xpcom/glue/FileUtils.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_FileUtils_h
   8 #define mozilla_FileUtils_h
   9
  10 #include "nscore.h"  // nullptr
  11
  12 #if defined(XP_UNIX)
  13 #  include <unistd.h>
  14 #elif defined(XP_WIN)
  15 #  include <io.h>
  16 #endif
  17 #include "prio.h"
  18 #include "prlink.h"
  19
  20 #include "mozilla/Scoped.h"
  21 #include "nsIFile.h"
  22 #include <errno.h>
  23 #include <limits.h>
  24
  25 namespace mozilla {
  26
  27 #if defined(XP_WIN)
  28 typedef void* filedesc_t;
  29 typedef const wchar_t* pathstr_t;
  30 #else
  31 typedef int filedesc_t;
  32 typedef const char* pathstr_t;
  33 #endif
  34
  35 /**
  36  * ScopedCloseFD is a RAII wrapper for POSIX file descriptors
  37  *
  38  * Instances |close()| their fds when they go out of scope.
  39  */
  40 struct ScopedCloseFDTraits {
  41   typedef int type;
  42   static type empty() { return -1; }
  43   static void release(type aFd) {
  44     if (aFd != -1) {
  45       while (close(aFd) == -1 && errno == EINTR) {
  46       }
  47     }
  48   }
  49 };
  50 typedef Scoped<ScopedCloseFDTraits> ScopedClose;
  51
  52 #if defined(MOZILLA_INTERNAL_API)
  53
  54 /**
  55  * AutoFDClose is a RAII wrapper for PRFileDesc.
  56  *
  57  * Instances |PR_Close| their fds when they go out of scope.
  58  **/
  59 struct ScopedClosePRFDTraits {
  60   typedef PRFileDesc* type;
  61   static type empty() { return nullptr; }
  62   static void release(type aFd) {
  63     if (aFd) {
  64       PR_Close(aFd);
  65     }
  66   }
  67 };
  68 typedef Scoped<ScopedClosePRFDTraits> AutoFDClose;
  69
  70 /* RAII wrapper for FILE descriptors */
  71 struct ScopedCloseFileTraits {
  72   typedef FILE* type;
  73   static type empty() { return nullptr; }
  74   static void release(type aFile) {
  75     if (aFile) {
  76       fclose(aFile);
  77     }
  78   }
  79 };
  80 typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
  81
  82 /**
  83  * Fallocate efficiently and continuously allocates files via fallocate-type
  84  * APIs. This is useful for avoiding fragmentation. On sucess the file be padded
  85  * with zeros to grow to aLength.
  86  *
  87  * @param aFD file descriptor.
  88  * @param aLength length of file to grow to.
  89  * @return true on success.
  90  */
  91 bool fallocate(PRFileDesc* aFD, int64_t aLength);
  92
  93 /**
  94  * Use readahead to preload shared libraries into the file cache before loading.
  95  * WARNING: This function should not be used without a telemetry field trial
  96  *          demonstrating a clear performance improvement!
  97  *
  98  * @param aFile nsIFile representing path to shared library
  99  */
 100 void ReadAheadLib(nsIFile* aFile);
 101
 102 /**
 103  * Use readahead to preload a file into the file cache before reading.
 104  * WARNING: This function should not be used without a telemetry field trial
 105  *          demonstrating a clear performance improvement!
 106  *
 107  * @param aFile nsIFile representing path to shared library
 108  * @param aOffset Offset into the file to begin preloading
 109  * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
 110  * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
 111  *        return its internal, opened file descriptor instead of closing it.
 112  */
 113 void ReadAheadFile(nsIFile* aFile, const size_t aOffset = 0,
 114                    const size_t aCount = SIZE_MAX,
 115                    filedesc_t* aOutFd = nullptr);
 116
 117 /*
 118  * Wrappers for PR_GetLibraryName and PR_GetLibraryFilePathname.
 119  */
 120 PathString GetLibraryName(pathstr_t aDirectory, const char* aLib);
 121 PathString GetLibraryFilePathname(pathstr_t aName, PRFuncPtr aAddr);
 122
 123 #endif  // MOZILLA_INTERNAL_API
 124
 125 /**
 126  * Use readahead to preload shared libraries into the file cache before loading.
 127  * WARNING: This function should not be used without a telemetry field trial
 128  *          demonstrating a clear performance improvement!
 129  *
 130  * @param aFilePath path to shared library
 131  */
 132 void ReadAheadLib(pathstr_t aFilePath);
 133
 134 /**
 135  * Use readahead to preload a file into the file cache before loading.
 136  * WARNING: This function should not be used without a telemetry field trial
 137  *          demonstrating a clear performance improvement!
 138  *
 139  * @param aFilePath path to shared library
 140  * @param aOffset Offset into the file to begin preloading
 141  * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
 142  * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
 143  *        return its internal, opened file descriptor instead of closing it.
 144  */
 145 void ReadAheadFile(pathstr_t aFilePath, const size_t aOffset = 0,
 146                    const size_t aCount = SIZE_MAX,
 147                    filedesc_t* aOutFd = nullptr);
 148
 149 /**
 150  * Use readahead to preload a file into the file cache before reading.
 151  * When this function exits, the file pointer is guaranteed to be in the same
 152  * position it was in before this function was called.
 153  * WARNING: This function should not be used without a telemetry field trial
 154  *          demonstrating a clear performance improvement!
 155  *
 156  * @param aFd file descriptor opened for read access
 157  * (on Windows, file must be opened with FILE_FLAG_SEQUENTIAL_SCAN)
 158  * @param aOffset Offset into the file to begin preloading
 159  * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
 160  */
 161 void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
 162                const size_t aCount = SIZE_MAX);
 163
 164 #if defined(XP_UNIX)
 165 #  define MOZ_TEMP_FAILURE_RETRY(exp)        \
 166     (__extension__({                         \
 167       typeof(exp) _rc;                       \
 168       do {                                   \
 169         _rc = (exp);                         \
 170       } while (_rc == -1 && errno == EINTR); \
 171       _rc;                                   \
 172     }))
 173 #endif
 174
 175 }  // namespace mozilla
 176
 177 #endif