[PATCH weston 1/4] tests: Don't rely on build directory layout

[Emil Velikov]

Hi Pekka,

On 18 June 2018 at 15:40, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> From: Daniel Stone <daniels at collabora.com>
>
> Rather than having a hardcoded dependency on the build-directory layout,
> use an explicit module-map environment variable, which rewrites requests
> for modules and helper/libexec binaries to specific paths.
>
> This will help with migration to Meson where setting up the paths
> according to autotools would be painful and unnecessary.
>
Surely one didn't need a build system, to make nice improvements.
I guess, sometimes, tools do need to give us a wake-up call.


> +WL_EXPORT size_t
> +weston_module_path_from_env(const char *name, char *path, size_t path_len)
> +{
> +       const char *mapping = getenv("WESTON_MODULE_MAP");
> +       const char *end;
> +
strlen(name) once and use it throughout?


> +       if (!mapping)
> +               return 0;
> +
> +       end = mapping + strlen(mapping);
> +       while (mapping < end && *mapping) {
> +               const char *filename, *next;
> +
> +               /* early out: impossibly short string */
> +               if ((size_t)(end - mapping) < strlen(name) + 1)
> +                       return 0;
> +
> +               filename = &mapping[strlen(name) + 1];
> +               next = strchrnul(mapping, ';');
> +
> +               if (strncmp(mapping, name, strlen(name)) == 0 &&
> +                   mapping[strlen(name)] == '=') {
> +                       size_t file_len = next - filename; /* no trailing NUL */
> +                       if (file_len >= path_len)
> +                               return 0;
> +                       strncpy(path, filename, file_len);
> +                       path[file_len] = '\0';
A simple stat() can, more or less, ensure that we're not giving random
rubbish to the caller.
Worth it, or more of an overkill?

-Emil