getMainExecutable: Fix hand-rolled AT_EXECPATH search for older branches

[kevans]

Summary

Once we hit AT_NULL, we need to bail out of the loop; not just the enclosing
switch. This fixes basic usage (e.g. cc --version) when AT_EXECPATH isn't
present on older branches (e.g. under qemu-user-static, at the moment),
where we would previously run off the end of ::environ.

Signed-off-by: Kyle Evans <[e-mail]>

[arichardson]

Since there are only two cases I'd be tempted to use an if instead of a switch. That would avoid the need for a go-to.

[kevans]

Sure; I have no strong preference.

[arichardson]

LGTM if @emaste / @dim are also happy with it.

[emaste]

I will commit this shortly (and then merge the change into FreeBSD's copy).

[MaskRay]

We are using git now. Please use git commit --amend --author=

Thanks for stripping unneeded Phabricator tags.

I usually do this when committing: arcfilter; git fetch origin master && git rebase origin/master; last-minute-testing && git push origin HEAD:master where arcfilter is a shell function which drops unneeded Phabricator tags (Subscribers:, Summary:, Tags:, Reviewers:) but keeps Differential Revision: and Reviewed By:

arcfilter () {
        arc amend
        git log -1 --pretty=%B | awk '/Reviewers:|Subscribers:/{p=1} /Reviewed By:|Differential Revision:/{p=0} !p && !/^Summary:$/ {sub(/^Summary: /,"");print}' | git commit --amend -F -
}

Also, we don't use Signed-off-by:

llvm/lib/Support/Unix/Path.inc

 #else
   // elf_aux_info(AT_EXECPATH, ... is not available in all supported versions,
   // fall back to finding the ELF auxiliary vectors after the process's
   // environment.
   char **p = ::environ;
   while (*p++ != 0)
     ;
   // Iterate through auxiliary vectors for AT_EXECPATH.
-  for (;;) {
-    switch (*(uintptr_t *)p++) {
-    case AT_EXECPATH:
+  for (; *(uintptr_t *)p != AT_NULL; p++) {
+    if (*(uintptr_t *)p++ == AT_EXECPATH)
       return *p;
-    case AT_NULL:
-      break;
-    }
-    p++;
   }
 #endif
   // Fall back to argv[0] if auxiliary vectors are not available.
   if (getprogpath(exe_path, argv0) != NULL)
     return exe_path;
 #elif defined(__NetBSD__) || defined(__OpenBSD__) || defined(__minix) ||       \
     defined(__DragonFly__) || defined(__FreeBSD_kernel__) || defined(_AIX)
   const char *curproc = "/proc/curproc/file";