[llvm] 21e5e17 - getMainExecutable: Fix hand-rolled AT_EXECPATH for older FreeBSD

[Ed Maste via llvm-commits]

Author: Ed Maste
Date: 2020-05-07T17:05:17-04:00
New Revision: 21e5e1724b75a4fc66ddb8b7e31b7c85b8f9c67b

URL: https://github.com/llvm/llvm-project/commit/21e5e1724b75a4fc66ddb8b7e31b7c85b8f9c67b
DIFF: https://github.com/llvm/llvm-project/commit/21e5e1724b75a4fc66ddb8b7e31b7c85b8f9c67b.diff

LOG: getMainExecutable: Fix hand-rolled AT_EXECPATH for older FreeBSD

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
emu-user-static, at the moment), where we would previously run off
the end of ::environ.

Patch By: kevans

Reviewed By: arichardson

Differential Revision:	https://reviews.llvm.org/D79239

Added: 
    

Modified: 
    llvm/lib/Support/Unix/Path.inc

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index 783a7ace1005..bf720b318ded 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -207,14 +207,9 @@ std::string getMainExecutable(const char *argv0, void *MainAddr) {
   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.