Discussion:
fix module qsort_r
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Bruno Haible
2016-10-16 20:12:14 UTC
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Hi Paul,

The module 'qsort_r' does not work at all on systems that don't have this function.
For example, on AIX 7.1, with a gnulib testdir:

test-qsort_r.c: In function 'main':
test-qsort_r.c:40:3: warning: implicit declaration of function 'qsort_r' [-Wimplicit-function-declaration]
qsort_r (buf, sizeof buf - 1, 1, cmp, &forward);
^
gcc -mlong-double-64 -D_ALL_SOURCE -std=gnu11 -g -O2 -o test-qsort_r test-qsort_r.o ../gllib/libgnu.a -lm -lm -lm -lm -lm -lm -lm -lm -lm -lm
ld: 0711-317 ERROR: Undefined symbol: .qsort_r
ld: 0711-345 Use the -bloadmap or -bnoquiet option to obtain more information.
collect2: error: ld returned 8 exit status
make: 1254-004 The error code from the last command is 1.

The problems are:
1) The gl_FUNC_QSORT_R macro finds that
checking for qsort_r signature... GNU
2) The function does not get declared in gnulib's stdlib.h replacement.
3) It also is not included in libgnu.a (neither qsort.o nor qsort_r.o gets
included in gl_LIBOBJS).

Ad 1) Yes really it needs an AC_CHECK_FUNC call, because a program such as
============================================================================
#define __EXTENSIONS__ 1
#define _ALL_SOURCE 1
#define _DARWIN_C_SOURCE 1
#define _GNU_SOURCE 1
#include <stdlib.h>
#define qsort_t any_nonexistent_name
void qsort_r (void *, size_t, size_t,
int (*) (void const *, void const *,
void *),
void *);
void (*p) (void *, size_t, size_t,
int (*) (void const *, void const *,
void *),
void *) = qsort_r;
int main () { return 0; }
============================================================================
compiles and links perfectly fine.

Ad 2) The idiom in stdlib.h is incomplete. You need to pick the complete one
(e.g. copy&paste from the 'ptsname_r' declaration).

Additionally:
4) The qsort_r function would not be warned about in GNULIB_POSIXCHECK mode.

Here's a proposed fix.


2016-10-16 Bruno Haible <***@clisp.org>

qsort_r: Fix macrology for platforms that lack the function.
* m4/stdlib_h.m4 (gl_STDLIB_H): Check for qsort_r.
(gl_STDLIB_H_DEFAULTS): Initialize HAVE_QSORT_R.
* modules/stdlib (Makefile.am): Substitute HAVE_QSORT_R.
* lib/stdlib.in.h (qsort_r): Provide declaration if the function does
not exist.
* m4/qsort_r.m4 (gl_FUNC_QSORT_R): Use AC_CHECK_FUNCS to test whether
the function exists.
* modules/qsort_r: Add comments.

diff --git a/lib/stdlib.in.h b/lib/stdlib.in.h
index 70dc88d..db3253b 100644
--- a/lib/stdlib.in.h
+++ b/lib/stdlib.in.h
@@ -521,6 +521,9 @@ _GL_CXXALIASWARN (putenv);
#endif

#if @GNULIB_QSORT_R@
+/* Sort an array of NMEMB elements, starting at address BASE, each element
+ occupying SIZE bytes, in ascending order according to the comparison
+ function COMPARE. */
# if @REPLACE_QSORT_R@
# if !(defined __cplusplus && defined GNULIB_NAMESPACE)
# undef qsort_r
@@ -535,12 +538,24 @@ _GL_CXXALIAS_RPL (qsort_r, void, (void *base, size_t nmemb, size_t size,
void *),
void *arg));
# else
+# if !@HAVE_QSORT_R@
+_GL_FUNCDECL_SYS (qsort_r, void, (void *base, size_t nmemb, size_t size,
+ int (*compare) (void const *, void const *,
+ void *),
+ void *arg) _GL_ARG_NONNULL ((1, 4)));
+# endif
_GL_CXXALIAS_SYS (qsort_r, void, (void *base, size_t nmemb, size_t size,
int (*compare) (void const *, void const *,
void *),
void *arg));
# endif
_GL_CXXALIASWARN (qsort_r);
+#elif defined GNULIB_POSIXCHECK
+# undef qsort_r
+# if HAVE_RAW_DECL_QSORT_R
+_GL_WARN_ON_USE (qsort_r, "qsort_r is not portable - "
+ "use gnulib module qsort_r for portability");
+# endif
#endif


diff --git a/m4/qsort_r.m4 b/m4/qsort_r.m4
index f3d2927..f1de7d4 100644
--- a/m4/qsort_r.m4
+++ b/m4/qsort_r.m4
@@ -14,35 +14,39 @@ AC_DEFUN([gl_FUNC_QSORT_R],

AC_REQUIRE([gl_STDLIB_H_DEFAULTS])

