[PATCH] Fix getMainExecutable on GNU/Hurd

[Samuel Thibault via llvm-commits]

Hello,

On GNU/Hurd, llvm-config is returning bogus value, such as:

$ llvm-config-6.0 --includedir
/usr/include

while it should be:
$ llvm-config-6.0 --includedir
/usr/lib/llvm-6.0/include

This is because getMainExecutable does not get the actual installation
path. On GNU/Hurd, /proc/self/exe is indeed a symlink to the path that
was used to start the program, and not the eventual binary file. Llvm's
getMainExecutable thus needs to run realpath over it to get the actual
place where llvm was installed (/usr/lib/llvm-6.0/bin/llvm-config), and
not /usr/bin/llvm-config-6.0. This will not change the result on Linux,
where /proc/self/exe already points to the eventual file.

Could the attached patch thus be considered to fix this?

Samuel
-------------- next part --------------
[hurd] Make getMainExecutable get the real binary path

Index: lib/Support/Unix/Path.inc
===================================================================
--- lib/Support/Unix/Path.inc        (révision 344957)
+++ lib/Support/Unix/Path.inc        (copie de travail)
@@ -180,8 +180,22 @@ std::string getMainExecutable(const char *argv0, v
   if (sys::fs::exists(aPath)) {
       // /proc is not always mounted under Linux (chroot for example).
       ssize_t len = readlink(aPath.str().c_str(), exe_path, sizeof(exe_path));
-      if (len >= 0)
-          return std::string(exe_path, len);
+      if (len >= 0) {
+          if (len >= sizeof(exe_path))
+              len = sizeof(exe_path)-1;
+          exe_path[len] = '\0';
+
+#if _POSIX_VERSION >= 200112 || defined(__GLIBC__)
+          char *real_path = realpath(exe_path, NULL);
+          std::string ret = std::string(real_path);
+          free(real_path);
+          return ret;
+#else
+          char real_path[MAXPATHLEN];
+          realpath(exe_path, real_path);
+          return std::string(real_path);
+#endif
+      }
   } else {
       // Fall back to the classical detection.
       if (getprogpath(exe_path, argv0))