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      1 //===--- raw_ostream.cpp - Implement the raw_ostream classes --------------===//
      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 // This implements support for bulk buffered stream output.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #include "llvm/Support/raw_ostream.h"
     15 #include "llvm/ADT/STLExtras.h"
     16 #include "llvm/ADT/SmallVector.h"
     17 #include "llvm/ADT/StringExtras.h"
     18 #include "llvm/Config/config.h"
     19 #include "llvm/Support/Compiler.h"
     20 #include "llvm/Support/ErrorHandling.h"
     21 #include "llvm/Support/Format.h"
     22 #include "llvm/Support/Process.h"
     23 #include "llvm/Support/Program.h"
     24 #include "llvm/Support/system_error.h"
     25 #include <cctype>
     26 #include <cerrno>
     27 #include <sys/stat.h>
     28 #include <sys/types.h>
     29 
     30 #if defined(HAVE_UNISTD_H)
     31 # include <unistd.h>
     32 #endif
     33 #if defined(HAVE_FCNTL_H)
     34 # include <fcntl.h>
     35 #endif
     36 #if defined(HAVE_SYS_UIO_H) && defined(HAVE_WRITEV)
     37 #  include <sys/uio.h>
     38 #endif
     39 
     40 #if defined(__CYGWIN__)
     41 #include <io.h>
     42 #endif
     43 
     44 #if defined(_MSC_VER)
     45 #include <io.h>
     46 #include <fcntl.h>
     47 #ifndef STDIN_FILENO
     48 # define STDIN_FILENO 0
     49 #endif
     50 #ifndef STDOUT_FILENO
     51 # define STDOUT_FILENO 1
     52 #endif
     53 #ifndef STDERR_FILENO
     54 # define STDERR_FILENO 2
     55 #endif
     56 #endif
     57 
     58 using namespace llvm;
     59 
     60 raw_ostream::~raw_ostream() {
     61   // raw_ostream's subclasses should take care to flush the buffer
     62   // in their destructors.
     63   assert(OutBufCur == OutBufStart &&
     64          "raw_ostream destructor called with non-empty buffer!");
     65 
     66   if (BufferMode == InternalBuffer)
     67     delete [] OutBufStart;
     68 }
     69 
     70 // An out of line virtual method to provide a home for the class vtable.
     71 void raw_ostream::handle() {}
     72 
     73 size_t raw_ostream::preferred_buffer_size() const {
     74   // BUFSIZ is intended to be a reasonable default.
     75   return BUFSIZ;
     76 }
     77 
     78 void raw_ostream::SetBuffered() {
     79   // Ask the subclass to determine an appropriate buffer size.
     80   if (size_t Size = preferred_buffer_size())
     81     SetBufferSize(Size);
     82   else
     83     // It may return 0, meaning this stream should be unbuffered.
     84     SetUnbuffered();
     85 }
     86 
     87 void raw_ostream::SetBufferAndMode(char *BufferStart, size_t Size,
     88                                    BufferKind Mode) {
     89   assert(((Mode == Unbuffered && BufferStart == 0 && Size == 0) ||
     90           (Mode != Unbuffered && BufferStart && Size)) &&
     91          "stream must be unbuffered or have at least one byte");
     92   // Make sure the current buffer is free of content (we can't flush here; the
     93   // child buffer management logic will be in write_impl).
     94   assert(GetNumBytesInBuffer() == 0 && "Current buffer is non-empty!");
     95 
     96   if (BufferMode == InternalBuffer)
     97     delete [] OutBufStart;
     98   OutBufStart = BufferStart;
     99   OutBufEnd = OutBufStart+Size;
    100   OutBufCur = OutBufStart;
    101   BufferMode = Mode;
    102 
    103   assert(OutBufStart <= OutBufEnd && "Invalid size!");
    104 }
    105 
    106 raw_ostream &raw_ostream::operator<<(unsigned long N) {
    107   // Zero is a special case.
    108   if (N == 0)
    109     return *this << '0';
    110 
    111   char NumberBuffer[20];
    112   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
    113   char *CurPtr = EndPtr;
    114 
    115   while (N) {
    116     *--CurPtr = '0' + char(N % 10);
    117     N /= 10;
    118   }
    119   return write(CurPtr, EndPtr-CurPtr);
    120 }
    121 
    122 raw_ostream &raw_ostream::operator<<(long N) {
    123   if (N <  0) {
    124     *this << '-';
    125     // Avoid undefined behavior on LONG_MIN with a cast.
