From e6c4979a424af1e3bf6ac44c1a99677400f2464c Mon Sep 17 00:00:00 2001
From: =?utf8?q?Tim-Philipp=20M=C3=BCller?= <tim.muller@collabora.co.uk>
Date: Mon, 10 Oct 2011 18:28:11 +0100
Subject: [PATCH] splitfilesrc: check bytes actually read, just in case

Handle corner case where we try to read beyond the end of the
last file part, in which case we want to return a short read.
If we get fewer bytes than expected for any other file part,
we should just error out, since something fishy's going on
then.
---
 gst/multifile/gstsplitfilesrc.c | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/gst/multifile/gstsplitfilesrc.c b/gst/multifile/gstsplitfilesrc.c
index 35559fa..3fcdf07 100644
--- a/gst/multifile/gstsplitfilesrc.c
+++ b/gst/multifile/gstsplitfilesrc.c
@@ -499,7 +499,6 @@ gst_split_file_src_create (GstBaseSrc * basesrc, guint64 offset, guint size,
   buf = gst_buffer_new_and_alloc (size);
 
   GST_BUFFER_OFFSET (buf) = offset;
-  GST_BUFFER_OFFSET_END (buf) = offset + size;
 
   data = GST_BUFFER_DATA (buf);
 
@@ -507,6 +506,7 @@ gst_split_file_src_create (GstBaseSrc * basesrc, guint64 offset, guint size,
 
   while (size > 0) {
     guint64 bytes_to_end_of_part;
+    gsize read = 0;
 
     /* we want the offset into the file part */
     read_offset = offset - cur_part.start;
@@ -530,14 +530,14 @@ gst_split_file_src_create (GstBaseSrc * basesrc, guint64 offset, guint size,
     stream = G_INPUT_STREAM (cur_part.stream);
 
     /* NB: we won't try to read beyond EOF */
-    if (!g_input_stream_read_all (stream, data, to_read, NULL, cancel, &err))
+    if (!g_input_stream_read_all (stream, data, to_read, &read, cancel, &err))
       goto read_failed;
 
-    GST_LOG_OBJECT (src, "read %u bytes", to_read);
+    GST_LOG_OBJECT (src, "read %u bytes", (guint) read);
 
-    data += to_read;
-    size -= to_read;
-    offset += to_read;
+    data += read;
+    size -= read;
+    offset += read;
 
     /* are we done? */
     if (size == 0)
@@ -545,15 +545,24 @@ gst_split_file_src_create (GstBaseSrc * basesrc, guint64 offset, guint size,
 
     GST_LOG_OBJECT (src, "%u bytes left to read for this chunk", size);
 
-    if (src->cur_part == src->num_parts - 1) {
-      /* FIXME: at end, need to truncate buffer */
-      break;
+    /* corner case, this should never really happen (assuming basesrc clips
+     * requests beyond the file size) */
+    if (read < to_read) {
+      if (src->cur_part == src->num_parts - 1) {
+        /* last file part, stop reading and truncate buffer */
+        GST_BUFFER_SIZE (buf) = offset - GST_BUFFER_OFFSET (buf);
+        break;
+      } else {
+        goto file_part_changed;
+      }
     }
 
     ++src->cur_part;
     cur_part = src->parts[src->cur_part];
   }
 
+  GST_BUFFER_OFFSET_END (buf) = offset;
+
   *buffer = buf;
   GST_LOG_OBJECT (src, "read %u bytes into buf %p", GST_BUFFER_SIZE (buf), buf);
   return GST_FLOW_OK;
@@ -583,6 +592,14 @@ read_failed:
     gst_buffer_unref (buf);
     return GST_FLOW_ERROR;
   }
+file_part_changed:
+  {
+    GST_ELEMENT_ERROR (src, RESOURCE, READ,
+        ("Read error while reading file part %s", cur_part.path),
+        ("Short read in file part, file may have been modified since start"));
+    gst_buffer_unref (buf);
+    return GST_FLOW_ERROR;
+  }
 cancelled:
   {
     GST_DEBUG_OBJECT (src, "I/O operation cancelled from another thread");
-- 
2.7.4