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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/process/launch.h"
      6 
      7 #include <dirent.h>
      8 #include <errno.h>
      9 #include <fcntl.h>
     10 #include <signal.h>
     11 #include <stdlib.h>
     12 #include <sys/resource.h>
     13 #include <sys/time.h>
     14 #include <sys/types.h>
     15 #include <sys/wait.h>
     16 #include <unistd.h>
     17 
     18 #include <iterator>
     19 #include <limits>
     20 #include <set>
     21 
     22 #include "base/allocator/type_profiler_control.h"
     23 #include "base/command_line.h"
     24 #include "base/compiler_specific.h"
     25 #include "base/debug/debugger.h"
     26 #include "base/debug/stack_trace.h"
     27 #include "base/file_util.h"
     28 #include "base/files/dir_reader_posix.h"
     29 #include "base/logging.h"
     30 #include "base/memory/scoped_ptr.h"
     31 #include "base/posix/eintr_wrapper.h"
     32 #include "base/process/kill.h"
     33 #include "base/process/process_metrics.h"
     34 #include "base/strings/stringprintf.h"
     35 #include "base/synchronization/waitable_event.h"
     36 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
     37 #include "base/threading/platform_thread.h"
     38 #include "base/threading/thread_restrictions.h"
     39 
     40 #if defined(OS_CHROMEOS)
     41 #include <sys/ioctl.h>
     42 #endif
     43 
     44 #if defined(OS_FREEBSD)
     45 #include <sys/event.h>
     46 #include <sys/ucontext.h>
     47 #endif
     48 
     49 #if defined(OS_MACOSX)
     50 #include <crt_externs.h>
     51 #include <sys/event.h>
     52 #else
     53 extern char** environ;
     54 #endif
     55 
     56 namespace base {
     57 
     58 namespace {
     59 
     60 // Get the process's "environment" (i.e. the thing that setenv/getenv
     61 // work with).
     62 char** GetEnvironment() {
     63 #if defined(OS_MACOSX)
     64   return *_NSGetEnviron();
     65 #else
     66   return environ;
     67 #endif
     68 }
     69 
     70 // Set the process's "environment" (i.e. the thing that setenv/getenv
     71 // work with).
     72 void SetEnvironment(char** env) {
     73 #if defined(OS_MACOSX)
     74   *_NSGetEnviron() = env;
     75 #else
     76   environ = env;
     77 #endif
     78 }
     79 
     80 // Set the calling thread's signal mask to new_sigmask and return
     81 // the previous signal mask.
     82 sigset_t SetSignalMask(const sigset_t& new_sigmask) {
     83   sigset_t old_sigmask;
     84 #if defined(OS_ANDROID)
     85   // POSIX says pthread_sigmask() must be used in multi-threaded processes,
     86   // but Android's pthread_sigmask() was broken until 4.1:
     87   // https://code.google.com/p/android/issues/detail?id=15337
     88   // http://stackoverflow.com/questions/13777109/pthread-sigmask-on-android-not-working
     89   RAW_CHECK(sigprocmask(SIG_SETMASK, &new_sigmask, &old_sigmask) == 0);
     90 #else
     91   RAW_CHECK(pthread_sigmask(SIG_SETMASK, &new_sigmask, &old_sigmask) == 0);
     92 #endif
     93   return old_sigmask;
     94 }
     95 
     96 #if !defined(OS_LINUX) || \
     97     (!defined(__i386__) && !defined(__x86_64__) && !defined(__arm__))
     98 void ResetChildSignalHandlersToDefaults() {
     99   // The previous signal handlers are likely to be meaningless in the child's
    100   // context so we reset them to the defaults for now. http://crbug.com/44953
    101   // These signal handlers are set up at least in browser_main_posix.cc:
    102   // BrowserMainPartsPosix::PreEarlyInitialization and stack_trace_posix.cc:
    103   // EnableInProcessStackDumping.