    126     N = -(unsigned long)N;
    127   }
    128 
    129   return this->operator<<(static_cast<unsigned long>(N));
    130 }
    131 
    132 raw_ostream &raw_ostream::operator<<(unsigned long long N) {
    133   // Output using 32-bit div/mod when possible.
    134   if (N == static_cast<unsigned long>(N))
    135     return this->operator<<(static_cast<unsigned long>(N));
    136 
    137   char NumberBuffer[20];
    138   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
    139   char *CurPtr = EndPtr;
    140 
    141   while (N) {
    142     *--CurPtr = '0' + char(N % 10);
    143     N /= 10;
    144   }
    145   return write(CurPtr, EndPtr-CurPtr);
    146 }
    147 
    148 raw_ostream &raw_ostream::operator<<(long long N) {
    149   if (N < 0) {
    150     *this << '-';
    151     // Avoid undefined behavior on INT64_MIN with a cast.
    152     N = -(unsigned long long)N;
    153   }
    154 
    155   return this->operator<<(static_cast<unsigned long long>(N));
    156 }
    157 
    158 raw_ostream &raw_ostream::write_hex(unsigned long long N) {
    159   // Zero is a special case.
    160   if (N == 0)
    161     return *this << '0';
    162 
    163   char NumberBuffer[20];
    164   char *EndPtr = NumberBuffer+sizeof(NumberBuffer);
    165   char *CurPtr = EndPtr;
    166 
    167   while (N) {
    168     uintptr_t x = N % 16;
    169     *--CurPtr = (x < 10 ? '0' + x : 'a' + x - 10);
    170     N /= 16;
    171   }
    172 
    173   return write(CurPtr, EndPtr-CurPtr);
    174 }
    175 
    176 raw_ostream &raw_ostream::write_escaped(StringRef Str,
    177                                         bool UseHexEscapes) {
    178   for (unsigned i = 0, e = Str.size(); i != e; ++i) {
    179     unsigned char c = Str[i];
    180 
    181     switch (c) {
    182     case '\\':
    183       *this << '\\' << '\\';
    184       break;
    185     case '\t':
    186       *this << '\\' << 't';
    187       break;
    188     case '\n':
    189       *this << '\\' << 'n';
    190       break;
    191     case '"':
    192       *this << '\\' << '"';
    193       break;
    194     default:
    195       if (std::isprint(c)) {
    196         *this << c;
    197         break;
    198       }
    199 
    200       // Write out the escaped representation.
    201       if (UseHexEscapes) {
    202         *this << '\\' << 'x';
    203         *this << hexdigit((c >> 4 & 0xF));
    204         *this << hexdigit((c >> 0) & 0xF);
    205       } else {
    206         // Always use a full 3-character octal escape.
    207         *this << '\\';
    208         *this << char('0' + ((c >> 6) & 7));
    209         *this << char('0' + ((c >> 3) & 7));
    210         *this << char('0' + ((c >> 0) & 7));
    211       }
    212     }
    213   }
    214 
    215   return *this;
    216 }
    217 
    218 raw_ostream &raw_ostream::operator<<(const void *P) {
    219   *this << '0' << 'x';
    220 
    221   return write_hex((uintptr_t) P);
    222 }
    223 
    224 raw_ostream &raw_ostream::operator<<(double N) {
    225 #ifdef _WIN32
    226   // On MSVCRT and compatible, output of %e is incompatible to Posix
    227   // by default. Number of exponent digits should be at least 2. "%+03d"
    228   // FIXME: Implement our formatter to here or Support/Format.h!
