[LTP] [PATCH v4 1/2] Add SAFE_MPROTECT() macro

[Cyril Hrubis]

Hi!
> +	int rval;
> +	char prot_buf[16];
> +
> +	switch (prot) {
> +	case PROT_NONE:
> +		snprintf(prot_buf, 16, "PROT_NONE");
> +		break;
> +	case PROT_WRITE:
> +		snprintf(prot_buf, 16, "PROT_WRITE");
> +		break;
> +	case PROT_READ:
> +		snprintf(prot_buf, 16, "PROT_READ");
> +		break;
> +	case PROT_EXEC:
> +		snprintf(prot_buf, 16, "PROT_EXEC");
> +		break;
> +	default:
> +		snprintf(prot_buf, 16, "UNKNOWN");
> +		break;
> +	}

This is ugly and does not work.

First of all we can just do:

	char *prot_name;


	switch (prot) {
	case PROT_NONE:
		prot_name = "PROT_NONE";
	break;
	...
	}

And secondly it does not work for common combinations, like (PROT_READ | PROT_WRITE).

So I guess that the easiest solution is to walk the bits and append the
string something as:

#define PROT_READ_NAME "PROT_READ | "
#define PROT_WRITE_NAME "PROT_WRITE | "
#define PROT_EXEC_NAME "PROT_EXEC | "

static const char *prot_to_str(int prot, char *buf, size_t buf_len)
{
	char *orig_buf = buf;

	if (buf_len < sizeof(PROT_READ_NAME) + sizeof(PROT_WRITE_NAME) + sizeof(PROT_EXEC_NAME))
		return "BUFFER TOO SMALL!!!";

	if (prot == 0)
		return "PROT_NONE";

	*buf = 0;

	if (prot & PROT_READ) {
		strcpy(buf, PROT_READ_NAME);
		buf += sizeof(PROT_READ_NAME)-1;
	}

	if (prot & PROT_WRITE) {
		strcpy(buf, PROT_WRITE_NAME);
		buf += sizeof(PROT_WRITE_NAME)-1;
	}

	if (prot & PROT_EXEC) {
		strcpy(buf, PROT_EXEC_NAME);
		buf += sizeof(PROT_EXEC_NAME)-1;
	}

	if (orig_buf != buf)
		buf[-3] = 0;

	return buf;
}

Also I would put the code that translates the prot into string into a
separate function because that code should be used in the safe_mmap() as
well.

> +	tst_res_(file, lineno, TDEBUG,
> +		"mprotect(%p, %d, %s)", addr, len, prot_buf);

Can we print hexadecimal value of the prot here as well?

		"mprotect(%p, %d, %s(%x))", addr, len, prot_to_str(prot, buf, sizeof(buf)), prot);

> +	rval = mprotect(addr, len, prot);
> +
> +	if (rval == -1) {
> +		tst_brkm_(file, lineno, TBROK | TERRNO, NULL,
> +			"mprotect() failed");
> +	} else if (rval) {
> +		tst_brkm_(file, lineno, TBROK | TERRNO, NULL,
> +			"Invalid mprotect() return value %d", rval);
> +	}
> +
> +	return rval;
> +}
> +
>  int safe_mincore(const char *file, const int lineno, void *start,
>  	size_t length, unsigned char *vec)
>  {
> -- 
> 2.35.3
> 
> 
> -- 
> Mailing list info: https://lists.linux.it/listinfo/ltp

-- 
Cyril Hrubis
chrubis@suse.cz