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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"
/*
* Having trouble finding a portable way to get this. sysconf(_SC_PAGE_SIZE)
* seems appropriate, but we don't have that on the device. Some systems
* have getpagesize(2), though the linux man page has some odd cautions.
*/
#define DEFAULT_PAGE_SIZE 4096
/*
* Create an anonymous shared memory segment large enough to hold "length"
* bytes. The actual segment may be larger because mmap() operates on
* page boundaries (usually 4K).
*/
static void* sysCreateAnonShmem(size_t length)
{
void* ptr;
ptr = mmap(NULL, length, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANON, -1, 0);
if (ptr == MAP_FAILED) {
LOGW("mmap(%d, RW, SHARED|ANON) failed: %s\n", (int) length,
strerror(errno));
return NULL;
}
return ptr;
}
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;
}
/*
* Pull the contents of a file into an new shared memory segment. We grab
* everything from fd's current offset on.
*
* We need to know the length ahead of time so we can allocate a segment
* of sufficient size.
*/
int sysLoadFileInShmem(int fd, MemMapping* pMap)
{
off_t start;
size_t length, actual;
void* memPtr;
assert(pMap != NULL);
if (getFileStartAndLength(fd, &start, &length) < 0)
return -1;
memPtr = sysCreateAnonShmem(length);
if (memPtr == NULL)
return -1;
actual = read(fd, memPtr, length);
if (actual != length) {
LOGE("only read %d of %d bytes\n", (int) actual, (int) length);
sysReleaseShmem(pMap);
return -1;
}
pMap->baseAddr = pMap->addr = memPtr;
pMap->baseLength = pMap->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;
}
/*
* Map part of a file (from fd's current offset) into a shared, read-only
* memory segment.
*
* On success, returns 0 and fills out "pMap". On failure, returns a nonzero
* value and does not disturb "pMap".
*/
int sysMapFileSegmentInShmem(int fd, off_t start, long length,
MemMapping* pMap)
{
off_t dummy;
size_t fileLength, actualLength;
off_t actualStart;
int adjust;
void* memPtr;
assert(pMap != NULL);
if (getFileStartAndLength(fd, &dummy, &fileLength) < 0)
return -1;
if (start + length > (long)fileLength) {
LOGW("bad segment: st=%d len=%ld flen=%d\n",
(int) start, length, (int) fileLength);
return -1;
}
/* adjust to be page-aligned */
adjust = start % DEFAULT_PAGE_SIZE;
actualStart = start - adjust;
actualLength = length + adjust;
memPtr = mmap(NULL, actualLength, PROT_READ, MAP_FILE | MAP_SHARED,
fd, actualStart);
if (memPtr == MAP_FAILED) {
LOGW("mmap(%d, R, FILE|SHARED, %d, %d) failed: %s\n",
(int) actualLength, fd, (int) actualStart, strerror(errno));
return -1;
}
pMap->baseAddr = memPtr;
pMap->baseLength = actualLength;
pMap->addr = (char*)memPtr + adjust;
pMap->length = length;
LOGVV("mmap seg (st=%d ln=%d): bp=%p bl=%d ad=%p ln=%d\n",
(int) start, (int) length,
pMap->baseAddr, (int) pMap->baseLength,
pMap->addr, (int) pMap->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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