1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/xpcom/glue/FileUtils.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,218 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef mozilla_FileUtils_h
1.10 +#define mozilla_FileUtils_h
1.11 +
1.12 +#include "nscore.h" // nullptr
1.13 +
1.14 +#if defined(XP_UNIX)
1.15 +# include <unistd.h>
1.16 +#elif defined(XP_WIN)
1.17 +# include <io.h>
1.18 +#endif
1.19 +#include "prio.h"
1.20 +
1.21 +#include "mozilla/Scoped.h"
1.22 +#include "nsIFile.h"
1.23 +#include <errno.h>
1.24 +#include <limits.h>
1.25 +
1.26 +namespace mozilla {
1.27 +
1.28 +#if defined(XP_WIN)
1.29 +typedef void* filedesc_t;
1.30 +typedef const wchar_t* pathstr_t;
1.31 +#else
1.32 +typedef int filedesc_t;
1.33 +typedef const char* pathstr_t;
1.34 +#endif
1.35 +
1.36 +/**
1.37 + * ScopedCloseFD is a RAII wrapper for POSIX file descriptors
1.38 + *
1.39 + * Instances |close()| their fds when they go out of scope.
1.40 + */
1.41 +struct ScopedCloseFDTraits
1.42 +{
1.43 + typedef int type;
1.44 + static type empty() { return -1; }
1.45 + static void release(type fd) {
1.46 + if (fd != -1) {
1.47 + while ((close(fd) == -1) && (errno == EINTR)) {
1.48 + ;
1.49 + }
1.50 + }
1.51 + }
1.52 +};
1.53 +typedef Scoped<ScopedCloseFDTraits> ScopedClose;
1.54 +
1.55 +#if !defined(XPCOM_GLUE)
1.56 +
1.57 +/**
1.58 + * AutoFDClose is a RAII wrapper for PRFileDesc.
1.59 + *
1.60 + * Instances |PR_Close| their fds when they go out of scope.
1.61 + **/
1.62 +struct ScopedClosePRFDTraits
1.63 +{
1.64 + typedef PRFileDesc* type;
1.65 + static type empty() { return nullptr; }
1.66 + static void release(type fd) {
1.67 + if (fd != nullptr) {
1.68 + PR_Close(fd);
1.69 + }
1.70 + }
1.71 +};
1.72 +typedef Scoped<ScopedClosePRFDTraits> AutoFDClose;
1.73 +
1.74 +/* RAII wrapper for FILE descriptors */
1.75 +struct ScopedCloseFileTraits
1.76 +{
1.77 + typedef FILE *type;
1.78 + static type empty() { return nullptr; }
1.79 + static void release(type f) {
1.80 + if (f) {
1.81 + fclose(f);
1.82 + }
1.83 + }
1.84 +};
1.85 +typedef Scoped<ScopedCloseFileTraits> ScopedCloseFile;
1.86 +
1.87 +/**
1.88 + * Fallocate efficiently and continuously allocates files via fallocate-type APIs.
1.89 + * This is useful for avoiding fragmentation.
1.90 + * On sucess the file be padded with zeros to grow to aLength.
1.91 + *
1.92 + * @param aFD file descriptor.
1.93 + * @param aLength length of file to grow to.
1.94 + * @return true on success.
1.95 + */
1.96 +NS_COM_GLUE bool fallocate(PRFileDesc *aFD, int64_t aLength);
1.97 +
1.98 +/**
1.99 + * Use readahead to preload shared libraries into the file cache before loading.
1.100 + * WARNING: This function should not be used without a telemetry field trial
1.101 + * demonstrating a clear performance improvement!
1.102 + *
1.103 + * @param aFile nsIFile representing path to shared library
1.104 + */
1.105 +NS_COM_GLUE void ReadAheadLib(nsIFile* aFile);
1.106 +
1.107 +/**
1.108 + * Use readahead to preload a file into the file cache before reading.
1.109 + * WARNING: This function should not be used without a telemetry field trial
1.110 + * demonstrating a clear performance improvement!
1.111 + *
1.112 + * @param aFile nsIFile representing path to shared library
1.113 + * @param aOffset Offset into the file to begin preloading
1.114 + * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
1.115 + * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
1.116 + * return its internal, opened file descriptor instead of closing it.
1.117 + */
1.118 +NS_COM_GLUE void ReadAheadFile(nsIFile* aFile, const size_t aOffset = 0,
1.119 + const size_t aCount = SIZE_MAX,
1.120 + filedesc_t* aOutFd = nullptr);
1.121 +
1.122 +#endif // !defined(XPCOM_GLUE)
1.123 +
1.124 +/**
1.125 + * Use readahead to preload shared libraries into the file cache before loading.
