lib/profile/InstrProfilingFile.c

/*===- InstrProfilingFile.c - Write instrumentation to a file -------------===*\
|*
|* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|* See https://llvm.org/LICENSE.txt for license information.
|* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|*
\*===----------------------------------------------------------------------===*/

#if !defined(__Fuchsia__)

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef _MSC_VER
/* For _alloca. */
#include <malloc.h>
#endif
#if defined(_WIN32)
#include "WindowsMMap.h"
/* For _chsize_s */
#include <io.h>
#include <process.h>
#else
#include <sys/file.h>
#include <sys/mman.h>
#include <unistd.h>
#if defined(__linux__)
#include <sys/types.h>
#endif
#endif

#include "InstrProfiling.h"
#include "InstrProfilingInternal.h"
#include "InstrProfilingPort.h"
#include "InstrProfilingUtil.h"

/* From where is profile name specified.
 * The order the enumerators define their
 * precedence. Re-order them may lead to
 * runtime behavior change. */
typedef enum ProfileNameSpecifier {
  PNS_unknown = 0,
  PNS_default,
  PNS_command_line,
  PNS_environment,
  PNS_runtime_api
} ProfileNameSpecifier;

static const char *getPNSStr(ProfileNameSpecifier PNS) {
  switch (PNS) {
  case PNS_default:
    return "default setting";
  case PNS_command_line:
    return "command line";
  case PNS_environment:
    return "environment variable";
  case PNS_runtime_api:
    return "runtime API";
  default:
    return "Unknown";
  }
}

#define MAX_PID_SIZE 16
/* Data structure holding the result of parsed filename pattern. */
typedef struct lprofFilename {
  /* File name string possibly with %p or %h specifiers. */
  const char *FilenamePat;
  /* A flag indicating if FilenamePat's memory is allocated
   * by runtime. */
  unsigned OwnsFilenamePat;
  const char *ProfilePathPrefix;
  char PidChars[MAX_PID_SIZE];
  char Hostname[COMPILER_RT_MAX_HOSTLEN];
  unsigned NumPids;
  unsigned NumHosts;
  /* When in-process merging is enabled, this parameter specifies
   * the total number of profile data files shared by all the processes
   * spawned from the same binary. By default the value is 1. If merging
   * is not enabled, its value should be 0. This parameter is specified
   * by the %[0-9]m specifier. For instance %2m enables merging using
   * 2 profile data files. %1m is equivalent to %m. Also %m specifier
   * can only appear once at the end of the name pattern. */
  unsigned MergePoolSize;
  ProfileNameSpecifier PNS;
} lprofFilename;

static lprofFilename lprofCurFilename = {0, 0, 0, {0},        {0},
                                         0, 0, 0, PNS_unknown};

static int ProfileMergeRequested = 0;
static int isProfileMergeRequested() { return ProfileMergeRequested; }
static void setProfileMergeRequested(int EnableMerge) {
  ProfileMergeRequested = EnableMerge;
}

static FILE *ProfileFile = NULL;
static FILE *getProfileFile() { return ProfileFile; }
static void setProfileFile(FILE *File) { ProfileFile = File; }

COMPILER_RT_VISIBILITY void __llvm_profile_set_file_object(FILE *File,
                                                           int EnableMerge) {
  if (__llvm_profile_is_continuous_mode_enabled()) {
    PROF_WARN("__llvm_profile_set_file_object(fd=%d) not supported, because "
              "continuous sync mode (%%c) is enabled",
              fileno(File));
    return;
  }
  setProfileFile(File);
  setProfileMergeRequested(EnableMerge);
}

static int getCurFilenameLength();
static const char *getCurFilename(char *FilenameBuf, int ForceUseBuf);
static unsigned doMerging() {
  return lprofCurFilename.MergePoolSize || isProfileMergeRequested();
}

/* Return 1 if there is an error, otherwise return  0.  */
static uint32_t fileWriter(ProfDataWriter *This, ProfDataIOVec *IOVecs,
                           uint32_t NumIOVecs) {
  uint32_t I;
  FILE *File = (FILE *)This->WriterCtx;
  for (I = 0; I < NumIOVecs; I++) {
    if (IOVecs[I].Data) {
      if (fwrite(IOVecs[I].Data, IOVecs[I].ElmSize, IOVecs[I].NumElm, File) !=
          IOVecs[I].NumElm)
        return 1;
    } else {
      if (fseek(File, IOVecs[I].ElmSize * IOVecs[I].NumElm, SEEK_CUR) == -1)
        return 1;
    }
  }
  return 0;
}

