[MPlayer-dev-eng] [patch 3/5] Fix stream_write_buffer to make sure all requested bytes are written

[Tobias Diedrich]

Reimar Döffinger wrote:
> On Tue, Jan 04, 2011 at 09:35:04PM +0100, Tobias Diedrich wrote:
> > Index: mplayer-patchset1/stream/stream.c
> > ===================================================================
> > --- mplayer-patchset1.orig/stream/stream.c	2010-12-21 20:45:31.157756000 +0100
> > +++ mplayer-patchset1/stream/stream.c	2010-12-21 20:48:16.229732000 +0100
> > @@ -324,13 +324,16 @@
> >  }
> >  
> >  int stream_write_buffer(stream_t *s, unsigned char *buf, int len) {
> > -  int rd;
> > -  if(!s->write_buffer)
> > +  int rd = 0;
> > +  if(!s->write_buffer || len < 0)
> >      return -1;
> > -  rd = s->write_buffer(s, buf, len);
> > -  if(rd < 0)
> > -    return -1;
> > -  s->pos += rd;
> > +  while (rd < len) {
> > +    int ret = s->write_buffer(s, buf+rd, len-rd);
> > +    if (ret < 0)
> > +      return -1;
> > +    rd += ret;
> > +    s->pos += ret;
> > +  }
> 
> I think this is a risky place to do it, I'd be more in favour of only
> adding an assert here and fix all write_buffer implementations to make
> sure this issue never happens.
> There is also the issue that if write_buffer ever ends up returning 0
> this would become an endless loop.

Something more like this?

Index: mplayer-patchset1/stream/stream.c
===================================================================
--- mplayer-patchset1.orig/stream/stream.c	2011-01-06 16:16:21.982600000 +0100
+++ mplayer-patchset1/stream/stream.c	2011-01-06 16:47:28.561260000 +0100
@@ -28,6 +28,7 @@
 #endif
 #include <fcntl.h>
 #include <strings.h>
+#include <assert.h>
 
 #include "config.h"
 
@@ -331,6 +332,7 @@
   if(rd < 0)
     return -1;
   s->pos += rd;
+  assert(rd == len && "stream_write_buffer(): unexpected short write");
   return rd;
 }
 
Index: mplayer-patchset1/stream/stream_file.c
===================================================================
--- mplayer-patchset1.orig/stream/stream_file.c	2011-01-06 16:18:13.945756000 +0100
+++ mplayer-patchset1/stream/stream_file.c	2011-01-06 16:45:35.911193000 +0100
@@ -52,13 +52,32 @@
 };
 
 static int fill_buffer(stream_t *s, char* buffer, int max_len){
-  int r = read(s->fd,buffer,max_len);
-  return (r <= 0) ? -1 : r;
+  int nr = 0;
+  int r;
+  while (nr < max_len) {
+    r = read(s->fd,buffer,max_len);
+    if (r < 0)
+      return -1;
+    max_len -= r;
+    buffer += r;
+    nr += r;
+    if (r == 0)
+      break;
+  }
+  return nr;
 }
 
 static int write_buffer(stream_t *s, char* buffer, int len) {
-  int r = write(s->fd,buffer,len);
-  return (r <= 0) ? -1 : r;
+  int r;
+  int wr = 0;
+  while (wr < len) {
+    r = write(s->fd,buffer,len);
+    if (r <= 0)
+      return -1;
+    wr += r;
+    buffer += r;
+  }
+  return len;
 }
 
 static int seek(stream_t *s,off_t newpos) {

-- 
Tobias						PGP: http://8ef7ddba.uguu.de