[PR] instr: change assert to allow FD 0 return by __open()

Summary: In some cases __open() is returning 0 for me.  The open
syscall will return a negative number (-1) on error so 0 should be
valid.

This happens when one compiles a BOLT instrumented executable of
pyston (python implementation) and afterwards pip installs a package
which needs to be compiled and sets CFLAGS=-pipe.  I could not reduce
it down to a small testcase but I guess it one can trigger when
manually closing std{in, out, err}.  Everything seems to work
normally when disabling the assert for 0 in getBinaryPath() - I
decided to also modify the second case in readDescriptions() even
though I did not run into that one yet.

(cherry picked from FBD32409548)

1 files changed, 2 insertions, 2 deletions

diff --git a/bolt/runtime/instr.cpp b/bolt/runtime/instr.cpp
index f6c9916037c0..86fb772b15c2 100644
--- a/bolt/runtime/instr.cpp
+++ b/bolt/runtime/instr.cpp
@@ -626,7 +626,7 @@ static char *getBinaryPath() {
   uint64_t FDdir = __open(DirPath,
                           /*flags=*/0 /*O_RDONLY*/,
                           /*mode=*/0666);
-  assert(static_cast<int64_t>(FDdir) > 0,
+  assert(static_cast<int64_t>(FDdir) >= 0,
          "failed to open /proc/self/map_files");
 
   while (long Nread = __getdents(FDdir, (struct dirent *)Buf, BufSize)) {
@@ -662,7 +662,7 @@ ProfileWriterContext readDescriptions() {
   uint64_t FD = __open(BinPath,
                        /*flags=*/0 /*O_RDONLY*/,
                        /*mode=*/0666);
-  assert(static_cast<int64_t>(FD) > 0, "failed to open binary path");
+  assert(static_cast<int64_t>(FD) >= 0, "failed to open binary path");
 
   Result.FileDesc = FD;