) { }
    782 
    783     void Execute(ProcessMonitor *monitor);
    784 
    785 private:
    786     lldb::tid_t m_tid;
    787     void *m_info;
    788     bool &m_result;
    789     int &m_err;
    790 };
    791 
    792 void
    793 SiginfoOperation::Execute(ProcessMonitor *monitor)
    794 {
    795     if (PTRACE(PTRACE_GETSIGINFO, m_tid, NULL, m_info, 0)) {
    796         m_result = false;
    797         m_err = errno;
    798     }
    799     else
    800         m_result = true;
    801 }
    802 
    803 //------------------------------------------------------------------------------
    804 /// @class EventMessageOperation
    805 /// @brief Implements ProcessMonitor::GetEventMessage.
    806 class EventMessageOperation : public Operation
    807 {
    808 public:
    809     EventMessageOperation(lldb::tid_t tid, unsigned long *message, bool &result)
    810         : m_tid(tid), m_message(message), m_result(result) { }
    811 
    812     void Execute(ProcessMonitor *monitor);
    813 
    814 private:
    815     lldb::tid_t m_tid;
    816     unsigned long *m_message;
    817     bool &m_result;
    818 };
    819 
    820 void
    821 EventMessageOperation::Execute(ProcessMonitor *monitor)
    822 {
    823     if (PTRACE(PTRACE_GETEVENTMSG, m_tid, NULL, m_message, 0))
    824         m_result = false;
    825     else
    826         m_result = true;
    827 }
    828 
    829 //------------------------------------------------------------------------------
    830 /// @class KillOperation
    831 /// @brief Implements ProcessMonitor::BringProcessIntoLimbo.
    832 class KillOperation : public Operation
    833 {
    834 public:
    835     KillOperation(bool &result) : m_result(result) { }
    836 
    837     void Execute(ProcessMonitor *monitor);
    838 
    839 private:
    840     bool &m_result;
    841 };
    842 
    843 void
    844 KillOperation::Execute(ProcessMonitor *monitor)
    845 {
    846     lldb::pid_t pid = monitor->GetPID();
    847 
    848     if (PTRACE(PTRACE_KILL, pid, NULL, NULL, 0))
    849         m_result = false;
    850     else
    851         m_result = true;
    852 }
    853 
    854 //------------------------------------------------------------------------------
    855 /// @class KillOperation
    856 /// @brief Implements ProcessMonitor::BringProcessIntoLimbo.
    857 class DetachOperation : public Operation
    858 {
    859 public:
    860     DetachOperation(lldb::tid_t tid, Error &result) : m_tid(tid), m_error(result) { }
    861 
    862     void Execute(ProcessMonitor *monitor);
    863 
    864 private:
    865     lldb::tid_t m_tid;
    866     Error &m_error;
    867 };
    868 
    869 void
    870 DetachOperation::Execute(ProcessMonitor *monitor)
    871 {
    872     if (ptrace(PT_DETACH, m_tid, NULL, 0) < 0)
    873         m_error.SetErrorToErrno();
    874 }
    875 
    876 ProcessMonitor::OperationArgs::OperationArgs(ProcessMonitor *monitor)
    877     : m_monitor(monitor)
    878 {
    879     sem_init(&m_semaphore, 0, 0);
    880 }
    881 
    882 ProcessMonitor::OperationArgs::~OperationArgs()
    883 {
    884     sem_destroy(&m_semaphore);
    885 }
    886 
    887 ProcessMonitor::LaunchArgs::LaunchArgs(ProcessMonitor *monitor,
    888                                        lldb_private::Module *module,
    889                                        char const **argv,
    890                                        char const **envp,
    891                                        const char *stdin_path,
    892                                        const char *stdout_path,
    893                                        const char *stderr_path,
    894                                        const char *working_dir)
    895     : OperationArgs(monitor),
    896       m_module(module),
    897       m_argv(argv),
    898       m_envp(envp),
    899       m_stdin_path(stdin_path),
    900       m_stdout_path(stdout_path),
    901       m_stderr_path(stderr_path),
    902       m_working_dir(working_dir) { }
    903 
    904 ProcessMonitor::LaunchArgs::~LaunchArgs()
    905 { }
    906 
    907 ProcessMonitor::AttachArgs::AttachArgs(ProcessMonitor *monitor,
    908                                        lldb::pid_t pid)
    909     : OperationArgs(monitor), m_pid(pid) { }
    910 
    911 ProcessMonitor::AttachArgs::~AttachArgs()
    912 { }
    913 
    914 //------------------------------------------------------------------------------
    915 /// The basic design of the ProcessMonitor is built around two threads.
    916 ///
    917 /// One thread (@see SignalThread) simply blocks on a call to waitpid() looking
    918 /// for changes in the debugee state.  When a change is detected a
    919 /// ProcessMessage is sent to the associated ProcessLinux instance.  This thread
    920 /// "drives" state changes in the debugger.
    921 ///
    922 /// The second thread (@see OperationThread) is responsible for two things 1)
    923 /// launching or attaching to the inferior process, and then 2) servicing
    924 /// operations such as register reads/writes, stepping, etc.  See the comments
    925 /// on the Operation class for more info as to why this is needed.
    926 ProcessMonitor::ProcessMonitor(ProcessPOSIX *process,
    927                                Module *module,
    928                                const char *argv[],
    929                                const char *envp[],
    930                                const char *stdin_path,
    931                                const char *stdout_path,
    932                                const char *stderr_path,
    933                                const char *working_dir,
    934                                lldb_private::Error &error)
    935     : m_process(static_cast<ProcessLinux *>(process)),
    936       m_operation_thread(LLDB_INVALID_HOST_THREAD),
    937       m_monitor_thread(LLDB_INVALID_HOST_THREAD),
    938       m_pid(LLDB_INVALID_PROCESS_ID),
    939       m_terminal_fd(-1),
    940       m_client_fd(-1),
    941       m_server_fd(-1)
    942 {
    943     std::unique_ptr<LaunchArgs> args;
    944 
    945     args.reset(new LaunchArgs(this, module, argv, envp,
    946                               stdin_path, stdout_path, stderr_path, working_dir));
    947 
    948     // Server/client descriptors.
    949     if (!EnableIPC())
    950     {
    951         error.SetErrorToGenericError();
    952         error.SetErrorString("Monitor failed to initialize.");
    953     }
    954 
    955     StartLaunchOpThread(args.get(), error);
    956     if (!error.Success())
    957         return;
    958 
    959 WAIT_AGAIN:
    960     // Wait for the operation thread to initialize.
    961     if (sem_wait(&args->m_semaphore))
    962     {
    963         if (errno == EINTR)
    964             goto WAIT_AGAIN;
    965         else
    966         {
    967             error.SetErrorToErrno();
    968             return;
    969         }
    970     }
    971 
    972     // Check that the launch was a success.
