Support/MemoryBuffer: Replace all uses of std::string *ErrMsg with error_code &ec. And fix clients.

llvm-svn: 121379
diff --git a/llvm/lib/Support/CommandLine.cpp b/llvm/lib/Support/CommandLine.cpp
index a99e46d..e856509 100644
--- a/llvm/lib/Support/CommandLine.cpp
+++ b/llvm/lib/Support/CommandLine.cpp
@@ -22,6 +22,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
 #include "llvm/Target/TargetRegistry.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/Path.h"
@@ -464,8 +465,9 @@
       if (FileStat && FileStat->getSize() != 0) {
 
         // Mmap the response file into memory.
+        error_code ec;
         OwningPtr<MemoryBuffer>
-          respFilePtr(MemoryBuffer::getFile(respFile.c_str()));
+          respFilePtr(MemoryBuffer::getFile(respFile.c_str(), ec));
 
         // If we could open the file, parse its contents, otherwise
         // pass the @file option verbatim.
diff --git a/llvm/lib/Support/FileUtilities.cpp b/llvm/lib/Support/FileUtilities.cpp
index 7220085..77de94d 100644
--- a/llvm/lib/Support/FileUtilities.cpp
+++ b/llvm/lib/Support/FileUtilities.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Support/Path.h"
+#include "llvm/Support/system_error.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/SmallString.h"
 #include <cstdlib>
@@ -199,11 +200,20 @@
 
   // Now its safe to mmap the files into memory becasue both files
   // have a non-zero size.
-  OwningPtr<MemoryBuffer> F1(MemoryBuffer::getFile(FileA.c_str(), Error));
-  OwningPtr<MemoryBuffer> F2(MemoryBuffer::getFile(FileB.c_str(), Error));
-  if (F1 == 0 || F2 == 0)
+  error_code ec;
+  OwningPtr<MemoryBuffer> F1(MemoryBuffer::getFile(FileA.c_str(), ec));
+  if (F1 == 0) {
+    if (Error)
+      *Error = ec.message();
     return 2;
-  
+  }
+  OwningPtr<MemoryBuffer> F2(MemoryBuffer::getFile(FileB.c_str(), ec));
+  if (F2 == 0) {
+    if (Error)
+      *Error = ec.message();
+    return 2;
+  }
+
   // Okay, now that we opened the files, scan them for the first difference.
   const char *File1Start = F1->getBufferStart();
   const char *File2Start = F2->getBufferStart();
diff --git a/llvm/lib/Support/MemoryBuffer.cpp b/llvm/lib/Support/MemoryBuffer.cpp
index 07a5ed4..0966f90 100644
--- a/llvm/lib/Support/MemoryBuffer.cpp
+++ b/llvm/lib/Support/MemoryBuffer.cpp
@@ -19,6 +19,7 @@
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
 #include "llvm/Support/Program.h"
+#include "llvm/Support/system_error.h"
 #include <cassert>
 #include <cstdio>
 #include <cstring>
@@ -143,19 +144,19 @@
 /// in *ErrStr with a reason.  If stdin is empty, this API (unlike getSTDIN)
 /// returns an empty buffer.
 MemoryBuffer *MemoryBuffer::getFileOrSTDIN(StringRef Filename,
-                                           std::string *ErrStr,
+                                           error_code &ec,
                                            int64_t FileSize) {
   if (Filename == "-")
-    return getSTDIN(ErrStr);
-  return getFile(Filename, ErrStr, FileSize);
+    return getSTDIN(ec);
+  return getFile(Filename, ec, FileSize);
 }
 
 MemoryBuffer *MemoryBuffer::getFileOrSTDIN(const char *Filename,
-                                           std::string *ErrStr,
+                                           error_code &ec,
                                            int64_t FileSize) {
   if (strcmp(Filename, "-") == 0)
-    return getSTDIN(ErrStr);
-  return getFile(Filename, ErrStr, FileSize);
+    return getSTDIN(ec);
+  return getFile(Filename, ec, FileSize);
 }
 
 //===----------------------------------------------------------------------===//
@@ -185,14 +186,14 @@
 };
 }
 
-MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, std::string *ErrStr,
+MemoryBuffer *MemoryBuffer::getFile(StringRef Filename, error_code &ec,
                                     int64_t FileSize) {
   // Ensure the path is null terminated.
   SmallString<256> PathBuf(Filename.begin(), Filename.end());
-  return MemoryBuffer::getFile(PathBuf.c_str(), ErrStr, FileSize);
+  return MemoryBuffer::getFile(PathBuf.c_str(), ec, FileSize);
 }
 
