Add av_file_map() and av_file_unmap() functions.

Originally committed as revision 26073 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavutil/file.c

@@ -0,0 +1,123 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "file.h"
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#if HAVE_MMAP
+#include <sys/mman.h>
+#endif
+
+typedef struct {
+    const AVClass *class;
+    int   log_offset;
+    void *log_ctx;
+} FileLogContext;
+
+static const AVClass file_log_ctx_class = {
+    "FILE", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT,
+    offsetof(FileLogContext, log_offset), offsetof(FileLogContext, log_ctx)
+};
+
+int av_file_map(const char *filename, uint8_t **bufptr, size_t *size,
+                int log_offset, void *log_ctx)
+{
+    FileLogContext file_log_ctx = { &file_log_ctx_class, log_offset, log_ctx };
+    int err, fd = open(filename, O_RDONLY);
+    struct stat st;
+    av_unused void *ptr;
+    off_t off_size;
+    char errbuf[128];
+    size_t max_size = HAVE_MMAP ? SIZE_MAX : FF_INTERNAL_MEM_TYPE_MAX_VALUE;
+    *bufptr = NULL;
+
+    if (fd < 0) {
+        err = AVERROR(errno);
+        av_strerror(err, errbuf, sizeof(errbuf));
+        av_log(&file_log_ctx, AV_LOG_ERROR, "Cannot read file '%s': %s\n", filename, errbuf);
+        return err;
+    }
+
+    if (lstat(filename, &st) < 0) {
+        err = AVERROR(errno);
+        av_strerror(err, errbuf, sizeof(errbuf));
+        av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in lstat(): %s\n", errbuf);
+        close(fd);
+        return err;
+    }
+
+    off_size = st.st_size;
+    if (off_size > max_size) {
+        av_log(&file_log_ctx, AV_LOG_ERROR,
+               "File size for file '%s' is too big\n", filename);
+        close(fd);
+        return AVERROR(EINVAL);
+    }
+    *size = off_size;
+
+#if HAVE_MMAP
+    ptr = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+    if ((int)(ptr) == -1) {
+        err = AVERROR(errno);
+        av_strerror(err, errbuf, sizeof(errbuf));
+        av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in mmap(): %s\n", errbuf);
+        close(fd);
+        return err;
+    }
+    *bufptr = ptr;
+#else
+    *bufptr = av_malloc(*size);
+    if (!*bufptr) {
+        av_log(&file_log_ctx, AV_LOG_ERROR, "Memory allocation error occurred\n");
+        close(fd);
+        return AVERROR(ENOMEM);
+    }
+    read(fd, *bufptr, *size);
+#endif
+
+    close(fd);
+    return 0;
+}
+
+void av_file_unmap(uint8_t *bufptr, size_t size)
+{
+#if HAVE_MMAP
+    munmap(bufptr, size);
+#else
+    av_free(bufptr);
+#endif
+}
+
+#ifdef TEST
+
+#undef printf
+
+int main(void)
+{
+    uint8_t *buf;
+    size_t size;
+    if (av_file_map("file.c", &buf, &size, 0, NULL) < 0)
+        return 1;
+
+    buf[0] = 's';
+    printf("%s", buf);
+    av_file_unmap(buf, size);
+    return 0;
+}
+#endif