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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* System utilities.
*/
#include "DexFile.h"
#include "SysUtil.h"
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#ifdef HAVE_POSIX_FILEMAP
#include <sys/mman.h>
#endif
#include <limits.h>
#include <errno.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)
{
#ifdef HAVE_POSIX_FILEMAP
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;
#else
LOGE("sysCreateAnonShmem not implemented.\n");
return NULL;
#endif
}
/*
* Create a private anonymous storage area.
*/
int sysCreatePrivateMap(size_t length, MemMapping* pMap)
{
void* memPtr;
memPtr = sysCreateAnonShmem(length);
if (memPtr == NULL)
return -1;
pMap->addr = pMap->baseAddr = memPtr;
pMap->length = pMap->baseLength = length;
return 0;
}
/*
* Determine the current offset and remaining length of the open file.
*/
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)
{
#ifdef HAVE_POSIX_FILEMAP
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;
#else
LOGE("sysLoadFileInShmem not implemented.\n");
return -1;
#endif
}
#ifndef HAVE_POSIX_FILEMAP
int sysFakeMapFile(int fd, MemMapping* pMap)
{
/* No MMAP, just fake it by copying the bits.
For Win32 we could use MapViewOfFile if really necessary
(see libs/utils/FileMap.cpp).
*/
off_t start;
size_t length;
void* memPtr;
assert(pMap != NULL);
if (getFileStartAndLength(fd, &start, &length) < 0)
return -1;
memPtr = malloc(length);
if (read(fd, memPtr, length) < 0) {
LOGW("read(fd=%d, start=%d, length=%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;
}
#endif
/*
* Map a file (from fd's current offset) into a shared, read-only memory
* segment. The file offset must be a multiple of the system page size.
*
* On success, returns 0 and fills out "pMap". On failure, returns a nonzero
* value and does not disturb "pMap".
*/
int sysMapFileInShmemReadOnly(int fd, MemMapping* pMap)
{
#ifdef HAVE_POSIX_FILEMAP
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, RO, 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;
#else
return sysFakeMapFile(fd, pMap);
#endif
}
/*
* Map a file (from fd's current offset) into a private, read-write memory
* segment that will be marked read-only (a/k/a "writable read-only"). The
* file offset must be a multiple of the system page size.
*
* In some cases the mapping will be fully writable (e.g. for files on
* FAT filesystems).
*
* On success, returns 0 and fills out "pMap". On failure, returns a nonzero
* value and does not disturb "pMap".
*/
int sysMapFileInShmemWritableReadOnly(int fd, MemMapping* pMap)
{
#ifdef HAVE_POSIX_FILEMAP
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 | PROT_WRITE, MAP_FILE | MAP_PRIVATE,
fd, start);
if (memPtr == MAP_FAILED) {
LOGW("mmap(%d, R/W, FILE|PRIVATE, %d, %d) failed: %s\n", (int) length,
fd, (int) start, strerror(errno));
return -1;
}
if (mprotect(memPtr, length, PROT_READ) < 0) {
/* this fails with EACCESS on FAT filesystems, e.g. /sdcard */
int err = errno;
LOGV("mprotect(%p, %d, PROT_READ) failed: %s\n",
memPtr, length, strerror(err));
LOGD("mprotect(RO) failed (%d), file will remain read-write\n", err);
}
pMap->baseAddr = pMap->addr = memPtr;
pMap->baseLength = pMap->length = length;
return 0;
#else
return sysFakeMapFile(fd, pMap);
#endif
}
/*
* 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)
{
#ifdef HAVE_POSIX_FILEMAP
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;
#else
LOGE("sysMapFileSegmentInShmem not implemented.\n");
return -1;
#endif
}
/*
* Change the access rights on one or more pages to read-only or read-write.
*
* Returns 0 on success.
*/
int sysChangeMapAccess(void* addr, size_t length, int wantReadWrite,
MemMapping* pMap)
{
#ifdef HAVE_POSIX_FILEMAP
/*
* Verify that "addr" is part of this mapping file.
*/
if (addr < pMap->baseAddr ||
(u1*)addr >= (u1*)pMap->baseAddr + pMap->baseLength)
{
LOGE("Attempted to change %p; map is %p - %p\n",
addr, pMap->baseAddr, (u1*)pMap->baseAddr + pMap->baseLength);
return -1;
}
/*
* Align "addr" to a page boundary and adjust "length" appropriately.
* (The address must be page-aligned, the length doesn't need to be,
* but we do need to ensure we cover the same range.)
*/
u1* alignAddr = (u1*) ((int) addr & ~(SYSTEM_PAGE_SIZE-1));
size_t alignLength = length + ((u1*) addr - alignAddr);
//LOGI("%p/%zd --> %p/%zd\n", addr, length, alignAddr, alignLength);
int prot = wantReadWrite ? (PROT_READ|PROT_WRITE) : (PROT_READ);
if (mprotect(alignAddr, alignLength, prot) != 0) {
int err = errno;
LOGV("mprotect (%p,%zd,%d) failed: %s\n",
alignAddr, alignLength, prot, strerror(errno));
return (errno != 0) ? errno : -1;
}
#endif
/* for "fake" mapping, no need to do anything */
return 0;
}
/*
* Release a memory mapping.
*/
void sysReleaseShmem(MemMapping* pMap)
{
#ifdef HAVE_POSIX_FILEMAP
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;
}
#else
/* Free the bits allocated by sysMapFileInShmem. */
if (pMap->baseAddr != NULL) {
free(pMap->baseAddr);
pMap->baseAddr = NULL;
}
pMap->baseLength = 0;
#endif
}
/*
* Make a copy of a MemMapping.
*/
void sysCopyMap(MemMapping* dst, const MemMapping* src)
{
memcpy(dst, src, sizeof(MemMapping));
}
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