posix: fd_mgmt: add fd_mgmt option group

Signed-off-by: Chris Friedt <[email protected]>

lib/libc/Kconfig

@@ -102,6 +102,7 @@ config NEWLIB_LIBC
 	depends on !NATIVE_APPLICATION
 	depends on NEWLIB_LIBC_SUPPORTED
 	select NEED_LIBC_MEM_PARTITION
+	imply POSIX_FD_MGMT_ALIAS_LSEEK
 	help
 	  Build with newlib library. The newlib library is expected to be
 	  part of the SDK in this case.

lib/os/fdtable.c

@@ -366,7 +366,7 @@ int fsync(int fd)
 FUNC_ALIAS(fsync, _fsync, int);
 #endif /* CONFIG_POSIX_FSYNC */
 
-off_t lseek(int fd, off_t offset, int whence)
+off_t zvfs_lseek(int fd, off_t offset, int whence)
 {
 	if (_check_fd(fd) < 0) {
 		return -1;
@@ -375,7 +375,6 @@ off_t lseek(int fd, off_t offset, int whence)
 	return z_fdtable_call_ioctl(fdtable[fd].vtable, fdtable[fd].obj, ZFD_IOCTL_LSEEK,
 			  offset, whence);
 }
-FUNC_ALIAS(lseek, _lseek, off_t);
 
 int ioctl(int fd, unsigned long request, ...)
 {
@@ -393,26 +392,16 @@ int ioctl(int fd, unsigned long request, ...)
 	return res;
 }
 
-int fcntl(int fd, int cmd, ...)
+int zvfs_fcntl(int fd, int cmd, va_list args)
 {
-	va_list args;
 	int res;
 
 	if (_check_fd(fd) < 0) {
 		return -1;
 	}
 
-	/* Handle fdtable commands. */
-	if (cmd == F_DUPFD) {
-		/* Not implemented so far. */
-		errno = EINVAL;
-		return -1;
-	}
-
 	/* The rest of commands are per-fd, handled by ioctl vmethod. */
-	va_start(args, cmd);
 	res = fdtable[fd].vtable->ioctl(fdtable[fd].obj, cmd, args);
-	va_end(args);
 
 	return res;
 }

lib/posix/options/CMakeLists.txt

@@ -41,6 +41,9 @@ zephyr_library_sources_ifdef(CONFIG_POSIX_API perror.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_ASYNCHRONOUS_IO aio.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_CONFSTR confstr.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_ENV env.c)
+zephyr_library_sources_ifdef(CONFIG_POSIX_FD_MGMT
+  fd_mgmt.c
+)
 zephyr_library_sources_ifdef(CONFIG_POSIX_FS fs.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MQUEUE mqueue.c)
 zephyr_library_sources_ifdef(CONFIG_POSIX_MULTI_PROCESS

lib/posix/options/Kconfig

@@ -29,6 +29,7 @@ rsource "Kconfig.confstr"
 rsource "Kconfig.env"
 rsource "Kconfig.eventfd"
 rsource "Kconfig.fdtable"
+rsource "Kconfig.fd_mgmt"
 rsource "Kconfig.fnmatch"
 rsource "Kconfig.fs"
 rsource "Kconfig.getentropy"

lib/posix/options/Kconfig.fd_mgmt

@@ -0,0 +1,36 @@
+# Copyright (c) 2024 Tenstorrent AI ULC
+#
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig POSIX_FD_MGMT
+	bool "POSIX file descriptor management"
+	default y if POSIX_API
+	help
+	  Select 'y' here and Zephyr will provide implementations for the POSIX_FD_MGMT Option Group.
+	  This includes support for dup(), dup2(), fcntl(), fseeko(), ftello(), ftruncate(),
+	  and lseek().
+
+	  For more information, please see
+	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html
+
+if POSIX_FD_MGMT
+
+# These options are intended to be used for compatibility with external POSIX
+# implementations such as those in Newlib or Picolibc.
+
+config POSIX_FD_MGMT_ALIAS_FCNTL
+	bool
+	help
+	  Select 'y' here and Zephyr will provide an alias for fcntl() as _fcntl().
+
+config POSIX_FD_MGMT_ALIAS_FTRUNCATE
+	bool
+	help
+	  Select 'y' here and Zephyr will provide an alias for ftruncate() as _ftruncate().
+
+config POSIX_FD_MGMT_ALIAS_LSEEK
+	bool
+	help
+	  Select 'y' here and Zephyr will provide an alias for lseek() as _lseek().
+
+endif # POSIX_FD_MGMT

lib/posix/options/fd_mgmt.c

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2024, Tenstorrent AI ULC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <zephyr/posix/unistd.h>
+#include <zephyr/posix/sys/select.h>
+#include <zephyr/posix/sys/socket.h>
+#include <zephyr/sys/fdtable.h>
+
+/* prototypes for external, not-yet-public, functions in fdtable.c or fs.c */
+int zvfs_fcntl(int fd, int cmd, va_list arg);
+int zvfs_ftruncate(int fd, off_t length);
+off_t zvfs_lseek(int fd, off_t offset, int whence);
+
+int fcntl(int fd, int cmd, ...)
+{
+	int ret;
+	va_list args;
+
+	va_start(args, cmd);
+	ret = zvfs_fcntl(fd, cmd, args);
+	va_end(args);
+
+	return ret;
+}
+#ifdef CONFIG_POSIX_FD_MGMT_ALIAS_FCNTL
+FUNC_ALIAS(fcntl, _fcntl, int);
+#endif /* CONFIG_POSIX_FD_MGMT_ALIAS_FCNTL */
+
+int ftruncate(int fd, off_t length)
+{
+	return zvfs_ftruncate(fd, length);
+}
+#ifdef CONFIG_POSIX_FD_MGMT_ALIAS_FTRUNCATE
+FUNC_ALIAS(ftruncate, _ftruncate, int);
+#endif /* CONFIG_POSIX_FD_MGMT_ALIAS_FTRUNCATE */
+
+off_t lseek(int fd, off_t offset, int whence)
+{
+	return zvfs_lseek(fd, offset, whence);
+}
+#ifdef CONFIG_POSIX_FD_MGMT_ALIAS_LSEEK
+FUNC_ALIAS(lseek, _lseek, off_t);
+#endif /* CONFIG_POSIX_FD_MGMT_ALIAS_LSEEK */

lib/posix/options/fs.c

@@ -421,7 +421,7 @@ int mkdir(const char *path, mode_t mode)
  * @brief Truncate file to specified length.
  *
  */
-int ftruncate(int fd, off_t length)
+int zvfs_ftruncate(int fd, off_t length)
 {
 	int rc;
 	struct posix_fs_desc *ptr = NULL;