Revert "fdtable: read, write, close: only execute methods if non-NULL"

This reverts commit a9a909c.

PR #73978 introduced a regression.
Unfortunately this PR cannot be reverted without reverting also
Let's revert both PRs to stabilize main again towards the 3.7 release.

For more details on the issue see
zephyrproject-rtos/zephyr#75205

(cherry picked from commit 846556f)

Original-Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
GitOrigin-RevId: 846556f
Change-Id: I6589633d3c009e1ecb5fa3f3264fff054c655fad
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5678584
Tested-by: ChromeOS Prod (Robot) <chromeos-ci-prod@chromeos-bot.iam.gserviceaccount.com>
Reviewed-by: Fabio Baltieri <fabiobaltieri@google.com>
Commit-Queue: Fabio Baltieri <fabiobaltieri@google.com>

lib/os/fdtable.c

@@ -301,7 +301,7 @@ int zvfs_alloc_fd(void *obj, const struct fd_op_vtable *vtable)
  return fd;
 }
 
-static ssize_t zvfs_rw(int fd, void *buf, size_t sz, bool is_write)
+ssize_t zvfs_read(int fd, void *buf, size_t sz)
 {
  ssize_t res;
 
@@ -310,57 +310,63 @@ static ssize_t zvfs_rw(int fd, void *buf, size_t sz, bool is_write)
  }
 
  (void)k_mutex_lock(&fdtable[fd].lock, K_FOREVER);
-
- if (is_write) {
- if (fdtable[fd].vtable->write_offset == NULL) {
- res = -1;
- errno = EIO;
- } else {
- res = fdtable[fd].vtable->write_offset(fdtable[fd].obj, buf, sz,
- fdtable[fd].offset);
- }
- } else {
- if (fdtable[fd].vtable->read == NULL) {
- res = -1;
- errno = EIO;
- } else {
- res = fdtable[fd].vtable->read_offset(fdtable[fd].obj, buf, sz,
- fdtable[fd].offset);
- }
- }
+ res = fdtable[fd].vtable->read_offs(fdtable[fd].obj, buf, sz, fdtable[fd].offset);
  if (res > 0) {
- fdtable[fd].offset += res;
+ switch (fdtable[fd].mode & ZVFS_MODE_IFMT) {
+ case ZVFS_MODE_IFDIR:
+ case ZVFS_MODE_IFBLK:
+ case ZVFS_MODE_IFSHM:
+ case ZVFS_MODE_IFREG:
+ fdtable[fd].offset += res;
+ break;
+ default:
+ break;
+ }
  }
-
-unlock:
  k_mutex_unlock(&fdtable[fd].lock);
 
  return res;
 }
 
-ssize_t zvfs_read(int fd, void *buf, size_t sz)
-{
- return zvfs_rw(fd, buf, sz, false);
-}
-
 ssize_t zvfs_write(int fd, const void *buf, size_t sz)
 {
- return zvfs_rw(fd, (void *)buf, sz, true);
+ ssize_t res;
+
+ if (_check_fd(fd) < 0) {
+ return -1;
+ }
+
+ (void)k_mutex_lock(&fdtable[fd].lock, K_FOREVER);
+ res = fdtable[fd].vtable->write_offs(fdtable[fd].obj, buf, sz, fdtable[fd].offset);
+ if (res > 0) {
+ switch (fdtable[fd].mode & ZVFS_MODE_IFMT) {
+ case ZVFS_MODE_IFDIR:
+ case ZVFS_MODE_IFBLK:
+ case ZVFS_MODE_IFSHM:
+ case ZVFS_MODE_IFREG:
+ fdtable[fd].offset += res;
+ break;
+ default:
+ break;
+ }
+ }
+ k_mutex_unlock(&fdtable[fd].lock);
+
+ return res;
 }
 
 int zvfs_close(int fd)
 {
- int res = 0;
+ int res;
 
  if (_check_fd(fd) < 0) {
  return -1;
  }
 
  (void)k_mutex_lock(&fdtable[fd].lock, K_FOREVER);
- if (fdtable[fd].vtable->close != NULL) {
- /* close() is optional - e.g. stdinout_fd_op_vtable */
- res = fdtable[fd].vtable->close(fdtable[fd].obj);
- }
+
+ res = fdtable[fd].vtable->close(fdtable[fd].obj);
+
  k_mutex_unlock(&fdtable[fd].lock);
 
  zvfs_free_fd(fd);