WasmFS: Add nanosecond support to WasmFS (#19629)

This PR adds nanosecond support for file times in WasmFS, specifically when
used for utime and stat. This PR was separated from #19561

Author: jameshu15869

system/lib/wasmfs/file.cpp

@@ -100,7 +100,7 @@ Directory::Handle::insertDataFile(const std::string& name, mode_t mode) {
     return nullptr;
   }
   cacheChild(name, child, DCacheKind::Normal);
-  setMTime(time(NULL));
+  updateMTime();
   return child;
 }
 
@@ -115,7 +115,7 @@ Directory::Handle::insertDirectory(const std::string& name, mode_t mode) {
     return nullptr;
   }
   cacheChild(name, child, DCacheKind::Normal);
-  setMTime(time(NULL));
+  updateMTime();
   return child;
 }
 
@@ -131,7 +131,7 @@ Directory::Handle::insertSymlink(const std::string& name,
     return nullptr;
   }
   cacheChild(name, child, DCacheKind::Normal);
-  setMTime(time(NULL));
+  updateMTime();
   return child;
 }
 
@@ -181,9 +181,8 @@ int Directory::Handle::insertMove(const std::string& name,
   file->locked().setParent(getDir());
 
   // TODO: Moving mount points probably shouldn't update the mtime.
-  auto now = time(NULL);
-  oldParent->locked().setMTime(now);
-  setMTime(now);
+  oldParent->locked().updateMTime();
+  updateMTime();
 
   return 0;
 }
@@ -204,7 +203,7 @@ int Directory::Handle::removeChild(const std::string& name) {
     entry->second.file->locked().setParent(nullptr);
     dcache.erase(entry);
   }
-  setMTime(time(NULL));
+  updateMTime();
   return 0;
 }
 

system/lib/wasmfs/file.h

@@ -19,6 +19,7 @@
 #include <variant>
 #include <vector>
 #include <wasi/api.h>
+#include <time.h>
 
 namespace wasmfs {
 
@@ -96,7 +97,9 @@ class File : public std::enable_shared_from_this<File> {
 protected:
   File(FileKind kind, mode_t mode, backend_t backend)
     : kind(kind), mode(mode), backend(backend) {
-    atime = mtime = ctime = time(NULL);
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    atime = mtime = ctime = ts;
   }
 
   // A mutex is needed for multiple accesses to the same file.
@@ -108,9 +111,9 @@ class File : public std::enable_shared_from_this<File> {
 
   mode_t mode = 0; // User and group mode bits for access permission.
 
-  time_t atime = 0; // Time when the content was last accessed.
-  time_t mtime = 0; // Time when the file content was last modified.
-  time_t ctime = 0; // Time when the file node was last modified.
+  struct timespec atime; // Time when the content was last accessed.
+  struct timespec mtime; // Time when the file content was last modified.
+  struct timespec ctime; // Time when the file node was last modified.
 
   // Reference to parent of current file node. This can be used to
   // traverse up the directory tree. A weak_ptr ensures that the ref
@@ -314,12 +317,42 @@ class File::Handle {
     // directory, for example).
     file->mode = (file->mode & S_IFMT) | (mode & ~S_IFMT);
   }
-  time_t getCTime() { return file->ctime; }
-  void setCTime(time_t time) { file->ctime = time; }
-  time_t getMTime() { return file->mtime; }
-  void setMTime(time_t time) { file->mtime = time; }
-  time_t getATime() { return file->atime; }
-  void setATime(time_t time) { file->atime = time; }
+  struct timespec getCTime() {
+    return file->ctime;
+  }
+  void setCTime(struct timespec time) {
+    file->ctime = time;
+  }
+  // updateCTime() updates the ctime to the current time.
+  void updateCTime() {
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    file->ctime = ts;
+  }
+  struct timespec getMTime() {
+    return file->mtime;
+  }
+  void setMTime(struct timespec time) {
+    file->mtime = time;
+  }
+  // updateMTime() updates the mtime to the current time.
+  void updateMTime() {
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    file->mtime = ts;
+  }
+  struct timespec getATime() {
+    return file->atime;
+  }
+  void setATime(struct timespec time) {
+    file->atime = time;
+  }
+  // updateATime() updates the atime to the current time.
+  void updateATime() {
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    file->atime = ts;
+  }
 
   // Note: parent.lock() creates a new shared_ptr to the same Directory
   // specified by the parent weak_ptr.

system/lib/wasmfs/syscalls.cpp

@@ -24,6 +24,7 @@
 #include <utility>
 #include <vector>
 #include <wasi/api.h>
+#include <time.h>
 
 #include "backend.h"
 #include "file.h"
@@ -167,7 +168,7 @@ static __wasi_errno_t writeAtOffset(OffsetHandling setOffset,
     lockedOpenFile.setPosition(offset + bytesWritten);
   }
   if (bytesWritten) {
-    lockedFile.setMTime(time(NULL));
+    lockedFile.updateMTime();
   }
   return __WASI_ERRNO_SUCCESS;
 }
@@ -383,9 +384,9 @@ int __syscall_newfstatat(int dirfd, intptr_t path, intptr_t buf, int flags) {
   buffer->st_blocks = (buffer->st_size + 511) / 512;
   // Specifies the preferred blocksize for efficient disk I/O.
   buffer->st_blksize = 4096;
-  buffer->st_atim.tv_sec = lockedFile.getATime();
-  buffer->st_mtim.tv_sec = lockedFile.getMTime();
-  buffer->st_ctim.tv_sec = lockedFile.getCTime();
+  buffer->st_atim = lockedFile.getATime();
+  buffer->st_mtim = lockedFile.getMTime();
+  buffer->st_ctim = lockedFile.getCTime();
   return __WASI_ERRNO_SUCCESS;
 }
 
