[xml] xmlReaderForFilename / xmlReaderForFd have different behaviours on fifo

[philippe theveny <philippe theveny ens-lyon fr>]

Hi,

I am experiencing a difference in reading in a fifo with 
xmlReaderForFilename and with xmlReaderForFd. The former always fails 
while the latter succeeds.

This seems not to be related with the system since I can reproduce the 
same behaviors on Linux (kernel 2.6.32; glibc-2.11.1; libxml2-2.7.6) and 
on FreeBSD (7.2-RELEASE-p7; libxml2-2.7.3).

Here are my experiments, where the binary 'reader' is compiled from the 
source example http://xmlsoft.org/examples/reader1.c. Everything is fine 
with a pipe, but not with a fifo:

$ echo "<a/>" | ./reader -
0 1 a 1 0

$ mkfifo fifo
$ echo "<a/>" >fifo&
[1] 13078
$ ./reader fifo
fifo:1: parser error : Extra content at the end of the document

^
fifo : failed to parse
[1]+  Done                    echo "<a/>" > fifo


And with a modified version using xmlReaderForFd:

$ diff -u reader1.c reader-fd.c
--- reader1.c   2010-07-29 11:36:14.000000000 +0200
+++ reader-fd.c 2010-07-29 12:40:16.000000000 +0200
@@ -11,6 +11,7 @@
  * copy: see Copyright for the status of this software.
  */

+#include <fcntl.h>
 #include <stdio.h>
 #include <libxml/xmlreader.h>

@@ -61,8 +62,10 @@
 {
   xmlTextReaderPtr reader;
   int ret;
+  int fd;

-  reader = xmlReaderForFile (filename, NULL, 0);
+  fd = open (filename, O_RDONLY);
+  reader = xmlReaderForFd (fd, NULL, NULL, 0);
   if (reader != NULL)
     {
       ret = xmlTextReaderRead (reader);
@@ -81,6 +84,7 @@
     {
       fprintf (stderr, "Unable to open %s\n", filename);
     }
+  close (fd);
 }

$ echo "<a/>" >fifo&
[1] 13083
$ ./reader-fd fifo
0 1 a 1 0
[1]+  Done                    echo "<a/>" > fifo


IMHO, this is quite unfortunate since it prevent to feed through a fifo 
applications using xmlReaderForFilename. It is intended? Am I missing 
something?


Best regards,
Philippe Theveny