X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=folly%2FFile.h;h=459251428d370b37431e191493b55f57f72000d5;hb=140c62d25d930cdbdacaa337d254a2471875a4be;hp=edcad92025bcf996ffd4ed66dd77766c9f414520;hpb=9d6c66ddc8f6f38eef4c6f1c09abb3b30f888057;p=folly.git

diff --git a/folly/File.h b/folly/File.h
index edcad920..45925142 100644
--- a/folly/File.h
+++ b/folly/File.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 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 +17,15 @@
 #ifndef FOLLY_FILE_H_
 #define FOLLY_FILE_H_
 
+#include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
-#include <fcntl.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <folly/Portability.h>
+#include <folly/Range.h>
 
 namespace folly {
 
@@ -37,15 +43,15 @@ class File {
    * Create a File object from an existing file descriptor.
    * Takes ownership of the file descriptor if ownsFd is true.
    */
-  /* implicit */ File(int fd,
-                      bool ownsFd = false);
+  explicit File(int fd, bool ownsFd = false);
 
   /**
    * Open and create a file object.  Throws on error.
    */
-  /* implicit */ 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);
+  explicit File(
+      const std::string& name, int flags = O_RDONLY, mode_t mode = 0666);
+  explicit File(StringPiece name, int flags = O_RDONLY, mode_t mode = 0666);
 
   ~File();
 
@@ -54,14 +60,6 @@ class File {
    */
   static File temporary();
 
-  /**
-   * Attempts to open the file at the given path.  Returns an 'closed` File
-   * instance on failure, which will evaluate to false.
-   */
-  static File tryOpen(const char* name,
-                      int flags = O_RDONLY,
-                      mode_t mode = 0644);
-
   /**
    * Return the file descriptor, or -1 if the file was closed.
    */
@@ -71,9 +69,14 @@ class File {
    * Returns 'true' iff the file was successfully opened.
    */
   explicit operator bool() const {
-    return fd_ >= 0;
+    return fd_ != -1;
   }
 
+  /**
+   * Duplicate file descriptor and return File that owns it.
+   */
+  File dup() const;
+
   /**
    * If we own the file descriptor, close the file and throw on error.
    * Otherwise, do nothing.
@@ -87,9 +90,10 @@ class File {
   bool closeNoThrow();
 
   /**
-   * Releases the file descriptor; no longer owned by this File.
+   * Returns and releases the file descriptor; no longer owned by this File.
+   * Returns -1 if the File object didn't wrap a file.
    */
-  void release();
+  int release() noexcept;
 
   /**
    * Swap this File with another.
@@ -97,10 +101,29 @@ class File {
   void swap(File& other);
 
   // movable
-  File(File&&);
+  File(File&&) noexcept;
   File& operator=(File&&);
 
+  // FLOCK (INTERPROCESS) LOCKS
+  //
+  // NOTE THAT THESE LOCKS ARE flock() LOCKS.  That is, they may only be used
+  // for inter-process synchronization -- an attempt to acquire a second lock
+  // on the same file descriptor from the same process may succeed.  Attempting
+  // to acquire a second lock on a different file descriptor for the same file
+  // should fail, but some systems might implement flock() using fcntl() locks,
+  // in which case it will succeed.
+  void lock();
+  bool try_lock();
+  void unlock();
+
+  void lock_shared();
+  bool try_lock_shared();
+  void unlock_shared();
+
  private:
+  void doLock(int op);
+  bool doTryLock(int op);
+
   // unique
   File(const File&) = delete;
   File& operator=(const File&) = delete;
@@ -111,6 +134,7 @@ class File {
 
 void swap(File& a, File& b);
 
+
 }  // namespace folly
 
 #endif /* FOLLY_FILE_H_ */