/* TODO: make buffer size controllable by an internal option, and compiler can pass the size
   to runtime via a variable. */
static uint32_t orderFileWriter(FILE *File, const uint32_t *DataStart) {
  if (fwrite(DataStart, sizeof(uint32_t), INSTR_ORDER_FILE_BUFFER_SIZE, File) !=
      INSTR_ORDER_FILE_BUFFER_SIZE)
    return 1;
  return 0;
}

static void initFileWriter(ProfDataWriter *This, FILE *File) {
  This->Write = fileWriter;
  This->WriterCtx = File;
}

COMPILER_RT_VISIBILITY ProfBufferIO *
lprofCreateBufferIOInternal(void *File, uint32_t BufferSz) {
  FreeHook = &free;
  DynamicBufferIOBuffer = (uint8_t *)calloc(BufferSz, 1);
  VPBufferSize = BufferSz;
  ProfDataWriter *fileWriter =
      (ProfDataWriter *)calloc(sizeof(ProfDataWriter), 1);
  initFileWriter(fileWriter, File);
  ProfBufferIO *IO = lprofCreateBufferIO(fileWriter);
  IO->OwnFileWriter = 1;
  return IO;
}

static void setupIOBuffer() {
  const char *BufferSzStr = 0;
  BufferSzStr = getenv("LLVM_VP_BUFFER_SIZE");
  if (BufferSzStr && BufferSzStr[0]) {
    VPBufferSize = atoi(BufferSzStr);
    DynamicBufferIOBuffer = (uint8_t *)calloc(VPBufferSize, 1);
  }
}

/* Read profile data in \c ProfileFile and merge with in-memory
   profile counters. Returns -1 if there is fatal error, otheriwse
   0 is returned. Returning 0 does not mean merge is actually
   performed. If merge is actually done, *MergeDone is set to 1.
*/
static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {
  uint64_t ProfileFileSize;
  char *ProfileBuffer;

  if (fseek(ProfileFile, 0L, SEEK_END) == -1) {
    PROF_ERR("Unable to merge profile data, unable to get size: %s\n",
             strerror(errno));
    return -1;
  }
  ProfileFileSize = ftell(ProfileFile);

  /* Restore file offset.  */
  if (fseek(ProfileFile, 0L, SEEK_SET) == -1) {
    PROF_ERR("Unable to merge profile data, unable to rewind: %s\n",
             strerror(errno));
    return -1;
  }

  /* Nothing to merge.  */
  if (ProfileFileSize < sizeof(__llvm_profile_header)) {
    if (ProfileFileSize)
      PROF_WARN("Unable to merge profile data: %s\n",
                "source profile file is too small.");
    return 0;
  }

  ProfileBuffer = mmap(NULL, ProfileFileSize, PROT_READ, MAP_SHARED | MAP_FILE,
                       fileno(ProfileFile), 0);
  if (ProfileBuffer == MAP_FAILED) {
    PROF_ERR("Unable to merge profile data, mmap failed: %s\n",
             strerror(errno));
    return -1;
  }

  if (__llvm_profile_check_compatibility(ProfileBuffer, ProfileFileSize)) {
    (void)munmap(ProfileBuffer, ProfileFileSize);
    PROF_WARN("Unable to merge profile data: %s\n",
              "source profile file is not compatible.");
    return 0;
  }

  /* Now start merging */
  __llvm_profile_merge_from_buffer(ProfileBuffer, ProfileFileSize);

  // Truncate the file in case merging of value profile did not happend to
  // prevent from leaving garbage data at the end of the profile file.
  COMPILER_RT_FTRUNCATE(ProfileFile, __llvm_profile_get_size_for_buffer());

  (void)munmap(ProfileBuffer, ProfileFileSize);
  *MergeDone = 1;

  return 0;
}

/* Create the directory holding the file, if needed. */
static void createProfileDir(const char *Filename) {
  size_t Length = strlen(Filename);
  if (lprofFindFirstDirSeparator(Filename)) {
    char *Copy = (char *)COMPILER_RT_ALLOCA(Length + 1);
    strncpy(Copy, Filename, Length + 1);
    __llvm_profile_recursive_mkdir(Copy);
  }
}

