1 files changed, 220 insertions, 0 deletions
diff --git a/xpcom/glue/FileUtils.h b/xpcom/glue/FileUtils.h
new file mode 100644
index 000000000..aaf912b21
--- /dev/null
+++ b/xpcom/glue/FileUtils.h
@@ -0,0 +1,220 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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 <unistd.h>
+#elif defined(XP_WIN)
+# include <io.h>
+#endif
+#include "prio.h"
+
+#include "mozilla/Scoped.h"
+#include "nsIFile.h"
+#include <errno.h>
+#include <limits.h>
+
+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 aFd)
+  {
+    if (aFd != -1) {
+      while (close(aFd) == -1 && errno == EINTR) {
+      }
+    }
+  }
+};
+typedef Scoped<ScopedCloseFDTraits> 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 aFd)
+  {
+    if (aFd) {
+      PR_Close(aFd);
+    }
+  }
+};
+typedef Scoped<ScopedClosePRFDTraits> AutoFDClose;
+
+/* RAII wrapper for FILE descriptors */
+struct ScopedCloseFileTraits
+{
+  typedef FILE* type;
+  static type empty() { return nullptr; }
+  static void release(type aFile)
+  {
+    if (aFile) {
+      fclose(aFile);
+    }
+  }
+};
+typedef Scoped<ScopedCloseFileTraits> 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.
+ */
+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
+ */
+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.
+ */
+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
+ */
+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.
+ */
+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)
+ */
+void ReadAhead(filedesc_t aFd, const size_t aOffset = 0,
+               const size_t aCount = SIZE_MAX);
+
+
+#if defined(MOZ_WIDGET_GONK) || defined(XP_UNIX)
+#define MOZ_TEMP_FAILURE_RETRY(exp) (__extension__({ \
+  typeof (exp) _rc; \
+  do { \
+    _rc = (exp); \
+  } while (_rc == -1 && errno == EINTR); \
+  _rc; \
+}))
+#endif
+
+/* Define ReadSysFile() and WriteSysFile() only on GONK to avoid unnecessary
+ * libxul 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 */
+
+#ifndef WriteSysFile_PRESENT
+#define WriteSysFile_PRESENT
+#endif /* WriteSysFile_PRESENT */
+
+/**
+ * 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);
+
+bool WriteSysFile(const char* aFilename, const char* aBuf);
+
+#endif /* (MOZ_WIDGET_GONK || DEBUG) && XP_UNIX */
+
+} // namespace mozilla
+
+#endif