-MemoryBuffer *MemoryBuffer::getFile(const char *Filename, std::string *ErrStr,
+MemoryBuffer *MemoryBuffer::getFile(const char *Filename, error_code &ec,
                                     int64_t FileSize) {
   int OpenFlags = O_RDONLY;
 #ifdef O_BINARY
@@ -200,15 +201,15 @@
 #endif
   int FD = ::open(Filename, OpenFlags);
   if (FD == -1) {
-    if (ErrStr) *ErrStr = sys::StrError();
+    ec = error_code(errno, posix_category());
     return 0;
   }
 
-  return getOpenFile(FD, Filename, ErrStr, FileSize);
+  return getOpenFile(FD, Filename, ec, FileSize);
 }
 
 MemoryBuffer *MemoryBuffer::getOpenFile(int FD, const char *Filename,
-                                        std::string *ErrStr, int64_t FileSize) {
+                                        error_code &ec, int64_t FileSize) {
   FileCloser FC(FD); // Close FD on return.
 
   // If we don't know the file size, use fstat to find out.  fstat on an open
@@ -217,7 +218,7 @@
     struct stat FileInfo;
     // TODO: This should use fstat64 when available.
     if (fstat(FD, &FileInfo) == -1) {
-      if (ErrStr) *ErrStr = sys::StrError();
+      ec = error_code(errno, posix_category());
       return 0;
     }
     FileSize = FileInfo.st_size;
@@ -240,8 +241,9 @@
 
   MemoryBuffer *Buf = MemoryBuffer::getNewUninitMemBuffer(FileSize, Filename);
   if (!Buf) {
-    // Failed to create a buffer.
-    if (ErrStr) *ErrStr = "could not allocate buffer";
+    // Failed to create a buffer. The only way it can fail is if
+    // new(std::nothrow) returns 0.
+    ec = make_error_code(errc::not_enough_memory);
     return 0;
   }
 
@@ -255,7 +257,7 @@
       if (errno == EINTR)
         continue;
       // Error while reading.
-      if (ErrStr) *ErrStr = sys::StrError();
+      ec = error_code(errno, posix_category());
       return 0;
     } else if (NumRead == 0) {
       // We hit EOF early, truncate and terminate buffer.
@@ -274,7 +276,7 @@
 // MemoryBuffer::getSTDIN implementation.
 //===----------------------------------------------------------------------===//
 
-MemoryBuffer *MemoryBuffer::getSTDIN(std::string *ErrStr) {
+MemoryBuffer *MemoryBuffer::getSTDIN(error_code &ec) {
   // Read in all of the data from stdin, we cannot mmap stdin.
   //
   // FIXME: That isn't necessarily true, we should try to mmap stdin and
@@ -290,7 +292,7 @@
     ReadBytes = read(0, Buffer.end(), ChunkSize);
     if (ReadBytes == -1) {
       if (errno == EINTR) continue;
-      if (ErrStr) *ErrStr = sys::StrError();
+      ec = error_code(errno, posix_category());
       return 0;
     }
     Buffer.set_size(Buffer.size() + ReadBytes);
diff --git a/llvm/lib/Support/SourceMgr.cpp b/llvm/lib/Support/SourceMgr.cpp
index 0dc1331..f53169a 100644
--- a/llvm/lib/Support/SourceMgr.cpp
+++ b/llvm/lib/Support/SourceMgr.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
 using namespace llvm;
 
 namespace {
@@ -48,13 +49,13 @@
 /// ~0, otherwise it returns the buffer ID of the stacked file.
 unsigned SourceMgr::AddIncludeFile(const std::string &Filename,
                                    SMLoc IncludeLoc) {
-
-  MemoryBuffer *NewBuf = MemoryBuffer::getFile(Filename.c_str());
+  error_code ec;
+  MemoryBuffer *NewBuf = MemoryBuffer::getFile(Filename.c_str(), ec);
 
   // If the file didn't exist directly, see if it's in an include path.
   for (unsigned i = 0, e = IncludeDirectories.size(); i != e && !NewBuf; ++i) {
     std::string IncFile = IncludeDirectories[i] + "/" + Filename;
-    NewBuf = MemoryBuffer::getFile(IncFile.c_str());
+    NewBuf = MemoryBuffer::getFile(IncFile.c_str(), ec);
   }
 
   if (NewBuf == 0) return ~0U;
diff --git a/llvm/lib/Support/system_error.cpp b/llvm/lib/Support/system_error.cpp
index cd18906..56898de 100644
--- a/llvm/lib/Support/system_error.cpp
+++ b/llvm/lib/Support/system_error.cpp
@@ -96,6 +96,15 @@
   return s;
 }
 
+const error_category&
+posix_category() {
+#ifdef LLVM_ON_WIN32
+  return generic_category();
+#else
+  return system_category();
+#endif
+}
+
 // error_condition
 
 std::string