    104   signal(SIGHUP, SIG_DFL);
    105   signal(SIGINT, SIG_DFL);
    106   signal(SIGILL, SIG_DFL);
    107   signal(SIGABRT, SIG_DFL);
    108   signal(SIGFPE, SIG_DFL);
    109   signal(SIGBUS, SIG_DFL);
    110   signal(SIGSEGV, SIG_DFL);
    111   signal(SIGSYS, SIG_DFL);
    112   signal(SIGTERM, SIG_DFL);
    113 }
    114 
    115 #else
    116 
    117 // TODO(jln): remove the Linux special case once kernels are fixed.
    118 
    119 // Internally the kernel makes sigset_t an array of long large enough to have
    120 // one bit per signal.
    121 typedef uint64_t kernel_sigset_t;
    122 
    123 // This is what struct sigaction looks like to the kernel at least on X86 and
    124 // ARM. MIPS, for instance, is very different.
    125 struct kernel_sigaction {
    126   void* k_sa_handler;  // For this usage it only needs to be a generic pointer.
    127   unsigned long k_sa_flags;
    128   void* k_sa_restorer;  // For this usage it only needs to be a generic pointer.
    129   kernel_sigset_t k_sa_mask;
    130 };
    131 
    132 // glibc's sigaction() will prevent access to sa_restorer, so we need to roll
    133 // our own.
    134 int sys_rt_sigaction(int sig, const struct kernel_sigaction* act,
    135                      struct kernel_sigaction* oact) {
    136   return syscall(SYS_rt_sigaction, sig, act, oact, sizeof(kernel_sigset_t));
    137 }
    138 
    139 // This function is intended to be used in between fork() and execve() and will
    140 // reset all signal handlers to the default.
    141 // The motivation for going through all of them is that sa_restorer can leak
    142 // from parents and help defeat ASLR on buggy kernels.  We reset it to NULL.
    143 // See crbug.com/177956.
    144 void ResetChildSignalHandlersToDefaults(void) {
    145   for (int signum = 1; ; ++signum) {
    146     struct kernel_sigaction act = {0};
    147     int sigaction_get_ret = sys_rt_sigaction(signum, NULL, &act);
    148     if (sigaction_get_ret && errno == EINVAL) {
    149 #if !defined(NDEBUG)
    150       // Linux supports 32 real-time signals from 33 to 64.
    151       // If the number of signals in the Linux kernel changes, someone should
    152       // look at this code.
    153       const int kNumberOfSignals = 64;
    154       RAW_CHECK(signum == kNumberOfSignals + 1);
    155 #endif  // !defined(NDEBUG)
    156       break;
    157     }
    158     // All other failures are fatal.
    159     if (sigaction_get_ret) {
    160       RAW_LOG(FATAL, "sigaction (get) failed.");
    161     }
    162 
    163     // The kernel won't allow to re-set SIGKILL or SIGSTOP.
    164     if (signum != SIGSTOP && signum != SIGKILL) {
    165       act.k_sa_handler = reinterpret_cast<void*>(SIG_DFL);
    166       act.k_sa_restorer = NULL;
    167       if (sys_rt_sigaction(signum, &act, NULL)) {
    168         RAW_LOG(FATAL, "sigaction (set) failed.");
    169       }
    170     }
    171 #if !defined(NDEBUG)
    172     // Now ask the kernel again and check that no restorer will leak.
    173     if (sys_rt_sigaction(signum, NULL, &act) || act.k_sa_restorer) {
    174       RAW_LOG(FATAL, "Cound not fix sa_restorer.");
    175     }
    176 #endif  // !defined(NDEBUG)
    177   }
    178 }
    179 #endif  // !defined(OS_LINUX) ||
    180         // (!defined(__i386__) && !defined(__x86_64__) && !defined(__arm__))
    181 
    182 }  // anonymous namespace
    183 
    184 // A class to handle auto-closing of DIR*'s.
