From 5ea0705af7ff3e31d669808cc1c39b673b7122f8 Mon Sep 17 00:00:00 2001 From: Janne Blomqvist Date: Sat, 11 Jun 2011 13:19:49 +0300 Subject: [PATCH] Figure out whether a file is seekable with lseek() From-SVN: r174946 --- libgfortran/ChangeLog | 5 +++++ libgfortran/io/unix.c | 12 ++++++------ 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/libgfortran/ChangeLog b/libgfortran/ChangeLog index bcd62f52c32..d54878b189f 100644 --- a/libgfortran/ChangeLog +++ b/libgfortran/ChangeLog @@ -1,3 +1,8 @@ +2011-06-11 Janne Blomqvist + + * io/unix.c (fd_to_stream): Figure out if a fd is seekable by + trying lseek(). + 2011-06-10 Daniel Carrera * caf/mpi.c (_gfortran_caf_sync_all, diff --git a/libgfortran/io/unix.c b/libgfortran/io/unix.c index c257766d653..e3ae6072290 100644 --- a/libgfortran/io/unix.c +++ b/libgfortran/io/unix.c @@ -952,15 +952,15 @@ fd_to_stream (int fd) if (S_ISREG (statbuf.st_mode)) s->file_length = statbuf.st_size; - else if (S_ISBLK (statbuf.st_mode)) + else { - /* Hopefully more portable than ioctl(fd, BLKGETSIZE64, &size)? */ - gfc_offset cur = lseek (fd, 0, SEEK_CUR); + /* Some character special files are seekable but most are not, + so figure it out by trying to seek. On Linux, /dev/null is + an example of such a special file. */ s->file_length = lseek (fd, 0, SEEK_END); - lseek (fd, cur, SEEK_SET); + if (s->file_length > 0) + lseek (fd, 0, SEEK_SET); } - else - s->file_length = -1; if (!(S_ISREG (statbuf.st_mode) || S_ISBLK (statbuf.st_mode)) || options.all_unbuffered -- 2.30.2