(Wangle) Possibly undefined behavior in collect

[folly.git] / folly / FileUtil.h

diff --git a/folly/FileUtil.h b/folly/FileUtil.h
index 13dbe5a0f8bd8c06bfc39a54ccc5e2810aea8238..5adcd62d6c0df6a869c1d8aecb37a6fca3833132 100644 (file)
--- a/folly/FileUtil.h
+++ b/folly/FileUtil.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2014 Facebook, Inc.
+ * Copyright 2015 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,9 +17,9 @@
 #ifndef FOLLY_FILEUTIL_H_
 #define FOLLY_FILEUTIL_H_
 
-#include "folly/Conv.h"
-#include "folly/Portability.h"
-#include "folly/ScopeGuard.h"
+#include <folly/Conv.h>
+#include <folly/Portability.h>
+#include <folly/ScopeGuard.h>
 
 #include <cassert>
 #include <limits>
@@ -123,7 +123,7 @@ bool readFile(const char* file_name, Container& out,
                 "readFile: only containers with byte-sized elements accepted");
   assert(file_name);
 
-  const auto fd = open(file_name, O_RDONLY);
+  const auto fd = openNoInt(file_name, O_RDONLY);
   if (fd == -1) return false;
 
   size_t soFar = 0; // amount of bytes successfully read
@@ -131,7 +131,7 @@ bool readFile(const char* file_name, Container& out,
     assert(out.size() >= soFar); // resize better doesn't throw
     out.resize(soFar);
     // Ignore errors when closing the file
-    close(fd);
+    closeNoInt(fd);
   };
 
   // Obtain file size:
@@ -166,6 +166,32 @@ bool readFile(const char* file_name, Container& out,
   return true;
 }
 
+/**
+ * Writes container to file. The container is assumed to be
+ * contiguous, with element size equal to 1, and offering STL-like
+ * methods empty(), size(), and indexed access
+ * (e.g. std::vector<char>, std::string, fbstring, StringPiece).
+ *
+ * "flags" dictates the open flags to use. Default is to create file
+ * if it doesn't exist and truncate it.
+ *
+ * Returns: true on success or false on failure. In the latter case
+ * errno will be set appropriately by the failing system primitive.
+ */
+template <class Container>
+bool writeFile(const Container& data, const char* filename,
+              int flags = O_WRONLY | O_CREAT | O_TRUNC) {
+  static_assert(sizeof(data[0]) == 1,
+                "writeFile works with element size equal to 1");
+  int fd = open(filename, flags, 0666);
+  if (fd == -1) {
+    return false;
+  }
+  bool ok = data.empty() ||
+    writeFull(fd, &data[0], data.size()) == static_cast<ssize_t>(data.size());
+  return closeNoInt(fd) == 0 && ok;
+}
+
 }  // namespaces
 
 #endif /* FOLLY_FILEUTIL_H_ */