Add MD5 protocol

This is a write-only protocol which computes the md5sum of data written,
and on close writes this to the designated output or stdout if none
is specified.  It can be used to test muxers without writing an actual
file.

Originally committed as revision 24309 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/Makefile

@@ -284,6 +284,7 @@ OBJS-$(CONFIG_FILE_PROTOCOL)             += file.o
 OBJS-$(CONFIG_GOPHER_PROTOCOL)           += gopher.o
 OBJS-$(CONFIG_HTTP_PROTOCOL)             += http.o httpauth.o
 OBJS-$(CONFIG_MMST_PROTOCOL)             += mmst.o asf.o
+OBJS-$(CONFIG_MD5_PROTOCOL)              += md5proto.o
 OBJS-$(CONFIG_PIPE_PROTOCOL)             += file.o
 
 # external or internal rtmp

libavformat/allformats.c

@@ -223,6 +223,7 @@ void av_register_all(void)
     REGISTER_PROTOCOL (GOPHER, gopher);
     REGISTER_PROTOCOL (HTTP, http);
     REGISTER_PROTOCOL (MMST, mmst);
+    REGISTER_PROTOCOL (MD5,  md5);
     REGISTER_PROTOCOL (PIPE, pipe);
     REGISTER_PROTOCOL (RTMP, rtmp);
 #if CONFIG_LIBRTMP

libavformat/md5proto.c

@@ -0,0 +1,92 @@
+/*
+ * Copyright (c) 2010 Mans Rullgard
+ *
+ * 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 <stdio.h>
+#include "libavutil/avstring.h"
+#include "libavutil/md5.h"
+#include "libavutil/mem.h"
+#include "libavutil/error.h"
+#include "avformat.h"
+#include "avio.h"
+
+#define PRIV_SIZE 128
+
+static int md5_open(URLContext *h, const char *filename, int flags)
+{
+    if (PRIV_SIZE < av_md5_size) {
+        av_log(NULL, AV_LOG_ERROR, "Insuffient size for MD5 context\n");
+        return -1;
+    }
+
+    if (flags != URL_WRONLY)
+        return AVERROR(EINVAL);
+
+    av_md5_init(h->priv_data);
+
+    return 0;
+}
+
+static int md5_write(URLContext *h, const unsigned char *buf, int size)
+{
+    av_md5_update(h->priv_data, buf, size);
+    return size;
+}
+
+static int md5_close(URLContext *h)
+{
+    const char *filename = h->filename;
+    uint8_t md5[16], buf[64];
+    URLContext *out;
+    int i, err = 0;
+
+    av_md5_final(h->priv_data, md5);
+    for (i = 0; i < sizeof(md5); i++)
+        snprintf(buf + i*2, 3, "%02x", md5[i]);
+    buf[i*2] = '\n';
+
+    av_strstart(filename, "md5:", &filename);
+
+    if (*filename) {
+        err = url_open(&out, filename, URL_WRONLY);
+        if (err)
+            return err;
+        err = url_write(out, buf, i*2+1);
+        url_close(out);
+    } else {
+        if (fwrite(buf, 1, i*2+1, stdout) < i*2+1)
+            err = AVERROR(errno);
+    }
+
+    return err;
+}
+
+static int md5_get_handle(URLContext *h)
+{
+    return (intptr_t)h->priv_data;
+}
+
+URLProtocol md5_protocol = {
+    .name                = "md5",
+    .url_open            = md5_open,
+    .url_write           = md5_write,
+    .url_close           = md5_close,
+    .url_get_file_handle = md5_get_handle,
+    .priv_data_size      = PRIV_SIZE,
+};