From 1074f45959f35f8730a097fdc3d142039071ade7 Mon Sep 17 00:00:00 2001 From: Bruno Haible Date: Fri, 16 Jan 2009 00:24:35 +0100 Subject: [PATCH] Make fflush-after-ungetc POSIX compliant on glibc systems. --- ChangeLog | 12 ++++++++++++ lib/fflush.c | 19 +++++++++++++++---- lib/fseeko.c | 37 +++++++++++++++++++++++-------------- m4/fflush.m4 | 29 ++++++++++++++++++++++------- 4 files changed, 72 insertions(+), 25 deletions(-) diff --git a/ChangeLog b/ChangeLog index fb11852c6..63e69d48d 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,15 @@ +2009-01-15 Bruno Haible + + Make fflush-after-ungetc POSIX compliant on glibc systems. + * m4/fflush.m4 (gl_FUNC_FFLUSH): Test also the behaviour of fflush + after ungetc. + * lib/fflush.c (clear_ungetc_buffer): Implement for glibc systems. + (rpl_fflush): On glibc systems, simply call the system's fflush + function after clearing the ungetc buffer. + * lib/fseeko.c (rpl_fseeko): Don't try to lseek past the end of file. + Instead, lseek only to the end of file, then use the system's fseeko + for the rest. On glibc systems, reset the EOF indicator bit. + 2009-01-15 Jim Meyering openmp.m4: revert quote-adding change, for portability to older autoconf diff --git a/lib/fflush.c b/lib/fflush.c index 22d7d02f3..977278991 100644 --- a/lib/fflush.c +++ b/lib/fflush.c @@ -1,5 +1,5 @@ /* fflush.c -- allow flushing input streams - Copyright (C) 2007-2008 Free Software Foundation, Inc. + Copyright (C) 2007-2009 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -34,7 +34,11 @@ static inline void clear_ungetc_buffer (FILE *fp) { -#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ +#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ + if (fp->_flags & _IO_IN_BACKUP) + /* _IO_free_backup_area is a bit complicated. Simply call fseek. */ + fseek (fp, 0, SEEK_CUR); +#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ if (HASUB (fp)) { fp_->_p += fp_->_r; @@ -123,6 +127,12 @@ rpl_fflush (FILE *stream) pushed-back bytes and the read-ahead bytes. */ clear_ungetc_buffer (stream); +#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ + + return fflush (stream); + +#else + /* POSIX does not specify fflush behavior for non-seekable input streams. Some implementations purge unread data, some return EBADF, some do nothing. */ @@ -140,7 +150,7 @@ rpl_fflush (FILE *stream) if (result != 0) return result; -#if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ +# if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ { /* Disable seek optimization for the next fseeko call. This tells the @@ -154,7 +164,7 @@ rpl_fflush (FILE *stream) } return result; -#else +# else pos = lseek (fileno (stream), pos, SEEK_SET); if (pos == -1) @@ -165,5 +175,6 @@ rpl_fflush (FILE *stream) return 0; +# endif #endif } diff --git a/lib/fseeko.c b/lib/fseeko.c index ac0af5785..47beac42e 100644 --- a/lib/fseeko.c +++ b/lib/fseeko.c @@ -1,5 +1,5 @@ /* An fseeko() function that, together with fflush(), is POSIX compliant. - Copyright (C) 2007-2008 Free Software Foundation, Inc. + Copyright (C) 2007-2009 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -86,7 +86,14 @@ rpl_fseeko (FILE *fp, off_t offset, int whence) #error "Please port gnulib fseeko.c to your platform! Look at the code in fpurge.c, then report this to bug-gnulib." #endif { - off_t pos = lseek (fileno (fp), offset, whence); + /* We get here when an fflush() call immediately preceded this one. We + know there are no buffers. + POSIX requires us to modify the file descriptor's position. + But we cannot position beyond end of file here. */ + off_t pos = + lseek (fileno (fp), + whence == SEEK_END && offset > 0 ? 0 : offset, + whence); if (pos == -1) { #if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ @@ -94,20 +101,22 @@ rpl_fseeko (FILE *fp, off_t offset, int whence) #endif return -1; } - else - { -#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ - fp_->_offset = pos; - fp_->_flags |= __SOFF; - fp_->_flags &= ~__SEOF; + +#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ + fp->_flags &= ~_IO_EOF_SEEN; +#elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ + fp_->_offset = pos; + fp_->_flags |= __SOFF; + fp_->_flags &= ~__SEOF; #elif defined __EMX__ /* emx+gcc */ - fp->_flags &= ~_IOEOF; + fp->_flags &= ~_IOEOF; #elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */ - fp->_flag &= ~_IOEOF; + fp->_flag &= ~_IOEOF; #endif - return 0; - } + /* If we were not requested to position beyond end of file, we're + done. */ + if (!(whence == SEEK_END && offset > 0)) + return 0; } - else - return fseeko (fp, offset, whence); + return fseeko (fp, offset, whence); } diff --git a/m4/fflush.m4 b/m4/fflush.m4 index 97f12843d..da30e1fe6 100644 --- a/m4/fflush.m4 +++ b/m4/fflush.m4 @@ -1,6 +1,6 @@ -# fflush.m4 serial 6 +# fflush.m4 serial 7 -# Copyright (C) 2007-2008 Free Software Foundation, Inc. +# Copyright (C) 2007-2009 Free Software Foundation, Inc. # This file is free software; the Free Software Foundation # gives unlimited permission to copy and/or distribute it, # with or without modifications, as long as this notice is preserved. @@ -22,6 +22,7 @@ AC_DEFUN([gl_FUNC_FFLUSH], ]], [[FILE *f = fopen ("conftest.txt", "r"); char buffer[10]; int fd; + int c; if (f == NULL) return 1; fd = fileno (f); @@ -30,17 +31,31 @@ AC_DEFUN([gl_FUNC_FFLUSH], /* For deterministic results, ensure f read a bigger buffer. */ if (lseek (fd, 0, SEEK_CUR) == 5) return 3; - /* POSIX requires fflush-fseek to set file offset of fd. */ + /* POSIX requires fflush-fseek to set file offset of fd. This fails + on BSD systems and on mingw. */ if (fflush (f) != 0 || fseek (f, 0, SEEK_CUR) != 0) return 4; if (lseek (fd, 0, SEEK_CUR) != 5) return 5; - /* TODO: Verify behaviour of fflush after ungetc, see - . */ + /* Verify behaviour of fflush after ungetc. See + */ + /* Verify behaviour of fflush after a backup ungetc. This fails on + mingw. */ + c = fgetc (f); + ungetc (c, f); + fflush (f); + if (fgetc (f) != c) + return 6; + /* Verify behaviour of fflush after a non-backup ungetc. This fails + on glibc 2.8 and on BSD systems. */ + c = fgetc (f); + ungetc ('@', f); + fflush (f); + if (fgetc (f) != c) + return 7; return 0; ]])], [gl_cv_func_fflush_stdin=yes], [gl_cv_func_fflush_stdin=no], - [dnl Pessimistically assume fflush is broken. This is wrong for - dnl at least glibc and cygwin; but lib/fflush.c takes this into account. + [dnl Pessimistically assume fflush is broken. gl_cv_func_fflush_stdin=no]) rm conftest.txt ]) -- 2.11.0