I basically have a wrapper around strftime() and compilation with
-Werror=format-nonliteral fails when the wrapper wants to call strftime,
because "format not a string literal, format string not checked".
The code in question looks like this:
#include<time.h>
#include<stdio.h>
#define SIZE 256
size_t my_strftime(char *s, size_t max, const char *fmt,
const struct tm *tm)
{
size_t ret;
ret = strftime(s, max, fmt, tm);
return ret;
}
int
main ()
{
char s[SIZE];
time_t curtime;
struct tm* loctime;
curtime = time(NULL);
loctime = localtime (&curtime);
my_strftime(s, SIZE, "Hello %A", loctime);
printf("%s", s);
return 0;
}
mue...@bigbox /tmp $ gcc -v -save-temp -Wformat -Wformat-nonliteral
-Werror=format-nonliteral -o mystrftime{,.c}
Using built-in specs.
gcc: unrecognized option '-save-temp'
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla
--enable-bootstrap --enable-shared --enable-threads=posix
--enable-checking=release --with-system-zlib --enable-__cxa_atexit
--disable-libunwind-exceptions
--enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk
--disable-dssi --enable-plugin
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre
--enable-libgcj-multifile --enable-java-maintainer-mode
--with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib
--with-cpu=generic --build=x86_64-redhat-linux
Thread model: posix
gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temp' '-Wformat' '-Wformat-nonliteral'
'-Werror=format-nonliteral' '-o' 'mystrftime' '-mtune=generic'
/usr/libexec/gcc/x86_64-redhat-linux/4.3.2/cc1 -quiet -v mystrftime.c -quiet
-dumpbase mystrftime.c -mtune=generic -auxbase mystrftime -Wformat
-Wformat-nonliteral -Werror=format-nonliteral -version -o /tmp/ccznk3Wo.s
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/4.3.2/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/4.3.2/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/include
/usr/lib/gcc/x86_64-redhat-linux/4.3.2/include
/usr/include
End of search list.
GNU C (GCC) version 4.3.2 20081105 (Red Hat 4.3.2-7) (x86_64-redhat-linux)
compiled by GNU C version 4.3.2 20081105 (Red Hat 4.3.2-7), GMP version
4.2.2, MPFR version 2.3.2.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: c99c7b3dc8e919a4b394102437269a84
mystrftime.c: In function my_strftime:
mystrftime.c:14: error: format not a string literal, format string not checked
mue...@bigbox /tmp $
I raised this issue on gcc-help (Message-ID:
<49a96972.5060...@informatik.uni-hamburg.de>) and got the tip to use
__attribute__(( format(strftime, 3, 0) )) but it doesn't work.
I think I want to make gcc
* know that the wrapper is not responsible for the format string and
thus the call to strftime is allowed
* pass the responsibility up to the callers and thus check whether they
call the wrapper with "good" strings.
but it doesn't seem possible.
I hope to have all needed information included. I can't, however, fulfil the
request from http://gcc.gnu.org/bugs.html to attach *.*i* files, because there
are none. Also, I searched the bugzilla for "format-nonliteral" and found
nothing related to this issue. I thus think it hasn't been filed yet.
--
Summary: Can't compile a wrapper around strftime with -
Werror=format-nonliteral
Product: gcc
Version: 4.3.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: 4tmuelle at informatik dot uni-hamburg dot de
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39438