    973     if (!args->m_error.Success())
    974     {
    975         StopOpThread();
    976         error = args->m_error;
    977         return;
    978     }
    979 
    980     // Finally, start monitoring the child process for change in state.
    981     m_monitor_thread = Host::StartMonitoringChildProcess(
    982         ProcessMonitor::MonitorCallback, this, GetPID(), true);
    983     if (!IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
    984     {
    985         error.SetErrorToGenericError();
    986         error.SetErrorString("Process launch failed.");
    987         return;
    988     }
    989 }
    990 
    991 ProcessMonitor::ProcessMonitor(ProcessPOSIX *process,
    992                                lldb::pid_t pid,
    993                                lldb_private::Error &error)
    994   : m_process(static_cast<ProcessLinux *>(process)),
    995       m_operation_thread(LLDB_INVALID_HOST_THREAD),
    996       m_monitor_thread(LLDB_INVALID_HOST_THREAD),
    997       m_pid(LLDB_INVALID_PROCESS_ID),
    998       m_terminal_fd(-1),
    999 
   1000       m_client_fd(-1),
   1001       m_server_fd(-1)
   1002 {
   1003     std::unique_ptr<AttachArgs> args;
   1004 
   1005     args.reset(new AttachArgs(this, pid));
   1006 
   1007     // Server/client descriptors.
   1008     if (!EnableIPC())
   1009     {
   1010         error.SetErrorToGenericError();
   1011         error.SetErrorString("Monitor failed to initialize.");
   1012     }
   1013 
   1014     StartAttachOpThread(args.get(), error);
   1015     if (!error.Success())
   1016         return;
   1017 
   1018 WAIT_AGAIN:
   1019     // Wait for the operation thread to initialize.
   1020     if (sem_wait(&args->m_semaphore))
   1021     {
   1022         if (errno == EINTR)
   1023             goto WAIT_AGAIN;
   1024         else
   1025         {
   1026             error.SetErrorToErrno();
   1027             return;
   1028         }
   1029     }
   1030 
   1031     // Check that the attach was a success.
   1032     if (!args->m_error.Success())
   1033     {
   1034         StopOpThread();
   1035         error = args->m_error;
   1036         return;
   1037     }
   1038 
   1039     // Finally, start monitoring the child process for change in state.
   1040     m_monitor_thread = Host::StartMonitoringChildProcess(
   1041         ProcessMonitor::MonitorCallback, this, GetPID(), true);
   1042     if (!IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
   1043     {
   1044         error.SetErrorToGenericError();
   1045         error.SetErrorString("Process attach failed.");
   1046         return;
   1047     }
   1048 }
   1049 
   1050 ProcessMonitor::~ProcessMonitor()
   1051 {
   1052     StopMonitor();
   1053 }
   1054 
   1055 //------------------------------------------------------------------------------
   1056 // Thread setup and tear down.
   1057 void
   1058 ProcessMonitor::StartLaunchOpThread(LaunchArgs *args, Error &error)
   1059 {
   1060     static const char *g_thread_name = "lldb.process.linux.operation";
   1061 
   1062     if (IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
   1063         return;
   1064 
   1065     m_operation_thread =
   1066         Host::ThreadCreate(g_thread_name, LaunchOpThread, args, &error);
   1067 }
   1068 
   1069 void *
   1070 ProcessMonitor::LaunchOpThread(void *arg)
   1071 {
   1072     LaunchArgs *args = static_cast<LaunchArgs*>(arg);
   1073 
   1074     if (!Launch(args)) {
   1075         sem_post(&args->m_semaphore);
   1076         return NULL;
   1077     }
   1078 
   1079     ServeOperation(args);
   1080     return NULL;
   1081 }
   1082 
   1083 bool
   1084 ProcessMonitor::Launch(LaunchArgs *args)
   1085 {
   1086     ProcessMonitor *monitor = args->m_monitor;
   1087     ProcessLinux &process = monitor->GetProcess();
   1088     const char **argv = args->m_argv;
   1089     const char **envp = args->m_envp;
   1090     const char *stdin_path = args->m_stdin_path;
   1091     const char *stdout_path = args->m_stdout_path;
   1092     const char *stderr_path = args->m_stderr_path;
   1093     const char *working_dir = args->m_working_dir;
   1094 
   1095     lldb_utility::PseudoTerminal terminal;
   1096     const size_t err_len = 1024;
   1097     char err_str[err_len];
   1098     lldb::pid_t pid;
   1099 
   1100     lldb::ThreadSP inferior;
   1101     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   1102 
   1103     // Propagate the environment if one is not supplied.
   1104     if (envp == NULL || envp[0] == NULL)
   1105         envp = const_cast<const char **>(environ);
   1106 
   1107     // Pseudo terminal setup.
   1108     if (!terminal.OpenFirstAvailableMaster(O_RDWR | O_NOCTTY, err_str, err_len))
   1109     {
   1110         args->m_error.SetErrorToGenericError();
   1111         args->m_error.SetErrorString("Could not open controlling TTY.");
   1112         goto FINISH;
   1113     }
   1114 
   1115     if ((pid = terminal.Fork(err_str, err_len)) == -1)
   1116     {
   1117         args->m_error.SetErrorToGenericError();
   1118         args->m_error.SetErrorString("Process fork failed.");
   1119         goto FINISH;
   1120     }
   1121 
   1122     // Recognized child exit status codes.
   1123     enum {
   1124         ePtraceFailed = 1,
   1125         eDupStdinFailed,
   1126         eDupStdoutFailed,
   1127         eDupStderrFailed,
   1128         eChdirFailed,
   1129         eExecFailed
   1130     };
   1131 
   1132     // Child process.
   1133     if (pid == 0)
   1134     {
   1135         // Trace this process.
   1136         if (PTRACE(PTRACE_TRACEME, 0, NULL, NULL, 0) < 0)
   1137             exit(ePtraceFailed);
   1138 
   1139         // Do not inherit setgid powers.
   1140         setgid(getgid());
   1141 
   1142         // Let us have our own process group.
   1143         setpgid(0, 0);
   1144 
   1145         // Dup file descriptors if needed.
   1146         //
   1147         // FIXME: If two or more of the paths are the same we needlessly open
   1148         // the same file multiple times.
   1149         if (stdin_path != NULL && stdin_path[0])
   1150             if (!DupDescriptor(stdin_path, STDIN_FILENO, O_RDONLY))
   1151                 exit(eDupStdinFailed);
   1152 
   1153         if (stdout_path != NULL && stdout_path[0])
   1154             if (!DupDescriptor(stdout_path, STDOUT_FILENO, O_WRONLY | O_CREAT))
   1155                 exit(eDupStdoutFailed);
   1156 
   1157         if (stderr_path != NULL && stderr_path[0])
   1158             if (!DupDescriptor(stderr_path, STDERR_FILENO, O_WRONLY | O_CREAT))
   1159                 exit(eDupStderrFailed);
   1160 
   1161         // Change working directory
   1162         if (working_dir != NULL && working_dir[0])
   1163           if (0 != ::chdir(working_dir))
   1164               exit(eChdirFailed);
   1165 
   1166         // Execute.  We should never return.