    185 class ScopedDIRClose {
    186  public:
    187   inline void operator()(DIR* x) const {
    188     if (x) {
    189       closedir(x);
    190     }
    191   }
    192 };
    193 typedef scoped_ptr_malloc<DIR, ScopedDIRClose> ScopedDIR;
    194 
    195 #if defined(OS_LINUX)
    196 static const char kFDDir[] = "/proc/self/fd";
    197 #elif defined(OS_MACOSX)
    198 static const char kFDDir[] = "/dev/fd";
    199 #elif defined(OS_SOLARIS)
    200 static const char kFDDir[] = "/dev/fd";
    201 #elif defined(OS_FREEBSD)
    202 static const char kFDDir[] = "/dev/fd";
    203 #elif defined(OS_OPENBSD)
    204 static const char kFDDir[] = "/dev/fd";
    205 #elif defined(OS_ANDROID)
    206 static const char kFDDir[] = "/proc/self/fd";
    207 #endif
    208 
    209 void CloseSuperfluousFds(const base::InjectiveMultimap& saved_mapping) {
    210   // DANGER: no calls to malloc are allowed from now on:
    211   // http://crbug.com/36678
    212 
    213   // Get the maximum number of FDs possible.
    214   size_t max_fds = GetMaxFds();
    215 
    216   DirReaderPosix fd_dir(kFDDir);
    217   if (!fd_dir.IsValid()) {
    218     // Fallback case: Try every possible fd.
    219     for (size_t i = 0; i < max_fds; ++i) {
    220       const int fd = static_cast<int>(i);
    221       if (fd == STDIN_FILENO || fd == STDOUT_FILENO || fd == STDERR_FILENO)
    222         continue;
    223       InjectiveMultimap::const_iterator j;
    224       for (j = saved_mapping.begin(); j != saved_mapping.end(); j++) {
    225         if (fd == j->dest)
    226           break;
    227       }
    228       if (j != saved_mapping.end())
    229         continue;
    230 
    231       // Since we're just trying to close anything we can find,
    232       // ignore any error return values of close().
    233       close(fd);
    234     }
    235     return;
    236   }
    237 
    238   const int dir_fd = fd_dir.fd();
    239 
    240   for ( ; fd_dir.Next(); ) {
    241     // Skip . and .. entries.
    242     if (fd_dir.name()[0] == '.')
    243       continue;
    244 
    245     char *endptr;
    246     errno = 0;
    247     const long int fd = strtol(fd_dir.name(), &endptr, 10);
    248     if (fd_dir.name()[0] == 0 || *endptr || fd < 0 || errno)
    249       continue;
    250     if (fd == STDIN_FILENO || fd == STDOUT_FILENO || fd == STDERR_FILENO)
    251       continue;
    252     InjectiveMultimap::const_iterator i;
    253     for (i = saved_mapping.begin(); i != saved_mapping.end(); i++) {
    254       if (fd == i->dest)
    255         break;
    256     }
    257     if (i != saved_mapping.end())
    258       continue;
    259     if (fd == dir_fd)
    260       continue;
    261 
    262     // When running under Valgrind, Valgrind opens several FDs for its
    263     // own use and will complain if we try to close them.  All of
    264     // these FDs are >= |max_fds|, so we can check against that here
    265     // before closing.  See https://bugs.kde.org/show_bug.cgi?id=191758
    266     if (fd < static_cast<int>(max_fds)) {
    267       int ret = IGNORE_EINTR(close(fd));
    268       DPCHECK(ret == 0);
    269     }
    270   }
    271 }
    272 
    273 bool LaunchProcess(const std::vector<std::string>& argv,
    274                    const LaunchOptions& options,
    275                    ProcessHandle* process_handle) {
    276   size_t fd_shuffle_size = 0;
    277   if (options.fds_to_remap) {
    278     fd_shuffle_size = options.fds_to_remap->size();
    279   }
    280 
    281   InjectiveMultimap fd_shuffle1;
    282   InjectiveMultimap fd_shuffle2;
    283   fd_shuffle1.reserve(fd_shuffle_size);
    284   fd_shuffle2.reserve(fd_shuffle_size);
    285 
    286   scoped_ptr<char*[]> argv_cstr(new char*[argv.size() + 1]);
    287   scoped_ptr<char*[]> new_environ;
    288   if (!options.environ.empty())
    289     new_environ = AlterEnvironment(GetEnvironment(), options.environ);
    290 
    291   sigset_t full_sigset;
    292   sigfillset(&full_sigset);
    293   const sigset_t orig_sigmask = SetSignalMask(full_sigset);
    294 
    295   pid_t pid;
    296 #if defined(OS_LINUX)
    297   if (options.clone_flags) {
    298     // Signal handling in this function assumes the creation of a new
    299     // process, so we check that a thread is not being created by mistake
    300     // and that signal handling follows the process-creation rules.
