Commit 55ca839e authored by Bruno Haible's avatar Bruno Haible

ftell, ftello: Work around Solaris bug.

parent 2d0c228f
2010-05-01 Bruno Haible <bruno@clisp.org>
ftell, ftello: Work around Solaris bug.
* m4/ftello.m4 (gl_FUNC_FTELLO): Detect Solaris bug.
* lib/ftello.c: Include stdio-impl.h.
(ftello): On Solaris, when _IOWRT is set, compute the result without
looking at _IOREAD.
* modules/ftello (Files): Add lib/stdio-impl.h.
* doc/posix-functions/ftell.texi: Mention Solaris bug.
* doc/posix-functions/ftello.texi: Likewise.
Reported by Eric Blake.
2010-05-01 Bruno Haible <bruno@clisp.org>
freading: Adapt to special meaning of _IOREAD flag on Solaris.
......@@ -10,6 +10,10 @@ Portability problems fixed by Gnulib:
@itemize
@item
This function mistakenly succeeds on pipes on some platforms: mingw.
@item
This function produces incorrect results after @code{putc} that followed a
@code{getc} call that reached EOF on some platforms:
Solaris 10.
@end itemize
Portability problems not fixed by Gnulib:
......
......@@ -15,6 +15,10 @@ IRIX 5.3, OSF/1 4.0, Solaris 2.5.1, mingw.
The declaration of @code{ftello} in @code{<stdio.h>} is not enabled by default
on some platforms: glibc 2.3.6.
@item
This function produces incorrect results after @code{putc} that followed a
@code{getc} call that reached EOF on some platforms:
Solaris 10.
@item
This function fails on seekable stdin, stdout, and stderr: cygwin <= 1.5.24.
@end itemize
......
......@@ -22,6 +22,8 @@
/* Get lseek. */
#include <unistd.h>
#include "stdio-impl.h"
off_t
ftello (FILE *fp)
#undef ftello
......@@ -36,6 +38,28 @@ ftello (FILE *fp)
return -1;
#endif
#if FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE /* Solaris */
/* The Solaris stdio leaves the _IOREAD flag set after reading from a file
reaches EOF and the program then starts writing to the file. ftello
gets confused by this. */
if (fp_->_flag & _IOWRT)
{
off_t pos;
/* Call ftello nevertheless, for the side effects that it does on fp. */
ftello (fp);
/* Compute the file position ourselves. */
pos = llseek (fileno (fp), (off_t) 0, SEEK_CUR);
if (pos >= 0)
{
if ((fp_->_flag & _IONBF) == 0 && fp_->_base != NULL)
pos += fp_->_ptr - fp_->_base;
}
return pos;
}
#endif
#if defined __SL64 && defined __SCLE /* Cygwin */
if ((fp->_flags & __SL64) == 0)
{
......
# ftello.m4 serial 6
dnl Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
# ftello.m4 serial 7
dnl Copyright (C) 2007-2010 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.
......@@ -10,7 +10,7 @@ AC_DEFUN([gl_FUNC_FTELLO],
AC_REQUIRE([AC_PROG_CC])
AC_REQUIRE([gl_STDIN_LARGE_OFFSET])
dnl Persuade glibc <stdio.h> to declare fseeko().
dnl Persuade glibc <stdio.h> to declare ftello().
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
AC_CACHE_CHECK([for ftello], [gl_cv_func_ftello],
......@@ -23,6 +23,93 @@ AC_DEFUN([gl_FUNC_FTELLO],
else
if test $gl_cv_var_stdin_large_offset = no; then
REPLACE_FTELLO=1
else
dnl Detect bug on Solaris.
dnl ftell and ftello produce incorrect results after putc that followed a
dnl getc call that reached EOF on Solaris. This is because the _IOREAD
dnl flag does not get cleared in this case, even though _IOWRT gets set,
dnl and ftell and ftello look whether the _IOREAD flag is set.
AC_REQUIRE([AC_CANONICAL_HOST])
AC_CACHE_CHECK([whether ftello works],
[gl_cv_func_ftello_works],
[
dnl Initial guess, used when cross-compiling or when /dev/tty cannot
dnl be opened.
changequote(,)dnl
case "$host_os" in
# Guess no on Solaris.
solaris*) gl_cv_func_ftello_works="guessing no" ;;
# Guess yes otherwise.
*) gl_cv_func_ftello_works="guessing yes" ;;
esac
changequote([,])dnl
AC_TRY_RUN([
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define TESTFILE "conftest.tmp"
int
main (void)
{
FILE *fp;
/* Create a file with some contents. */
fp = fopen (TESTFILE, "w");
if (fp == NULL)
return 70;
if (fwrite ("foogarsh", 1, 8, fp) < 8)
return 71;
if (fclose (fp))
return 72;
/* The file's contents is now "foogarsh". */
/* Try writing after reading to EOF. */
fp = fopen (TESTFILE, "r+");
if (fp == NULL)
return 73;
if (fseek (fp, -1, SEEK_END))
return 74;
if (!(getc (fp) == 'h'))
return 1;
if (!(getc (fp) == EOF))
return 2;
if (!(ftell (fp) == 8))
return 3;
if (!(ftell (fp) == 8))
return 4;
if (!(putc ('!', fp) == '!'))
return 5;
if (!(ftell (fp) == 9))
return 6;
if (!(fclose (fp) == 0))
return 7;
fp = fopen (TESTFILE, "r");
if (fp == NULL)
return 75;
{
char buf[10];
if (!(fread (buf, 1, 10, fp) == 9))
return 10;
if (!(memcmp (buf, "foogarsh!", 9) == 0))
return 11;
}
if (!(fclose (fp) == 0))
return 12;
/* The file's contents is now "foogarsh!". */
return 0;
}], [gl_cv_func_ftello_works=yes], [gl_cv_func_ftello_works=no], [:])
])
case "$gl_cv_func_ftello_works" in
*yes) ;;
*)
REPLACE_FTELLO=1
AC_DEFINE([FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE], [1],
[Define to 1 if the system's ftello function has the Solaris bug.])
;;
esac
fi
fi
if test $HAVE_FTELLO = 0 || test $REPLACE_FTELLO = 1; then
......
......@@ -3,6 +3,7 @@ ftello() function: Retrieve the position of a FILE stream.
Files:
lib/ftello.c
lib/stdio-impl.h
m4/ftello.m4
Depends-on:
......
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