Add av_file_map() and av_file_unmap() functions.

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

configure

@@ -1042,6 +1042,7 @@ HAVE_LIST="
     malloc_h
     memalign
     mkstemp
+    mmap
     pld
     posix_memalign
     round
@@ -2674,6 +2675,7 @@ check_func  inet_aton $network_extralibs
 check_func  isatty
 check_func  ${malloc_prefix}memalign            && enable memalign
 check_func  mkstemp
+check_func  mmap
 check_func  ${malloc_prefix}posix_memalign      && enable posix_memalign
 check_func  setrlimit
 check_func  strerror_r

doc/APIchanges

@@ -13,6 +13,9 @@ libavutil:   2009-03-08
 
 API changes, most recent first:
 
+2010-12-22 - r26073 - lavutil 50.36.0 - file.h
+  Add functions av_file_map() and av_file_unmap() in file.h.
+
 2010-12-19 - r26056 - lavutil 50.35.0 - error.h
   Add "not found" error codes:
   AVERROR_DEMUXER_NOT_FOUND

libavutil/Makefile

@@ -15,6 +15,7 @@ HEADERS = adler32.h                                                     \
           error.h                                                       \
           eval.h                                                        \
           fifo.h                                                        \
+          file.h                                                        \
           intfloat_readwrite.h                                          \
           intreadwrite.h                                                \
           lfg.h                                                         \
@@ -42,6 +43,7 @@ OBJS = adler32.o                                                        \
        error.o                                                          \
        eval.o                                                           \
        fifo.o                                                           \
+       file.o                                                           \
        intfloat_readwrite.o                                             \
        inverse.o                                                        \
        lfg.o                                                            \

libavutil/avutil.h

@@ -40,7 +40,7 @@
 #define AV_VERSION(a, b, c) AV_VERSION_DOT(a, b, c)
 
 #define LIBAVUTIL_VERSION_MAJOR 50
-#define LIBAVUTIL_VERSION_MINOR 35
+#define LIBAVUTIL_VERSION_MINOR 36
 #define LIBAVUTIL_VERSION_MICRO  0
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \

libavutil/file.c

+/*
+ * 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

libavutil/file.h

+/*
+ * 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
+ */
+
+#ifndef AVUTIL_FILE_H
+#define AVUTIL_FILE_H
+
+#include "avutil.h"
+
+/**
+ * @file misc file utilities
+ */
+
+/**
+ * Read the file with name filename, and put its content in a newly
+ * allocated buffer or map it with mmap() when available.
+ * In case of success set *bufptr to the read or mmapped buffer, and
+ * *size to the size in bytes of the buffer in *bufptr.
+ * The returned buffer must be released with av_file_unmap().
+ *
+ * @param log_offset loglevel offset used for logging
+ * @param log_ctx context used for logging
+ * @return a non negative number in case of success, a negative value
+ * corresponding to an AVERROR error code in case of failure
+ */
+int av_file_map(const char *filename, uint8_t **bufptr, size_t *size,
+                int log_offset, void *log_ctx);
+
+/**
+ * Unmap or free the buffer bufptr created by av_file_map().
+ *
+ * @param size size in bytes of bufptr, must be the same as returned
+ * by av_file_map()
+ */
+void av_file_unmap(uint8_t *bufptr, size_t size);
+
+#endif /* AVUTIL_FILE_H */

libavutil/mem.h

@@ -64,8 +64,10 @@
 
 #if LIBAVUTIL_VERSION_MAJOR < 51
 #   define FF_INTERNAL_MEM_TYPE unsigned int
+#   define FF_INTERNAL_MEM_TYPE_MAX_VALUE UINT_MAX
 #else
 #   define FF_INTERNAL_MEM_TYPE size_t
+#   define FF_INTERNAL_MEM_TYPE_MAX_VALUE SIZE_MAX
 #endif
 
 /**