re: valgrind

[RVP <rvp%SDF.ORG@localhost>]

On Mon, 21 Mar 2022, matthew green wrote:

> try clang, which usually has newer/better sanitizers.

Sanitizers are OK, but, they don't seem to work in some cases:

Case 1: Global allocation
---
$ cat global_alloc.c
#include <stdlib.h>
#include <string.h>

void* p;

int
main(void)
{
	p = malloc(1000);
	memset(p, '\0', 1000);
	return 0;
}
$ clang --version
clang version 13.0.1
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/llvm/bin
$ clang -Wall -g -fsanitize=address -o 1 global_alloc.c
$ env ASAN_OPTIONS=detect_leaks=1 ./1
$ 
---



Case 2: Static allocation
---
$ cat static_alloc.c
#include <stdlib.h>
#include <string.h>

static char*
mkbuf(size_t len)
{
	static void* sbuf = NULL;
	static size_t slen = 0;

	if (len > slen) {
		sbuf = realloc(sbuf, len);
		slen = len;
	}
	return sbuf;
}

int
main(void)
{
	char* p = mkbuf(1000);
	memset(p, '\0', 1000);
	return 0;
}
$ clang -Wall -g -fsanitize=address -o 2 static_alloc.c
$ env ASAN_OPTIONS=detect_leaks=1 ./2
$ 
---

Valgrind, of course, detects both those leaks.

-RVP

PS. Mouse's email server will, as usual, reject mails sent from SDF I
think... ;)