   1167         execve(argv[0],
   1168                const_cast<char *const *>(argv),
   1169                const_cast<char *const *>(envp));
   1170         exit(eExecFailed);
   1171     }
   1172 
   1173     // Wait for the child process to to trap on its call to execve.
   1174     pid_t wpid;
   1175     int status;
   1176     if ((wpid = waitpid(pid, &status, 0)) < 0)
   1177     {
   1178         args->m_error.SetErrorToErrno();
   1179         goto FINISH;
   1180     }
   1181     else if (WIFEXITED(status))
   1182     {
   1183         // open, dup or execve likely failed for some reason.
   1184         args->m_error.SetErrorToGenericError();
   1185         switch (WEXITSTATUS(status))
   1186         {
   1187             case ePtraceFailed:
   1188                 args->m_error.SetErrorString("Child ptrace failed.");
   1189                 break;
   1190             case eDupStdinFailed:
   1191                 args->m_error.SetErrorString("Child open stdin failed.");
   1192                 break;
   1193             case eDupStdoutFailed:
   1194                 args->m_error.SetErrorString("Child open stdout failed.");
   1195                 break;
   1196             case eDupStderrFailed:
   1197                 args->m_error.SetErrorString("Child open stderr failed.");
   1198                 break;
   1199             case eChdirFailed:
   1200                 args->m_error.SetErrorString("Child failed to set working directory.");
   1201                 break;
   1202             case eExecFailed:
   1203                 args->m_error.SetErrorString("Child exec failed.");
   1204                 break;
   1205             default:
   1206                 args->m_error.SetErrorString("Child returned unknown exit status.");
   1207                 break;
   1208         }
   1209         goto FINISH;
   1210     }
   1211     assert(WIFSTOPPED(status) && wpid == pid &&
   1212            "Could not sync with inferior process.");
   1213 
   1214     if (!SetDefaultPtraceOpts(pid))
   1215     {
   1216         args->m_error.SetErrorToErrno();
   1217         goto FINISH;
   1218     }
   1219 
   1220     // Release the master terminal descriptor and pass it off to the
   1221     // ProcessMonitor instance.  Similarly stash the inferior pid.
   1222     monitor->m_terminal_fd = terminal.ReleaseMasterFileDescriptor();
   1223     monitor->m_pid = pid;
   1224 
   1225     // Set the terminal fd to be in non blocking mode (it simplifies the
   1226     // implementation of ProcessLinux::GetSTDOUT to have a non-blocking
   1227     // descriptor to read from).
   1228     if (!EnsureFDFlags(monitor->m_terminal_fd, O_NONBLOCK, args->m_error))
   1229         goto FINISH;
   1230 
   1231     // Update the process thread list with this new thread.
   1232     // FIXME: should we be letting UpdateThreadList handle this?
   1233     // FIXME: by using pids instead of tids, we can only support one thread.
   1234     inferior.reset(process.CreateNewPOSIXThread(process, pid));
   1235 
   1236     if (log)
   1237         log->Printf ("ProcessMonitor::%s() adding pid = %" PRIu64, __FUNCTION__, pid);
   1238     process.GetThreadList().AddThread(inferior);
   1239 
   1240     process.AddThreadForInitialStopIfNeeded(pid);
   1241 
   1242     // Let our process instance know the thread has stopped.
   1243     process.SendMessage(ProcessMessage::Trace(pid));
   1244 
   1245 FINISH:
   1246     return args->m_error.Success();
   1247 }
   1248 
   1249 bool
   1250 ProcessMonitor::EnableIPC()
   1251 {
   1252     int fd[2];
   1253 
   1254     if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd))
   1255         return false;
   1256 
   1257     m_client_fd = fd[0];
   1258     m_server_fd = fd[1];
   1259     return true;
   1260 }
   1261 
   1262 void
   1263 ProcessMonitor::StartAttachOpThread(AttachArgs *args, lldb_private::Error &error)
   1264 {
   1265     static const char *g_thread_name = "lldb.process.linux.operation";
   1266 
   1267     if (IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
   1268         return;
   1269 
   1270     m_operation_thread =
   1271         Host::ThreadCreate(g_thread_name, AttachOpThread, args, &error);
   1272 }
   1273 
   1274 void *
   1275 ProcessMonitor::AttachOpThread(void *arg)
   1276 {
   1277     AttachArgs *args = static_cast<AttachArgs*>(arg);
   1278 
   1279     if (!Attach(args)) {
   1280         sem_post(&args->m_semaphore);
   1281         return NULL;
   1282     }
   1283 
   1284     ServeOperation(args);
   1285     return NULL;
   1286 }
   1287 
   1288 bool
   1289 ProcessMonitor::Attach(AttachArgs *args)
   1290 {
   1291     lldb::pid_t pid = args->m_pid;
   1292 
   1293     ProcessMonitor *monitor = args->m_monitor;
   1294     ProcessLinux &process = monitor->GetProcess();
   1295     lldb::ThreadSP inferior;
   1296     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   1297 
   1298     // Use a map to keep track of the threads which we have attached/need to attach.
   1299     Host::TidMap tids_to_attach;
   1300     if (pid <= 1)
   1301     {
   1302         args->m_error.SetErrorToGenericError();
   1303         args->m_error.SetErrorString("Attaching to process 1 is not allowed.");
   1304         goto FINISH;
   1305     }
   1306 
   1307     while (Host::FindProcessThreads(pid, tids_to_attach))
   1308     {
   1309         for (Host::TidMap::iterator it = tids_to_attach.begin();
   1310              it != tids_to_attach.end(); ++it)
   1311         {
   1312             if (it->second == false)
   1313             {
   1314                 lldb::tid_t tid = it->first;
   1315 
   1316                 // Attach to the requested process.
   1317                 // An attach will cause the thread to stop with a SIGSTOP.
   1318                 if (PTRACE(PTRACE_ATTACH, tid, NULL, NULL, 0) < 0)
   1319                 {
   1320                     // No such thread. The thread may have exited.
   1321                     // More error handling may be needed.
   1322                     if (errno == ESRCH)
   1323                     {
   1324                         tids_to_attach.erase(it);
   1325                         continue;
   1326                     }
   1327                     else
   1328                     {
   1329                         args->m_error.SetErrorToErrno();
   1330                         goto FINISH;
   1331                     }
   1332                 }
   1333 
   1334                 int status;
   1335                 // Need to use __WALL otherwise we receive an error with errno=ECHLD
   1336                 // At this point we should have a thread stopped if waitpid succeeds.
   1337                 if ((status = waitpid(tid, NULL, __WALL)) < 0)
   1338                 {
   1339                     // No such thread. The thread may have exited.
