[llvm] 1a6d571 - [Support] Skip attempts to access /proc/self/fd on FreeBSD

[Dimitry Andric via llvm-commits]

Author: Mateusz Guzik
Date: 2022-03-27T20:19:41+02:00
New Revision: 1a6d571174f8a6565d3bb94cbd184a3861bf4a17

URL: https://github.com/llvm/llvm-project/commit/1a6d571174f8a6565d3bb94cbd184a3861bf4a17
DIFF: https://github.com/llvm/llvm-project/commit/1a6d571174f8a6565d3bb94cbd184a3861bf4a17.diff

LOG: [Support] Skip attempts to access /proc/self/fd on FreeBSD

In contrast to Linux it does not provide entries which can be readlinked
-- these are just regular files, not giving the expected outcome. That's
on top of procfs not being mounted by default to begin with.

This is probably the case on other BSDs as well, so I expect there will
be more ifdefs added down the road.

Reviewed By: emaste, dim

Differential Revision: https://reviews.llvm.org/D122545

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 c30c3a6e365e6..c4345f13f0a6e 100644
--- a/llvm/lib/Support/Unix/Path.inc
+++ b/llvm/lib/Support/Unix/Path.inc
@@ -950,7 +950,15 @@ ErrorOr<basic_file_status> directory_entry::status() const {
   return s;
 }
 
-#if !defined(F_GETPATH)
+//
+// FreeBSD optionally provides /proc/self/fd, but it is incompatible with
+// Linux. The thing to use is realpath.
+//
+#if !defined(__FreeBSD__)
+#define TRY_PROC_SELF_FD
+#endif
+
+#if !defined(F_GETPATH) && defined(TRY_PROC_SELF_FD)
 static bool hasProcSelfFD() {
   // If we have a /proc filesystem mounted, we can quickly establish the
   // real name of the file with readlink
@@ -1137,6 +1145,7 @@ std::error_code openFileForRead(const Twine &Name, int &ResultFD,
     RealPath->append(Buffer, Buffer + strlen(Buffer));
 #else
   char Buffer[PATH_MAX];
+#if defined(TRY_PROC_SELF_FD)
   if (hasProcSelfFD()) {
     char ProcPath[64];
     snprintf(ProcPath, sizeof(ProcPath), "/proc/self/fd/%d", ResultFD);
@@ -1144,13 +1153,16 @@ std::error_code openFileForRead(const Twine &Name, int &ResultFD,
     if (CharCount > 0)
       RealPath->append(Buffer, Buffer + CharCount);
   } else {
+#endif
     SmallString<128> Storage;
     StringRef P = Name.toNullTerminatedStringRef(Storage);
 
     // Use ::realpath to get the real path name
     if (::realpath(P.begin(), Buffer) != nullptr)
       RealPath->append(Buffer, Buffer + strlen(Buffer));
+#if defined(TRY_PROC_SELF_FD)
   }
+#endif
 #endif
   return std::error_code();
 }