/* Open the profile data for merging. It opens the file in r+b mode with
 * file locking.  If the file has content which is compatible with the
 * current process, it also reads in the profile data in the file and merge
 * it with in-memory counters. After the profile data is merged in memory,
 * the original profile data is truncated and gets ready for the profile
 * dumper. With profile merging enabled, each executable as well as any of
 * its instrumented shared libraries dump profile data into their own data file.
*/
static FILE *openFileForMerging(const char *ProfileFileName, int *MergeDone) {
  FILE *ProfileFile = NULL;
  int rc;

  ProfileFile = getProfileFile();
  if (ProfileFile) {
    lprofLockFileHandle(ProfileFile);
  } else {
    createProfileDir(ProfileFileName);
    ProfileFile = lprofOpenFileEx(ProfileFileName);
  }
  if (!ProfileFile)
    return NULL;

  rc = doProfileMerging(ProfileFile, MergeDone);
  if (rc || (!*MergeDone && COMPILER_RT_FTRUNCATE(ProfileFile, 0L)) ||
      fseek(ProfileFile, 0L, SEEK_SET) == -1) {
    PROF_ERR("Profile Merging of file %s failed: %s\n", ProfileFileName,
             strerror(errno));
    fclose(ProfileFile);
    return NULL;
  }
  return ProfileFile;
}

static FILE *getFileObject(const char *OutputName) {
  FILE *File;
  File = getProfileFile();
  if (File != NULL) {
    return File;
  }

  return fopen(OutputName, "ab");
}

/* Write profile data to file \c OutputName.  */
static int writeFile(const char *OutputName) {
  int RetVal;
  FILE *OutputFile;

  int MergeDone = 0;
  VPMergeHook = &lprofMergeValueProfData;
  if (doMerging())
    OutputFile = openFileForMerging(OutputName, &MergeDone);
  else
    OutputFile = getFileObject(OutputName);

  if (!OutputFile)
    return -1;

  FreeHook = &free;
  setupIOBuffer();
  ProfDataWriter fileWriter;
  initFileWriter(&fileWriter, OutputFile);
  RetVal = lprofWriteData(&fileWriter, lprofGetVPDataReader(), MergeDone);

  if (OutputFile == getProfileFile()) {
    fflush(OutputFile);
    if (doMerging()) {
      lprofUnlockFileHandle(OutputFile);
    }
  } else {
    fclose(OutputFile);
  }

  return RetVal;
}

/* Write order data to file \c OutputName.  */
static int writeOrderFile(const char *OutputName) {
  int RetVal;
  FILE *OutputFile;

  OutputFile = fopen(OutputName, "w");

  if (!OutputFile) {
    PROF_WARN("can't open file with mode ab: %s\n", OutputName);
    return -1;
  }

  FreeHook = &free;
  setupIOBuffer();
  const uint32_t *DataBegin = __llvm_profile_begin_orderfile();
  RetVal = orderFileWriter(OutputFile, DataBegin);

  fclose(OutputFile);
  return RetVal;
}

#define LPROF_INIT_ONCE_ENV "__LLVM_PROFILE_RT_INIT_ONCE"

static void truncateCurrentFile(void) {
  const char *Filename;
  char *FilenameBuf;
  FILE *File;
  int Length;

  Length = getCurFilenameLength();
  FilenameBuf = (char *)COMPILER_RT_ALLOCA(Length + 1);
  Filename = getCurFilename(FilenameBuf, 0);
  if (!Filename)
    return;

  /* By pass file truncation to allow online raw profile
   * merging. */
  if (lprofCurFilename.MergePoolSize)
    return;

  /* Only create the profile directory and truncate an existing profile once.
   * In continuous mode, this is necessary, as the profile is written-to by the
   * runtime initializer. */
  int initialized = getenv(LPROF_INIT_ONCE_ENV) != NULL;
  if (initialized)
    return;
#if defined(_WIN32)
  _putenv(LPROF_INIT_ONCE_ENV "=" LPROF_INIT_ONCE_ENV);
#else
  setenv(LPROF_INIT_ONCE_ENV, LPROF_INIT_ONCE_ENV, 1);
#endif

  createProfileDir(Filename);

