Package: libdmalloc-dev Version: 5.5.1-1.1 Severity: normal Version of gcc: gcc-4.6 4.6.1-3 Version of libc6-dev: 2.13-10
When using any level of optimization in a program that enables GNU libc
extensions (defines _GNU_SOURCE), gcc turns strndup into a macro, which
confuses line 484 of dmalloc.h.
To illustrate, a test case, a.c
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <dmalloc.h>
int main(void)
{
static const char *s = "1234567";
char *p = strndup(s,4);
printf("%s\n", p);
return 0;
}
Compilation of a.c
gcc a.c -ldmalloc && ./a.out # prints "1234"
gcc -O2 a.c -ldmalloc && ./a.out # prints "1234"
gcc -D_GNU_SOURCE=1 a.c -ldmalloc && ./a.out # prints "1234"
gcc -D_GNU_SOURCE=1 -O2 a.c -ldmalloc && ./a.out # error
Looking at the output of gcc -E, line 484 turns from
char *strndup(const char *string, const DMALLOC_SIZE len);
into (split across several lines)
char *(__extension__ (__builtin_constant_p (const char *string) &&
((size_t)(const void *)((const char *string) + 1) - (size_t)(const void
*)(const char *string) == 1) ? (((__const char *) (const char
*string))[0] == '\0' ? (char *) calloc ((size_t) 1, (size_t) 1) : ({
size_t __len = strlen (const char *string) + 1; size_t __n = (const
size_t len); char *__retval; if (__n < __len) __len = __n + 1; __retval
= (char *) malloc (__len); if (__retval != ((void *)0)) { __retval[__len
- 1] = '\0'; __retval = (char *) memcpy (__retval, const char *string,
__len - 1); } __retval; })) : __strndup (const char *string, const
size_t len)));
which fails to compile with the error:
/usr/include/dmalloc.h:484:7: error: expected identifier or ‘(’ before
‘__extension__’
I'm not sure if this is a bug in dmalloc, or user error; maybe I did
something wrong, or perhaps dmalloc isn't designed to be used with
programs using both GCC optimization and GNU libc extensions. Either
way, a workaround is "#undef strndup" before "#include <dmalloc.h>".
Script with the above test case attached.
--
http://rjy.org.uk/
a.sh
Description: Bourne shell script