    229   int fpcl = _fpclass(N);
    230 
    231   // negative zero
    232   if (fpcl == _FPCLASS_NZ)
    233     return *this << "-0.000000e+00";
    234 
    235   char buf[16];
    236   unsigned len;
    237   len = snprintf(buf, sizeof(buf), "%e", N);
    238   if (len <= sizeof(buf) - 2) {
    239     if (len >= 5 && buf[len - 5] == 'e' && buf[len - 3] == '0') {
    240       int cs = buf[len - 4];
    241       if (cs == '+' || cs == '-') {
    242         int c1 = buf[len - 2];
    243         int c0 = buf[len - 1];
    244         if (isdigit(static_cast<unsigned char>(c1)) &&
    245             isdigit(static_cast<unsigned char>(c0))) {
    246           // Trim leading '0': "...e+012" -> "...e+12\0"
    247           buf[len - 3] = c1;
    248           buf[len - 2] = c0;
    249           buf[--len] = 0;
    250         }
    251       }
    252     }
    253     return this->operator<<(buf);
    254   }
    255 #endif
    256   return this->operator<<(format("%e", N));
    257 }
    258 
    259 
    260 
    261 void raw_ostream::flush_nonempty() {
    262   assert(OutBufCur > OutBufStart && "Invalid call to flush_nonempty.");
    263   size_t Length = OutBufCur - OutBufStart;
    264   OutBufCur = OutBufStart;
    265   write_impl(OutBufStart, Length);
    266 }
    267 
    268 raw_ostream &raw_ostream::write(unsigned char C) {
    269   // Group exceptional cases into a single branch.
    270   if (LLVM_UNLIKELY(OutBufCur >= OutBufEnd)) {
    271     if (LLVM_UNLIKELY(!OutBufStart)) {
    272       if (BufferMode == Unbuffered) {
    273         write_impl(reinterpret_cast<char*>(&C), 1);
    274         return *this;
    275       }
    276       // Set up a buffer and start over.
    277       SetBuffered();
    278       return write(C);
    279     }
    280 
    281     flush_nonempty();
    282   }
    283 
    284   *OutBufCur++ = C;
    285   return *this;
    286 }
    287 
    288 raw_ostream &raw_ostream::write(const char *Ptr, size_t Size) {
    289   // Group exceptional cases into a single branch.
    290   if (LLVM_UNLIKELY(size_t(OutBufEnd - OutBufCur) < Size)) {
    291     if (LLVM_UNLIKELY(!OutBufStart)) {
    292       if (BufferMode == Unbuffered) {
    293         write_impl(Ptr, Size);
    294         return *this;
    295       }
    296       // Set up a buffer and start over.
    297       SetBuffered();
    298       return write(Ptr, Size);
    299     }
    300 
    301     size_t NumBytes = OutBufEnd - OutBufCur;
    302 
    303     // If the buffer is empty at this point we have a string that is larger
    304     // than the buffer. Directly write the chunk that is a multiple of the
    305     // preferred buffer size and put the remainder in the buffer.
    306     if (LLVM_UNLIKELY(OutBufCur == OutBufStart)) {
    307       size_t BytesToWrite = Size - (Size % NumBytes);
    308       write_impl(Ptr, BytesToWrite);
    309       size_t BytesRemaining = Size - BytesToWrite;
    310       if (BytesRemaining > size_t(OutBufEnd - OutBufCur)) {
    311         // Too much left over to copy into our buffer.
    312         return write(Ptr + BytesToWrite, BytesRemaining);
    313       }
    314       copy_to_buffer(Ptr + BytesToWrite, BytesRemaining);
    315       return *this;
    316     }
    317 
    318     // We don't have enough space in the buffer to fit the string in. Insert as
    319     // much as possible, flush and start over with the remainder.
    320     copy_to_buffer(Ptr, NumBytes);
    321     flush_nonempty();
    322     return write(Ptr + NumBytes, Size - NumBytes);
    323   }
    324 
    325   copy_to_buffer(Ptr, Size);
    326 
    327   return *this;
    328 }
    329 
    330 void raw_ostream::copy_to_buffer(const char *Ptr, size_t Size) {
    331   assert(Size <= size_t(OutBufEnd - OutBufCur) && "Buffer overrun!");
    332 
    333   // Handle short strings specially, memcpy isn't very good at very short
    334   // strings.
    335   switch (Size) {
    336   case 4: OutBufCur[3] = Ptr[3]; // FALL THROUGH
    337   case 3: OutBufCur[2] = Ptr[2]; // FALL THROUGH
    338   case 2: OutBufCur[1] = Ptr[1]; // FALL THROUGH
    339   case 1: OutBufCur[0] = Ptr[0]; // FALL THROUGH
    340   case 0: break;
    341   default:
    342     memcpy(OutBufCur, Ptr, Size);
    343     break;
    344   }
    345 
    346   OutBufCur += Size;
    347 }
    348 
    349 // Formatted output.
    350 raw_ostream &raw_ostream::operator<<(const format_object_base &Fmt) {
    351   // If we have more than a few bytes left in our output buffer, try
    352   // formatting directly onto its end.