  /* Truncate the file.  Later we'll reopen and append. */
  File = fopen(Filename, "w");
  if (!File)
    return;
  fclose(File);
}

static void initializeProfileForContinuousMode(void) {
#if defined(__Fuchsia__) || defined(_WIN32)
  PROF_ERR("%s\n", "Continuous mode not yet supported on Fuchsia or Windows.");
#else // defined(__Fuchsia__) || defined(_WIN32)
  if (!__llvm_profile_is_continuous_mode_enabled())
    return;

  /* Get the sizes of various profile data sections. Taken from
   * __llvm_profile_get_size_for_buffer(). */
  const __llvm_profile_data *DataBegin = __llvm_profile_begin_data();
  const __llvm_profile_data *DataEnd = __llvm_profile_end_data();
  const uint64_t *CountersBegin = __llvm_profile_begin_counters();
  const uint64_t *CountersEnd = __llvm_profile_end_counters();
  const char *NamesBegin = __llvm_profile_begin_names();
  const char *NamesEnd = __llvm_profile_end_names();
  const uint64_t NamesSize = (NamesEnd - NamesBegin) * sizeof(char);
  uint64_t DataSize = __llvm_profile_get_data_size(DataBegin, DataEnd);
  uint64_t CountersSize = CountersEnd - CountersBegin;

  /* Check that the counter and data sections in this image are page-aligned. */
  unsigned PageSize = getpagesize();
  if ((intptr_t)CountersBegin % PageSize != 0) {
    PROF_ERR("Counters section not page-aligned (start = %p, pagesz = %u).\n",
             CountersBegin, PageSize);
    return;
  }
  if ((intptr_t)DataBegin % PageSize != 0) {
    PROF_ERR("Data section not page-aligned (start = %p, pagesz = %u).\n",
             DataBegin, PageSize);
    return;
  }

  /* Open the raw profile in append mode. */
  int Length = getCurFilenameLength();
  char *FilenameBuf = (char *)COMPILER_RT_ALLOCA(Length + 1);
  const char *Filename = getCurFilename(FilenameBuf, 0);
  if (!Filename)
    return;
  FILE *File = fopen(Filename, "a+b");
  if (!File)
    return;

  int Fileno = fileno(File);

  /* Check that the offset within the file is page-aligned. */
  off_t CurrentFileOffset = ftello(File);
  off_t OffsetModPage = CurrentFileOffset % PageSize;
  if (OffsetModPage != 0) {
    PROF_ERR("Continuous counter sync mode is enabled, but raw profile is not"
             "page-aligned. CurrentFileOffset = %" PRIu64 ", pagesz = %u.\n",
             (uint64_t) CurrentFileOffset, PageSize);
    return;
  }

  /* Determine how much padding is needed before/after the counters and after
   * the names. */
  uint64_t PaddingBytesBeforeCounters, PaddingBytesAfterCounters,
      PaddingBytesAfterNames;
  __llvm_profile_get_padding_sizes_for_counters(
      DataSize, CountersSize, NamesSize, &PaddingBytesBeforeCounters,
      &PaddingBytesAfterCounters, &PaddingBytesAfterNames);

  uint64_t PageAlignedCountersLength =
      (CountersSize * sizeof(uint64_t)) + PaddingBytesAfterCounters;
  uint64_t FileOffsetToCounters =
      CurrentFileOffset + sizeof(__llvm_profile_header) +
      (DataSize * sizeof(__llvm_profile_data)) + PaddingBytesBeforeCounters;

  /* Write the partial profile. This grows the file to a point where the mmap()
   * can succeed. Leak the file handle, as the file should stay open. */
  setProfileFile(File);
  int rc = writeFile(Filename);
  if (rc)
    PROF_ERR("Failed to write file \"%s\": %s\n", Filename, strerror(errno));
  setProfileFile(NULL);

  uint64_t *CounterMmap = (uint64_t *)mmap(
      (void *)CountersBegin, PageAlignedCountersLength, PROT_READ | PROT_WRITE,
      MAP_FIXED | MAP_SHARED, Fileno, FileOffsetToCounters);
  if (CounterMmap != CountersBegin) {
    PROF_ERR(
        "Continuous counter sync mode is enabled, but mmap() failed (%s).\n"
        "  - CountersBegin: %p\n"
        "  - PageAlignedCountersLength: %" PRIu64 "\n"
        "  - Fileno: %d\n"
        "  - FileOffsetToCounters: %" PRIu64 "\n",
        strerror(errno), CountersBegin, PageAlignedCountersLength, Fileno,
        FileOffsetToCounters);
    return;
  }
#endif // defined(__Fuchsia__) || defined(_WIN32)
}