   1340                     // More error handling may be needed.
   1341                     if (errno == ESRCH)
   1342                     {
   1343                         tids_to_attach.erase(it);
   1344                         continue;
   1345                     }
   1346                     else
   1347                     {
   1348                         args->m_error.SetErrorToErrno();
   1349                         goto FINISH;
   1350                     }
   1351                 }
   1352 
   1353                 if (!SetDefaultPtraceOpts(tid))
   1354                 {
   1355                     args->m_error.SetErrorToErrno();
   1356                     goto FINISH;
   1357                 }
   1358 
   1359                 // Update the process thread list with the attached thread.
   1360                 inferior.reset(process.CreateNewPOSIXThread(process, tid));
   1361 
   1362                 if (log)
   1363                     log->Printf ("ProcessMonitor::%s() adding tid = %" PRIu64, __FUNCTION__, tid);
   1364                 process.GetThreadList().AddThread(inferior);
   1365                 it->second = true;
   1366                 process.AddThreadForInitialStopIfNeeded(tid);
   1367             }
   1368         }
   1369     }
   1370 
   1371     if (tids_to_attach.size() > 0)
   1372     {
   1373         monitor->m_pid = pid;
   1374         // Let our process instance know the thread has stopped.
   1375         process.SendMessage(ProcessMessage::Trace(pid));
   1376     }
   1377     else
   1378     {
   1379         args->m_error.SetErrorToGenericError();
   1380         args->m_error.SetErrorString("No such process.");
   1381     }
   1382 
   1383  FINISH:
   1384     return args->m_error.Success();
   1385 }
   1386 
   1387 bool
   1388 ProcessMonitor::SetDefaultPtraceOpts(lldb::pid_t pid)
   1389 {
   1390     long ptrace_opts = 0;
   1391 
   1392     // Have the child raise an event on exit.  This is used to keep the child in
   1393     // limbo until it is destroyed.
   1394     ptrace_opts |= PTRACE_O_TRACEEXIT;
   1395 
   1396     // Have the tracer trace threads which spawn in the inferior process.
   1397     // TODO: if we want to support tracing the inferiors' child, add the
   1398     // appropriate ptrace flags here (PTRACE_O_TRACEFORK, PTRACE_O_TRACEVFORK)
   1399     ptrace_opts |= PTRACE_O_TRACECLONE;
   1400 
   1401     // Have the tracer notify us before execve returns
   1402     // (needed to disable legacy SIGTRAP generation)
   1403     ptrace_opts |= PTRACE_O_TRACEEXEC;
   1404 
   1405     return PTRACE(PTRACE_SETOPTIONS, pid, NULL, (void*)ptrace_opts, 0) >= 0;
   1406 }
   1407 
   1408 bool
   1409 ProcessMonitor::MonitorCallback(void *callback_baton,
   1410                                 lldb::pid_t pid,
   1411                                 bool exited,
   1412                                 int signal,
   1413                                 int status)
   1414 {
   1415     ProcessMessage message;
   1416     ProcessMonitor *monitor = static_cast<ProcessMonitor*>(callback_baton);
   1417     ProcessLinux *process = monitor->m_process;
   1418     assert(process);
   1419     bool stop_monitoring;
   1420     siginfo_t info;
   1421     int ptrace_err;
   1422 
   1423     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   1424 
   1425     if (exited)
   1426     {
   1427         if (log)
   1428             log->Printf ("ProcessMonitor::%s() got exit signal, tid = %"  PRIu64, __FUNCTION__, pid);
   1429         message = ProcessMessage::Exit(pid, status);
   1430         process->SendMessage(message);
   1431         return pid == process->GetID();
   1432     }
   1433 
   1434     if (!monitor->GetSignalInfo(pid, &info, ptrace_err)) {
   1435         if (ptrace_err == EINVAL) {
   1436             if (log)
   1437                 log->Printf ("ProcessMonitor::%s() resuming from group-stop", __FUNCTION__);
   1438             // inferior process is in 'group-stop', so deliver SIGSTOP signal
   1439             if (!monitor->Resume(pid, SIGSTOP)) {
   1440               assert(0 && "SIGSTOP delivery failed while in 'group-stop' state");
   1441             }
   1442             stop_monitoring = false;
   1443         } else {
   1444             // ptrace(GETSIGINFO) failed (but not due to group-stop). Most likely,
   1445             // this means the child pid is gone (or not being debugged) therefore
   1446             // stop the monitor thread if this is the main pid.
   1447             if (log)
   1448                 log->Printf ("ProcessMonitor::%s() GetSignalInfo failed: %s, tid = %" PRIu64 ", signal = %d, status = %d",
   1449                               __FUNCTION__, strerror(ptrace_err), pid, signal, status);
   1450             stop_monitoring = pid == monitor->m_process->GetID();
   1451         }
   1452     }
   1453     else {
   1454         switch (info.si_signo)
   1455         {
   1456         case SIGTRAP:
   1457             message = MonitorSIGTRAP(monitor, &info, pid);
   1458             break;
   1459 
   1460         default:
   1461             message = MonitorSignal(monitor, &info, pid);
   1462             break;
   1463         }
   1464 
   1465         process->SendMessage(message);
   1466         stop_monitoring = false;
   1467     }
   1468 
   1469     return stop_monitoring;
   1470 }
   1471 
   1472 ProcessMessage
   1473 ProcessMonitor::MonitorSIGTRAP(ProcessMonitor *monitor,
   1474                                const siginfo_t *info, lldb::pid_t pid)
   1475 {
   1476     ProcessMessage message;
   1477 
   1478     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   1479 
   1480     assert(monitor);
   1481     assert(info && info->si_signo == SIGTRAP && "Unexpected child signal!");
   1482 
   1483     switch (info->si_code)
   1484     {
   1485     default:
   1486         assert(false && "Unexpected SIGTRAP code!");
   1487         break;
   1488 
   1489     // TODO: these two cases are required if we want to support tracing
   1490     // of the inferiors' children
   1491     // case (SIGTRAP | (PTRACE_EVENT_FORK << 8)):
   1492     // case (SIGTRAP | (PTRACE_EVENT_VFORK << 8)):
   1493 
   1494     case (SIGTRAP | (PTRACE_EVENT_CLONE << 8)):
   1495     {
   1496         if (log)
   1497             log->Printf ("ProcessMonitor::%s() received thread creation event, code = %d", __FUNCTION__, info->si_code ^ SIGTRAP);
   1498 
   1499         unsigned long tid = 0;
   1500         if (!monitor->GetEventMessage(pid, &tid))
   1501             tid = -1;
   1502         message = ProcessMessage::NewThread(pid, tid);
   1503         break;
   1504     }
   1505 
   1506     case (SIGTRAP | (PTRACE_EVENT_EXEC << 8)):
   1507         // Don't follow the child by default and resume
   1508         monitor->Resume(pid, SIGCONT);
   1509         break;
   1510 
   1511     case (SIGTRAP | (PTRACE_EVENT_EXIT << 8)):
   1512     {
   1513         // The inferior process or one of its threads is about to exit.
