Use the ability to pwrite to simplify the ELF writer.

Now we don't have to do 2 synchronized passes to compute offsets and then
write the file.

This also includes a fix for the corner case of seeking in /dev/null. It
is not an error, but on some systems (Linux) the returned offset is
always 0. An error is signaled by returning -1. This is checked by
the existing tests now that "clang -o /dev/null ..." seeks.

llvm-svn: 234952

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Support/raw_ostream.cpp b/llvm/lib/Support/raw_ostream.cpp
index 044f8e0..6f9f910 100644
--- a/llvm/lib/Support/raw_ostream.cpp
+++ b/llvm/lib/Support/raw_ostream.cpp
@@ -625,7 +625,7 @@ void raw_fd_ostream::close() {
 uint64_t raw_fd_ostream::seek(uint64_t off) {
   flush();
   pos = ::lseek(FD, off, SEEK_SET);
-  if (pos != off)
+  if (pos == (uint64_t)-1)
     error_detected();
   return pos;
 }