If errno is zero strerror_r does not modify the buffer, leaving it unterminated.

This causes garbage to be printed out after error messages.

llvm-svn: 20165

2 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/System/Unix/MappedFile.inc b/llvm/lib/System/Unix/MappedFile.inc
index 07683c14392..409cea7e822 100644
--- a/llvm/lib/System/Unix/MappedFile.inc
+++ b/llvm/lib/System/Unix/MappedFile.inc
@@ -51,6 +51,7 @@ void MappedFile::initialize() {
     else if (options_&WRITE_ACCESS)
       mode = O_WRONLY;
     info_->fd_ = ::open(path_.c_str(),mode);
+
     if (info_->fd_ < 0) {
       delete info_;
       info_ = 0;
diff --git a/llvm/lib/System/Unix/Unix.h b/llvm/lib/System/Unix/Unix.h
index 6dc75545b66..75009d0746e 100644
--- a/llvm/lib/System/Unix/Unix.h
+++ b/llvm/lib/System/Unix/Unix.h
@@ -68,14 +68,17 @@
 
 inline void ThrowErrno(const std::string& prefix) {
     char buffer[MAXPATHLEN];
+    buffer[0] = 0;
 #ifdef HAVE_STRERROR_R
     // strerror_r is thread-safe.
-    strerror_r(errno,buffer,MAXPATHLEN-1);
+    if (errno)
+      strerror_r(errno,buffer,MAXPATHLEN-1);
 #elif HAVE_STRERROR
     // Copy the thread un-safe result of strerror into
     // the buffer as fast as possible to minimize impact
     // of collision of strerror in multiple threads.
-    strncpy(buffer,strerror(errno),MAXPATHLEN-1);
+    if (Errno)
+      strncpy(buffer,strerror(errno),MAXPATHLEN-1);
     buffer[MAXPATHLEN-1] = 0;
 #else
     // Strange that this system doesn't even have strerror