> > > FAIL: test-fflush2.sh
> > > FAIL: test-fpurge
> > > FAIL: test-ftell.sh
> > > FAIL: test-ftell2.sh
> > > FAIL: test-ftello.sh
> > > FAIL: test-ftello2.sh
>
> These would need debugging on a macOS 10.15 machine. Anyone willing to take
> this challenge?
The compilefarm now has a macOS 11.2 machine. These tests fail there as well.
I could debug it, and found that it is a regression introduced in macOS 10.15.0:
--- Libc-1272.250.1/stdio/FreeBSD/fflush.c 2015-02-04 23:57:51.000000000
+0100
+++ Libc-1353.11.2/stdio/FreeBSD/fflush.c 2019-09-21 00:18:36.000000000
+0200
...
@@ -110,12 +90,52 @@
int n, t;
t = fp->_flags;
- if ((t & __SWR) == 0)
- return (0);
if ((p = fp->_bf._base) == NULL)
return (0);
+ /*
+ * SUSv3 requires that fflush() on a seekable input stream updates the
file
+ * position indicator with the underlying seek function. Use a dumb
fseek
+ * for this (don't attempt to preserve the buffers).
+ */
+ if ((t & __SRD) != 0) {
+ if (fp->_seek == NULL) {
+ /*
+ * No way to seek this file -- just return "success."
+ */
+ return (0);
+ }
+
+ n = fp->_r;
+
+ if (n > 0) {
+ /*
+ * See _fseeko's dumb path.
+ */
+ if (_sseek(fp, (fpos_t)-n, SEEK_CUR) == -1) {
+ if (errno == ESPIPE) {
+ /*
+ * Ignore ESPIPE errors, since there's
no way to put the bytes
+ * back into the pipe.
+ */
+ return (0);
+ }
+ return (EOF);
+ }
+
+ if (HASUB(fp)) {
+ FREEUB(fp);
+ }
+ fp->_p = fp->_bf._base;
+ fp->_r = 0;
+ fp->_flags &= ~__SEOF;
+ memset(&fp->_mbstate, 0, sizeof(mbstate_t));
+ }
+ return (0);
+ }
+
+ if ((t & __SWR) != 0) {
n = fp->_p - p; /* write this much */
/*
@@ -142,6 +162,7 @@
return (EOF);
}
}
+ }
return (0);
}
They added new code to the function __sflush, which makes sense (in order to
make fflush() POSIX compliant). But __sflush is being called by ftello(),
and the new code in __sflush severely disturbs the functioning of ftello:
- it causes the ungetc buffer to be discarded,
- it causes a flush of buffered data (which no one has asked for),
- it returns a broken file position.
The bug was already spotted in the wild, in some non-GNU program:
<https://github.com/espeak-ng/espeak-ng/issues/674>.
This patch provides a workaround.
2021-03-20 Bruno Haible <br...@clisp.org>
ftello: Work around bug in macOS >= 10.15.
Reported by Martin Storsjö <mar...@martin.st> in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-12/msg00002.html>.
* m4/ungetc.m4 (gl_FUNC_UNGETC_WORKS): On macOS, don't define
FUNC_UNGETC_BROKEN. Instead, set gl_ftello_broken_after_ungetc to yes.
* m4/ftello.m4 (gl_FUNC_FTELLO): Invoke gl_FUNC_UNGETC_WORKS, and
arrange to provide the workaround if ftello is broken after ungetc.
* lib/ftello.c: Include <errno.h>, intprops.h.
(ftello) [FTELLO_BROKEN_AFTER_UNGETC]: Implement from scratch.
* modules/ftello (Files): Add m4/ungetc.m4.
(Depends-on): Add intprops.
* doc/posix-functions/ftello.texi: Mention the macOS bug.
diff --git a/doc/posix-functions/ftello.texi b/doc/posix-functions/ftello.texi
index 2561c5d..eab591f 100644
--- a/doc/posix-functions/ftello.texi
+++ b/doc/posix-functions/ftello.texi
@@ -20,6 +20,11 @@ This function produces incorrect results after @code{putc}
that followed a
@code{getc} call that reached EOF on some platforms:
Solaris 11 2010-11.
@item
+This function, when invoked after @code{ungetc}, throws away the @code{ungetc}
+buffer, changes the stream's file position, and returns the wrong position on
+some platforms:
+macOS 10.15 and newer.
+@item
This function fails on seekable stdin, stdout, and stderr: cygwin <= 1.5.24.
@item
On platforms where @code{off_t} is a 32-bit type, @code{ftello} does not work
diff --git a/lib/ftello.c b/lib/ftello.c
index c5a4e0c..da13694 100644
--- a/lib/ftello.c
+++ b/lib/ftello.c
@@ -19,6 +19,9 @@
/* Specification. */
#include <stdio.h>
+#include <errno.h>
+#include "intprops.h"
+
/* Get lseek. */
#include <unistd.h>
@@ -40,13 +43,79 @@ ftello (FILE *fp)
# endif
#endif
{
-#if LSEEK_PIPE_BROKEN
+#if FTELLO_BROKEN_AFTER_UNGETC /* macOS >= 10.15 */
+ /* The system's ftello() is completely broken, because it calls __sflush,
+ which makes side effects on the stream. */
+
+ /* Handle non-seekable files first. */
+ if (fp->_file < 0 || fp->_seek == NULL)
+ {
+ errno = ESPIPE;
+ return -1;
+ }
+
+ /* Determine the current offset, ignoring buffered and pushed-back bytes. */
+ off_t pos;
+
+ if (fp->_flags & __SOFF)
+ pos = fp->_offset;
+ else
+ {
+ pos = fp->_seek (fp->_cookie, 0, SEEK_CUR);
+ if (pos < 0)
+ return -1;
+ if (fp->_flags & __SOPT)
+ {
+ fp->_offset = pos;
+ fp->_flags |= __SOFF;
+ }
+ }
+
+ if (fp->_flags & __SRD)
+ {
+ /* Now consider buffered and pushed-back bytes from ungetc. */
+ if (fp->_ub._base != NULL)
+ /* Considering the buffered bytes, we are at position
+ pos - fp->_ur.
