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Re: avoid some warnings
From: |
Eric Blake |
Subject: |
Re: avoid some warnings |
Date: |
Thu, 04 Feb 2010 20:06:29 -0700 |
User-agent: |
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.23) Gecko/20090812 Thunderbird/2.0.0.23 Mnenhy/0.7.6.666 |
According to Jim Meyering on 2/1/2010 6:56 AM:
>> int (*f) (struct timeval *, GETTIMEOFDAY_TIMEZONE *);
>
> Sounds reasonable.
>
Done. Tested on cygwin (always works), mingw (always replaced), and on
Linux under both -D_GNU_SOURCE (configure prints almost, no longer
replaced) and -D_POSIX_C_SOURCE=200809L (configure prints yes).
--
Don't work too hard, make some time for fun as well!
Eric Blake address@hidden
From de4d0a383be20eb6cbeb09ecbd66a5514779b914 Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Sat, 30 Jan 2010 07:47:40 -0700
Subject: [PATCH] gettimeofday: expose type of second argument
Needed to silence compiler warnings such as:
test-gettimeofday.c:23: warning: initialization from incompatible pointer type
based on whether gettimeofday complies with POSIX or provides
the extension of struct timezone.
* m4/gettimeofday.m4 (gl_FUNC_GETTIMEOFDAY): Do better detection
of glibc extension signature, and define GETTIMEOFDAY_TIMEZONE.
* tests/test-gettimeofday.c: Use it to silence warning.
* doc/posix-functions/gettimeofday.texi (gettimeofday): Document
the issue.
Signed-off-by: Eric Blake <address@hidden>
---
ChangeLog | 9 +++++
doc/posix-functions/gettimeofday.texi | 12 +++++++
m4/gettimeofday.m4 | 58 +++++++++++++++++++++------------
tests/test-gettimeofday.c | 8 ++---
4 files changed, 61 insertions(+), 26 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index 093bdcf..65ee5b5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2010-02-04 Eric Blake <address@hidden>
+
+ gettimeofday: expose type of second argument
+ * m4/gettimeofday.m4 (gl_FUNC_GETTIMEOFDAY): Do better detection
+ of glibc extension signature, and define GETTIMEOFDAY_TIMEZONE.
+ * tests/test-gettimeofday.c: Use it to silence warning.
+ * doc/posix-functions/gettimeofday.texi (gettimeofday): Document
+ the issue.
+
2010-02-03 Jim Meyering <address@hidden>
regcomp.c: avoid the sole warning from gcc's -Wtype-limits
diff --git a/doc/posix-functions/gettimeofday.texi
b/doc/posix-functions/gettimeofday.texi
index 3f9d423..fda59a3 100644
--- a/doc/posix-functions/gettimeofday.texi
+++ b/doc/posix-functions/gettimeofday.texi
@@ -15,6 +15,15 @@ gettimeofday
This function is declared with a nonstandard function prototype (only one
argument, or ``...'' after the first argument) on some platforms.
@item
+On some platforms, the second argument has type @code{struct
+timezone*} rather than @code{void *}, making it an error to redeclare
+the function with the POSIX signature:
+glibc.
+However, rather than penalize these systems with a replacement
+function, gnulib defines @code{GETTIMEOFDAY_TIMEZONE} to the
+appropriate type for use in avoiding a compiler warning if assigning
address@hidden to a function pointer.
address@hidden
On some platforms, @code{gettimeofday} clobbers the buffer in which
@code{localtime} returns its result:
MacOS X 10.0.
@@ -22,4 +31,7 @@ gettimeofday
Portability problems not fixed by Gnulib:
@itemize
address@hidden
+Behavior is non-portable if the second argument to @code{gettimeofday}
+is not @code{NULL}.