    301     RAW_CHECK(
    302         !(options.clone_flags & (CLONE_SIGHAND | CLONE_THREAD | CLONE_VM)));
    303     pid = syscall(__NR_clone, options.clone_flags, 0, 0, 0);
    304   } else
    305 #endif
    306   {
    307     pid = fork();
    308   }
    309 
    310   // Always restore the original signal mask in the parent.
    311   if (pid != 0) {
    312     SetSignalMask(orig_sigmask);
    313   }
    314 
    315   if (pid < 0) {
    316     DPLOG(ERROR) << "fork";
    317     return false;
    318   } else if (pid == 0) {
    319     // Child process
    320 
    321     // DANGER: fork() rule: in the child, if you don't end up doing exec*(),
    322     // you call _exit() instead of exit(). This is because _exit() does not
    323     // call any previously-registered (in the parent) exit handlers, which
    324     // might do things like block waiting for threads that don't even exist
    325     // in the child.
    326 
    327     // If a child process uses the readline library, the process block forever.
    328     // In BSD like OSes including OS X it is safe to assign /dev/null as stdin.
    329     // See http://crbug.com/56596.
    330     int null_fd = HANDLE_EINTR(open("/dev/null", O_RDONLY));
    331     if (null_fd < 0) {
    332       RAW_LOG(ERROR, "Failed to open /dev/null");
    333       _exit(127);
    334     }
    335 
    336     file_util::ScopedFD null_fd_closer(&null_fd);
    337     int new_fd = HANDLE_EINTR(dup2(null_fd, STDIN_FILENO));
    338     if (new_fd != STDIN_FILENO) {
    339       RAW_LOG(ERROR, "Failed to dup /dev/null for stdin");
    340       _exit(127);
    341     }
    342 
    343     if (options.new_process_group) {
    344       // Instead of inheriting the process group ID of the parent, the child
    345       // starts off a new process group with pgid equal to its process ID.
    346       if (setpgid(0, 0) < 0) {
    347         RAW_LOG(ERROR, "setpgid failed");
    348         _exit(127);
    349       }
    350     }
    351 
    352     // Stop type-profiler.
    353     // The profiler should be stopped between fork and exec since it inserts
    354     // locks at new/delete expressions.  See http://crbug.com/36678.
    355     base::type_profiler::Controller::Stop();
    356 
    357     if (options.maximize_rlimits) {
    358       // Some resource limits need to be maximal in this child.
    359       std::set<int>::const_iterator resource;
    360       for (resource = options.maximize_rlimits->begin();
    361            resource != options.maximize_rlimits->end();
    362            ++resource) {
    363         struct rlimit limit;
    364         if (getrlimit(*resource, &limit) < 0) {
    365           RAW_LOG(WARNING, "getrlimit failed");
    366         } else if (limit.rlim_cur < limit.rlim_max) {
    367           limit.rlim_cur = limit.rlim_max;
    368           if (setrlimit(*resource, &limit) < 0) {
    369             RAW_LOG(WARNING, "setrlimit failed");
    370           }
    371         }
    372       }
    373     }
    374 
    375 #if defined(OS_MACOSX)
    376     RestoreDefaultExceptionHandler();
    377 #endif  // defined(OS_MACOSX)
    378 
    379     ResetChildSignalHandlersToDefaults();
    380     SetSignalMask(orig_sigmask);
    381 
    382 #if 0
    383     // When debugging it can be helpful to check that we really aren't making
    384     // any hidden calls to malloc.