    353   size_t NextBufferSize = 127;
    354   size_t BufferBytesLeft = OutBufEnd - OutBufCur;
    355   if (BufferBytesLeft > 3) {
    356     size_t BytesUsed = Fmt.print(OutBufCur, BufferBytesLeft);
    357 
    358     // Common case is that we have plenty of space.
    359     if (BytesUsed <= BufferBytesLeft) {
    360       OutBufCur += BytesUsed;
    361       return *this;
    362     }
    363 
    364     // Otherwise, we overflowed and the return value tells us the size to try
    365     // again with.
    366     NextBufferSize = BytesUsed;
    367   }
    368 
    369   // If we got here, we didn't have enough space in the output buffer for the
    370   // string.  Try printing into a SmallVector that is resized to have enough
    371   // space.  Iterate until we win.
    372   SmallVector<char, 128> V;
    373 
    374   while (1) {
    375     V.resize(NextBufferSize);
    376 
    377     // Try formatting into the SmallVector.
    378     size_t BytesUsed = Fmt.print(V.data(), NextBufferSize);
    379 
    380     // If BytesUsed fit into the vector, we win.
    381     if (BytesUsed <= NextBufferSize)
    382       return write(V.data(), BytesUsed);
    383 
    384     // Otherwise, try again with a new size.
    385     assert(BytesUsed > NextBufferSize && "Didn't grow buffer!?");
    386     NextBufferSize = BytesUsed;
    387   }
    388 }
    389 
    390 /// indent - Insert 'NumSpaces' spaces.
    391 raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
    392   static const char Spaces[] = "                                "
    393                                "                                "
    394                                "                ";
    395 
    396   // Usually the indentation is small, handle it with a fastpath.
    397   if (NumSpaces < array_lengthof(Spaces))
    398     return write(Spaces, NumSpaces);
    399 
    400   while (NumSpaces) {
    401     unsigned NumToWrite = std::min(NumSpaces,
    402                                    (unsigned)array_lengthof(Spaces)-1);
    403     write(Spaces, NumToWrite);
    404     NumSpaces -= NumToWrite;
    405   }
    406   return *this;
    407 }
    408 
    409 
    410 //===----------------------------------------------------------------------===//
    411 //  Formatted Output
    412 //===----------------------------------------------------------------------===//
    413 
    414 // Out of line virtual method.
    415 void format_object_base::home() {
    416 }
    417 
    418 //===----------------------------------------------------------------------===//
    419 //  raw_fd_ostream
    420 //===----------------------------------------------------------------------===//
    421 
    422 /// raw_fd_ostream - Open the specified file for writing. If an error
    423 /// occurs, information about the error is put into ErrorInfo, and the
    424 /// stream should be immediately destroyed; the string will be empty
    425 /// if no error occurred.
    426 raw_fd_ostream::raw_fd_ostream(const char *Filename, std::string &ErrorInfo,
    427                                unsigned Flags)
    428   : Error(false), UseAtomicWrites(false), pos(0)
    429 {
    430   assert(Filename != 0 && "Filename is null");
    431   // Verify that we don't have both "append" and "excl".
    432   assert((!(Flags & F_Excl) || !(Flags & F_Append)) &&
    433          "Cannot specify both 'excl' and 'append' file creation flags!");
    434 
    435   ErrorInfo.clear();
    436 
    437   // Handle "-" as stdout. Note that when we do this, we consider ourself
    438   // the owner of stdout. This means that we can do things like close the
    439   // file descriptor when we're done and set the "binary" flag globally.
    440   if (Filename[0] == '-' && Filename[1] == 0) {
    441     FD = STDOUT_FILENO;
    442     // If user requested binary then put stdout into binary mode if
    443     // possible.
    444     if (Flags & F_Binary)
    445       sys::Program::ChangeStdoutToBinary();
    446     // Close stdout when we're done, to detect any output errors.