   1514         // Maintain the process or thread in a state of "limbo" until we are
   1515         // explicitly commanded to detach, destroy, resume, etc.
   1516         unsigned long data = 0;
   1517         if (!monitor->GetEventMessage(pid, &data))
   1518             data = -1;
   1519         if (log)
   1520             log->Printf ("ProcessMonitor::%s() received limbo event, data = %lx, pid = %" PRIu64, __FUNCTION__, data, pid);
   1521         message = ProcessMessage::Limbo(pid, (data >> 8));
   1522         break;
   1523     }
   1524 
   1525     case 0:
   1526     case TRAP_TRACE:
   1527         if (log)
   1528             log->Printf ("ProcessMonitor::%s() received trace event, pid = %" PRIu64, __FUNCTION__, pid);
   1529         message = ProcessMessage::Trace(pid);
   1530         break;
   1531 
   1532     case SI_KERNEL:
   1533     case TRAP_BRKPT:
   1534         if (log)
   1535             log->Printf ("ProcessMonitor::%s() received breakpoint event, pid = %" PRIu64, __FUNCTION__, pid);
   1536         message = ProcessMessage::Break(pid);
   1537         break;
   1538 
   1539     case TRAP_HWBKPT:
   1540         if (log)
   1541             log->Printf ("ProcessMonitor::%s() received watchpoint event, pid = %" PRIu64, __FUNCTION__, pid);
   1542         message = ProcessMessage::Watch(pid, (lldb::addr_t)info->si_addr);
   1543         break;
   1544 
   1545     case SIGTRAP:
   1546     case (SIGTRAP | 0x80):
   1547         if (log)
   1548             log->Printf ("ProcessMonitor::%s() received system call stop event, pid = %" PRIu64, __FUNCTION__, pid);
   1549         // Ignore these signals until we know more about them
   1550         monitor->Resume(pid, eResumeSignalNone);
   1551     }
   1552 
   1553     return message;
   1554 }
   1555 
   1556 ProcessMessage
   1557 ProcessMonitor::MonitorSignal(ProcessMonitor *monitor,
   1558                               const siginfo_t *info, lldb::pid_t pid)
   1559 {
   1560     ProcessMessage message;
   1561     int signo = info->si_signo;
   1562 
   1563     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   1564 
   1565     // POSIX says that process behaviour is undefined after it ignores a SIGFPE,
   1566     // SIGILL, SIGSEGV, or SIGBUS *unless* that signal was generated by a
   1567     // kill(2) or raise(3).  Similarly for tgkill(2) on Linux.
   1568     //
   1569     // IOW, user generated signals never generate what we consider to be a
   1570     // "crash".
   1571     //
   1572     // Similarly, ACK signals generated by this monitor.
   1573     if (info->si_code == SI_TKILL || info->si_code == SI_USER)
   1574     {
   1575         if (log)
   1576             log->Printf ("ProcessMonitor::%s() received signal %s with code %s, pid = %d",
   1577                             __FUNCTION__,
   1578                             monitor->m_process->GetUnixSignals().GetSignalAsCString (signo),
   1579                             (info->si_code == SI_TKILL ? "SI_TKILL" : "SI_USER"),
   1580                             info->si_pid);
   1581 
   1582         if (info->si_pid == getpid())
   1583             return ProcessMessage::SignalDelivered(pid, signo);
   1584         else
   1585             return ProcessMessage::Signal(pid, signo);
   1586     }
   1587 
   1588     if (log)
   1589         log->Printf ("ProcessMonitor::%s() received signal %s", __FUNCTION__, monitor->m_process->GetUnixSignals().GetSignalAsCString (signo));
   1590 
   1591     if (signo == SIGSEGV) {
   1592         lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
   1593         ProcessMessage::CrashReason reason = GetCrashReasonForSIGSEGV(info);
   1594         return ProcessMessage::Crash(pid, reason, signo, fault_addr);
   1595     }
   1596 
   1597     if (signo == SIGILL) {
   1598         lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
   1599         ProcessMessage::CrashReason reason = GetCrashReasonForSIGILL(info);
   1600         return ProcessMessage::Crash(pid, reason, signo, fault_addr);
   1601     }
   1602 
   1603     if (signo == SIGFPE) {
   1604         lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
   1605         ProcessMessage::CrashReason reason = GetCrashReasonForSIGFPE(info);
   1606         return ProcessMessage::Crash(pid, reason, signo, fault_addr);
   1607     }
   1608 
   1609     if (signo == SIGBUS) {
   1610         lldb::addr_t fault_addr = reinterpret_cast<lldb::addr_t>(info->si_addr);
   1611         ProcessMessage::CrashReason reason = GetCrashReasonForSIGBUS(info);
   1612         return ProcessMessage::Crash(pid, reason, signo, fault_addr);
   1613     }
   1614 
   1615     // Everything else is "normal" and does not require any special action on
   1616     // our part.
   1617     return ProcessMessage::Signal(pid, signo);
   1618 }
   1619 
   1620 bool
   1621 ProcessMonitor::StopThread(lldb::tid_t tid)
   1622 {
   1623     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   1624 
   1625     // FIXME: Try to use tgkill or tkill
   1626     int ret = tgkill(m_pid, tid, SIGSTOP);
   1627     if (log)
   1628         log->Printf ("ProcessMonitor::%s(bp) stopping thread, tid = %" PRIu64 ", ret = %d", __FUNCTION__, tid, ret);
   1629 
   1630     // This can happen if a thread exited while we were trying to stop it.  That's OK.
   1631     // We'll get the signal for that later.
   1632     if (ret < 0)
   1633         return false;
   1634 
   1635     // Wait for the thread to stop
   1636     while (true)
   1637     {
   1638         int status = -1;
   1639         if (log)
   1640             log->Printf ("ProcessMonitor::%s(bp) waitpid...", __FUNCTION__);
   1641         lldb::pid_t wait_pid = ::waitpid (-1*m_pid, &status, __WALL);
   1642         if (log)
   1643             log->Printf ("ProcessMonitor::%s(bp) waitpid, pid = %" PRIu64 ", status = %d", __FUNCTION__, wait_pid, status);
   1644 
   1645         if (wait_pid == -1)
   1646         {
   1647             // If we got interrupted by a signal (in our process, not the
   1648             // inferior) try again.
   1649             if (errno == EINTR)
   1650                 continue;
   1651             else
   1652                 return false; // This is bad, but there's nothing we can do.
   1653         }
   1654 
   1655         // If this is a thread exit, we won't get any more information.
