gecko-dev/xpcom/glue/FileUtils.cpp

97 lines
2.8 KiB
C++

/* -*- 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/. */
#if defined(XP_UNIX)
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#elif defined(XP_WIN)
#include <windows.h>
#elif defined(XP_OS2)
#define INCL_DOSFILEMGR
#include <os2.h>
#endif
#include "nscore.h"
#include "private/pprio.h"
#include "mozilla/FileUtils.h"
bool
mozilla::fallocate(PRFileDesc *aFD, int64_t aLength)
{
#if defined(HAVE_POSIX_FALLOCATE)
return posix_fallocate(PR_FileDesc2NativeHandle(aFD), 0, aLength) == 0;
#elif defined(XP_WIN)
int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
if (oldpos == -1)
return false;
if (PR_Seek64(aFD, aLength, PR_SEEK_SET) != aLength)
return false;
bool retval = (0 != SetEndOfFile((HANDLE)PR_FileDesc2NativeHandle(aFD)));
PR_Seek64(aFD, oldpos, PR_SEEK_SET);
return retval;
#elif defined(XP_OS2)
return aLength <= UINT32_MAX
&& 0 == DosSetFileSize(PR_FileDesc2NativeHandle(aFD), (uint32_t)aLength);
#elif defined(XP_MACOSX)
int fd = PR_FileDesc2NativeHandle(aFD);
fstore_t store = {F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, aLength};
// Try to get a continous chunk of disk space
int ret = fcntl(fd, F_PREALLOCATE, &store);
if (-1 == ret) {
// OK, perhaps we are too fragmented, allocate non-continuous
store.fst_flags = F_ALLOCATEALL;
ret = fcntl(fd, F_PREALLOCATE, &store);
if (-1 == ret)
return false;
}
return 0 == ftruncate(fd, aLength);
#elif defined(XP_UNIX)
// The following is copied from fcntlSizeHint in sqlite
/* If the OS does not have posix_fallocate(), fake it. First use
** ftruncate() to set the file size, then write a single byte to
** the last byte in each block within the extended region. This
** is the same technique used by glibc to implement posix_fallocate()
** on systems that do not have a real fallocate() system call.
*/
int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
if (oldpos == -1)
return false;
struct stat buf;
int fd = PR_FileDesc2NativeHandle(aFD);
if (fstat(fd, &buf))
return false;
if (buf.st_size >= aLength)
return false;
const int nBlk = buf.st_blksize;
if (!nBlk)
return false;
if (ftruncate(fd, aLength))
return false;
int nWrite; // Return value from write()
int64_t iWrite = ((buf.st_size + 2 * nBlk - 1) / nBlk) * nBlk - 1; // Next offset to write to
while (iWrite < aLength) {
nWrite = 0;
if (PR_Seek64(aFD, iWrite, PR_SEEK_SET) == iWrite)
nWrite = PR_Write(aFD, "", 1);
if (nWrite != 1) break;
iWrite += nBlk;
}
PR_Seek64(aFD, oldpos, PR_SEEK_SET);
return nWrite == 1;
#endif
return false;
}