- AC_CACHE_CHECK([for qsort_r signature], [gl_cv_qsort_r_signature],
- [AC_LINK_IFELSE(
- [AC_LANG_PROGRAM([[#include <stdlib.h>
- void qsort_r (void *, size_t, size_t,
- int (*) (void const *, void const *,
- void *),
- void *);
- void (*p) (void *, size_t, size_t,
- int (*) (void const *, void const *,
- void *),
- void *) = qsort_r;
- ]])],
- [gl_cv_qsort_r_signature=GNU],
- [AC_LINK_IFELSE(
- [AC_LANG_PROGRAM([[#include <stdlib.h>
- void qsort_r (void *, size_t, size_t, void *,
- int (*) (void *,
- void const *,
- void const *));
- void (*p) (void *, size_t, size_t, void *,
- int (*) (void *, void const *,
- void const *)) = qsort_r;
- ]])],
- [gl_cv_qsort_r_signature=BSD],
- [gl_cv_qsort_r_signature=no])])])
-
- case $gl_cv_qsort_r_signature in
- GNU) HAVE_QSORT_R=1;;
- BSD) HAVE_QSORT_R=1 REPLACE_QSORT_R=1;;
- *) HAVE_QSORT_R=0 REPLACE_QSORT_R=1;;
- esac
+ AC_CHECK_FUNCS_ONCE([qsort_r])
+ if test $ac_cv_func_qsort_r = yes; then
+ AC_CACHE_CHECK([for qsort_r signature], [gl_cv_qsort_r_signature],
+ [AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM([[#include <stdlib.h>
+ void qsort_r (void *, size_t, size_t,
+ int (*) (void const *, void const *,
+ void *),
+ void *);
+ void (*p) (void *, size_t, size_t,
+ int (*) (void const *, void const *,
+ void *),
+ void *) = qsort_r;
+ ]])],
+ [gl_cv_qsort_r_signature=GNU],
+ [AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM([[#include <stdlib.h>
+ void qsort_r (void *, size_t, size_t, void *,
+ int (*) (void *,
+ void const *,
+ void const *));
+ void (*p) (void *, size_t, size_t, void *,
+ int (*) (void *, void const *,
+ void const *)) = qsort_r;
+ ]])],
+ [gl_cv_qsort_r_signature=BSD],
+ [gl_cv_qsort_r_signature=unknown])])])
+ case $gl_cv_qsort_r_signature in
+ GNU) ;;
+ BSD) REPLACE_QSORT_R=1 ;;
+ unknown) HAVE_QSORT_R=0 REPLACE_QSORT_R=1 ;;
+ esac
+ else
+ HAVE_QSORT_R=0
+ fi
])
diff --git a/m4/stdlib_h.m4 b/m4/stdlib_h.m4
index 19107c4..3999068 100644
--- a/m4/stdlib_h.m4
+++ b/m4/stdlib_h.m4
@@ -1,4 +1,4 @@
-# stdlib_h.m4 serial 42
+# stdlib_h.m4 serial 43
dnl Copyright (C) 2007-2016 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -21,7 +21,7 @@ AC_DEFUN([gl_STDLIB_H],
#endif
]], [_Exit atoll canonicalize_file_name getloadavg getsubopt grantpt
initstate initstate_r mkdtemp mkostemp mkostemps mkstemp mkstemps
- posix_openpt ptsname ptsname_r random random_r realpath rpmatch
+ posix_openpt ptsname ptsname_r qsort_r random random_r realpath rpmatch
secure_getenv setenv setstate setstate_r srandom srandom_r
strtod strtoll strtoull unlockpt unsetenv])
])
@@ -85,6 +85,7 @@ AC_DEFUN([gl_STDLIB_H_DEFAULTS],
HAVE_POSIX_OPENPT=1; AC_SUBST([HAVE_POSIX_OPENPT])
HAVE_PTSNAME=1; AC_SUBST([HAVE_PTSNAME])
HAVE_PTSNAME_R=1; AC_SUBST([HAVE_PTSNAME_R])
+ HAVE_QSORT_R=1; AC_SUBST([HAVE_QSORT_R])
HAVE_RANDOM=1; AC_SUBST([HAVE_RANDOM])
HAVE_RANDOM_H=1; AC_SUBST([HAVE_RANDOM_H])
HAVE_RANDOM_R=1; AC_SUBST([HAVE_RANDOM_R])
diff --git a/modules/qsort_r b/modules/qsort_r
index 52b57c0..6772edc 100644
--- a/modules/qsort_r
+++ b/modules/qsort_r
@@ -13,8 +13,10 @@ stdlib
configure.ac:
gl_FUNC_QSORT_R
if test $HAVE_QSORT_R = 0; then
+ # The function is missing from the system or has an unknown signature.
AC_LIBOBJ([qsort])
elif test $REPLACE_QSORT_R = 1; then
+ # The function exists, but it has the BSD signature.
AC_LIBOBJ([qsort_r])
fi
gl_STDLIB_MODULE_INDICATOR([qsort_r])
diff --git a/modules/stdlib b/modules/stdlib
index cbc5b01..27b1caa 100644
--- a/modules/stdlib
+++ b/modules/stdlib
@@ -79,6 +79,7 @@ stdlib.h: stdlib.in.h $(top_builddir)/config.status $(CXXDEFS_H) \
-e 's|@''HAVE_POSIX_OPENPT''@|$(HAVE_POSIX_OPENPT)|g' \
-e 's|@''HAVE_PTSNAME''@|$(HAVE_PTSNAME)|g' \
-e 's|@''HAVE_PTSNAME_R''@|$(HAVE_PTSNAME_R)|g' \
+ -e 's|@''HAVE_QSORT_R''@|$(HAVE_QSORT_R)|g' \
-e 's|@''HAVE_RANDOM''@|$(HAVE_RANDOM)|g' \
-e 's|@''HAVE_RANDOM_H''@|$(HAVE_RANDOM_H)|g' \
-e 's|@''HAVE_RANDOM_R''@|$(HAVE_RANDOM_R)|g' \
Paul Eggert
2016-10-27 00:47:32 UTC
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Thanks for doing all that. I gave the patch a quick scan just now and it
looks fine; please install when you find the time.
Bruno Haible
2016-10-27 07:23:40 UTC
Permalink
Raw Message
Post by Paul Eggert
I gave the patch a quick scan just now and it
looks fine; please install when you find the time.
Done.

Bruno

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