static const char *DefaultProfileName = "default.profraw";
static void resetFilenameToDefault(void) {
  if (lprofCurFilename.FilenamePat && lprofCurFilename.OwnsFilenamePat) {
    free((void *)lprofCurFilename.FilenamePat);
  }
  memset(&lprofCurFilename, 0, sizeof(lprofCurFilename));
  lprofCurFilename.FilenamePat = DefaultProfileName;
  lprofCurFilename.PNS = PNS_default;
}

static int containsMergeSpecifier(const char *FilenamePat, int I) {
  return (FilenamePat[I] == 'm' ||
          (FilenamePat[I] >= '1' && FilenamePat[I] <= '9' &&
           /* If FilenamePat[I] is not '\0', the next byte is guaranteed
            * to be in-bound as the string is null terminated. */
           FilenamePat[I + 1] == 'm'));
}

/* Parses the pattern string \p FilenamePat and stores the result to
 * lprofcurFilename structure. */
static int parseFilenamePattern(const char *FilenamePat,
                                unsigned CopyFilenamePat) {
  int NumPids = 0, NumHosts = 0, I;
  char *PidChars = &lprofCurFilename.PidChars[0];
  char *Hostname = &lprofCurFilename.Hostname[0];
  int MergingEnabled = 0;

  /* Clean up cached prefix and filename.  */
  if (lprofCurFilename.ProfilePathPrefix)
    free((void *)lprofCurFilename.ProfilePathPrefix);

  if (lprofCurFilename.FilenamePat && lprofCurFilename.OwnsFilenamePat) {
    free((void *)lprofCurFilename.FilenamePat);
  }

  memset(&lprofCurFilename, 0, sizeof(lprofCurFilename));

  if (!CopyFilenamePat)
    lprofCurFilename.FilenamePat = FilenamePat;
  else {
    lprofCurFilename.FilenamePat = strdup(FilenamePat);
    lprofCurFilename.OwnsFilenamePat = 1;
  }
  /* Check the filename for "%p", which indicates a pid-substitution. */
  for (I = 0; FilenamePat[I]; ++I)
    if (FilenamePat[I] == '%') {
      if (FilenamePat[++I] == 'p') {
        if (!NumPids++) {
          if (snprintf(PidChars, MAX_PID_SIZE, "%ld", (long)getpid()) <= 0) {
            PROF_WARN("Unable to get pid for filename pattern %s. Using the "
                      "default name.",
                      FilenamePat);
            return -1;
          }
        }
      } else if (FilenamePat[I] == 'h') {
        if (!NumHosts++)
          if (COMPILER_RT_GETHOSTNAME(Hostname, COMPILER_RT_MAX_HOSTLEN)) {
            PROF_WARN("Unable to get hostname for filename pattern %s. Using "
                      "the default name.",
                      FilenamePat);
            return -1;
          }
      } else if (FilenamePat[I] == 'c') {
        if (__llvm_profile_is_continuous_mode_enabled()) {
          PROF_WARN("%%c specifier can only be specified once in %s.\n",
                    FilenamePat);
          return -1;
        }
        if (MergingEnabled) {
          PROF_WARN("%%c specifier can not be used with profile merging (%%m) "
                    "in %s.\n",
                    FilenamePat);
          return -1;
        }

        __llvm_profile_enable_continuous_mode();
        I++; /* advance to 'c' */
      } else if (containsMergeSpecifier(FilenamePat, I)) {
        if (MergingEnabled) {
          PROF_WARN("%%m specifier can only be specified once in %s.\n",
                    FilenamePat);
          return -1;
        }
        if (__llvm_profile_is_continuous_mode_enabled()) {
          PROF_WARN("%%c specifier can not be used with profile merging (%%m) "
                    "in %s.\n",
                    FilenamePat);
          return -1;
        }
        MergingEnabled = 1;
        if (FilenamePat[I] == 'm')
          lprofCurFilename.MergePoolSize = 1;
        else {
          lprofCurFilename.MergePoolSize = FilenamePat[I] - '0';
          I++; /* advance to 'm' */
        }
      }
    }

  lprofCurFilename.NumPids = NumPids;
  lprofCurFilename.NumHosts = NumHosts;
  return 0;
}

static void parseAndSetFilename(const char *FilenamePat,
                                ProfileNameSpecifier PNS,
                                unsigned CopyFilenamePat) {

  const char *OldFilenamePat = lprofCurFilename.FilenamePat;
  ProfileNameSpecifier OldPNS = lprofCurFilename.PNS;