    385     void *malloc_thunk =
    386         reinterpret_cast<void*>(reinterpret_cast<intptr_t>(malloc) & ~4095);
    387     mprotect(malloc_thunk, 4096, PROT_READ | PROT_WRITE | PROT_EXEC);
    388     memset(reinterpret_cast<void*>(malloc), 0xff, 8);
    389 #endif  // 0
    390 
    391     // DANGER: no calls to malloc are allowed from now on:
    392     // http://crbug.com/36678
    393 
    394 #if defined(OS_CHROMEOS)
    395     if (options.ctrl_terminal_fd >= 0) {
    396       // Set process' controlling terminal.
    397       if (HANDLE_EINTR(setsid()) != -1) {
    398         if (HANDLE_EINTR(
    399                 ioctl(options.ctrl_terminal_fd, TIOCSCTTY, NULL)) == -1) {
    400           RAW_LOG(WARNING, "ioctl(TIOCSCTTY), ctrl terminal not set");
    401         }
    402       } else {
    403         RAW_LOG(WARNING, "setsid failed, ctrl terminal not set");
    404       }
    405     }
    406 #endif  // defined(OS_CHROMEOS)
    407 
    408     if (options.fds_to_remap) {
    409       for (FileHandleMappingVector::const_iterator
    410                it = options.fds_to_remap->begin();
    411            it != options.fds_to_remap->end(); ++it) {
    412         fd_shuffle1.push_back(InjectionArc(it->first, it->second, false));
    413         fd_shuffle2.push_back(InjectionArc(it->first, it->second, false));
    414       }
    415     }
    416 
    417     if (!options.environ.empty())
    418       SetEnvironment(new_environ.get());
    419 
    420     // fd_shuffle1 is mutated by this call because it cannot malloc.
    421     if (!ShuffleFileDescriptors(&fd_shuffle1))
    422       _exit(127);
    423 
    424     CloseSuperfluousFds(fd_shuffle2);
    425 
    426     for (size_t i = 0; i < argv.size(); i++)
    427       argv_cstr[i] = const_cast<char*>(argv[i].c_str());
    428     argv_cstr[argv.size()] = NULL;
    429     execvp(argv_cstr[0], argv_cstr.get());
    430 
    431     RAW_LOG(ERROR, "LaunchProcess: failed to execvp:");
    432     RAW_LOG(ERROR, argv_cstr[0]);
    433     _exit(127);
    434   } else {
    435     // Parent process
    436     if (options.wait) {
    437       // While this isn't strictly disk IO, waiting for another process to
    438       // finish is the sort of thing ThreadRestrictions is trying to prevent.
    439       base::ThreadRestrictions::AssertIOAllowed();
    440       pid_t ret = HANDLE_EINTR(waitpid(pid, 0, 0));
    441       DPCHECK(ret > 0);
    442     }
    443 
    444     if (process_handle)
    445       *process_handle = pid;
    446   }
    447 
    448   return true;
    449 }
    450 
    451 
    452 bool LaunchProcess(const CommandLine& cmdline,
    453                    const LaunchOptions& options,
    454                    ProcessHandle* process_handle) {
    455   return LaunchProcess(cmdline.argv(), options, process_handle);
    456 }
    457 
    458 void RaiseProcessToHighPriority() {
    459   // On POSIX, we don't actually do anything here.  We could try to nice() or
    460   // setpriority() or sched_getscheduler, but these all require extra rights.
    461 }
    462 
    463 // Return value used by GetAppOutputInternal to encapsulate the various exit
    464 // scenarios from the function.
