Fix seriously broken implementation of GetMagicNumber.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18422 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 12 insertions, 8 deletions

diff --git a/lib/System/Unix/Path.cpp b/lib/System/Unix/Path.cpp
index 70cc4f0103..5d2a4b688c 100644
--- a/lib/System/Unix/Path.cpp
+++ b/lib/System/Unix/Path.cpp
@@ -178,11 +178,13 @@ bool Path::getMagicNumber(std::string& Magic, unsigned len) const {
   int fd = ::open(path.c_str(),O_RDONLY);
   if (fd < 0)
     return false;
-  if (0 != ::read(fd, buf, len))
+  ssize_t bytes_read = ::read(fd, buf, len);
+  ::close(fd);
+  if (ssize_t(len) != bytes_read) {
+    Magic.clear();
     return false;
-  close(fd);
-  buf[len] = '\0';
-  Magic = buf;
+  }
+  Magic.assign(buf,len);
   return true;
 }
 
diff --git a/lib/System/Unix/Path.inc b/lib/System/Unix/Path.inc
index 70cc4f0103..5d2a4b688c 100644
--- a/lib/System/Unix/Path.inc
+++ b/lib/System/Unix/Path.inc
@@ -178,11 +178,13 @@ bool Path::getMagicNumber(std::string& Magic, unsigned len) const {
   int fd = ::open(path.c_str(),O_RDONLY);
   if (fd < 0)
     return false;
-  if (0 != ::read(fd, buf, len))
+  ssize_t bytes_read = ::read(fd, buf, len);
+  ::close(fd);
+  if (ssize_t(len) != bytes_read) {
+    Magic.clear();
     return false;
-  close(fd);
-  buf[len] = '\0';
-  Magic = buf;
+  }
+  Magic.assign(buf,len);
   return true;
 }