From bfd84b1c034d6b0413c293772662e1a5619d6b40 Mon Sep 17 00:00:00 2001
From: Kai Nacke <kai.nacke@de.ibm.com>
Date: Mon, 6 Jul 2020 05:53:29 -0400
Subject: [PATCH] [SystemZ/ZOS] Implement getMainExecutable() and
 is_local_impl()

Adds implementation of getMainExecutable() and is_local_impl() to
Support/Unix/Path.inc. Both are needed to compile LLVM for z/OS.

Reviewed By: hubert.reinterpretcast, emaste

Differential Revision: https://reviews.llvm.org/D82544
---
 llvm/lib/Support/Unix/Path.inc | 37 ++++++++++++++++++++++++++++++++++---
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Support/Unix/Path.inc b/llvm/lib/Support/Unix/Path.inc
index 824e8b0..c35db79 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -48,6 +48,8 @@ extern char **environ;
 #endif
 #elif defined(__DragonFly__)
 #include <sys/mount.h>
+#elif defined(__MVS__)
+#include <sys/ps.h>
 #endif
 
 // Both stdio.h and cstdio are included via different paths and
@@ -56,9 +58,13 @@ extern char **environ;
 #undef ferror
 #undef feof
 
+#if !defined(PATH_MAX)
 // For GNU Hurd
-#if defined(__GNU__) && !defined(PATH_MAX)
-# define PATH_MAX 4096
+#if defined(__GNU__)
+#define PATH_MAX 4096
+#elif defined(__MVS__)
+#define PATH_MAX _XOPEN_PATH_MAX
+#endif
 #endif
 
 #include <sys/types.h>
@@ -100,7 +106,8 @@ typedef uint_t uint;
 #define STATVFS_F_FRSIZE(vfs) static_cast<uint64_t>(vfs.f_bsize)
 #endif
 
-#if defined(__NetBSD__) || defined(__DragonFly__) || defined(__GNU__)
+#if defined(__NetBSD__) || defined(__DragonFly__) || defined(__GNU__) || \
+    defined(__MVS__)
 #define STATVFS_F_FLAG(vfs) (vfs).f_flag
 #else
 #define STATVFS_F_FLAG(vfs) (vfs).f_flags
@@ -265,6 +272,26 @@ std::string getMainExecutable(const char *argv0, void *MainAddr) {
   // Fall back to the classical detection.
   if (getprogpath(exe_path, argv0))
     return exe_path;
+#elif defined(__MVS__)
+  int token = 0;
+  W_PSPROC buf;
+  char exe_path[PS_PATHBLEN];
+  pid_t pid = getpid();
+
+  memset(&buf, 0, sizeof(buf));
+  buf.ps_pathptr = exe_path;
+  buf.ps_pathlen = sizeof(exe_path);
+
+  while (true) {
+    if ((token = w_getpsent(token, &buf, sizeof(buf))) <= 0)
+      break;
+    if (buf.ps_pid != pid)
+      continue;
+    char real_path[PATH_MAX];
+    if (realpath(exe_path, real_path))
+      return std::string(real_path);
+    break;  // Found entry, but realpath failed.
+  }
 #elif defined(HAVE_DLFCN_H) && defined(HAVE_DLADDR)
   // Use dladdr to get executable path if available.
   Dl_info DLInfo;
@@ -493,6 +520,10 @@ static bool is_local_impl(struct STATVFS &Vfs) {
 
   // vmount entry not found; "remote" is the conservative answer.
   return false;
+#elif defined(__MVS__)
+  // The file system can have an arbitrary structure on z/OS; must go with the
+  // conservative answer.
+  return false;
 #else
   return !!(STATVFS_F_FLAG(Vfs) & MNT_LOCAL);
 #endif
-- 
2.7.4