diff -r 000000000000 -r 6474c204b198 xpcom/glue/FileUtils.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/xpcom/glue/FileUtils.h Wed Dec 31 06:09:35 2014 +0100 @@ -0,0 +1,218 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_FileUtils_h +#define mozilla_FileUtils_h + +#include "nscore.h" // nullptr + +#if defined(XP_UNIX) +# include +#elif defined(XP_WIN) +# include +#endif +#include "prio.h" + +#include "mozilla/Scoped.h" +#include "nsIFile.h" +#include +#include + +namespace mozilla { + +#if defined(XP_WIN) +typedef void* filedesc_t; +typedef const wchar_t* pathstr_t; +#else +typedef int filedesc_t; +typedef const char* pathstr_t; +#endif + +/** + * ScopedCloseFD is a RAII wrapper for POSIX file descriptors + * + * Instances |close()| their fds when they go out of scope. + */ +struct ScopedCloseFDTraits +{ + typedef int type; + static type empty() { return -1; } + static void release(type fd) { + if (fd != -1) { + while ((close(fd) == -1) && (errno == EINTR)) { + ; + } + } + } +}; +typedef Scoped ScopedClose; + +#if !defined(XPCOM_GLUE) + +/** + * AutoFDClose is a RAII wrapper for PRFileDesc. + * + * Instances |PR_Close| their fds when they go out of scope. + **/ +struct ScopedClosePRFDTraits +{ + typedef PRFileDesc* type; + static type empty() { return nullptr; } + static void release(type fd) { + if (fd != nullptr) { + PR_Close(fd); + } + } +}; +typedef Scoped AutoFDClose; + +/* RAII wrapper for FILE descriptors */ +struct ScopedCloseFileTraits +{ + typedef FILE *type; + static type empty() { return nullptr; } + static void release(type f) { + if (f) { + fclose(f); + } + } +}; +typedef Scoped ScopedCloseFile; + +/** + * Fallocate efficiently and continuously allocates files via fallocate-type APIs. + * This is useful for avoiding fragmentation. + * On sucess the file be padded with zeros to grow to aLength. + * + * @param aFD file descriptor. + * @param aLength length of file to grow to. + * @return true on success. + */ +NS_COM_GLUE bool fallocate(PRFileDesc *aFD, int64_t aLength); + +/** + * Use readahead to preload shared libraries into the file cache before loading. + * WARNING: This function should not be used without a telemetry field trial + * demonstrating a clear performance improvement! + * + * @param aFile nsIFile representing path to shared library + */ +NS_COM_GLUE void ReadAheadLib(nsIFile* aFile); + +/** + * Use readahead to preload a file into the file cache before reading. + * WARNING: This function should not be used without a telemetry field trial + * demonstrating a clear performance improvement! + * + * @param aFile nsIFile representing path to shared library + * @param aOffset Offset into the file to begin preloading + * @param aCount Number of bytes to preload (SIZE_MAX implies file size) + * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will + * return its internal, opened file descriptor instead of closing it. + */ +NS_COM_GLUE void ReadAheadFile(nsIFile* aFile, const size_t aOffset = 0, + const size_t aCount = SIZE_MAX, + filedesc_t* aOutFd = nullptr); + +#endif // !defined(XPCOM_GLUE) + +/** + * Use readahead to preload shared libraries into the file cache before loading. + * WARNING: This function should not be used without a telemetry field trial + * demonstrating a clear performance improvement! + * + * @param aFilePath path to shared library + */ +NS_COM_GLUE void ReadAheadLib(pathstr_t aFilePath); + +/** + * Use readahead to preload a file into the file cache before loading. + * WARNING: This function should not be used without a telemetry field trial + * demonstrating a clear performance improvement! + * + * @param aFilePath path to shared library + * @param aOffset Offset into the file to begin preloading + * @param aCount Number of bytes to preload (SIZE_MAX implies file size) + * @param aOutFd Pointer to file descriptor. If specified, ReadAheadFile will + * return its internal, opened file descriptor instead of closing it. + */ +NS_COM_GLUE void ReadAheadFile(pathstr_t aFilePath, const size_t aOffset = 0, + const size_t aCount = SIZE_MAX, + filedesc_t* aOutFd = nullptr); + +/** + * Use readahead to preload a file into the file cache before reading. + * When this function exits, the file pointer is guaranteed to be in the same + * position it was in before this function was called. + * WARNING: This function should not be used without a telemetry field trial + * demonstrating a clear performance improvement! + * + * @param aFd file descriptor opened for read access + * (on Windows, file must be opened with FILE_FLAG_SEQUENTIAL_SCAN) + * @param aOffset Offset into the file to begin preloading + * @param aCount Number of bytes to preload (SIZE_MAX implies file size) + */ +NS_COM_GLUE void ReadAhead(filedesc_t aFd, const size_t aOffset = 0, + const size_t aCount = SIZE_MAX); + + +/* Define ReadSysFile() only on GONK to avoid unnecessary lubxul bloat. +Also define it in debug builds, so that unit tests for it can be written +and run in non-GONK builds. */ +#if (defined(MOZ_WIDGET_GONK) || defined(DEBUG)) && defined(XP_UNIX) + +#ifndef ReadSysFile_PRESENT +#define ReadSysFile_PRESENT +#endif /* ReadSysFile_PRESENT */ + +#define MOZ_TEMP_FAILURE_RETRY(exp) (__extension__({ \ + typeof (exp) _rc; \ + do { \ + _rc = (exp); \ + } while (_rc == -1 && errno == EINTR); \ + _rc; \ +})) + +/** + * Read the contents of a file. + * This function is intended for reading a single-lined text files from + * /sys/. If the file ends with a newline ('\n') then it will be discarded. + * The output buffer will always be '\0'-terminated on successful completion. + * If aBufSize == 0, then this function will return true if the file exists + * and is readable (it will not attempt to read anything from it). + * On failure the contents of aBuf after this call will be undefined and the + * value of the global variable errno will be set accordingly. + * @return true on success, notice that less than requested bytes could have + * been read if the file was smaller + */ +bool +ReadSysFile( + const char* aFilename, + char* aBuf, + size_t aBufSize); + +/** + * Parse the contents of a file, assuming it contains a decimal integer. + * @return true on success + */ +bool +ReadSysFile( + const char* aFilename, + int* aVal); + +/** + * Parse the contents of a file, assuming it contains a boolean value + * (either 0 or 1). + * @return true on success + */ +bool +ReadSysFile( + const char* aFilename, + bool* aVal); + +#endif /* (MOZ_WIDGET_GONK || DEBUG) && XP_UNIX */ + +} // namespace mozilla +#endif