   1656         if (WIFEXITED(status))
   1657         {
   1658             m_process->SendMessage(ProcessMessage::Exit(wait_pid, WEXITSTATUS(status)));
   1659             if (wait_pid == tid)
   1660                 return true;
   1661             continue;
   1662         }
   1663 
   1664         siginfo_t info;
   1665         int ptrace_err;
   1666         if (!GetSignalInfo(wait_pid, &info, ptrace_err))
   1667         {
   1668             if (log)
   1669             {
   1670                 log->Printf ("ProcessMonitor::%s() GetSignalInfo failed.", __FUNCTION__);
   1671 
   1672                 // This would be a particularly interesting case
   1673                 if (ptrace_err == EINVAL)
   1674                     log->Printf ("ProcessMonitor::%s() in group-stop", __FUNCTION__);
   1675             }
   1676             return false;
   1677         }
   1678 
   1679         // Handle events from other threads
   1680         if (log)
   1681             log->Printf ("ProcessMonitor::%s(bp) handling event, tid == %" PRIu64, __FUNCTION__, wait_pid);
   1682 
   1683         ProcessMessage message;
   1684         if (info.si_signo == SIGTRAP)
   1685             message = MonitorSIGTRAP(this, &info, wait_pid);
   1686         else
   1687             message = MonitorSignal(this, &info, wait_pid);
   1688 
   1689         POSIXThread *thread = static_cast<POSIXThread*>(m_process->GetThreadList().FindThreadByID(wait_pid).get());
   1690 
   1691         // When a new thread is created, we may get a SIGSTOP for the new thread
   1692         // just before we get the SIGTRAP that we use to add the thread to our
   1693         // process thread list.  We don't need to worry about that signal here.
   1694         assert(thread || message.GetKind() == ProcessMessage::eSignalMessage);
   1695 
   1696         if (!thread)
   1697         {
   1698             m_process->SendMessage(message);
   1699             continue;
   1700         }
   1701 
   1702         switch (message.GetKind())
   1703         {
   1704             case ProcessMessage::eInvalidMessage:
   1705                 break;
   1706 
   1707             // These need special handling because we don't want to send a
   1708             // resume even if we already sent a SIGSTOP to this thread. In
   1709             // this case the resume will cause the thread to disappear.  It is
   1710             // unlikely that we'll ever get eExitMessage here, but the same
   1711             // reasoning applies.
   1712             case ProcessMessage::eLimboMessage:
   1713             case ProcessMessage::eExitMessage:
   1714                 if (log)
   1715                     log->Printf ("ProcessMonitor::%s(bp) handling message", __FUNCTION__);
   1716                 // SendMessage will set the thread state as needed.
   1717                 m_process->SendMessage(message);
   1718                 // If this is the thread we're waiting for, stop waiting. Even
   1719                 // though this wasn't the signal we expected, it's the last
   1720                 // signal we'll see while this thread is alive.
   1721                 if (wait_pid == tid)
   1722                     return true;
   1723                 break;
   1724 
   1725             case ProcessMessage::eSignalMessage:
   1726                 if (log)
   1727                     log->Printf ("ProcessMonitor::%s(bp) handling message", __FUNCTION__);
   1728                 if (WSTOPSIG(status) == SIGSTOP)
   1729                 {
   1730                     m_process->AddThreadForInitialStopIfNeeded(tid);
   1731                     thread->SetState(lldb::eStateStopped);
   1732                 }
   1733                 else
   1734                 {
   1735                     m_process->SendMessage(message);
   1736                     // This isn't the stop we were expecting, but the thread is
   1737                     // stopped. SendMessage will handle processing of this event,
   1738                     // but we need to resume here to get the stop we are waiting
   1739                     // for (otherwise the thread will stop again immediately when
   1740                     // we try to resume).
   1741                     if (wait_pid == tid)
   1742                         Resume(wait_pid, eResumeSignalNone);
   1743                 }
   1744                 break;
   1745 
   1746             case ProcessMessage::eSignalDeliveredMessage:
   1747                 // This is the stop we're expecting.
   1748                 if (wait_pid == tid && WIFSTOPPED(status) && WSTOPSIG(status) == SIGSTOP && info.si_code == SI_TKILL)
   1749                 {
   1750                     if (log)
   1751                         log->Printf ("ProcessMonitor::%s(bp) received signal, done waiting", __FUNCTION__);
   1752                     thread->SetState(lldb::eStateStopped);
   1753                     return true;
   1754                 }
   1755                 // else fall-through
   1756             case ProcessMessage::eBreakpointMessage:
   1757             case ProcessMessage::eTraceMessage:
   1758             case ProcessMessage::eWatchpointMessage:
   1759             case ProcessMessage::eCrashMessage:
   1760             case ProcessMessage::eNewThreadMessage:
   1761                 if (log)
   1762                     log->Printf ("ProcessMonitor::%s(bp) handling message", __FUNCTION__);
   1763                 // SendMessage will set the thread state as needed.
   1764                 m_process->SendMessage(message);
   1765                 // This isn't the stop we were expecting, but the thread is
   1766                 // stopped. SendMessage will handle processing of this event,
   1767                 // but we need to resume here to get the stop we are waiting
   1768                 // for (otherwise the thread will stop again immediately when
   1769                 // we try to resume).