    447     ShouldClose = true;
    448     return;
    449   }
    450 
    451   int OpenFlags = O_WRONLY|O_CREAT;
    452 #ifdef O_BINARY
    453   if (Flags & F_Binary)
    454     OpenFlags |= O_BINARY;
    455 #endif
    456 
    457   if (Flags & F_Append)
    458     OpenFlags |= O_APPEND;
    459   else
    460     OpenFlags |= O_TRUNC;
    461   if (Flags & F_Excl)
    462     OpenFlags |= O_EXCL;
    463 
    464   while ((FD = open(Filename, OpenFlags, 0664)) < 0) {
    465     if (errno != EINTR) {
    466       ErrorInfo = "Error opening output file '" + std::string(Filename) + "'";
    467       ShouldClose = false;
    468       return;
    469     }
    470   }
    471 
    472   // Ok, we successfully opened the file, so it'll need to be closed.
    473   ShouldClose = true;
    474 }
    475 
    476 /// raw_fd_ostream ctor - FD is the file descriptor that this writes to.  If
    477 /// ShouldClose is true, this closes the file when the stream is destroyed.
    478 raw_fd_ostream::raw_fd_ostream(int fd, bool shouldClose, bool unbuffered)
    479   : raw_ostream(unbuffered), FD(fd),
    480     ShouldClose(shouldClose), Error(false), UseAtomicWrites(false) {
    481 #ifdef O_BINARY
    482   // Setting STDOUT and STDERR to binary mode is necessary in Win32
    483   // to avoid undesirable linefeed conversion.
    484   if (fd == STDOUT_FILENO || fd == STDERR_FILENO)
    485     setmode(fd, O_BINARY);
    486 #endif
    487 
    488   // Get the starting position.
    489   off_t loc = ::lseek(FD, 0, SEEK_CUR);
    490   if (loc == (off_t)-1)
    491     pos = 0;
    492   else
    493     pos = static_cast<uint64_t>(loc);
    494 }
    495 
    496 raw_fd_ostream::~raw_fd_ostream() {
    497   if (FD >= 0) {
    498     flush();
    499     if (ShouldClose)
    500       while (::close(FD) != 0)
    501         if (errno != EINTR) {
    502           error_detected();
    503           break;
    504         }
    505   }
    506 
    507 #ifdef __MINGW32__
    508   // On mingw, global dtors should not call exit().
    509   // report_fatal_error() invokes exit(). We know report_fatal_error()
    510   // might not write messages to stderr when any errors were detected
    511   // on FD == 2.
    512   if (FD == 2) return;
    513 #endif
    514 
    515   // If there are any pending errors, report them now. Clients wishing
    516   // to avoid report_fatal_error calls should check for errors with
    517   // has_error() and clear the error flag with clear_error() before
    518   // destructing raw_ostream objects which may have errors.
    519   if (has_error())
    520     report_fatal_error("IO failure on output stream.");
    521 }
    522 
    523 
    524 void raw_fd_ostream::write_impl(const char *Ptr, size_t Size) {
    525   assert(FD >= 0 && "File already closed.");
    526   pos += Size;
    527 
    528   do {
    529     ssize_t ret;
    530 
    531     // Check whether we should attempt to use atomic writes.
    532     if (LLVM_LIKELY(!UseAtomicWrites)) {
    533       ret = ::write(FD, Ptr, Size);
    534     } else {
    535       // Use ::writev() where available.
    536 #if defined(HAVE_WRITEV)
    537       const void *Addr = static_cast<const void *>(Ptr);
    538       struct iovec IOV = {const_cast<void *>(Addr), Size };
    539       ret = ::writev(FD, &IOV, 1);
    540 #else
    541       ret = ::write(FD, Ptr, Size);
    542 #endif
    543     }
    544 
    545     if (ret < 0) {
    546       // If it's a recoverable error, swallow it and retry the write.
    547       //
    548       // Ideally we wouldn't ever see EAGAIN or EWOULDBLOCK here, since
    549       // raw_ostream isn't designed to do non-blocking I/O. However, some
    550       // programs, such as old versions of bjam, have mistakenly used
    551       // O_NONBLOCK. For compatibility, emulate blocking semantics by
    552       // spinning until the write succeeds. If you don't want spinning,
    553       // don't use O_NONBLOCK file descriptors with raw_ostream.
    554       if (errno == EINTR || errno == EAGAIN
    555 #ifdef EWOULDBLOCK
    556           || errno == EWOULDBLOCK
    557 #endif
    558           )
    559         continue;
    560 
    561       // Otherwise it's a non-recoverable error. Note it and quit.
    562       error_detected();
    563       break;
    564     }
    565 
    566     // The write may have written some or all of the data. Update the
    567     // size and buffer pointer to reflect the remainder that needs
    568     // to be written. If there are no bytes left, we're done.
