avformat/mux_utils: Move ff_format_shift_data to new file for mux utils

It is only used by muxers. Given that it is not part of
the core muxing code and given that mux.c is already big enough,
it is moved to a new file for utility functions for muxing.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

6 files changed, 90 insertions, 64 deletions

diff --git a/libavformat/Makefile b/libavformat/Makefile
index 537f5a1124..52c53ea3db 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -17,6 +17,7 @@ OBJS = allformats.o         \
        isom_tags.o          \
        metadata.o           \
        mux.o                \
+       mux_utils.o          \
        options.o            \
        os_support.o         \
        protocols.o          \
diff --git a/libavformat/internal.h b/libavformat/internal.h
index a3fdab03af..eb18277cea 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -947,13 +947,6 @@ void ff_format_set_url(AVFormatContext *s, char *url);
 void avpriv_register_devices(const AVOutputFormat * const o[], const AVInputFormat * const i[]);
 
 /**
- * Make shift_size amount of space at read_start by shifting data in the output
- * at read_start until the current IO position. The underlying IO context must
- * be seekable.
- */
-int ff_format_shift_data(AVFormatContext *s, int64_t read_start, int shift_size);
-
-/**
  * Rescales a timestamp and the endpoints of an interval to which the temstamp
  * belongs, from a timebase `tb_in` to a timebase `tb_out`.
  *
diff --git a/libavformat/mux.h b/libavformat/mux.h
index 4f6e8a50e5..c220738942 100644
--- a/libavformat/mux.h
+++ b/libavformat/mux.h
@@ -96,4 +96,11 @@ enum AVWriteUncodedFrameFlags {
 
 };
 
+/**
+ * Make shift_size amount of space at read_start by shifting data in the output
+ * at read_start until the current IO position. The underlying IO context must
+ * be seekable.
+ */
+int ff_format_shift_data(AVFormatContext *s, int64_t read_start, int shift_size);
+
 #endif /* AVFORMAT_MUX_H */
diff --git a/libavformat/mux_utils.c b/libavformat/mux_utils.c
new file mode 100644
index 0000000000..7b79ffd1fb
--- /dev/null
+++ b/libavformat/mux_utils.c
@@ -0,0 +1,81 @@
+/*
+ * Various muxing utility functions
+ * Copyright (c) 2000, 2001, 2002 Fabrice Bellard
+ *
+ * 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 "avformat.h"
+#include "avio.h"
+#include "internal.h"
+#include "mux.h"
+
+int ff_format_shift_data(AVFormatContext *s, int64_t read_start, int shift_size)
+{
+    int ret;
+    int64_t pos, pos_end;
+    uint8_t *buf, *read_buf[2];
+    int read_buf_id = 0;
+    int read_size[2];
+    AVIOContext *read_pb;
+
+    buf = av_malloc_array(shift_size, 2);
+    if (!buf)
+        return AVERROR(ENOMEM);
+    read_buf[0] = buf;
+    read_buf[1] = buf + shift_size;
+
+    /* Shift the data: the AVIO context of the output can only be used for
+     * writing, so we re-open the same output, but for reading. It also avoids
+     * a read/seek/write/seek back and forth. */
+    avio_flush(s->pb);
+    ret = s->io_open(s, &read_pb, s->url, AVIO_FLAG_READ, NULL);
+    if (ret < 0) {
+        av_log(s, AV_LOG_ERROR, "Unable to re-open %s output file for shifting data\n", s->url);
+        goto end;
+    }
+
+    /* mark the end of the shift to up to the last data we wrote, and get ready
+     * for writing */
+    pos_end = avio_tell(s->pb);
+    avio_seek(s->pb, read_start + shift_size, SEEK_SET);
+
+    avio_seek(read_pb, read_start, SEEK_SET);
+    pos = avio_tell(read_pb);
+
+#define READ_BLOCK do {                                                             \
+    read_size[read_buf_id] = avio_read(read_pb, read_buf[read_buf_id], shift_size);  \
+    read_buf_id ^= 1;                                                               \
+} while (0)
+
+    /* shift data by chunk of at most shift_size */
+    READ_BLOCK;
+    do {
+        int n;
+        READ_BLOCK;
+        n = read_size[read_buf_id];
+        if (n <= 0)
+            break;
+        avio_write(s->pb, read_buf[read_buf_id], n);
+        pos += n;
+    } while (pos < pos_end);
+    ret = ff_format_io_close(s, &read_pb);
+
+end:
+    av_free(buf);
+    return ret;
+}
diff --git a/libavformat/segafilmenc.c b/libavformat/segafilmenc.c
index 7a412fe9cc..42d56fccd6 100644
--- a/libavformat/segafilmenc.c
+++ b/libavformat/segafilmenc.c
@@ -33,8 +33,8 @@
 #include "libavutil/intreadwrite.h"
 #include "libavcodec/bytestream.h"
 #include "avformat.h"
-#include "internal.h"
 #include "avio_internal.h"
+#include "mux.h"
 
 typedef struct FILMOutputContext {
     AVIOContext *header;
diff --git a/libavformat/utils.c b/libavformat/utils.c
index f31dda9b44..b53e2aff0c 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -1832,59 +1832,3 @@ void ff_format_set_url(AVFormatContext *s, char *url)
     av_freep(&s->url);
     s->url = url;
 }
-
-int ff_format_shift_data(AVFormatContext *s, int64_t read_start, int shift_size)
-{
-    int ret;
-    int64_t pos, pos_end;
-    uint8_t *buf, *read_buf[2];
-    int read_buf_id = 0;
-    int read_size[2];
-    AVIOContext *read_pb;
-
-    buf = av_malloc_array(shift_size, 2);
-    if (!buf)
-        return AVERROR(ENOMEM);
-    read_buf[0] = buf;
-    read_buf[1] = buf + shift_size;
-
-    /* Shift the data: the AVIO context of the output can only be used for
-     * writing, so we re-open the same output, but for reading. It also avoids
-     * a read/seek/write/seek back and forth. */
-    avio_flush(s->pb);
-    ret = s->io_open(s, &read_pb, s->url, AVIO_FLAG_READ, NULL);
-    if (ret < 0) {
-        av_log(s, AV_LOG_ERROR, "Unable to re-open %s output file for shifting data\n", s->url);
-        goto end;
-    }
-
-    /* mark the end of the shift to up to the last data we wrote, and get ready
-     * for writing */
-    pos_end = avio_tell(s->pb);
-    avio_seek(s->pb, read_start + shift_size, SEEK_SET);
-
-    avio_seek(read_pb, read_start, SEEK_SET);
-    pos = avio_tell(read_pb);
-
-#define READ_BLOCK do {                                                             \
-    read_size[read_buf_id] = avio_read(read_pb, read_buf[read_buf_id], shift_size);  \
-    read_buf_id ^= 1;                                                               \
-} while (0)
-
-    /* shift data by chunk of at most shift_size */
-    READ_BLOCK;
-    do {
-        int n;
-        READ_BLOCK;
-        n = read_size[read_buf_id];
-        if (n <= 0)
-            break;
-        avio_write(s->pb, read_buf[read_buf_id], n);
-        pos += n;
-    } while (pos < pos_end);
-    ret = ff_format_io_close(s, &read_pb);
-
-end:
-    av_free(buf);
-    return ret;
-}