Check in the implementation of the FileUtilities!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7487 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 56 insertions, 0 deletions

diff --git a/support/lib/Support/FileUtilities.cpp b/support/lib/Support/FileUtilities.cpp
new file mode 100644
index 0000000000..35bdf1e9a4
--- /dev/null
+++ b/support/lib/Support/FileUtilities.cpp
@@ -0,0 +1,56 @@
+//===- Support/FileUtilities.cpp - File System Utilities ------------------===//
+//
+// This file implements a family of utility functions which are useful for doing
+// various things with files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Support/FileUtilities.h"
+#include <fstream>
+#include <iostream>
+#include <cstdio>
+
+/// DiffFiles - Compare the two files specified, returning true if they are
+/// different or if there is a file error.  If you specify a string to fill in
+/// for the error option, it will set the string to an error message if an error
+/// occurs, allowing the caller to distinguish between a failed diff and a file
+/// system error.
+///
+bool DiffFiles(const std::string &FileA, const std::string &FileB,
+               std::string *Error) {
+  std::ifstream FileAStream(FileA.c_str());
+  if (!FileAStream) {
+    if (Error) *Error = "Couldn't open file '" + FileA + "'";
+    return true;
+  }
+
+  std::ifstream FileBStream(FileB.c_str());
+  if (!FileBStream) {
+    if (Error) *Error = "Couldn't open file '" + FileB + "'";
+    return true;
+  }
+
+  // Compare the two files...
+  int C1, C2;
+  do {
+    C1 = FileAStream.get();
+    C2 = FileBStream.get();
+    if (C1 != C2) return true;
+  } while (C1 != EOF);
+
+  return false;
+}
+
+
+/// MoveFileOverIfUpdated - If the file specified by New is different than Old,
+/// or if Old does not exist, move the New file over the Old file.  Otherwise,
+/// remove the New file.
+///
+void MoveFileOverIfUpdated(const std::string &New, const std::string &Old) {
+  if (DiffFiles(New, Old)) {
+    if (std::rename(New.c_str(), Old.c_str()))
+      std::cerr << "Error renaming '" << New << "' to '" << Old << "'!\n";
+  } else {
+    std::remove(New.c_str());
+  }  
+}