[FFmpeg-devel] [PATCH V1 1/2] lavf/avio: add a ffio_realloc_buf API for AVIO buffer realloc

[Jun Zhao]

From: tomajsjiang <tomajsjiang at tencent.com>

Add new API ffio_realloc_buf for AVIO buffer realloc.

Signed-off-by: Zhongxing Jiang <tomajsjiang at tencent.com>
---
 libavformat/avio_internal.h |    9 +++++++++
 libavformat/aviobuf.c       |   31 +++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+), 0 deletions(-)

diff --git a/libavformat/avio_internal.h b/libavformat/avio_internal.h
index 04c1ad5..eb628ac 100644
--- a/libavformat/avio_internal.h
+++ b/libavformat/avio_internal.h
@@ -87,6 +87,15 @@ int ffio_read_size(AVIOContext *s, unsigned char *buf, int size);
 int ffio_set_buf_size(AVIOContext *s, int buf_size);
 
 /**
+ * Reallocate a given buffer for AVIOContext.
+ *
+ * @param s the AVIOContext to realloc.
+ * @param buf_size required new buffer size.
+ * @return 0 on success, a negative AVERROR on failure.
+ */
+int ffio_realloc_buf(AVIOContext *s, int buf_size);
+
+/**
  * Ensures that the requested seekback buffer size will be available
  *
  * Will ensure that when reading sequentially up to buf_size, seeking
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 2d01102..3b59180 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -1093,6 +1093,37 @@ int ffio_set_buf_size(AVIOContext *s, int buf_size)
     return 0;
 }
 
+int ffio_realloc_buf(AVIOContext *s, int buf_size)
+{
+    uint8_t *buffer;
+    int data_size;
+
+    if (!s->buffer_size)
+        return ffio_set_buf_size(s, buf_size);
+
+    if (buf_size <= s->buffer_size)
+        return 0;
+
+    buffer = av_malloc(buf_size);
+    if (!buffer)
+        return AVERROR(ENOMEM);
+
+    data_size = s->write_flag ? (s->buf_ptr - s->buffer) : (s->buf_end - s->buf_ptr);
+    if (data_size > 0)
+        memcpy(buffer, s->write_flag ? s->buffer : s->buf_ptr, data_size);
+    av_free(s->buffer);
+    s->buffer = buffer;
+    s->orig_buffer_size = buf_size;
+    s->buffer_size = buf_size;
+    s->buf_ptr = s->write_flag ? (s->buffer + data_size) : s->buffer;
+    if (s->write_flag)
+        s->buf_ptr_max = s->buffer + data_size;
+
+    s->buf_end = s->write_flag ? (s->buffer + s->buffer_size) : (s->buf_ptr + data_size);
+
+    return 0;
+}
+
 static int url_resetbuf(AVIOContext *s, int flags)
 {
     av_assert1(flags == AVIO_FLAG_WRITE || flags == AVIO_FLAG_READ);
-- 
1.7.1