  /* The old profile name specifier takes precedence over the old one. */
  if (PNS < OldPNS)
    return;

  if (!FilenamePat)
    FilenamePat = DefaultProfileName;

  if (OldFilenamePat && !strcmp(OldFilenamePat, FilenamePat)) {
    lprofCurFilename.PNS = PNS;
    return;
  }

  /* When PNS >= OldPNS, the last one wins. */
  if (!FilenamePat || parseFilenamePattern(FilenamePat, CopyFilenamePat))
    resetFilenameToDefault();
  lprofCurFilename.PNS = PNS;

  if (!OldFilenamePat) {
    if (getenv("LLVM_PROFILE_VERBOSE"))
      PROF_NOTE("Set profile file path to \"%s\" via %s.\n",
                lprofCurFilename.FilenamePat, getPNSStr(PNS));
  } else {
    if (getenv("LLVM_PROFILE_VERBOSE"))
      PROF_NOTE("Override old profile path \"%s\" via %s to \"%s\" via %s.\n",
                OldFilenamePat, getPNSStr(OldPNS), lprofCurFilename.FilenamePat,
                getPNSStr(PNS));
  }

  truncateCurrentFile();
  initializeProfileForContinuousMode();
}

/* Return buffer length that is required to store the current profile
 * filename with PID and hostname substitutions. */
/* The length to hold uint64_t followed by 2 digit pool id including '_' */
#define SIGLEN 24
static int getCurFilenameLength() {
  int Len;
  if (!lprofCurFilename.FilenamePat || !lprofCurFilename.FilenamePat[0])
    return 0;

  if (!(lprofCurFilename.NumPids || lprofCurFilename.NumHosts ||
        lprofCurFilename.MergePoolSize))
    return strlen(lprofCurFilename.FilenamePat);

  Len = strlen(lprofCurFilename.FilenamePat) +
        lprofCurFilename.NumPids * (strlen(lprofCurFilename.PidChars) - 2) +
        lprofCurFilename.NumHosts * (strlen(lprofCurFilename.Hostname) - 2);
  if (lprofCurFilename.MergePoolSize)
    Len += SIGLEN;
  return Len;
}

/* Return the pointer to the current profile file name (after substituting
 * PIDs and Hostnames in filename pattern. \p FilenameBuf is the buffer
 * to store the resulting filename. If no substitution is needed, the
 * current filename pattern string is directly returned, unless ForceUseBuf
 * is enabled. */
static const char *getCurFilename(char *FilenameBuf, int ForceUseBuf) {
  int I, J, PidLength, HostNameLength, FilenamePatLength;
  const char *FilenamePat = lprofCurFilename.FilenamePat;

  if (!lprofCurFilename.FilenamePat || !lprofCurFilename.FilenamePat[0])
    return 0;

  if (!(lprofCurFilename.NumPids || lprofCurFilename.NumHosts ||
        lprofCurFilename.MergePoolSize ||
        __llvm_profile_is_continuous_mode_enabled())) {
    if (!ForceUseBuf)
      return lprofCurFilename.FilenamePat;

    FilenamePatLength = strlen(lprofCurFilename.FilenamePat);
    memcpy(FilenameBuf, lprofCurFilename.FilenamePat, FilenamePatLength);
    FilenameBuf[FilenamePatLength] = '\0';
    return FilenameBuf;
  }

  PidLength = strlen(lprofCurFilename.PidChars);
  HostNameLength = strlen(lprofCurFilename.Hostname);
  /* Construct the new filename. */
  for (I = 0, J = 0; FilenamePat[I]; ++I)
    if (FilenamePat[I] == '%') {
      if (FilenamePat[++I] == 'p') {
        memcpy(FilenameBuf + J, lprofCurFilename.PidChars, PidLength);
        J += PidLength;
      } else if (FilenamePat[I] == 'h') {
        memcpy(FilenameBuf + J, lprofCurFilename.Hostname, HostNameLength);
        J += HostNameLength;
      } else if (containsMergeSpecifier(FilenamePat, I)) {
        char LoadModuleSignature[SIGLEN];
        int S;
        int ProfilePoolId = getpid() % lprofCurFilename.MergePoolSize;
        S = snprintf(LoadModuleSignature, SIGLEN, "%" PRIu64 "_%d",
                     lprofGetLoadModuleSignature(), ProfilePoolId);
        if (S == -1 || S > SIGLEN)
          S = SIGLEN;
        memcpy(FilenameBuf + J, LoadModuleSignature, S);
        J += S;
        if (FilenamePat[I] != 'm')
          I++;
      }
      /* Drop any unknown substitutions. */
    } else
      FilenameBuf[J++] = FilenamePat[I];
  FilenameBuf[J] = 0;

