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[Patch, libfortran, committed] Return error when trying to seek a non-seekable buffered file
- From: Janne Blomqvist <blomqvist dot janne at gmail dot com>
- To: GCC Patches <gcc-patches at gcc dot gnu dot org>, Fortran List <fortran at gcc dot gnu dot org>
- Date: Sat, 11 Jun 2011 13:57:29 +0300
- Subject: [Patch, libfortran, committed] Return error when trying to seek a non-seekable buffered file
Hi,
In libgfortran, buffered and unbuffered IO should work the same except
for the buffering. For the unbuffered IO, seek and tell operations
reduce to calls to lseek(). Thus, if the file is not seekable, they
return -1 and set errno. Or strictly speaking, POSIX says that lseek()
on a non-seekable file is implementation-dependent, but AFAIK most
implementations return error. The attached patch makes buffered IO
behave the same.
Regtested on x86_64-unknown-linux-gnu, committed as obvious.
Index: ChangeLog
===================================================================
--- ChangeLog (revision 174946)
+++ ChangeLog (working copy)
@@ -1,5 +1,10 @@
2011-06-11 Janne Blomqvist <jb@gcc.gnu.org>
+ * io/unix.c (buf_seek): Return error if file is not seekable.
+ (buf_tell): Call buf_seek.
+
+2011-06-11 Janne Blomqvist <jb@gcc.gnu.org>
+
* io/unix.c (fd_to_stream): Figure out if a fd is seekable by
trying lseek().
Index: io/unix.c
===================================================================
--- io/unix.c (revision 174946)
+++ io/unix.c (working copy)
@@ -560,6 +560,11 @@ buf_write (unix_stream * s, const void *
static gfc_offset
buf_seek (unix_stream * s, gfc_offset offset, int whence)
{
+ if (s->file_length == -1)
+ {
+ errno = ESPIPE;
+ return -1;
+ }
switch (whence)
{
case SEEK_SET:
@@ -585,7 +590,7 @@ buf_seek (unix_stream * s, gfc_offset of
static gfc_offset
buf_tell (unix_stream * s)
{
- return s->logical_offset;
+ return buf_seek (s, 0, SEEK_CUR);
}
static int
--
Janne Blomqvist