https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116834
Harald van Dijk <harald at gigawatt dot nl> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |harald at gigawatt dot nl
--- Comment #4 from Harald van Dijk <harald at gigawatt dot nl> ---
(In reply to Sam James from comment #3)
> Please provide preprocessed source for the original.
Not entirely preprocessed (due to using __SIZE_TYPE__ rather than its expanded
version) but a self-contained compilable version of the original code from
comment #2 is:
typedef struct bstr {
unsigned char *start;
__SIZE_TYPE__ len;
} bstr;
__SIZE_TYPE__ talloc_get_size(const void *);
void resize_append(void *, bstr *, __SIZE_TYPE__);
void bstr_xappend(void *, bstr *, bstr);
static inline struct bstr bstr0(const char *s)
{
return (struct bstr){(unsigned char *)s, s ? __builtin_strlen(s) : 0};
}
void bstr_xappend_vasprintf(void *talloc_ctx, bstr *s, const char *fmt,
__builtin_va_list ap)
{
int size;
__builtin_va_list copy;
__builtin_va_copy(copy, ap);
__SIZE_TYPE__ avail = talloc_get_size(s->start) - s->len;
char *dest = s->start ? s->start + s->len : 0;
size = __builtin_vsnprintf(dest, avail, fmt, copy);
__builtin_va_end(copy);
if (size < 0) {
bstr_xappend(talloc_ctx, s, bstr0("format error: "));
bstr_xappend(talloc_ctx, s, bstr0(fmt));
return;
}
if (avail < 1 || size + 1 > avail) {
resize_append(talloc_ctx, s, size + 1);
__builtin_vsnprintf(s->start + s->len, size + 1, fmt, ap);
}
s->len += size;
}
$ gcc-14 -fsanitize=undefined -Wformat -O2 -c bug116834.c
bug116834.c: In function ‘bstr_xappend_vasprintf’:
bug116834.c:23:12: warning: null format string [-Wformat-truncation=]
23 | size = __builtin_vsnprintf(dest, avail, fmt, copy);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
$ gcc-14 --version
gcc-14 (Ubuntu 14.2.0-4ubuntu2~24.04) 14.2.0
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This is free software; see the source for copying conditions. There is NO
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