From: Ben Langmuir <blangmuir@apple.com>
Date: Mon, 9 Feb 2015 21:55:44 +0000 (+0000)
Subject: Be more conservative about gethostname()'s truncating behaviour
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=c6957806f1a3c34b1c6838b387083eb65436f69a;p=clang

Be more conservative about gethostname()'s truncating behaviour

Don't assume it will provide an error or null-terminate the string on
truncation, since POSIX doesn't guarantee either behaviour (although
Linux and Darwin at least will do the 'right thing').

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@228613 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index e1d9351aa3..c1ad805420 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -2029,8 +2029,12 @@ std::string CompilerInvocation::getModuleHash() const {
   // running, so mangle the hostname in to the module hash to separate them.
   char hostname[256];
   hostname[0] = 0;
-  if (gethostname(hostname, 255) == 0)
+  if (gethostname(hostname, 255) == 0) {
+    // Forcibly null-terminate the result, since POSIX doesn't require that
+    // truncation result in an error or that truncated names be null-terminated.
+    hostname[sizeof(hostname)-1] = 0;
     code = hash_combine(code, StringRef(hostname));
+  }
   // Ignore failures in gethostname() by not including the hostname in the hash.
 #endif