gecko-dev/xpcom/glue/FileUtils.cpp
Gabriele Svelto c7edb0ffaf Bug 1234176 - Introduce and use the WriteSysFile() helper function. r=dhylands
--HG--
extra : rebase_source : c976b7434f660bc7b5fdc19bce800990c96443cb
2015-12-29 11:49:50 +01:00

569 lines
14 KiB
C++

/* -*- 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/. */
#include <errno.h>
#include <stdio.h>
#include "nscore.h"
#include "nsStringGlue.h"
#include "private/pprio.h"
#include "mozilla/Assertions.h"
#include "mozilla/FileUtils.h"
#if defined(XP_MACOSX)
#include <fcntl.h>
#include <unistd.h>
#include <mach/machine.h>
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <limits.h>
#elif defined(XP_UNIX)
#include <fcntl.h>
#include <unistd.h>
#if defined(LINUX)
#include <elf.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#elif defined(XP_WIN)
#include <windows.h>
#endif
// Functions that are not to be used in standalone glue must be implemented
// within this #if block
#if !defined(XPCOM_GLUE)
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_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 (ret == -1) {
// OK, perhaps we are too fragmented, allocate non-continuous
store.fst_flags = F_ALLOCATEALL;
ret = fcntl(fd, F_PREALLOCATE, &store);
if (ret == -1) {
return false;
}
}
return ftruncate(fd, aLength) == 0;
#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;
}
#ifdef ReadSysFile_PRESENT
bool
mozilla::ReadSysFile(
const char* aFilename,
char* aBuf,
size_t aBufSize)
{
int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_RDONLY));
if (fd < 0) {
return false;
}
ScopedClose autoClose(fd);
if (aBufSize == 0) {
return true;
}
ssize_t bytesRead;
size_t offset = 0;
do {
bytesRead = MOZ_TEMP_FAILURE_RETRY(read(fd, aBuf + offset,
aBufSize - offset));
if (bytesRead == -1) {
return false;
}
offset += bytesRead;
} while (bytesRead > 0 && offset < aBufSize);
MOZ_ASSERT(offset <= aBufSize);
if (offset > 0 && aBuf[offset - 1] == '\n') {
offset--;
}
if (offset == aBufSize) {
MOZ_ASSERT(offset > 0);
offset--;
}
aBuf[offset] = '\0';
return true;
}
bool
mozilla::ReadSysFile(
const char* aFilename,
int* aVal)
{
char valBuf[32];
if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
return false;
}
return sscanf(valBuf, "%d", aVal) == 1;
}
bool
mozilla::ReadSysFile(
const char* aFilename,
bool* aVal)
{
int v;
if (!ReadSysFile(aFilename, &v)) {
return false;
}
*aVal = (v != 0);
return true;
}
#endif /* ReadSysFile_PRESENT */
#ifdef WriteSysFile_PRESENT
bool
mozilla::WriteSysFile(
const char* aFilename,
const char* aBuf)
{
size_t aBufSize = strlen(aBuf);
int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_WRONLY));
if (fd < 0) {
return false;
}
ScopedClose autoClose(fd);
ssize_t bytesWritten;
size_t offset = 0;
do {
bytesWritten = MOZ_TEMP_FAILURE_RETRY(write(fd, aBuf + offset,
aBufSize - offset));
if (bytesWritten == -1) {
return false;
}
offset += bytesWritten;
} while (bytesWritten > 0 && offset < aBufSize);
MOZ_ASSERT(offset == aBufSize);
return true;
}
#endif /* WriteSysFile_PRESENT */
void
mozilla::ReadAheadLib(nsIFile* aFile)
{
#if defined(XP_WIN)
nsAutoString path;
if (!aFile || NS_FAILED(aFile->GetPath(path))) {
return;
}
ReadAheadLib(path.get());
#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
nsAutoCString nativePath;
if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
return;
}
ReadAheadLib(nativePath.get());
#endif
}
void
mozilla::ReadAheadFile(nsIFile* aFile, const size_t aOffset,
const size_t aCount, mozilla::filedesc_t* aOutFd)
{
#if defined(XP_WIN)
nsAutoString path;
if (!aFile || NS_FAILED(aFile->GetPath(path))) {
return;
}
ReadAheadFile(path.get(), aOffset, aCount, aOutFd);