@end itemize
diff --git a/m4/gettimeofday.m4 b/m4/gettimeofday.m4
index 2155627..32e4f29 100644
--- a/m4/gettimeofday.m4
+++ b/m4/gettimeofday.m4
@@ -1,4 +1,4 @@
-# serial 13
+# serial 14
# Copyright (C) 2001-2003, 2005, 2007, 2009-2010 Free Software Foundation, Inc.
# This file is free software; the Free Software Foundation
@@ -14,30 +14,46 @@ AC_DEFUN([gl_FUNC_GETTIMEOFDAY],
AC_REQUIRE([gl_HEADER_SYS_TIME_H_DEFAULTS])
AC_CHECK_FUNCS_ONCE([gettimeofday])
- AC_CACHE_CHECK([for gettimeofday with POSIX signature],
- [gl_cv_func_gettimeofday_posix_signature],
- [AC_COMPILE_IFELSE(
- [AC_LANG_PROGRAM(
- [[#include <sys/time.h>
- struct timeval c;
- ]],
- [[
- int (*f) (struct timeval *restrict, void *restrict) = gettimeofday;
- int x = f (&c, 0);
- return !(x | c.tv_sec | c.tv_usec);
- ]])],
- [gl_cv_func_gettimeofday_posix_signature=yes],
- [gl_cv_func_gettimeofday_posix_signature=no])])
-
- gl_FUNC_GETTIMEOFDAY_CLOBBER
-
- if test $gl_cv_func_gettimeofday_posix_signature != yes; then
- REPLACE_GETTIMEOFDAY=1
- if test $gl_cv_func_gettimeofday_clobber != yes; then
+ gl_gettimeofday_timezone=void
+ if test $ac_cv_func_gettimeofday = yes; then
+ gl_FUNC_GETTIMEOFDAY_CLOBBER
+ AC_CACHE_CHECK([for gettimeofday with POSIX signature],
+ [gl_cv_func_gettimeofday_posix_signature],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <sys/time.h>
+ struct timeval c;
+ int gettimeofday (struct timeval *restrict, void *restrict);
+ ]],
+ [[/* glibc uses struct timezone * rather than the POSIX void *
+ if _GNU_SOURCE is defined. However, since the only portable
+ use of gettimeofday uses NULL as the second parameter, and
+ since the glibc definition is actually more typesafe, it is
+ not worth wrapping this to get a compliant signature. */
+ int (*f) (struct timeval *restrict, void *restrict)
+ = gettimeofday;
+ int x = f (&c, 0);
+ return !(x | c.tv_sec | c.tv_usec);
+ ]])],
+ [gl_cv_func_gettimeofday_posix_signature=yes],
+ [AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <sys/time.h>
+int gettimeofday (struct timeval *restrict, struct timezone *restrict);
+ ]])],
+ [gl_cv_func_gettimeofday_posix_signature=almost],
+ [gl_cv_func_gettimeofday_posix_signature=no])])])
+ if test $gl_cv_func_gettimeofday_posix_signature = almost; then
+ gl_gettimeofday_timezone='struct timezone'
+ elif test $gl_cv_func_gettimeofday_posix_signature != yes; then
+ REPLACE_GETTIMEOFDAY=1
AC_LIBOBJ([gettimeofday])
gl_PREREQ_GETTIMEOFDAY
fi
fi
+ AC_DEFINE_UNQUOTED([GETTIMEOFDAY_TIMEZONE], [$gl_gettimeofday_timezone],
+ [Define this to 'void' or 'struct timezone' to match the system's
+ declaration of the second argument to gettimeofday.])
])
diff --git a/tests/test-gettimeofday.c b/tests/test-gettimeofday.c
index 2a07814..ff2bc72 100644
--- a/tests/test-gettimeofday.c
+++ b/tests/test-gettimeofday.c
@@ -20,7 +20,8 @@
#include <sys/time.h>
#include "signature.h"
-SIGNATURE_CHECK (gettimeofday, int, (struct timeval *, void *));
+SIGNATURE_CHECK (gettimeofday, int,
+ (struct timeval *, GETTIMEOFDAY_TIMEZONE *));
#include <time.h>
@@ -42,8 +43,5 @@ main (void)
fprintf (stderr, "gettimeofday still clobbers the localtime buffer!\n");
return 1;
}
- else
- {
- return 0;
- }
+ return 0;
}
--
1.6.4.2
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