    569     Ptr += ret;
    570     Size -= ret;
    571   } while (Size > 0);
    572 }
    573 
    574 void raw_fd_ostream::close() {
    575   assert(ShouldClose);
    576   ShouldClose = false;
    577   flush();
    578   while (::close(FD) != 0)
    579     if (errno != EINTR) {
    580       error_detected();
    581       break;
    582     }
    583   FD = -1;
    584 }
    585 
    586 uint64_t raw_fd_ostream::seek(uint64_t off) {
    587   flush();
    588   pos = ::lseek(FD, off, SEEK_SET);
    589   if (pos != off)
    590     error_detected();
    591   return pos;
    592 }
    593 
    594 size_t raw_fd_ostream::preferred_buffer_size() const {
    595 #if !defined(_MSC_VER) && !defined(__MINGW32__) && !defined(__minix)
    596   // Windows and Minix have no st_blksize.
    597   assert(FD >= 0 && "File not yet open!");
    598   struct stat statbuf;
    599   if (fstat(FD, &statbuf) != 0)
    600     return 0;
    601 
    602   // If this is a terminal, don't use buffering. Line buffering
    603   // would be a more traditional thing to do, but it's not worth
    604   // the complexity.
    605   if (S_ISCHR(statbuf.st_mode) && isatty(FD))
    606     return 0;
    607   // Return the preferred block size.
    608   return statbuf.st_blksize;
    609 #else
    610   return raw_ostream::preferred_buffer_size();
    611 #endif
    612 }
    613 
    614 raw_ostream &raw_fd_ostream::changeColor(enum Colors colors, bool bold,
    615                                          bool bg) {
    616   if (sys::Process::ColorNeedsFlush())
    617     flush();
    618   const char *colorcode =
    619     (colors == SAVEDCOLOR) ? sys::Process::OutputBold(bg)
    620     : sys::Process::OutputColor(colors, bold, bg);
    621   if (colorcode) {
    622     size_t len = strlen(colorcode);
    623     write(colorcode, len);
    624     // don't account colors towards output characters
    625     pos -= len;
    626   }
    627   return *this;
    628 }
    629 
    630 raw_ostream &raw_fd_ostream::resetColor() {
    631   if (sys::Process::ColorNeedsFlush())
    632     flush();
    633   const char *colorcode = sys::Process::ResetColor();
    634   if (colorcode) {
    635     size_t len = strlen(colorcode);
    636     write(colorcode, len);
    637     // don't account colors towards output characters
    638     pos -= len;
    639   }
    640   return *this;
    641 }
    642 
    643 raw_ostream &raw_fd_ostream::reverseColor() {
    644   if (sys::Process::ColorNeedsFlush())
    645     flush();
    646   const char *colorcode = sys::Process::OutputReverse();
    647   if (colorcode) {
    648     size_t len = strlen(colorcode);
    649     write(colorcode, len);
    650     // don't account colors towards output characters
    651     pos -= len;
    652   }
    653   return *this;
    654 }
    655 
    656 bool raw_fd_ostream::is_displayed() const {
    657   return sys::Process::FileDescriptorIsDisplayed(FD);
    658 }
    659 
    660 bool raw_fd_ostream::has_colors() const {
    661   return sys::Process::FileDescriptorHasColors(FD);
    662 }
    663 
    664 //===----------------------------------------------------------------------===//
    665 //  outs(), errs(), nulls()
    666 //===----------------------------------------------------------------------===//
    667 
    668 /// outs() - This returns a reference to a raw_ostream for standard output.
    669 /// Use it like: outs() << "foo" << "bar";
    670 raw_ostream &llvm::outs() {
    671   // Set buffer settings to model stdout behavior.
    672   // Delete the file descriptor when the program exists, forcing error
    673   // detection. If you don't want this behavior, don't use outs().
    674   static raw_fd_ostream S(STDOUT_FILENO, true);
    675   return S;
    676 }
    677 
    678 /// errs() - This returns a reference to a raw_ostream for standard error.
    679 /// Use it like: errs() << "foo" << "bar";
    680 raw_ostream &llvm::errs() {
    681   // Set standard error to be unbuffered by default.
    682   static raw_fd_ostream S(STDERR_FILENO, false, true);
    683   return S;
    684 }
    685 
    686 /// nulls() - This returns a reference to a raw_ostream which discards output.
