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Diffstat (limited to 'minzip/SysUtil.c')
| -rw-r--r-- | minzip/SysUtil.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/minzip/SysUtil.c b/minzip/SysUtil.c new file mode 100644 index 000000000..49a2522d6 --- /dev/null +++ b/minzip/SysUtil.c @@ -0,0 +1,212 @@ +/* + * 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; + } +} + |