@@ -1093,21 +1094,23 @@ int __syscall_utimensat(int dirFD, intptr_t path_, intptr_t times_, int flags) {
     return err;
   }
 
-  // TODO: Set tv_nsec (nanoseconds) as well.
   // TODO: Handle tv_nsec being UTIME_NOW or UTIME_OMIT.
   // TODO: Check for write access to the file (see man page for specifics).
-  time_t aSeconds, mSeconds;
+  struct timespec aTime, mTime;
+  
   if (times == NULL) {
-    aSeconds = time(NULL);
-    mSeconds = aSeconds;
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    aTime = ts;
+    mTime = ts;
   } else {
-    aSeconds = times[0].tv_sec;
-    mSeconds = times[1].tv_sec;
+    aTime = times[0];
+    mTime = times[1];
   }
 
   auto locked = parsed.getFile()->locked();
-  locked.setATime(aSeconds);
-  locked.setMTime(mSeconds);
+  locked.setATime(aTime);
+  locked.setMTime(mTime);
 
   return 0;
 }
@@ -1131,7 +1134,7 @@ int __syscall_fchmodat(int dirfd, intptr_t path, int mode, ...) {
   auto lockedFile = parsed.getFile()->locked();
   lockedFile.setMode(mode);
   // On POSIX, ctime is updated on metadata changes, like chmod.
-  lockedFile.setCTime(time(NULL));
+  lockedFile.updateCTime();
   return 0;
 }
 
@@ -1146,7 +1149,7 @@ int __syscall_fchmod(int fd, int mode) {
   }
   auto lockedFile = openFile->locked().getFile()->locked();
   lockedFile.setMode(mode);
-  lockedFile.setCTime(time(NULL));
+  lockedFile.updateCTime();
   return 0;
 }
 

test/fs/test_fs_js_api.c

@@ -374,8 +374,11 @@ void test_fs_utime() {
     assert(utimeStats.st_atime == 10);
     assert(utimeStats.st_atim.tv_sec == 10);
 
-    // WasmFS correctly sets both times, but the legacy API sets both times to the max of atime and mtime.
+    // WasmFS correctly sets both times, but the legacy API sets both times to the max of atime and mtime
+    // and does not correctly handle nanseconds.
 #if WASMFS
+    assert(utimeStats.st_atim.tv_nsec == 500000000);
+    
     assert(utimeStats.st_mtime == 8);
     assert(utimeStats.st_mtim.tv_sec == 8);
 #else

test/other/metadce/test_metadce_cxx_wasmfs.imports

@@ -1,4 +1,5 @@
 env.__cxa_throw
+env._emscripten_get_now_is_monotonic
 env._wasmfs_copy_preloaded_file_data
 env._wasmfs_get_num_preloaded_dirs
 env._wasmfs_get_num_preloaded_files

test/other/metadce/test_metadce_cxx_wasmfs.jssize

@@ -1 +1 @@
-12363
+12507

test/other/metadce/test_metadce_cxx_wasmfs.sent

@@ -1,4 +1,5 @@
 __cxa_throw
+_emscripten_get_now_is_monotonic
 _wasmfs_copy_preloaded_file_data
 _wasmfs_get_num_preloaded_dirs
 _wasmfs_get_num_preloaded_files
@@ -11,6 +12,7 @@ abort
 emscripten_console_error
 emscripten_date_now
 emscripten_err
+emscripten_get_now
 emscripten_memcpy_big
 emscripten_out
 emscripten_resize_heap

test/other/metadce/test_metadce_cxx_wasmfs.size

@@ -1 +1 @@
-164024
+164449

test/other/metadce/test_metadce_files_wasmfs.exports

@@ -1,4 +1,4 @@
-q
 r
 s
 t
+u

test/other/metadce/test_metadce_files_wasmfs.funcs

@@ -1,3 +1,4 @@
+$__clock_gettime
 $__cxx_global_array_dtor
 $__cxx_global_array_dtor.1
 $__cxx_global_array_dtor.2
@@ -27,7 +28,6 @@ $__pthread_mutex_lock
 $__stdio_close
 $__stdio_seek
 $__stdio_write
-$__time
 $__unlockfile
 $__wasi_fd_close
 $__wasi_fd_write

test/other/metadce/test_metadce_files_wasmfs.imports

@@ -14,3 +14,4 @@ a.m
 a.n
 a.o
 a.p
+a.q

test/other/metadce/test_metadce_files_wasmfs.jssize

@@ -1 +1 @@
-6830
+6902

test/other/metadce/test_metadce_files_wasmfs.sent

@@ -14,3 +14,4 @@ m
 n
 o
 p
+q

test/other/metadce/test_metadce_files_wasmfs.size

@@ -1 +1 @@
-51954
+52403