use 0666 as the default permissions for new files

Summary: Seems like there is no real need to restrict permissions by default?

Test Plan: fbconfig -r folly/test && fbmake runtests_opt

@override-unit-failures

Reviewed By: tudorb@fb.com

FB internal diff: D1205527

folly/File.h

@@ -43,7 +43,7 @@ class File {
   /**
    * Open and create a file object.  Throws on error.
    */
-  explicit File(const char* name, int flags = O_RDONLY, mode_t mode = 0644);
+  explicit File(const char* name, int flags = O_RDONLY, mode_t mode = 0666);
 
   ~File();
 

folly/FileUtil.h

@@ -37,7 +37,7 @@ namespace folly {
  * until all data is written.  Note that *Full wrappers weaken the thread
  * semantics of underlying system calls.
  */
-int openNoInt(const char* name, int flags, mode_t mode=0644);
+int openNoInt(const char* name, int flags, mode_t mode = 0666);
 int closeNoInt(int fd);
 int dupNoInt(int fd);
 int dup2NoInt(int oldfd, int newfd);

folly/experimental/TestUtil.cpp

@@ -51,7 +51,7 @@ TemporaryFile::TemporaryFile(StringPiece namePrefix,
     closeOnDestruction_(closeOnDestruction),
     fd_(-1),
     path_(generateUniquePath(std::move(dir), namePrefix)) {
-  fd_ = open(path_.c_str(), O_RDWR | O_CREAT | O_EXCL, 0644);
+  fd_ = open(path_.c_str(), O_RDWR | O_CREAT | O_EXCL, 0666);
   checkUnixError(fd_, "open failed");
 
   if (scope_ == Scope::UNLINK_IMMEDIATELY) {

folly/experimental/test/TestUtilTest.cpp

@@ -81,7 +81,7 @@ void testTemporaryDirectory(TemporaryDirectory::Scope scope) {
     EXPECT_TRUE(fs::is_directory(path));
 
     fs::path fp = path / "bar";
-    int fd = open(fp.c_str(), O_RDWR | O_CREAT | O_TRUNC, 0644);
+    int fd = open(fp.c_str(), O_RDWR | O_CREAT | O_TRUNC, 0666);
     EXPECT_NE(fd, -1);
     close(fd);