From 90c61f66909affa269dfb396f0e5cc67f4e4de44 Mon Sep 17 00:00:00 2001
From: Benjamin Barenblat <bbaren@mit.edu>
Date: Sun, 21 Feb 2016 20:14:05 -0500
Subject: Implement mkdir/rmdir

---
 src/operations.cc   | 41 +++++++++++++++++++++++++++++++++++++++--
 src/posix_extras.cc | 20 ++++++++++++++++++++
 src/posix_extras.h  | 12 ++++++++++--
 3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/src/operations.cc b/src/operations.cc
index b62fdf0..382974e 100644
--- a/src/operations.cc
+++ b/src/operations.cc
@@ -123,8 +123,7 @@ int Mknod(const char* const c_path, const mode_t mode,
   try {
     const std::string path(c_path);
     if (path == "/") {
-      // They're asking to create the mount point.  Huh?
-      return -EEXIST;
+      return -EISDIR;
     } else {
       root_->MkNod(EncodePath(path).c_str(), mode, dev);
       return 0;
@@ -208,6 +207,24 @@ int Unlink(const char* c_path) noexcept {
   }
 }
 
+int Mkdir(const char* const c_path, const mode_t mode) noexcept {
+  try {
+    const std::string path(c_path);
+    if (path == "/") {
+      // They're asking to create the mount point.  Huh?
+      return -EEXIST;
+    } else {
+      root_->MkDir(EncodePath(path).c_str(), mode);
+      return 0;
+    }
+  } catch (const std::system_error& e) {
+    return -e.code().value();
+  } catch (...) {
+    LOG(ERROR) << "mknod: caught unexpected value";
+    return -ENOTRECOVERABLE;
+  }
+}
+
 int Opendir(const char* const path, fuse_file_info* const file_info) noexcept {
   return OpenResource<Directory>(path, O_DIRECTORY, &file_info->fh);
 }
@@ -248,6 +265,24 @@ int Releasedir(const char*, fuse_file_info* const file_info) noexcept {
   return ReleaseResource<Directory>(file_info->fh);
 }
 
+int Rmdir(const char* c_path) noexcept {
+  try {
+    const std::string path(c_path);
+    if (path == "/") {
+      // Removing the root is probably a bad idea.
+      return -EPERM;
+    } else {
+      root_->RmDirAt(EncodePath(path).c_str());
+      return 0;
+    }
+  } catch (const std::system_error& e) {
+    return -e.code().value();
+  } catch (...) {
+    LOG(ERROR) << "unlink: caught unexpected value";
+    return -ENOTRECOVERABLE;
+  }
+}
+
 }  // namespace
 
 fuse_operations FuseOperations(File* const root) {
@@ -274,9 +309,11 @@ fuse_operations FuseOperations(File* const root) {
   result.release = &Release;
   result.unlink = &Unlink;
 
+  result.mkdir = &Mkdir;
   result.opendir = &Opendir;
   result.readdir = &Readdir;
   result.releasedir = &Releasedir;
+  result.rmdir = &Rmdir;
 
   return result;
 }
diff --git a/src/posix_extras.cc b/src/posix_extras.cc
index 7b82f0a..5fc60f6 100644
--- a/src/posix_extras.cc
+++ b/src/posix_extras.cc
@@ -78,6 +78,16 @@ struct stat File::LinkStatAt(const char* const path) const {
   return result;
 }
 
+void File::MkDir(const char* const path, const mode_t mode) const {
+  if (path[0] == '/') {
+    throw std::invalid_argument("absolute path");
+  }
+
+  if (mkdirat(fd_, path, mode | S_IFDIR) == -1) {
+    throw SystemError();
+  }
+}
+
 void File::MkNod(const char* const path, const mode_t mode,
                  const dev_t dev) const {
   if (path[0] == '/') {
@@ -119,6 +129,16 @@ std::vector<std::uint8_t> File::Read(off_t offset, size_t bytes) const {
   return result;
 }
 
+void File::RmDirAt(const char* const path) const {
+  if (path[0] == '/') {
+    throw std::invalid_argument("absolute path");
+  }
+
+  if (unlinkat(fd_, path, AT_REMOVEDIR) == -1) {
+    throw SystemError();
+  }
+}
+
 void File::UnlinkAt(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 f92bff7..41117f2 100644
--- a/src/posix_extras.h
+++ b/src/posix_extras.h
@@ -69,8 +69,12 @@ class File {
   // indeed be relative (i.e., it must not start with '/').
   struct stat LinkStatAt(const char* path) const;
 
-  // Creates a file or directory at the path relative to the file descriptor.
-  // The path must indeed be relative (i.e., it must not start with '/').
+  // Creates a directory at the path relative to the file descriptor.  The path
+  // must indeed be relative (i.e., it must not start with '/').
+  void MkDir(const char* path, mode_t mode) const;
+
+  // Creates a file at the path relative to the file descriptor.  The path must
+  // indeed be relative (i.e., it must not start with '/').
   void MkNod(const char* path, mode_t mode, dev_t dev) const;
 
   // Calls openat(2) on the path relative to the file descriptor.  The path must
@@ -85,6 +89,10 @@ class File {
   // fewer bytes are returned.
   std::vector<std::uint8_t> Read(off_t, size_t) 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;
+
   // Removes the file at the path relative to the file descriptor.  The path
   // must indeed be relative (i.e., it must not start with '/').
   void UnlinkAt(const char* path) const;
-- 
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