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;
+    }
+}
+