Libav 0.7.1
libavutil/file.c
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00001 /*
00002  * This file is part of Libav.
00003  *
00004  * Libav is free software; you can redistribute it and/or
00005  * modify it under the terms of the GNU Lesser General Public
00006  * License as published by the Free Software Foundation; either
00007  * version 2.1 of the License, or (at your option) any later version.
00008  *
00009  * Libav is distributed in the hope that it will be useful,
00010  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00011  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012  * Lesser General Public License for more details.
00013  *
00014  * You should have received a copy of the GNU Lesser General Public
00015  * License along with Libav; if not, write to the Free Software
00016  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00017  */
00018 
00019 #include "file.h"
00020 #include <fcntl.h>
00021 #include <sys/stat.h>
00022 #include <unistd.h>
00023 #if HAVE_MMAP
00024 #include <sys/mman.h>
00025 #elif HAVE_MAPVIEWOFFILE
00026 #include <io.h>
00027 #include <windows.h>
00028 #endif
00029 
00030 typedef struct {
00031     const AVClass *class;
00032     int   log_offset;
00033     void *log_ctx;
00034 } FileLogContext;
00035 
00036 static const AVClass file_log_ctx_class = {
00037     "FILE", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT,
00038     offsetof(FileLogContext, log_offset), offsetof(FileLogContext, log_ctx)
00039 };
00040 
00041 int av_file_map(const char *filename, uint8_t **bufptr, size_t *size,
00042                 int log_offset, void *log_ctx)
00043 {
00044     FileLogContext file_log_ctx = { &file_log_ctx_class, log_offset, log_ctx };
00045     int err, fd = open(filename, O_RDONLY);
00046     struct stat st;
00047     av_unused void *ptr;
00048     off_t off_size;
00049     char errbuf[128];
00050     *bufptr = NULL;
00051 
00052     if (fd < 0) {
00053         err = AVERROR(errno);
00054         av_strerror(err, errbuf, sizeof(errbuf));
00055         av_log(&file_log_ctx, AV_LOG_ERROR, "Cannot read file '%s': %s\n", filename, errbuf);
00056         return err;
00057     }
00058 
00059     if (fstat(fd, &st) < 0) {
00060         err = AVERROR(errno);
00061         av_strerror(err, errbuf, sizeof(errbuf));
00062         av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in fstat(): %s\n", errbuf);
00063         close(fd);
00064         return err;
00065     }
00066 
00067     off_size = st.st_size;
00068     if (off_size > SIZE_MAX) {
00069         av_log(&file_log_ctx, AV_LOG_ERROR,
00070                "File size for file '%s' is too big\n", filename);
00071         close(fd);
00072         return AVERROR(EINVAL);
00073     }
00074     *size = off_size;
00075 
00076 #if HAVE_MMAP
00077     ptr = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
00078     if (ptr == MAP_FAILED) {
00079         err = AVERROR(errno);
00080         av_strerror(err, errbuf, sizeof(errbuf));
00081         av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in mmap(): %s\n", errbuf);
00082         close(fd);
00083         return err;
00084     }
00085     *bufptr = ptr;
00086 #elif HAVE_MAPVIEWOFFILE
00087     {
00088         HANDLE mh, fh = (HANDLE)_get_osfhandle(fd);
00089 
00090         mh = CreateFileMapping(fh, NULL, PAGE_READONLY, 0, 0, NULL);
00091         if (!mh) {
00092             av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in CreateFileMapping()\n");
00093             close(fd);
00094             return -1;
00095         }
00096 
00097         ptr = MapViewOfFile(mh, FILE_MAP_READ, 0, 0, *size);
00098         CloseHandle(mh);
00099         if (!ptr) {
00100             av_log(&file_log_ctx, AV_LOG_ERROR, "Error occurred in MapViewOfFile()\n");
00101             close(fd);
00102             return -1;
00103         }
00104 
00105         *bufptr = ptr;
00106     }
00107 #else
00108     *bufptr = av_malloc(*size);
00109     if (!*bufptr) {
00110         av_log(&file_log_ctx, AV_LOG_ERROR, "Memory allocation error occurred\n");
00111         close(fd);
00112         return AVERROR(ENOMEM);
00113     }
00114     read(fd, *bufptr, *size);
00115 #endif
00116 
00117     close(fd);
00118     return 0;
00119 }
00120 
00121 void av_file_unmap(uint8_t *bufptr, size_t size)
00122 {
00123 #if HAVE_MMAP
00124     munmap(bufptr, size);
00125 #elif HAVE_MAPVIEWOFFILE
00126     UnmapViewOfFile(bufptr);
00127 #else
00128     av_free(bufptr);
00129 #endif
00130 }
00131 
00132 #ifdef TEST
00133 
00134 #undef printf
00135 
00136 int main(void)
00137 {
00138     uint8_t *buf;
00139     size_t size;
00140     if (av_file_map("file.c", &buf, &size, 0, NULL) < 0)
00141         return 1;
00142 
00143     buf[0] = 's';
00144     printf("%s", buf);
00145     av_file_unmap(buf, size);
00146     return 0;
00147 }
00148 #endif