   1770                 if (wait_pid == tid)
   1771                     Resume(wait_pid, eResumeSignalNone);
   1772                 break;
   1773         }
   1774     }
   1775     return false;
   1776 }
   1777 
   1778 ProcessMessage::CrashReason
   1779 ProcessMonitor::GetCrashReasonForSIGSEGV(const siginfo_t *info)
   1780 {
   1781     ProcessMessage::CrashReason reason;
   1782     assert(info->si_signo == SIGSEGV);
   1783 
   1784     reason = ProcessMessage::eInvalidCrashReason;
   1785 
   1786     switch (info->si_code)
   1787     {
   1788     default:
   1789         assert(false && "unexpected si_code for SIGSEGV");
   1790         break;
   1791     case SEGV_MAPERR:
   1792         reason = ProcessMessage::eInvalidAddress;
   1793         break;
   1794     case SEGV_ACCERR:
   1795         reason = ProcessMessage::ePrivilegedAddress;
   1796         break;
   1797     }
   1798 
   1799     return reason;
   1800 }
   1801 
   1802 ProcessMessage::CrashReason
   1803 ProcessMonitor::GetCrashReasonForSIGILL(const siginfo_t *info)
   1804 {
   1805     ProcessMessage::CrashReason reason;
   1806     assert(info->si_signo == SIGILL);
   1807 
   1808     reason = ProcessMessage::eInvalidCrashReason;
   1809 
   1810     switch (info->si_code)
   1811     {
   1812     default:
   1813         assert(false && "unexpected si_code for SIGILL");
   1814         break;
   1815     case ILL_ILLOPC:
   1816         reason = ProcessMessage::eIllegalOpcode;
   1817         break;
   1818     case ILL_ILLOPN:
   1819         reason = ProcessMessage::eIllegalOperand;
   1820         break;
   1821     case ILL_ILLADR:
   1822         reason = ProcessMessage::eIllegalAddressingMode;
   1823         break;
   1824     case ILL_ILLTRP:
   1825         reason = ProcessMessage::eIllegalTrap;
   1826         break;
   1827     case ILL_PRVOPC:
   1828         reason = ProcessMessage::ePrivilegedOpcode;
   1829         break;
   1830     case ILL_PRVREG:
   1831         reason = ProcessMessage::ePrivilegedRegister;
   1832         break;
   1833     case ILL_COPROC:
   1834         reason = ProcessMessage::eCoprocessorError;
   1835         break;
   1836     case ILL_BADSTK:
   1837         reason = ProcessMessage::eInternalStackError;
   1838         break;
   1839     }
   1840 
   1841     return reason;
   1842 }
   1843 
   1844 ProcessMessage::CrashReason
   1845 ProcessMonitor::GetCrashReasonForSIGFPE(const siginfo_t *info)
   1846 {
   1847     ProcessMessage::CrashReason reason;
   1848     assert(info->si_signo == SIGFPE);
   1849 
   1850     reason = ProcessMessage::eInvalidCrashReason;
   1851 
   1852     switch (info->si_code)
   1853     {
   1854     default:
   1855         assert(false && "unexpected si_code for SIGFPE");
   1856         break;
   1857     case FPE_INTDIV:
   1858         reason = ProcessMessage::eIntegerDivideByZero;
   1859         break;
   1860     case FPE_INTOVF:
   1861         reason = ProcessMessage::eIntegerOverflow;
   1862         break;
   1863     case FPE_FLTDIV:
   1864         reason = ProcessMessage::eFloatDivideByZero;
   1865         break;
   1866     case FPE_FLTOVF:
   1867         reason = ProcessMessage::eFloatOverflow;
   1868         break;
   1869     case FPE_FLTUND:
   1870         reason = ProcessMessage::eFloatUnderflow;
   1871         break;
   1872     case FPE_FLTRES:
   1873         reason = ProcessMessage::eFloatInexactResult;
   1874         break;
   1875     case FPE_FLTINV:
   1876         reason = ProcessMessage::eFloatInvalidOperation;
   1877         break;
   1878     case FPE_FLTSUB:
   1879         reason = ProcessMessage::eFloatSubscriptRange;
   1880         break;
   1881     }
   1882 
   1883     return reason;
   1884 }
   1885 
   1886 ProcessMessage::CrashReason
   1887 ProcessMonitor::GetCrashReasonForSIGBUS(const siginfo_t *info)
   1888 {
   1889     ProcessMessage::CrashReason reason;
   1890     assert(info->si_signo == SIGBUS);
   1891 
   1892     reason = ProcessMessage::eInvalidCrashReason;
   1893 
   1894     switch (info->si_code)
   1895     {
   1896     default:
   1897         assert(false && "unexpected si_code for SIGBUS");
   1898         break;
   1899     case BUS_ADRALN:
   1900         reason = ProcessMessage::eIllegalAlignment;
   1901         break;
   1902     case BUS_ADRERR:
   1903         reason = ProcessMessage::eIllegalAddress;
   1904         break;
   1905     case BUS_OBJERR:
   1906         reason = ProcessMessage::eHardwareError;
   1907         break;
   1908     }
   1909 
   1910     return reason;
   1911 }
   1912 
   1913 void
   1914 ProcessMonitor::ServeOperation(OperationArgs *args)
   1915 {
   1916     int status;
   1917     pollfd fdset;
   1918 
   1919     ProcessMonitor *monitor = args->m_monitor;
   1920 
   1921     fdset.fd = monitor->m_server_fd;
   1922     fdset.events = POLLIN | POLLPRI;
   1923     fdset.revents = 0;
   1924 
   1925     // We are finised with the arguments and are ready to go.  Sync with the
   1926     // parent thread and start serving operations on the inferior.
   1927     sem_post(&args->m_semaphore);
   1928 
   1929     for (;;)
   1930     {
   1931         if ((status = poll(&fdset, 1, -1)) < 0)
   1932         {
   1933             switch (errno)
   1934             {
   1935             default:
   1936                 assert(false && "Unexpected poll() failure!");
   1937                 continue;
   1938 
   1939             case EINTR: continue; // Just poll again.
   1940             case EBADF: return;   // Connection terminated.
   1941             }
   1942         }
   1943 
   1944         assert(status == 1 && "Too many descriptors!");
   1945 
   1946         if (fdset.revents & POLLIN)
   1947         {
   1948             Operation *op = NULL;
   1949 
   1950         READ_AGAIN:
   1951             if ((status = read(fdset.fd, &op, sizeof(op))) < 0)
   1952             {
   1953                 // There is only one acceptable failure.
   1954                 assert(errno == EINTR);
   1955                 goto READ_AGAIN;
   1956             }
   1957             if (status == 0)
   1958                 continue; // Poll again. The connection probably terminated.
   1959             assert(status == sizeof(op));
   1960             op->Execute(monitor);
   1961             write(fdset.fd, &op, sizeof(op));
   1962         }
   1963     }
   1964 }
   1965 
   1966 void
   1967 ProcessMonitor::DoOperation(Operation *op)
   1968 {
   1969     int status;
   1970     Operation *ack = NULL;
   1971     Mutex::Locker lock(m_server_mutex);
   1972 
   1973     // FIXME: Do proper error checking here.
   1974     write(m_client_fd, &op, sizeof(op));
   1975 
   1976 READ_AGAIN:
   1977     if ((status = read(m_client_fd, &ack, sizeof(ack))) < 0)
   1978     {
   1979         // If interrupted by a signal handler try again.  Otherwise the monitor
   1980         // thread probably died and we have a stale file descriptor -- abort the
   1981         // operation.
