[WasmFS] Support utime()

.circleci/config.yml

@@ -384,7 +384,7 @@ jobs:
       - run-tests:
           # also add a little select testing for wasm2js in -O3
           # also add a little select wasmfs testing
-          test_targets: "core3 wasm2js3.test_memorygrowth_2 wasmfs.test_hello_world wasmfs.test_hello_world_standalone wasmfs.test_unistd_links* wasmfs.test_atexit_standalone wasmfs.test_emscripten_get_now wasmfs.test_dyncall_specific_minimal_runtime core2ss.test_pthread_dylink"
+          test_targets: "core3 wasm2js3.test_memorygrowth_2 wasmfs.test_hello_world wasmfs.test_hello_world_standalone wasmfs.test_unistd_links* wasmfs.test_atexit_standalone wasmfs.test_emscripten_get_now wasmfs.test_dyncall_specific_minimal_runtime core2ss.test_pthread_dylink wasmfs.test_utime"
   test-wasm2js1:
     executor: bionic
     steps:

emcc.py

@@ -1922,6 +1922,7 @@ def default_setting(name, new_default):
 
   if settings.WASMFS:
     state.forced_stdlibs.append('libwasmfs')
+    state.forced_stdlibs.append('libwasmfs_libc')
     settings.FILESYSTEM = 0
     settings.SYSCALLS_REQUIRE_FILESYSTEM = 0
     settings.JS_LIBRARIES.append((0, 'library_wasmfs.js'))

system/lib/wasmfs/file.cpp

@@ -114,7 +114,8 @@ size_t Symlink::getSize() {
 
 ParsedPath getParsedPath(std::vector<std::string> pathParts,
                          long& err,
-                         std::shared_ptr<File> forbiddenAncestor) {
+                         std::shared_ptr<File> forbiddenAncestor,
+                         std::optional<__wasi_fd_t> baseFD) {
   std::shared_ptr<Directory> curr;
   auto begin = pathParts.begin();
 
@@ -132,7 +133,20 @@ ParsedPath getParsedPath(std::vector<std::string> pathParts,
       return ParsedPath{curr->locked(), curr};
     }
   } else {
-    curr = wasmFS.getCWD();
+    // This is a relative path. It is either relative to the current working
+    // directory if no base FD is given, or if the base FD is the special value
+    // indicating the CWD.
+    if (baseFD && *baseFD != AT_FDCWD) {
+      auto lockedOpenDir = wasmFS.getLockedFileTable()[*baseFD].locked();
+      auto openDir = lockedOpenDir.getFile();
+      if (!openDir->is<Directory>()) {
+        err = -EBADF;
+        return ParsedPath{{}, nullptr};
+      }
+      curr = openDir->dynCast<Directory>();
+    } else {
+      curr = wasmFS.getCWD();
+    }
   }
 
   for (auto pathPart = begin; pathPart != pathParts.end() - 1; ++pathPart) {
@@ -255,5 +269,4 @@ std::vector<std::string> splitPath(char* pathname) {
 
   return pathParts;
 }
-
 } // namespace wasmfs

system/lib/wasmfs/file.h

@@ -29,7 +29,6 @@ using backend_t = Backend*;
 const backend_t NullBackend = nullptr;
 
 class File : public std::enable_shared_from_this<File> {
-
 public:
   enum FileKind { DataFileKind = 0, DirectoryKind, SymlinkKind };
 
@@ -134,7 +133,6 @@ class File : public std::enable_shared_from_this<File> {
 };
 
 class DataFile : public File {
-
   virtual __wasi_errno_t read(uint8_t* buf, size_t len, off_t offset) = 0;
   virtual __wasi_errno_t
   write(const uint8_t* buf, size_t len, off_t offset) = 0;
@@ -271,12 +269,17 @@ struct ParsedPath {
 // TODO: When locking the directory structure is refactored, parent should be
 // returned as a pointer, similar to child.
 // Will return an empty handle if the parent is not a directory.
+//
 // Will error if the forbiddenAncestor is encountered while processing.
 // If the forbiddenAncestor is encountered, err will be set to EINVAL and
 // an empty parent handle will be returned.
+//
+// If baseFD is provided, and the path is relative, then it will be interpreted
+// relative to the base. That is the behavior that the *at() syscalls require.
 ParsedPath getParsedPath(std::vector<std::string> pathParts,
                          long& err,
-                         std::shared_ptr<File> forbiddenAncestor = nullptr);
+                         std::shared_ptr<File> forbiddenAncestor = nullptr,
+                         std::optional<__wasi_fd_t> baseFD = {});
 