#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
nsAutoCString nativePath;
if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
return;
}
ReadAheadFile(nativePath.get(), aOffset, aCount, aOutFd);
#endif
}
#endif // !defined(XPCOM_GLUE)
#if defined(LINUX) && !defined(ANDROID)
static const unsigned int bufsize = 4096;
#ifdef __LP64__
typedef Elf64_Ehdr Elf_Ehdr;
typedef Elf64_Phdr Elf_Phdr;
static const unsigned char ELFCLASS = ELFCLASS64;
typedef Elf64_Off Elf_Off;
#else
typedef Elf32_Ehdr Elf_Ehdr;
typedef Elf32_Phdr Elf_Phdr;
static const unsigned char ELFCLASS = ELFCLASS32;
typedef Elf32_Off Elf_Off;
#endif
#elif defined(XP_MACOSX)
#if defined(__i386__)
static const uint32_t CPU_TYPE = CPU_TYPE_X86;
#elif defined(__x86_64__)
static const uint32_t CPU_TYPE = CPU_TYPE_X86_64;
#elif defined(__ppc__)
static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC;
#elif defined(__ppc64__)
static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC64;
#else
#error Unsupported CPU type
#endif
#ifdef __LP64__
#undef LC_SEGMENT
#define LC_SEGMENT LC_SEGMENT_64
#undef MH_MAGIC
#define MH_MAGIC MH_MAGIC_64
#define cpu_mach_header mach_header_64
#define segment_command segment_command_64
#else
#define cpu_mach_header mach_header
#endif
class ScopedMMap
{
public:
explicit ScopedMMap(const char* aFilePath)
: buf(nullptr)
{
fd = open(aFilePath, O_RDONLY);
if (fd < 0) {
return;
}
struct stat st;
if (fstat(fd, &st) < 0) {
return;
}
size = st.st_size;
buf = (char*)mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0);
}
~ScopedMMap()
{
if (buf) {
munmap(buf, size);
}
if (fd >= 0) {
close(fd);
}
}
operator char*() { return buf; }
int getFd() { return fd; }
private:
int fd;
char* buf;
size_t size;
};
#endif
void
mozilla::ReadAhead(mozilla::filedesc_t aFd, const size_t aOffset,
const size_t aCount)
{
#if defined(XP_WIN)
LARGE_INTEGER fpOriginal;
LARGE_INTEGER fpOffset;
#if defined(HAVE_LONG_LONG)
fpOffset.QuadPart = 0;
#else
fpOffset.u.LowPart = 0;
fpOffset.u.HighPart = 0;
#endif
// Get the current file pointer so that we can restore it. This isn't
// really necessary other than to provide the same semantics regarding the
// file pointer that other platforms do
if (!SetFilePointerEx(aFd, fpOffset, &fpOriginal, FILE_CURRENT)) {
return;
}
if (aOffset) {
#if defined(HAVE_LONG_LONG)
fpOffset.QuadPart = static_cast<LONGLONG>(aOffset);
#else
fpOffset.u.LowPart = aOffset;
fpOffset.u.HighPart = 0;
#endif
if (!SetFilePointerEx(aFd, fpOffset, nullptr, FILE_BEGIN)) {
return;
}
}
char buf[64 * 1024];
size_t totalBytesRead = 0;
DWORD dwBytesRead;
// Do dummy reads to trigger kernel-side readhead via FILE_FLAG_SEQUENTIAL_SCAN.
// Abort when underfilling because during testing the buffers are read fully
// A buffer that's not keeping up would imply that readahead isn't working right
while (totalBytesRead < aCount &&
ReadFile(aFd, buf, sizeof(buf), &dwBytesRead, nullptr) &&
dwBytesRead == sizeof(buf)) {
totalBytesRead += dwBytesRead;
}
// Restore the file pointer
SetFilePointerEx(aFd, fpOriginal, nullptr, FILE_BEGIN);
#elif defined(LINUX) && !defined(ANDROID)
readahead(aFd, aOffset, aCount);
#elif defined(XP_MACOSX)
struct radvisory ra;
ra.ra_offset = aOffset;
ra.ra_count = aCount;
// The F_RDADVISE fcntl is equivalent to Linux' readahead() system call.
fcntl(aFd, F_RDADVISE, &ra);
#endif
}
void
mozilla::ReadAheadLib(mozilla::pathstr_t aFilePath)
{
if (!aFilePath) {
return;
}
#if defined(XP_WIN)
ReadAheadFile(aFilePath);
#elif defined(LINUX) && !defined(ANDROID)
int fd = open(aFilePath, O_RDONLY);
if (fd < 0) {
return;
}
union
{
char buf[bufsize];
Elf_Ehdr ehdr;
} elf;
// Read ELF header (ehdr) and program header table (phdr).
