Re: [PATCH] mingw: simplify PATH handling

From: Johannes Sixt <j6t@kdbg.org>
Date: May 20, 2017, 17:00 UTC
Message-ID: <5d4f08c0-07e2-b59c-a132-d165a21323df@kdbg.org>
In-Reply-To: <c5b7292f-6367-e4a9-2ee0-96b93b1b587f@web.de>

Am 20.05.2017 um 17:29 schrieb René Scharfe:

Show 25 quoted lines

> -static char *path_lookup(const char *cmd, char **path, int exe_only)
> +static char *path_lookup(const char *cmd, int exe_only)
>   {
> +	const char *path;
>   	char *prog = NULL;
>   	int len = strlen(cmd);
>   	int isexe = len >= 4 && !strcasecmp(cmd+len-4, ".exe");
>   
>   	if (strchr(cmd, '/') || strchr(cmd, '\\'))
> -		prog = xstrdup(cmd);
> +		return xstrdup(cmd);
>   
> -	while (!prog && *path)
> -		prog = lookup_prog(*path++, cmd, isexe, exe_only);
> +	path = mingw_getenv("PATH");
> +	if (!path)
> +		return NULL;
> +
> +	for (; !prog && *path; path++) {
> +		const char *sep = strchrnul(path, ';');
> +		if (sep == path)
> +			continue;
> +		prog = lookup_prog(path, sep - path, cmd, isexe, exe_only);
> +		path = sep;
> +	}

The loop termination does not work here. When the final PATH component is investigated, sep points to the NUL. This pointer is assigned to path, which is incremented and now points one past NUL. Then the loop condition (*path) accesses the char behind NUL.

Show 18 quoted lines

>   
>   	return prog;
>   }
> @@ -1569,13 +1527,10 @@ static pid_t mingw_spawnve_fd(const char *cmd, const char **argv, char **deltaen
>   	}
>   
>   	if (getenv("GIT_STRACE_COMMANDS")) {
> -		char **path = get_path_split();
> -		char *p = path_lookup("strace.exe", path, 1);
> +		char *p = path_lookup("strace.exe", 1);
>   		if (!p) {
> -			free_path_split(path);
>   			return error("strace not found!");
>   		}
> -		free_path_split(path);
>   		if (xutftowcs_path(wcmd, p) < 0) {
>   			free(p);
>   			return -1;

Upstream does not have this hunk.

Otherwise, good catch!

-- Hannes