Revert "posix: device_io: implement pread() and pwrite()"

This reverts commit 2d72966516.

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
https://github.com/zephyrproject-rtos/zephyr/issues/75205

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

lib/os/fdtable.c

@@ -308,21 +308,9 @@ int zvfs_alloc_fd(void *obj, const struct fd_op_vtable *vtable)
 	return fd;
 }
 
-static bool supports_pread_pwrite(uint32_t mode)
+static ssize_t zvfs_rw(int fd, void *buf, size_t sz, bool is_write)
 {
-	switch (mode & ZVFS_MODE_IFMT) {
-	case ZVFS_MODE_IFSHM:
-		return true;
-	default:
-		return false;
-	}
-}
-
-static ssize_t zvfs_rw(int fd, void *buf, size_t sz, bool is_write, const size_t *from_offset)
-{
-	bool prw;
 	ssize_t res;
-	const size_t *off;
 
 	if (_check_fd(fd) < 0) {
 		return -1;
@@ -330,40 +318,24 @@ static ssize_t zvfs_rw(int fd, void *buf, size_t sz, bool is_write, const size_t
 
 	(void)k_mutex_lock(&fdtable[fd].lock, K_FOREVER);
 
-	prw = supports_pread_pwrite(fdtable[fd].mode);
-	if (from_offset != NULL && !prw) {
-		/*
-		 * Seekable file types should support pread() / pwrite() and per-fd offset passing.
-		 * Otherwise, it's a bug.
-		 */
-		errno = ENOTSUP;
-		res = -1;
-		goto unlock;
-	}
-
-	/* If there is no specified from_offset, then use the current offset of the fd */
-	off = (from_offset == NULL) ? &fdtable[fd].offset : from_offset;
-
 	if (is_write) {
-		if (fdtable[fd].vtable->write_offs == NULL) {
+		if (fdtable[fd].vtable->write_offset == NULL) {
 			res = -1;
 			errno = EIO;
 		} else {
-			res = fdtable[fd].vtable->write_offs(fdtable[fd].obj, buf, sz, *off);
+			res = fdtable[fd].vtable->write_offset(fdtable[fd].obj, buf, sz,
+							       fdtable[fd].offset);
 		}
 	} else {
-		if (fdtable[fd].vtable->read_offs == NULL) {
+		if (fdtable[fd].vtable->read == NULL) {
 			res = -1;
 			errno = EIO;
 		} else {
-			res = fdtable[fd].vtable->read_offs(fdtable[fd].obj, buf, sz, *off);
+			res = fdtable[fd].vtable->read_offset(fdtable[fd].obj, buf, sz,
+							      fdtable[fd].offset);
 		}
 	}
-	if (res > 0 && prw && from_offset == NULL) {
+	if (res > 0) {
-		/*
-		 * only update the fd offset when from_offset is not specified
-		 * See pread() / pwrite()
-		 */
 		fdtable[fd].offset += res;
 	}
 
@@ -373,14 +345,14 @@ unlock:
 	return res;
 }
 
-ssize_t zvfs_read(int fd, void *buf, size_t sz, const size_t *from_offset)
+ssize_t zvfs_read(int fd, void *buf, size_t sz)
 {
-	return zvfs_rw(fd, buf, sz, false, from_offset);
+	return zvfs_rw(fd, buf, sz, false);
 }
 
-ssize_t zvfs_write(int fd, const void *buf, size_t sz, const size_t *from_offset)
+ssize_t zvfs_write(int fd, const void *buf, size_t sz)
 {
-	return zvfs_rw(fd, (void *)buf, sz, true, from_offset);
+	return zvfs_rw(fd, (void *)buf, sz, true);
 }
 
 int zvfs_close(int fd)
@@ -522,7 +494,7 @@ static ssize_t stdinout_read_vmeth(void *obj, void *buffer, size_t count)
 static ssize_t stdinout_write_vmeth(void *obj, const void *buffer, size_t count)
 {
 #if defined(CONFIG_BOARD_NATIVE_POSIX)
-	return zvfs_write(1, buffer, count, NULL);
+	return zvfs_write(1, buffer, count);
 #elif defined(CONFIG_NEWLIB_LIBC) || defined(CONFIG_ARCMWDT_LIBC)
 	return z_impl_zephyr_write_stdout(buffer, count);
 #else

lib/posix/options/device_io.c

@@ -15,8 +15,8 @@
 /* prototypes for external, not-yet-public, functions in fdtable.c or fs.c */
 int zvfs_close(int fd);
 int zvfs_open(const char *name, int flags);
-ssize_t zvfs_read(int fd, void *buf, size_t sz, size_t *from_offset);
+ssize_t zvfs_read(int fd, void *buf, size_t sz);
-ssize_t zvfs_write(int fd, const void *buf, size_t sz, size_t *from_offset);
+ssize_t zvfs_write(int fd, const void *buf, size_t sz);
 
 int close(int fd)
 {
@@ -41,33 +41,9 @@ int poll(struct pollfd *fds, int nfds, int timeout)
 	return zsock_poll(fds, nfds, timeout);
 }
 
-ssize_t pread(int fd, void *buf, size_t count, off_t offset)
-{
-	size_t off = (size_t)offset;
-
-	if (offset < 0) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	return zvfs_read(fd, buf, count, (size_t *)&off);
-}
-
-ssize_t pwrite(int fd, void *buf, size_t count, off_t offset)
-{
-	size_t off = (size_t)offset;
-
-	if (offset < 0) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	return zvfs_write(fd, buf, count, (size_t *)&off);
-}
-
 ssize_t read(int fd, void *buf, size_t sz)
 {
-	return zvfs_read(fd, buf, sz, NULL);
+	return zvfs_read(fd, buf, sz);
 }
 #ifdef CONFIG_POSIX_DEVICE_IO_ALIAS_READ
 FUNC_ALIAS(read, _read, ssize_t);
@@ -81,7 +57,7 @@ int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struc
 
 ssize_t write(int fd, const void *buf, size_t sz)
 {
-	return zvfs_write(fd, buf, sz, NULL);
+	return zvfs_write(fd, buf, sz);
 }
 #ifdef CONFIG_POSIX_DEVICE_IO_ALIAS_WRITE
 FUNC_ALIAS(write, _write, ssize_t);