+ Considering also the pushed-back bytes, we are at position
+ pos - fp->_ur - fp->_r. */
+ pos = pos - fp->_ur - fp->_r;
+ else
+ /* Considering the buffered bytes, we are at position
+ pos - fp->_r. */
+ pos = pos - fp->_r;
+ if (pos < 0)
+ {
+ errno = EIO;
+ return -1;
+ }
+ }
+ else if ((fp->_flags & __SWR) && fp->_p != NULL)
+ {
+ /* Consider the buffered bytes. */
+ off_t buffered = fp->_p - fp->_bf._base;
+
+ /* Compute pos + buffered, with overflow check. */
+ off_t sum;
+ if (! INT_ADD_OK (pos, buffered, &sum))
+ {
+ errno = EOVERFLOW;
+ return -1;
+ }
+ pos = sum;
+ }
+
+ return pos;
+
+#else
+
+# if LSEEK_PIPE_BROKEN
/* mingw gives bogus answers rather than failure on non-seekable files. */
if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
return -1;
-#endif
+# endif
-#if FTELLO_BROKEN_AFTER_SWITCHING_FROM_READ_TO_WRITE /* Solaris */
+# 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. */
@@ -66,9 +135,9 @@ ftello (FILE *fp)
}
return pos;
}
-#endif
+# endif
-#if defined __SL64 && defined __SCLE /* Cygwin */
+# if defined __SL64 && defined __SCLE /* Cygwin */
if ((fp->_flags & __SL64) == 0)
{
/* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
@@ -80,6 +149,9 @@ ftello (FILE *fp)
fp->_seek64 = tmp->_seek64;
fclose (tmp);
}
-#endif
+# endif
+
return ftello (fp);
+
+#endif
}
diff --git a/m4/ftello.m4 b/m4/ftello.m4
index 1a0f7bc..65bec39 100644
--- a/m4/ftello.m4
+++ b/m4/ftello.m4
@@ -1,4 +1,4 @@
-# ftello.m4 serial 13
+# ftello.m4 serial 14
dnl Copyright (C) 2007-2021 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -130,6 +130,15 @@ main (void)
;;
esac
fi
+ if test $REPLACE_FTELLO = 0; then
+ dnl Detect bug on macOS >= 10.15.
+ gl_FUNC_UNGETC_WORKS
+ if test $gl_ftello_broken_after_ungetc = yes; then
+ REPLACE_FTELLO=1
+ AC_DEFINE([FTELLO_BROKEN_AFTER_UNGETC], [1],
+ [Define to 1 if the system's ftello function has the macOS bug.])
+ fi
+ fi
fi
])
diff --git a/m4/ungetc.m4 b/m4/ungetc.m4
index b648fea..dd5d1dd 100644
--- a/m4/ungetc.m4
+++ b/m4/ungetc.m4
@@ -1,4 +1,4 @@
-# ungetc.m4 serial 9
+# ungetc.m4 serial 10
dnl Copyright (C) 2009-2021 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -55,11 +55,19 @@ AC_DEFUN_ONCE([gl_FUNC_UNGETC_WORKS],
esac
])
])
+ gl_ftello_broken_after_ungetc=no
case "$gl_cv_func_ungetc_works" in
*yes) ;;
*)
- AC_DEFINE([FUNC_UNGETC_BROKEN], [1],
- [Define to 1 if ungetc is broken when used on arbitrary bytes.])
+ dnl On macOS >= 10.15, where the above program fails with exit code 6,
+ dnl we fix it through an ftello override.
+ case "$host_os" in
+ darwin*) gl_ftello_broken_after_ungetc=yes ;;
+ *)
+ AC_DEFINE([FUNC_UNGETC_BROKEN], [1],
+ [Define to 1 if ungetc is broken when used on arbitrary bytes.])
+ ;;
+ esac
;;
esac
])
diff --git a/modules/ftello b/modules/ftello
index 6de0859..fc6bafb 100644
--- a/modules/ftello
+++ b/modules/ftello
@@ -6,6 +6,7 @@ lib/ftello.c
lib/stdio-impl.h
m4/fseeko.m4
m4/ftello.m4
+m4/ungetc.m4
Depends-on:
stdio
@@ -13,6 +14,7 @@ extensions
largefile
sys_types
lseek [test $HAVE_FTELLO = 0 || test $REPLACE_FTELLO = 1]
+intprops [test $HAVE_FTELLO = 0 || test $REPLACE_FTELLO = 1]
# Just to guarantee consistency between ftell() and ftello().
ftell