    465 enum GetAppOutputInternalResult {
    466   EXECUTE_FAILURE,
    467   EXECUTE_SUCCESS,
    468   GOT_MAX_OUTPUT,
    469 };
    470 
    471 // Executes the application specified by |argv| and wait for it to exit. Stores
    472 // the output (stdout) in |output|. If |do_search_path| is set, it searches the
    473 // path for the application; in that case, |envp| must be null, and it will use
    474 // the current environment. If |do_search_path| is false, |argv[0]| should fully
    475 // specify the path of the application, and |envp| will be used as the
    476 // environment. Redirects stderr to /dev/null.
    477 // If we successfully start the application and get all requested output, we
    478 // return GOT_MAX_OUTPUT, or if there is a problem starting or exiting
    479 // the application we return RUN_FAILURE. Otherwise we return EXECUTE_SUCCESS.
    480 // The GOT_MAX_OUTPUT return value exists so a caller that asks for limited
    481 // output can treat this as a success, despite having an exit code of SIG_PIPE
    482 // due to us closing the output pipe.
    483 // In the case of EXECUTE_SUCCESS, the application exit code will be returned
    484 // in |*exit_code|, which should be checked to determine if the application
    485 // ran successfully.
    486 static GetAppOutputInternalResult GetAppOutputInternal(
    487     const std::vector<std::string>& argv,
    488     char* const envp[],
    489     std::string* output,
    490     size_t max_output,
    491     bool do_search_path,
    492     int* exit_code) {
    493   // Doing a blocking wait for another command to finish counts as IO.
    494   base::ThreadRestrictions::AssertIOAllowed();
    495   // exit_code must be supplied so calling function can determine success.
    496   DCHECK(exit_code);
    497   *exit_code = EXIT_FAILURE;
    498 
    499   int pipe_fd[2];
    500   pid_t pid;
    501   InjectiveMultimap fd_shuffle1, fd_shuffle2;
    502   scoped_ptr<char*[]> argv_cstr(new char*[argv.size() + 1]);
    503 
    504   fd_shuffle1.reserve(3);
    505   fd_shuffle2.reserve(3);
    506 
    507   // Either |do_search_path| should be false or |envp| should be null, but not
    508   // both.
    509   DCHECK(!do_search_path ^ !envp);
    510 
    511   if (pipe(pipe_fd) < 0)
    512     return EXECUTE_FAILURE;
    513 
    514   switch (pid = fork()) {
    515     case -1:  // error
    516       close(pipe_fd[0]);
    517       close(pipe_fd[1]);
    518       return EXECUTE_FAILURE;
    519     case 0:  // child
    520       {
    521 #if defined(OS_MACOSX)
    522         RestoreDefaultExceptionHandler();
    523 #endif
    524         // DANGER: no calls to malloc are allowed from now on:
    525         // http://crbug.com/36678
    526 
    527         // Obscure fork() rule: in the child, if you don't end up doing exec*(),
    528         // you call _exit() instead of exit(). This is because _exit() does not
    529         // call any previously-registered (in the parent) exit handlers, which
    530         // might do things like block waiting for threads that don't even exist
    531         // in the child.
    532         int dev_null = open("/dev/null", O_WRONLY);
    533         if (dev_null < 0)
    534           _exit(127);
    535 
    536         // Stop type-profiler.
    537         // The profiler should be stopped between fork and exec since it inserts
    538         // locks at new/delete expressions.  See http://crbug.com/36678.
    539         base::type_profiler::Controller::Stop();
    540 
    541         fd_shuffle1.push_back(InjectionArc(pipe_fd[1], STDOUT_FILENO, true));
    542         fd_shuffle1.push_back(InjectionArc(dev_null, STDERR_FILENO, true));
    543         fd_shuffle1.push_back(InjectionArc(dev_null, STDIN_FILENO, true));
    544         // Adding another element here? Remeber to increase the argument to
    545         // reserve(), above.
