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/*
* Copyright 2006 The Android Open Source Project
*
* System utilities.
*/
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <limits.h>
#include <errno.h>
#include <assert.h>
#define LOG_TAG "sysutil"
#include "Log.h"
#include "SysUtil.h"
static int getFileStartAndLength(int fd, off_t *start_, size_t *length_)
{
off_t start, end;
size_t length;
assert(start_ != NULL);
assert(length_ != NULL);
// TODO: isn't start always 0 for the single call site? just use fstat instead?
start = TEMP_FAILURE_RETRY(lseek(fd, 0L, SEEK_CUR));
end = TEMP_FAILURE_RETRY(lseek(fd, 0L, SEEK_END));
if (TEMP_FAILURE_RETRY(lseek(fd, start, SEEK_SET)) == -1 ||
start == (off_t) -1 || end == (off_t) -1) {
LOGE("could not determine length of file\n");
return -1;
}
length = end - start;
if (length == 0) {
LOGE("file is empty\n");
return -1;
}
*start_ = start;
*length_ = length;
return 0;
}
/*
* Map a file (from fd's current offset) into a private, read-only memory
* segment. The file offset must be a multiple of the page size.
*
* On success, returns 0 and fills out "pMap". On failure, returns a nonzero
* value and does not disturb "pMap".
*/
static int sysMapFD(int fd, MemMapping* pMap)
{
off_t start;
size_t length;
void* memPtr;
assert(pMap != NULL);
if (getFileStartAndLength(fd, &start, &length) < 0)
return -1;
memPtr = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, start);
if (memPtr == MAP_FAILED) {
LOGW("mmap(%d, R, PRIVATE, %d, %d) failed: %s\n", (int) length,
fd, (int) start, strerror(errno));
return -1;
}
pMap->addr = memPtr;
pMap->length = length;
pMap->range_count = 1;
pMap->ranges = malloc(sizeof(MappedRange));
pMap->ranges[0].addr = memPtr;
pMap->ranges[0].length = length;
return 0;
}
static int sysMapBlockFile(FILE* mapf, MemMapping* pMap)
{
char block_dev[PATH_MAX+1];
size_t size;
unsigned int blksize;
unsigned int blocks;
unsigned int range_count;
unsigned int i;
if (fgets(block_dev, sizeof(block_dev), mapf) == NULL) {
LOGW("failed to read block device from header\n");
return -1;
}
for (i = 0; i < sizeof(block_dev); ++i) {
if (block_dev[i] == '\n') {
block_dev[i] = 0;
break;
}
}
if (fscanf(mapf, "%zu %u\n%u\n", &size, &blksize, &range_count) != 3) {
LOGW("failed to parse block map header\n");
return -1;
}
blocks = ((size-1) / blksize) + 1;
pMap->range_count = range_count;
pMap->ranges = malloc(range_count * sizeof(MappedRange));
memset(pMap->ranges, 0, range_count * sizeof(MappedRange));
// Reserve enough contiguous address space for the whole file.
unsigned char* reserve;
reserve = mmap64(NULL, blocks * blksize, PROT_NONE, MAP_PRIVATE | MAP_ANON, -1, 0);
if (reserve == MAP_FAILED) {
LOGW("failed to reserve address space: %s\n", strerror(errno));
return -1;
}
pMap->ranges[range_count-1].addr = reserve;
pMap->ranges[range_count-1].length = blocks * blksize;
int fd = open(block_dev, O_RDONLY);
if (fd < 0) {
LOGW("failed to open block device %s: %s\n", block_dev, strerror(errno));
return -1;
}
unsigned char* next = reserve;
for (i = 0; i < range_count; ++i) {
int start, end;
if (fscanf(mapf, "%d %d\n", &start, &end) != 2) {
LOGW("failed to parse range %d in block map\n", i);
return -1;
}
void* addr = mmap64(next, (end-start)*blksize, PROT_READ, MAP_PRIVATE | MAP_FIXED, fd, ((off64_t)start)*blksize);
if (addr == MAP_FAILED) {
LOGW("failed to map block %d: %s\n", i, strerror(errno));
return -1;
}
pMap->ranges[i].addr = addr;
pMap->ranges[i].length = (end-start)*blksize;
next += pMap->ranges[i].length;
}
pMap->addr = reserve;
pMap->length = size;
LOGI("mmapped %d ranges\n", range_count);
return 0;
}
int sysMapFile(const char* fn, MemMapping* pMap)
{
memset(pMap, 0, sizeof(*pMap));
if (fn && fn[0] == '@') {
// A map of blocks
FILE* mapf = fopen(fn+1, "r");
if (mapf == NULL) {
LOGV("Unable to open '%s': %s\n", fn+1, strerror(errno));
return -1;
}
if (sysMapBlockFile(mapf, pMap) != 0) {
LOGW("Map of '%s' failed\n", fn);
return -1;
}
fclose(mapf);
} else {
// This is a regular file.
int fd = open(fn, O_RDONLY, 0);
if (fd < 0) {
LOGE("Unable to open '%s': %s\n", fn, strerror(errno));
return -1;
}
if (sysMapFD(fd, pMap) != 0) {
LOGE("Map of '%s' failed\n", fn);
close(fd);
return -1;
}
close(fd);
}
return 0;
}
/*
* Release a memory mapping.
*/
void sysReleaseMap(MemMapping* pMap)
{
int i;
for (i = 0; i < pMap->range_count; ++i) {
if (munmap(pMap->ranges[i].addr, pMap->ranges[i].length) < 0) {
LOGW("munmap(%p, %d) failed: %s\n",
pMap->ranges[i].addr, (int)pMap->ranges[i].length, strerror(errno));
}
}
free(pMap->ranges);
pMap->ranges = NULL;
pMap->range_count = 0;
}
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