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authorThe Android Open Source Project <initial-contribution@android.com>2009-03-04 04:28:42 +0100
committerThe Android Open Source Project <initial-contribution@android.com>2009-03-04 04:28:42 +0100
commitc24a8e688a6312764254beac2b2520bb0c5e998d (patch)
tree7df23711566b358047301d8413ee399105546e8b /minzip/SysUtil.c
parentauto import from //depot/cupcake/@135843 (diff)
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Diffstat (limited to 'minzip/SysUtil.c')
-rw-r--r--minzip/SysUtil.c212
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;
+ }
+}
+