    546 
    547         std::copy(fd_shuffle1.begin(), fd_shuffle1.end(),
    548                   std::back_inserter(fd_shuffle2));
    549 
    550         if (!ShuffleFileDescriptors(&fd_shuffle1))
    551           _exit(127);
    552 
    553         CloseSuperfluousFds(fd_shuffle2);
    554 
    555         for (size_t i = 0; i < argv.size(); i++)
    556           argv_cstr[i] = const_cast<char*>(argv[i].c_str());
    557         argv_cstr[argv.size()] = NULL;
    558         if (do_search_path)
    559           execvp(argv_cstr[0], argv_cstr.get());
    560         else
    561           execve(argv_cstr[0], argv_cstr.get(), envp);
    562         _exit(127);
    563       }
    564     default:  // parent
    565       {
    566         // Close our writing end of pipe now. Otherwise later read would not
    567         // be able to detect end of child's output (in theory we could still
    568         // write to the pipe).
    569         close(pipe_fd[1]);
    570 
    571         output->clear();
    572         char buffer[256];
    573         size_t output_buf_left = max_output;
    574         ssize_t bytes_read = 1;  // A lie to properly handle |max_output == 0|
    575                                  // case in the logic below.
    576 
    577         while (output_buf_left > 0) {
    578           bytes_read = HANDLE_EINTR(read(pipe_fd[0], buffer,
    579                                     std::min(output_buf_left, sizeof(buffer))));
    580           if (bytes_read <= 0)
    581             break;
    582           output->append(buffer, bytes_read);
    583           output_buf_left -= static_cast<size_t>(bytes_read);
    584         }
    585         close(pipe_fd[0]);
    586 
    587         // Always wait for exit code (even if we know we'll declare
    588         // GOT_MAX_OUTPUT).
    589         bool success = WaitForExitCode(pid, exit_code);
    590 
    591         // If we stopped because we read as much as we wanted, we return
    592         // GOT_MAX_OUTPUT (because the child may exit due to |SIGPIPE|).
    593         if (!output_buf_left && bytes_read > 0)
    594           return GOT_MAX_OUTPUT;
    595         else if (success)
    596           return EXECUTE_SUCCESS;
    597         return EXECUTE_FAILURE;
    598       }
    599   }
    600 }
    601 
    602 bool GetAppOutput(const CommandLine& cl, std::string* output) {
    603   return GetAppOutput(cl.argv(), output);
    604 }
    605 
    606 bool GetAppOutput(const std::vector<std::string>& argv, std::string* output) {
    607   // Run |execve()| with the current environment and store "unlimited" data.
    608   int exit_code;
    609   GetAppOutputInternalResult result = GetAppOutputInternal(
    610       argv, NULL, output, std::numeric_limits<std::size_t>::max(), true,
    611       &exit_code);
    612   return result == EXECUTE_SUCCESS && exit_code == EXIT_SUCCESS;
    613 }
    614 
    615 // TODO(viettrungluu): Conceivably, we should have a timeout as well, so we
    616 // don't hang if what we're calling hangs.
    617 bool GetAppOutputRestricted(const CommandLine& cl,
    618                             std::string* output, size_t max_output) {
    619   // Run |execve()| with the empty environment.
    620   char* const empty_environ = NULL;
    621   int exit_code;
    622   GetAppOutputInternalResult result = GetAppOutputInternal(
    623       cl.argv(), &empty_environ, output, max_output, false, &exit_code);
    624   return result == GOT_MAX_OUTPUT || (result == EXECUTE_SUCCESS &&
    625                                       exit_code == EXIT_SUCCESS);
    626 }
    627 
    628 bool GetAppOutputWithExitCode(const CommandLine& cl,
    629                               std::string* output,
    630                               int* exit_code) {
    631   // Run |execve()| with the current environment and store "unlimited" data.
    632   GetAppOutputInternalResult result = GetAppOutputInternal(
    633       cl.argv(), NULL, output, std::numeric_limits<std::size_t>::max(), true,
    634       exit_code);
    635   return result == EXECUTE_SUCCESS;
    636 }
    637 
    638 }  // namespace base
    639