From 4f9c17ee5044c68a358a92e90772eea5b3966e3c Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@mit.edu>
Date: Sun, 21 Feb 2016 20:19:12 -0500
Subject: Implement rename

---
 src/operations.cc   | 34 ++++++++++++++++++++++++++++++++++
 src/posix_extras.cc | 11 +++++++++++
 src/posix_extras.h  |  5 +++++
 3 files changed, 50 insertions(+)

diff --git a/src/operations.cc b/src/operations.cc
index 382974e..697f901 100644
--- a/src/operations.cc
+++ b/src/operations.cc
@@ -136,6 +136,39 @@ int Mknod(const char* const c_path, const mode_t mode,
   }
 }
 
+int Chmod(const char* const c_path, const mode_t mode) noexcept {
+  try {
+    const std::string path(c_path);
+    root_->ChModAt(path == "/" ? "." : EncodePath(path).c_str(), mode);
+    return 0;
+  } catch (const std::system_error& e) {
+    return -e.code().value();
+  } catch (...) {
+    LOG(ERROR) << "getattr: caught unexpected value";
+    return -ENOTRECOVERABLE;
+  }
+}
+
+int Rename(const char* const c_old_path,
+           const char* const c_new_path) noexcept {
+  try {
+    const std::string old_path(c_old_path);
+    const std::string new_path(c_new_path);
+    if (old_path == "/" || new_path == "/") {
+      return -EINVAL;
+    } else {
+      root_->RenameAt(EncodePath(old_path).c_str(),
+                      EncodePath(new_path).c_str());
+      return 0;
+    }
+  } catch (const std::system_error& e) {
+    return -e.code().value();
+  } catch (...) {
+    LOG(ERROR) << "mknod: caught unexpected value";
+    return -ENOTRECOVERABLE;
+  }
+}
+
 int Open(const char* const path, fuse_file_info* const file_info) noexcept {
   return OpenResource<File>(path, file_info->flags, &file_info->fh);
 }
@@ -302,6 +335,7 @@ fuse_operations FuseOperations(File* const root) {
   result.fgetattr = &Fgetattr;
 
   result.mknod = &Mknod;
+  result.rename = &Rename;
   result.open = &Open;
   result.read = &Read;
   result.write = &Write;
diff --git a/src/posix_extras.cc b/src/posix_extras.cc
index 5fc60f6..17fe275 100644
--- a/src/posix_extras.cc
+++ b/src/posix_extras.cc
@@ -25,6 +25,7 @@
 #include <dirent.h>
 #include <fcntl.h>
 #include <glog/logging.h>
+#include <stdio.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
@@ -129,6 +130,16 @@ std::vector<std::uint8_t> File::Read(off_t offset, size_t bytes) const {
   return result;
 }
 
+void File::RenameAt(const char* old_path, const char* new_path) const {
+  if (old_path[0] == '/' || new_path[0] == '/') {
+    throw std::invalid_argument("absolute path");
+  }
+
+  if (renameat(fd_, old_path, fd_, new_path) == -1) {
+    throw SystemError();
+  }
+}
+
 void File::RmDirAt(const char* const path) const {
   if (path[0] == '/') {
     throw std::invalid_argument("absolute path");
diff --git a/src/posix_extras.h b/src/posix_extras.h
index 41117f2..b9e9da6 100644
--- a/src/posix_extras.h
+++ b/src/posix_extras.h
@@ -89,6 +89,11 @@ class File {
   // fewer bytes are returned.
   std::vector<std::uint8_t> Read(off_t, size_t) const;
 
+  // Renames a file from old_path to new_path.  Both paths are interpreted
+  // relative to the file descriptor, and both must indeed be relative (i.e.,
+  // they must not start with '/').
+  void RenameAt(const char* old_path, const char* new_path) const;
+
   // Removes the directory at the path relative to the file descriptor.  The
   // path must indeed be relative (i.e., it must not start with '/').
   void RmDirAt(const char* path) const;
-- 
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