    687 raw_ostream &llvm::nulls() {
    688   static raw_null_ostream S;
    689   return S;
    690 }
    691 
    692 
    693 //===----------------------------------------------------------------------===//
    694 //  raw_string_ostream
    695 //===----------------------------------------------------------------------===//
    696 
    697 raw_string_ostream::~raw_string_ostream() {
    698   flush();
    699 }
    700 
    701 void raw_string_ostream::write_impl(const char *Ptr, size_t Size) {
    702   OS.append(Ptr, Size);
    703 }
    704 
    705 //===----------------------------------------------------------------------===//
    706 //  raw_svector_ostream
    707 //===----------------------------------------------------------------------===//
    708 
    709 // The raw_svector_ostream implementation uses the SmallVector itself as the
    710 // buffer for the raw_ostream. We guarantee that the raw_ostream buffer is
    711 // always pointing past the end of the vector, but within the vector
    712 // capacity. This allows raw_ostream to write directly into the correct place,
    713 // and we only need to set the vector size when the data is flushed.
    714 
    715 raw_svector_ostream::raw_svector_ostream(SmallVectorImpl<char> &O) : OS(O) {
    716   // Set up the initial external buffer. We make sure that the buffer has at
    717   // least 128 bytes free; raw_ostream itself only requires 64, but we want to
    718   // make sure that we don't grow the buffer unnecessarily on destruction (when
    719   // the data is flushed). See the FIXME below.
    720   OS.reserve(OS.size() + 128);
    721   SetBuffer(OS.end(), OS.capacity() - OS.size());
    722 }
    723 
    724 raw_svector_ostream::~raw_svector_ostream() {
    725   // FIXME: Prevent resizing during this flush().
    726   flush();
    727 }
    728 
    729 /// resync - This is called when the SmallVector we're appending to is changed
    730 /// outside of the raw_svector_ostream's control.  It is only safe to do this
    731 /// if the raw_svector_ostream has previously been flushed.
    732 void raw_svector_ostream::resync() {
    733   assert(GetNumBytesInBuffer() == 0 && "Didn't flush before mutating vector");
    734 
    735   if (OS.capacity() - OS.size() < 64)
    736     OS.reserve(OS.capacity() * 2);
    737   SetBuffer(OS.end(), OS.capacity() - OS.size());
    738 }
    739 
    740 void raw_svector_ostream::write_impl(const char *Ptr, size_t Size) {
    741   // If we're writing bytes from the end of the buffer into the smallvector, we
    742   // don't need to copy the bytes, just commit the bytes because they are
    743   // already in the right place.
    744   if (Ptr == OS.end()) {
    745     assert(OS.size() + Size <= OS.capacity() && "Invalid write_impl() call!");
    746     OS.set_size(OS.size() + Size);
    747   } else {
    748     assert(GetNumBytesInBuffer() == 0 &&
    749            "Should be writing from buffer if some bytes in it");
    750     // Otherwise, do copy the bytes.
    751     OS.append(Ptr, Ptr+Size);
    752   }
    753 
    754   // Grow the vector if necessary.
    755   if (OS.capacity() - OS.size() < 64)
    756     OS.reserve(OS.capacity() * 2);
    757 
    758   // Update the buffer position.
    759   SetBuffer(OS.end(), OS.capacity() - OS.size());
    760 }
    761 
    762 uint64_t raw_svector_ostream::current_pos() const {
    763    return OS.size();
    764 }
    765 
    766 StringRef raw_svector_ostream::str() {
    767   flush();
    768   return StringRef(OS.begin(), OS.size());
    769 }
    770 
    771 //===----------------------------------------------------------------------===//
    772 //  raw_null_ostream
    773 //===----------------------------------------------------------------------===//
    774 
    775 raw_null_ostream::~raw_null_ostream() {
    776 #ifndef NDEBUG
    777   // ~raw_ostream asserts that the buffer is empty. This isn't necessary
    778   // with raw_null_ostream, but it's better to have raw_null_ostream follow
    779   // the rules than to change the rules just for raw_null_ostream.
    780   flush();
    781 #endif
    782 }
    783 
    784 void raw_null_ostream::write_impl(const char *Ptr, size_t Size) {
    785 }
    786 
    787 uint64_t raw_null_ostream::current_pos() const {
    788   return 0;
    789 }
    790