1.126 + * WARNING: This function should not be used without a telemetry field trial
1.127 + * demonstrating a clear performance improvement!
1.128 + *
1.129 + * @param aFilePath path to shared library
1.130 + */
1.131 +NS_COM_GLUE void ReadAheadLib(pathstr_t aFilePath);
1.132 +
1.133 +/**
1.134 + * Use readahead to preload a file into the file cache before loading.
1.135 + * WARNING: This function should not be used without a telemetry field trial
1.136 + * demonstrating a clear performance improvement!
1.137 + *
1.138 + * @param aFilePath path to shared library
1.139 + * @param aOffset Offset into the file to begin preloading
1.140 + * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
1.141 + * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will
1.142 + * return its internal, opened file descriptor instead of closing it.
1.143 + */
1.144 +NS_COM_GLUE void ReadAheadFile(pathstr_t aFilePath, const size_t aOffset = 0,
1.145 + const size_t aCount = SIZE_MAX,
1.146 + filedesc_t* aOutFd = nullptr);
1.147 +
1.148 +/**
1.149 + * Use readahead to preload a file into the file cache before reading.
1.150 + * When this function exits, the file pointer is guaranteed to be in the same
1.151 + * position it was in before this function was called.
1.152 + * WARNING: This function should not be used without a telemetry field trial
1.153 + * demonstrating a clear performance improvement!
1.154 + *
1.155 + * @param aFd file descriptor opened for read access
1.156 + * (on Windows, file must be opened with FILE_FLAG_SEQUENTIAL_SCAN)
1.157 + * @param aOffset Offset into the file to begin preloading
1.158 + * @param aCount Number of bytes to preload (SIZE_MAX implies file size)
1.159 + */
1.160 +NS_COM_GLUE void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
1.161 + const size_t aCount = SIZE_MAX);
1.162 +
1.163 +
1.164 +/* Define ReadSysFile() only on GONK to avoid unnecessary lubxul bloat.
1.165 +Also define it in debug builds, so that unit tests for it can be written
1.166 +and run in non-GONK builds. */
1.167 +#if (defined(MOZ_WIDGET_GONK) || defined(DEBUG)) && defined(XP_UNIX)
1.168 +
1.169 +#ifndef ReadSysFile_PRESENT
1.170 +#define ReadSysFile_PRESENT
1.171 +#endif /* ReadSysFile_PRESENT */
1.172 +
1.173 +#define MOZ_TEMP_FAILURE_RETRY(exp) (__extension__({ \
1.174 + typeof (exp) _rc; \
1.175 + do { \
1.176 + _rc = (exp); \
1.177 + } while (_rc == -1 && errno == EINTR); \
1.178 + _rc; \
1.179 +}))
1.180 +
1.181 +/**
1.182 + * Read the contents of a file.
1.183 + * This function is intended for reading a single-lined text files from
1.184 + * /sys/. If the file ends with a newline ('\n') then it will be discarded.
1.185 + * The output buffer will always be '\0'-terminated on successful completion.
1.186 + * If aBufSize == 0, then this function will return true if the file exists
1.187 + * and is readable (it will not attempt to read anything from it).
1.188 + * On failure the contents of aBuf after this call will be undefined and the
1.189 + * value of the global variable errno will be set accordingly.
1.190 + * @return true on success, notice that less than requested bytes could have
1.191 + * been read if the file was smaller
1.192 + */
1.193 +bool
1.194 +ReadSysFile(
1.195 + const char* aFilename,
1.196 + char* aBuf,
1.197 + size_t aBufSize);
1.198 +
1.199 +/**
1.200 + * Parse the contents of a file, assuming it contains a decimal integer.
1.201 + * @return true on success
1.202 + */
1.203 +bool
1.204 +ReadSysFile(
1.205 + const char* aFilename,
1.206 + int* aVal);
1.207 +
1.208 +/**
1.209 + * Parse the contents of a file, assuming it contains a boolean value
1.210 + * (either 0 or 1).
1.211 + * @return true on success
1.212 + */
1.213 +bool
1.214 +ReadSysFile(
1.215 + const char* aFilename,
1.216 + bool* aVal);
1.217 +
1.218 +#endif /* (MOZ_WIDGET_GONK || DEBUG) && XP_UNIX */
1.219 +
1.220 +} // namespace mozilla
1.221 +#endif