// We check that the ELF magic is found, that the ELF class matches
// our own, and that the program header table as defined in the ELF
// headers fits in the buffer we read.
if ((read(fd, elf.buf, bufsize) <= 0) ||
(memcmp(elf.buf, ELFMAG, 4)) ||
(elf.ehdr.e_ident[EI_CLASS] != ELFCLASS) ||
// Upcast e_phentsize so the multiplication is done in the same precision
// as the subsequent addition, to satisfy static analyzers and avoid
// issues with abnormally large program header tables.
(elf.ehdr.e_phoff + (static_cast<Elf_Off>(elf.ehdr.e_phentsize) *
elf.ehdr.e_phnum) >= bufsize)) {
close(fd);
return;
}
// The program header table contains segment definitions. One such
// segment type is PT_LOAD, which describes how the dynamic loader
// is going to map the file in memory. We use that information to
// find the biggest offset from the library that will be mapped in
// memory.
Elf_Phdr* phdr = (Elf_Phdr*)&elf.buf[elf.ehdr.e_phoff];
Elf_Off end = 0;
for (int phnum = elf.ehdr.e_phnum; phnum; phdr++, phnum--) {
if ((phdr->p_type == PT_LOAD) &&
(end < phdr->p_offset + phdr->p_filesz)) {
end = phdr->p_offset + phdr->p_filesz;
}
}
// Let the kernel read ahead what the dynamic loader is going to
// map in memory soon after.
if (end > 0) {
ReadAhead(fd, 0, end);
}
close(fd);
#elif defined(XP_MACOSX)
ScopedMMap buf(aFilePath);
char* base = buf;
if (!base) {
return;
}
// An OSX binary might either be a fat (universal) binary or a
// Mach-O binary. A fat binary actually embeds several Mach-O
// binaries. If we have a fat binary, find the offset where the
// Mach-O binary for our CPU type can be found.
struct fat_header* fh = (struct fat_header*)base;
if (OSSwapBigToHostInt32(fh->magic) == FAT_MAGIC) {
uint32_t nfat_arch = OSSwapBigToHostInt32(fh->nfat_arch);
struct fat_arch* arch = (struct fat_arch*)&buf[sizeof(struct fat_header)];
for (; nfat_arch; arch++, nfat_arch--) {
if (OSSwapBigToHostInt32(arch->cputype) == CPU_TYPE) {
base += OSSwapBigToHostInt32(arch->offset);
break;
}
}
if (base == buf) {
return;
}
}
// Check Mach-O magic in the Mach header
struct cpu_mach_header* mh = (struct cpu_mach_header*)base;
if (mh->magic != MH_MAGIC) {
return;
}
// The Mach header is followed by a sequence of load commands.
// Each command has a header containing the command type and the
// command size. LD_SEGMENT commands describes how the dynamic
// loader is going to map the file in memory. We use that
// information to find the biggest offset from the library that
// will be mapped in memory.
char* cmd = &base[sizeof(struct cpu_mach_header)];
uint32_t end = 0;
for (uint32_t ncmds = mh->ncmds; ncmds; ncmds--) {
struct segment_command* sh = (struct segment_command*)cmd;
if (sh->cmd != LC_SEGMENT) {
continue;
}
if (end < sh->fileoff + sh->filesize) {
end = sh->fileoff + sh->filesize;
}
cmd += sh->cmdsize;
}
// Let the kernel read ahead what the dynamic loader is going to
// map in memory soon after.
if (end > 0) {
ReadAhead(buf.getFd(), base - buf, end);
}
#endif
}
void
mozilla::ReadAheadFile(mozilla::pathstr_t aFilePath, const size_t aOffset,
const size_t aCount, mozilla::filedesc_t* aOutFd)
{
#if defined(XP_WIN)
if (!aFilePath) {
if (aOutFd) {
*aOutFd = INVALID_HANDLE_VALUE;
}
return;
}
HANDLE fd = CreateFileW(aFilePath, GENERIC_READ, FILE_SHARE_READ, nullptr,
OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, nullptr);
if (aOutFd) {
*aOutFd = fd;
}
if (fd == INVALID_HANDLE_VALUE) {
return;
}
ReadAhead(fd, aOffset, aCount);
if (!aOutFd) {
CloseHandle(fd);
}
#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
if (!aFilePath) {
if (aOutFd) {
*aOutFd = -1;
}
return;
}
int fd = open(aFilePath, O_RDONLY);
if (aOutFd) {
*aOutFd = fd;
}
if (fd < 0) {
return;
}
size_t count;
if (aCount == SIZE_MAX) {
struct stat st;
if (fstat(fd, &st) < 0) {
if (!aOutFd) {
close(fd);
}
return;
}
count = st.st_size;
} else {
count = aCount;
}
ReadAhead(fd, aOffset, count);
if (!aOutFd) {
close(fd);
}
#endif
}