Add tentative fsync wrapper.

Fsync is a POSIX API that may not be available or useful on all systems.

CHANGELOG.md

@@ -2,6 +2,7 @@
 All notable changes to this project will be documented in this file.
 
 ## Unreleased - ???
+- Add `file/sync` as a wrapper around fsync.
 - Documentation fixes
 - ev/thread-chan deadlock bug fixed
 - Re-add removed support for non-blocking net/connect on windows.

src/core/ev.c

@@ -1722,7 +1722,7 @@ void janet_loop1_impl(int has_timeout, JanetTimestamp to) {
             }
             if (fiber != NULL) {
                 fiber->flags &= ~JANET_FIBER_EV_FLAG_IN_FLIGHT;
-                jo->bytes_transfered = (ULONG_PTR) num_bytes_transferred;
+                jo->bytes_transferred = (ULONG_PTR) num_bytes_transferred;
                 fiber->ev_callback(fiber, result ? JANET_ASYNC_EVENT_COMPLETE : JANET_ASYNC_EVENT_FAILED);
             } else {
                 janet_free((void *) jo);
@@ -2472,7 +2472,7 @@ void ev_callback_read(JanetFiber *fiber, JanetAsyncEvent event) {
         case JANET_ASYNC_EVENT_FAILED:
         case JANET_ASYNC_EVENT_COMPLETE: {
             /* Called when read finished */
-            uint32_t ev_bytes = (uint32_t) state->overlapped.bytes_transfered;
+            uint32_t ev_bytes = (uint32_t) state->overlapped.bytes_transferred;
             state->bytes_read += ev_bytes;
             if (state->bytes_read == 0 && (state->mode != JANET_ASYNC_READMODE_RECVFROM)) {
                 janet_schedule(fiber, janet_wrap_nil());
@@ -2722,7 +2722,7 @@ void ev_callback_write(JanetFiber *fiber, JanetAsyncEvent event) {
         case JANET_ASYNC_EVENT_FAILED:
         case JANET_ASYNC_EVENT_COMPLETE: {
             /* Called when write finished */
-            uint32_t ev_bytes = (uint32_t) state->overlapped.bytes_transfered;
+            uint32_t ev_bytes = (uint32_t) state->overlapped.bytes_transferred;
             if (ev_bytes == 0 && (state->mode != JANET_ASYNC_WRITEMODE_SENDTO)) {
                 janet_cancel(fiber, janet_cstringv("disconnect"));
                 janet_async_end(fiber);

src/core/io.c

@@ -320,6 +320,41 @@ static int cfun_io_gc(void *p, size_t len) {
     return 0;
 }
 
+/* Cross-platform fsync binding for Janet */
+JANET_CORE_FN(cfun_io_fsync,
+              "(file/sync f)",
+              "Flushes all operating system buffers to disk for file `f`. Guarantees data is physically "
+              "written to disk in a platform-dependent way. Returns the file handle if successful, raises error if not.") {
+    janet_fixarity(argc, 1);
+    JanetFile *iof = janet_getabstract(argv, 0, &janet_file_type);
+    if (iof->flags & JANET_FILE_CLOSED)
+        janet_panic("file is closed");
+#ifdef JANET_WINDOWS
+    {
+        intptr_t fd = _fileno(iof->file);
+        if (fd < 0)
+            janet_panic("invalid file descriptor");
+        HANDLE hFile = (HANDLE)_get_osfhandle(fd);
+        if (hFile == INVALID_HANDLE_VALUE)
+            janet_panic("invalid file handle");
+        if (!FlushFileBuffers(hFile))
+            janet_panic("could not flush file buffers");
+    }
+#elif defined(_POSIX_VERSION)
+    {
+        int fd = fileno(iof->file);
+        if (fd < 0)
+            janet_panic("invalid file descriptor");
+        if (fsync(fd) != 0)
+            janet_panic("could not fsync file");
+    }
+#else
+    janet_panic("fsync not supported on this platform");
+#endif
+    return argv[0];
+}
+
+
 /* Close a file */
 JANET_CORE_FN(cfun_io_fclose,
               "(file/close f)",
@@ -394,6 +429,7 @@ static JanetMethod io_file_methods[] = {
     {"seek", cfun_io_fseek},
     {"tell", cfun_io_ftell},
     {"write", cfun_io_fwrite},
+    {"sync", cfun_io_fsync},
     {NULL, NULL}
 };
 
@@ -846,6 +882,7 @@ void janet_lib_io(JanetTable *env) {
         JANET_CORE_REG("file/flush", cfun_io_fflush),
         JANET_CORE_REG("file/seek", cfun_io_fseek),
         JANET_CORE_REG("file/tell", cfun_io_ftell),
+        JANET_CORE_REG("file/sync", cfun_io_fsync),
         JANET_REG_END
     };
     janet_core_cfuns_ext(env, NULL, io_cfuns);

src/core/util.h

@@ -213,7 +213,7 @@ typedef struct {
         OVERLAPPED overlapped;
         WSAOVERLAPPED wsaoverlapped;
     } as;
-    uint32_t bytes_transfered;
+    uint32_t bytes_transferred;
 } JanetOverlapped;
 #endif
 #endif

test/suite-io.janet

@@ -55,7 +55,8 @@
   (file/flush f)
   (file/seek f :set 0)
   (assert (= 0 (file/tell f)) "start of file again")
-  (assert (= (string (file/read f :all)) "foo\n") "temp files work"))
+  (assert (= (string (file/read f :all)) "foo\n") "temp files work")
+  (assert-no-error "fsync" (file/sync f)))
 
 # issue #1055 - 2c927ea76
 (let [b @""]
@@ -74,9 +75,13 @@
 (defn to-b [a] (buffer/push b a))
 (xprintf to-b "123")
 (assert (deep= b @"123\n") "xprintf to buffer")
-
-
 (assert-error "cannot print to 3" (xprintf 3 "123"))
 
+# file/sync
+(with [f (file/temp "wb")]
+  (file/write f "123abc")
+  (file/flush f)
+  (file/sync f))
+
 (end-suite)