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

[Pekka Paalanen]

On Tue, 19 Jun 2018 18:30:13 +0100
Emil Velikov <emil.l.velikov at gmail.com> wrote:

> 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.

The driving force behind a change should be stated in the commit
message. Granted, this paragraph was added by me, Daniel wrote only the
first paragraph. I didn't see the first paragraph as sufficient
rationale. The patch also allows loading external backends which we
specifically do not want to support at the time.

> 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?
> 

Might as well, since 'name' doesn't change.

> 
> > +       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?

If a mapping exists, we need to return the mapped-to path. If we return
nothing, then the caller will use the default path and a broken module
map could go unnoticed if there actually is something in the default
path.


Thanks,
pq
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