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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 <limits.h>
#include <errno.h>
#include <assert.h>
#define LOG_TAG "minzip"
#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);
start = lseek(fd, 0L, SEEK_CUR);
end = lseek(fd, 0L, SEEK_END);
(void) lseek(fd, start, SEEK_SET);
if (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 shared, 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".
*/
int sysMapFileInShmem(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_FILE | MAP_SHARED, fd, start);
if (memPtr == MAP_FAILED) {
LOGW("mmap(%d, R, FILE|SHARED, %d, %d) failed: %s\n", (int) length,
fd, (int) start, strerror(errno));
return -1;
}
pMap->baseAddr = pMap->addr = memPtr;
pMap->baseLength = pMap->length = length;
return 0;
}
/*
* Release a memory mapping.
*/
void sysReleaseShmem(MemMapping* pMap)
{
if (pMap->baseAddr == NULL && pMap->baseLength == 0)
return;
if (munmap(pMap->baseAddr, pMap->baseLength) < 0) {
LOGW("munmap(%p, %d) failed: %s\n",
pMap->baseAddr, (int)pMap->baseLength, strerror(errno));
} else {
LOGV("munmap(%p, %d) succeeded\n", pMap->baseAddr, pMap->baseLength);
pMap->baseAddr = NULL;
pMap->baseLength = 0;
}
}
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