   1982         if (errno == EINTR)
   1983             goto READ_AGAIN;
   1984         return;
   1985     }
   1986 
   1987     assert(status == sizeof(ack));
   1988     assert(ack == op && "Invalid monitor thread response!");
   1989 }
   1990 
   1991 size_t
   1992 ProcessMonitor::ReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
   1993                            Error &error)
   1994 {
   1995     size_t result;
   1996     ReadOperation op(vm_addr, buf, size, error, result);
   1997     DoOperation(&op);
   1998     return result;
   1999 }
   2000 
   2001 size_t
   2002 ProcessMonitor::WriteMemory(lldb::addr_t vm_addr, const void *buf, size_t size,
   2003                             lldb_private::Error &error)
   2004 {
   2005     size_t result;
   2006     WriteOperation op(vm_addr, buf, size, error, result);
   2007     DoOperation(&op);
   2008     return result;
   2009 }
   2010 
   2011 bool
   2012 ProcessMonitor::ReadRegisterValue(lldb::tid_t tid, unsigned offset, const char* reg_name,
   2013                                   unsigned size, RegisterValue &value)
   2014 {
   2015     bool result;
   2016     ReadRegOperation op(tid, offset, reg_name, value, result);
   2017     DoOperation(&op);
   2018     return result;
   2019 }
   2020 
   2021 bool
   2022 ProcessMonitor::WriteRegisterValue(lldb::tid_t tid, unsigned offset,
   2023                                    const char* reg_name, const RegisterValue &value)
   2024 {
   2025     bool result;
   2026     WriteRegOperation op(tid, offset, reg_name, value, result);
   2027     DoOperation(&op);
   2028     return result;
   2029 }
   2030 
   2031 bool
   2032 ProcessMonitor::ReadGPR(lldb::tid_t tid, void *buf, size_t buf_size)
   2033 {
   2034     bool result;
   2035     ReadGPROperation op(tid, buf, buf_size, result);
   2036     DoOperation(&op);
   2037     return result;
   2038 }
   2039 
   2040 bool
   2041 ProcessMonitor::ReadFPR(lldb::tid_t tid, void *buf, size_t buf_size)
   2042 {
   2043     bool result;
   2044     ReadFPROperation op(tid, buf, buf_size, result);
   2045     DoOperation(&op);
   2046     return result;
   2047 }
   2048 
   2049 bool
   2050 ProcessMonitor::ReadRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset)
   2051 {
   2052     bool result;
   2053     ReadRegisterSetOperation op(tid, buf, buf_size, regset, result);
   2054     DoOperation(&op);
   2055     return result;
   2056 }
   2057 
   2058 bool
   2059 ProcessMonitor::WriteGPR(lldb::tid_t tid, void *buf, size_t buf_size)
   2060 {
   2061     bool result;
   2062     WriteGPROperation op(tid, buf, buf_size, result);
   2063     DoOperation(&op);
   2064     return result;
   2065 }
   2066 
   2067 bool
   2068 ProcessMonitor::WriteFPR(lldb::tid_t tid, void *buf, size_t buf_size)
   2069 {
   2070     bool result;
   2071     WriteFPROperation op(tid, buf, buf_size, result);
   2072     DoOperation(&op);
   2073     return result;
   2074 }
   2075 
   2076 bool
   2077 ProcessMonitor::WriteRegisterSet(lldb::tid_t tid, void *buf, size_t buf_size, unsigned int regset)
   2078 {
   2079     bool result;
   2080     WriteRegisterSetOperation op(tid, buf, buf_size, regset, result);
   2081     DoOperation(&op);
   2082     return result;
   2083 }
   2084 
   2085 bool
   2086 ProcessMonitor::Resume(lldb::tid_t tid, uint32_t signo)
   2087 {
   2088     bool result;
   2089     Log *log (ProcessPOSIXLog::GetLogIfAllCategoriesSet (POSIX_LOG_PROCESS));
   2090 
   2091     if (log)
   2092         log->Printf ("ProcessMonitor::%s() resuming thread = %"  PRIu64 " with signal %s", __FUNCTION__, tid,
   2093                                  m_process->GetUnixSignals().GetSignalAsCString (signo));
   2094     ResumeOperation op(tid, signo, result);
   2095     DoOperation(&op);
   2096     if (log)
   2097         log->Printf ("ProcessMonitor::%s() resuming result = %s", __FUNCTION__, result ? "true" : "false");
   2098     return result;
   2099 }
   2100 
   2101 bool
   2102 ProcessMonitor::SingleStep(lldb::tid_t tid, uint32_t signo)
   2103 {
   2104     bool result;
   2105     SingleStepOperation op(tid, signo, result);
   2106     DoOperation(&op);
   2107     return result;
   2108 }
   2109 
   2110 bool
   2111 ProcessMonitor::BringProcessIntoLimbo()
   2112 {
   2113     bool result;
   2114     KillOperation op(result);
   2115     DoOperation(&op);
   2116     return result;
   2117 }
   2118 
   2119 bool
   2120 ProcessMonitor::GetSignalInfo(lldb::tid_t tid, void *siginfo, int &ptrace_err)
   2121 {
   2122     bool result;
   2123     SiginfoOperation op(tid, siginfo, result, ptrace_err);
   2124     DoOperation(&op);
   2125     return result;
   2126 }
   2127 
   2128 bool
   2129 ProcessMonitor::GetEventMessage(lldb::tid_t tid, unsigned long *message)
   2130 {
   2131     bool result;
   2132     EventMessageOperation op(tid, message, result);
   2133     DoOperation(&op);
   2134     return result;
   2135 }
   2136 
   2137 lldb_private::Error
   2138 ProcessMonitor::Detach(lldb::tid_t tid)
   2139 {
   2140     lldb_private::Error error;
   2141     if (tid != LLDB_INVALID_THREAD_ID)
   2142     {
   2143         DetachOperation op(tid, error);
   2144         DoOperation(&op);
   2145     }
   2146     return error;
   2147 }
   2148 
   2149 bool
   2150 ProcessMonitor::DupDescriptor(const char *path, int fd, int flags)
   2151 {
   2152     int target_fd = open(path, flags, 0666);
   2153 
   2154     if (target_fd == -1)
   2155         return false;
   2156 
   2157     return (dup2(target_fd, fd) == -1) ? false : true;
   2158 }
   2159 
   2160 void
   2161 ProcessMonitor::StopMonitoringChildProcess()
   2162 {
   2163     lldb::thread_result_t thread_result;
   2164 
   2165     if (IS_VALID_LLDB_HOST_THREAD(m_monitor_thread))
   2166     {
   2167         Host::ThreadCancel(m_monitor_thread, NULL);
   2168         Host::ThreadJoin(m_monitor_thread, &thread_result, NULL);
   2169         m_monitor_thread = LLDB_INVALID_HOST_THREAD;
   2170     }
   2171 }
   2172 
   2173 void
   2174 ProcessMonitor::StopMonitor()
   2175 {
   2176     StopMonitoringChildProcess();
   2177     StopOpThread();
   2178     CloseFD(m_terminal_fd);
   2179     CloseFD(m_client_fd);
   2180     CloseFD(m_server_fd);
   2181 }
   2182 
   2183 void
   2184 ProcessMonitor::StopOpThread()
   2185 {
   2186     lldb::thread_result_t result;
   2187 
   2188     if (!IS_VALID_LLDB_HOST_THREAD(m_operation_thread))
   2189         return;
   2190 
   2191     Host::ThreadCancel(m_operation_thread, NULL);
   2192     Host::ThreadJoin(m_operation_thread, &result, NULL);
   2193     m_operation_thread = LLDB_INVALID_HOST_THREAD;
   2194 }
   2195 
   2196 void
   2197 ProcessMonitor::CloseFD(int &fd)
   2198 {
   2199     if (fd != -1)
   2200     {
   2201         close(fd);
   2202         fd = -1;
   2203     }
   2204 }
   2205