  return FilenameBuf;
}

/* Returns the pointer to the environment variable
 * string. Returns null if the env var is not set. */
static const char *getFilenamePatFromEnv(void) {
  const char *Filename = getenv("LLVM_PROFILE_FILE");
  if (!Filename || !Filename[0])
    return 0;
  return Filename;
}

COMPILER_RT_VISIBILITY
const char *__llvm_profile_get_path_prefix(void) {
  int Length;
  char *FilenameBuf, *Prefix;
  const char *Filename, *PrefixEnd;

  if (lprofCurFilename.ProfilePathPrefix)
    return lprofCurFilename.ProfilePathPrefix;

  Length = getCurFilenameLength();
  FilenameBuf = (char *)COMPILER_RT_ALLOCA(Length + 1);
  Filename = getCurFilename(FilenameBuf, 0);
  if (!Filename)
    return "\0";

  PrefixEnd = lprofFindLastDirSeparator(Filename);
  if (!PrefixEnd)
    return "\0";

  Length = PrefixEnd - Filename + 1;
  Prefix = (char *)malloc(Length + 1);
  if (!Prefix) {
    PROF_ERR("Failed to %s\n", "allocate memory.");
    return "\0";
  }
  memcpy(Prefix, Filename, Length);
  Prefix[Length] = '\0';
  lprofCurFilename.ProfilePathPrefix = Prefix;
  return Prefix;
}

COMPILER_RT_VISIBILITY
const char *__llvm_profile_get_filename(void) {
  int Length;
  char *FilenameBuf;
  const char *Filename;

  Length = getCurFilenameLength();
  FilenameBuf = (char *)malloc(Length + 1);
  if (!FilenameBuf) {
    PROF_ERR("Failed to %s\n", "allocate memory.");
    return "\0";
  }
  Filename = getCurFilename(FilenameBuf, 1);
  if (!Filename)
    return "\0";

  return FilenameBuf;
}

/* This method is invoked by the runtime initialization hook
 * InstrProfilingRuntime.o if it is linked in. Both user specified
 * profile path via -fprofile-instr-generate= and LLVM_PROFILE_FILE
 * environment variable can override this default value. */
COMPILER_RT_VISIBILITY
void __llvm_profile_initialize_file(void) {
  const char *EnvFilenamePat;
  const char *SelectedPat = NULL;
  ProfileNameSpecifier PNS = PNS_unknown;
  int hasCommandLineOverrider = (INSTR_PROF_PROFILE_NAME_VAR[0] != 0);

  EnvFilenamePat = getFilenamePatFromEnv();
  if (EnvFilenamePat) {
    /* Pass CopyFilenamePat = 1, to ensure that the filename would be valid
       at the  moment when __llvm_profile_write_file() gets executed. */
    parseAndSetFilename(EnvFilenamePat, PNS_environment, 1);
    return;
  } else if (hasCommandLineOverrider) {
    SelectedPat = INSTR_PROF_PROFILE_NAME_VAR;
    PNS = PNS_command_line;
  } else {
    SelectedPat = NULL;
    PNS = PNS_default;
  }

  parseAndSetFilename(SelectedPat, PNS, 0);
}

/* This API is directly called by the user application code. It has the
 * highest precedence compared with LLVM_PROFILE_FILE environment variable
 * and command line option -fprofile-instr-generate=<profile_name>.
 */
COMPILER_RT_VISIBILITY
void __llvm_profile_set_filename(const char *FilenamePat) {
  if (__llvm_profile_is_continuous_mode_enabled())
    return;
  parseAndSetFilename(FilenamePat, PNS_runtime_api, 1);
}