 // Call getDir if one needs a parent directory of a file path.
 // TODO: Remove this when directory structure locking is refactored and use

system/lib/wasmfs/syscalls.cpp

@@ -458,24 +458,31 @@ static long doMkdir(char* path, long mode, backend_t backend = NullBackend) {
   // Check if the requested directory already exists.
   if (parsedPath.child) {
     return -EEXIST;
-  } else {
-    // Mask rwx permissions for user, group and others, and the sticky bit.
-    // This prevents users from entering S_IFREG for example.
-    // https://www.gnu.org/software/libc/manual/html_node/Permission-Bits.html
-    mode &= S_IRWXUGO | S_ISVTX;
-
-    // By default, the backend that the directory is created in is the same as
-    // the parent directory. However, if a backend is passed as a parameter,
-    // then that backend is used.
-    if (!backend) {
-      backend = parsedPath.parent->unlocked()->getBackend();
-    }
-    // Create an empty in-memory directory.
-    auto created = backend->createDirectory(mode);
+  }
 
-    parsedPath.parent->setEntry(pathParts.back(), created);
-    return 0;
+  // Mask rwx permissions for user, group and others, and the sticky bit.
+  // This prevents users from entering S_IFREG for example.
+  // https://www.gnu.org/software/libc/manual/html_node/Permission-Bits.html
+  mode &= S_IRWXUGO | S_ISVTX;
+
+  // By default, the backend that the directory is created in is the same as
+  // the parent directory. However, if a backend is passed as a parameter,
+  // then that backend is used.
+  if (!backend) {
+    backend = parsedPath.parent->unlocked()->getBackend();
   }
+  // Create an empty in-memory directory.
+  auto created = backend->createDirectory(mode);
+  parsedPath.parent->setEntry(pathParts.back(), created);
+
+  // Update the times.
+  auto lockedFile = created->locked();
+  time_t now = time(NULL);
+  lockedFile.atime() = now;
+  lockedFile.mtime() = now;
+  lockedFile.ctime() = now;
+
+  return 0;
 }
 
 // This function is exposed to users and allows users to specify a particular
@@ -936,4 +943,30 @@ long __syscall_readlink(char* path, char* buf, size_t bufSize) {
 
   return bytes;
 }
+
+long __syscall_utimensat(int dirFD,
+                         char* path,
+                         const struct timespec times[2],
+                         int flags) {
+  // TODO: support flags here
+  assert(flags == 0);
+
+  auto pathParts = splitPath(path);
+
+  long err;
+  auto parsedPath = getParsedPath(pathParts, err, nullptr, dirFD);
+  if (!parsedPath.parent) {
+    return err;
+  }
+
+  // TODO: tv_nsec (nanoseconds) as well? but time_t is seconds as an integer
+  auto aSeconds = times[0].tv_sec;
+  auto mSeconds = times[1].tv_sec;
+
+  auto locked = parsedPath.child->locked();
+  locked.atime() = aSeconds;
+  locked.mtime() = mSeconds;
+
+  return 0;
+}
 }

tools/system_libs.py

@@ -1431,6 +1431,21 @@ def can_use(self):
     return settings.WASMFS
 
 
+# Libc components of WasmFS, which uses more libc code than the JS filesystem.
+# This must be a separate library than libwasmfs because the build commands
+# are different for libc code.
+class libwasmfs_libc(MTLibrary, DebugLibrary, AsanInstrumentedLibrary, MuslInternalLibrary):
+  name = 'libwasmfs_libc'
+
+  def get_files(self):
+    return files_in_path(
+        path='system/lib/libc/musl/src/time',
+        filenames=['utime.c'])
+
+  def can_use(self):
+    return settings.WASMFS
+
+
 class libhtml5(Library):
   name = 'libhtml5'