/* The public API for writing profile data into the file with name
 * set by previous calls to __llvm_profile_set_filename or
 * __llvm_profile_override_default_filename or
 * __llvm_profile_initialize_file. */
COMPILER_RT_VISIBILITY
int __llvm_profile_write_file(void) {
  int rc, Length;
  const char *Filename;
  char *FilenameBuf;
  int PDeathSig = 0;

  if (lprofProfileDumped() || __llvm_profile_is_continuous_mode_enabled()) {
    PROF_NOTE("Profile data not written to file: %s.\n", "already written");
    return 0;
  }

  Length = getCurFilenameLength();
  FilenameBuf = (char *)COMPILER_RT_ALLOCA(Length + 1);
  Filename = getCurFilename(FilenameBuf, 0);

  /* Check the filename. */
  if (!Filename) {
    PROF_ERR("Failed to write file : %s\n", "Filename not set");
    return -1;
  }

  /* Check if there is llvm/runtime version mismatch.  */
  if (GET_VERSION(__llvm_profile_get_version()) != INSTR_PROF_RAW_VERSION) {
    PROF_ERR("Runtime and instrumentation version mismatch : "
             "expected %d, but get %d\n",
             INSTR_PROF_RAW_VERSION,
             (int)GET_VERSION(__llvm_profile_get_version()));
    return -1;
  }

  // Temporarily suspend getting SIGKILL when the parent exits.
  PDeathSig = lprofSuspendSigKill();

  /* Write profile data to the file. */
  rc = writeFile(Filename);
  if (rc)
    PROF_ERR("Failed to write file \"%s\": %s\n", Filename, strerror(errno));

  // Restore SIGKILL.
  if (PDeathSig == 1)
    lprofRestoreSigKill();

  return rc;
}

COMPILER_RT_VISIBILITY
int __llvm_profile_dump(void) {
  if (!doMerging())
    PROF_WARN("Later invocation of __llvm_profile_dump can lead to clobbering "
              " of previously dumped profile data : %s. Either use %%m "
              "in profile name or change profile name before dumping.\n",
              "online profile merging is not on");
  int rc = __llvm_profile_write_file();
  lprofSetProfileDumped();
  return rc;
}

/* Order file data will be saved in a file with suffx .order. */
static const char *OrderFileSuffix = ".order";

COMPILER_RT_VISIBILITY
int __llvm_orderfile_write_file(void) {
  int rc, Length, LengthBeforeAppend, SuffixLength;
  const char *Filename;
  char *FilenameBuf;
  int PDeathSig = 0;

  SuffixLength = strlen(OrderFileSuffix);
  Length = getCurFilenameLength() + SuffixLength;
  FilenameBuf = (char *)COMPILER_RT_ALLOCA(Length + 1);
  Filename = getCurFilename(FilenameBuf, 1);

  /* Check the filename. */
  if (!Filename) {
    PROF_ERR("Failed to write file : %s\n", "Filename not set");
    return -1;
  }

  /* Append order file suffix */
  LengthBeforeAppend = strlen(Filename);
  memcpy(FilenameBuf + LengthBeforeAppend, OrderFileSuffix, SuffixLength);
  FilenameBuf[LengthBeforeAppend + SuffixLength] = '\0';

  /* Check if there is llvm/runtime version mismatch.  */
  if (GET_VERSION(__llvm_profile_get_version()) != INSTR_PROF_RAW_VERSION) {
    PROF_ERR("Runtime and instrumentation version mismatch : "
             "expected %d, but get %d\n",
             INSTR_PROF_RAW_VERSION,
             (int)GET_VERSION(__llvm_profile_get_version()));
    return -1;
  }

  // Temporarily suspend getting SIGKILL when the parent exits.
  PDeathSig = lprofSuspendSigKill();

  /* Write order data to the file. */
  rc = writeOrderFile(Filename);
  if (rc)
    PROF_ERR("Failed to write file \"%s\": %s\n", Filename, strerror(errno));

  // Restore SIGKILL.
  if (PDeathSig == 1)
    lprofRestoreSigKill();

  return rc;
}

COMPILER_RT_VISIBILITY
int __llvm_orderfile_dump(void) {
  int rc = __llvm_orderfile_write_file();
  return rc;
}

static void writeFileWithoutReturn(void) { __llvm_profile_write_file(); }

COMPILER_RT_VISIBILITY
int __llvm_profile_register_write_file_atexit(void) {
  static int HasBeenRegistered = 0;

  if (HasBeenRegistered)
    return 0;

  lprofSetupValueProfiler();

  HasBeenRegistered = 1;
  return atexit(writeFileWithoutReturn);
}

#endif