posix: options: implement POSIX_SYSTEM_DATABASE Option Group

Provide an implementation for the POSIX_SYSTEM_DATABASE Option
Group.

Signed-off-by: Chris Friedt <cfriedt@tenstorrent.com>

Author: cfriedt

lib/posix/options/CMakeLists.txt

@@ -121,6 +121,13 @@ if (NOT CONFIG_TC_PROVIDES_POSIX_SPIN_LOCKS)
   zephyr_library_sources_ifdef(CONFIG_POSIX_SPIN_LOCKS spinlock.c)
 endif()
 
+if (NOT CONFIG_TC_PROVIDES_POSIX_SYSTEM_DATABASE)
+  zephyr_library_sources_ifdef(CONFIG_POSIX_SYSTEM_DATABASE
+    system_database_priv.c
+    system_database.c
+  )
+endif()
+
 if (NOT CONFIG_TC_PROVIDES_POSIX_SYSTEM_DATABASE_R)
   zephyr_library_sources_ifdef(CONFIG_POSIX_SYSTEM_DATABASE_R
     system_database_priv.c

lib/posix/options/Kconfig

@@ -28,6 +28,7 @@ rsource "Kconfig.semaphore"
 rsource "Kconfig.signal"
 rsource "Kconfig.spinlock"
 rsource "Kconfig.sync_io"
+rsource "Kconfig.system_database"
 rsource "Kconfig.system_database_r"
 rsource "Kconfig.timer"
 rsource "Kconfig.xsi"

lib/posix/options/Kconfig.system_database

@@ -0,0 +1,13 @@
+# Copyright (c) 2024 Tenstorrent AI ULC
+#
+# SPDX-License-Identifier: Apache-2.0
+
+config POSIX_SYSTEM_DATABASE
+	bool "POSIX System Database"
+	select POSIX_SYSTEM_DATABASE_R
+	help
+	  Select 'y' here, and the system will support getgrgid(), getgrnam(), getpwnam(), and
+	  getpwuid().
+
+	  For more information, please see
+	  https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_subprofiles.html

lib/posix/options/system_database.c

@@ -0,0 +1,85 @@
+/*
+ * Copyright (c) 2024 Tenstorrent AI ULC
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "system_database_priv.h"
+
+#include <errno.h>
+#include <stddef.h>
+#include <string.h>
+
+#include <zephyr/posix/grp.h>
+#include <zephyr/posix/pwd.h>
+#include <zephyr/sys/util.h>
+
+static char gr_line_buf[CONFIG_POSIX_GETGR_R_SIZE_MAX];
+static char pw_line_buf[CONFIG_POSIX_GETPW_R_SIZE_MAX];
+
+static struct group gr;
+static struct passwd pw;
+
+struct group *getgrgid(gid_t gid)
+{
+	int ret;
+	struct group *result;
+
+	ret = __getgr_r(NULL, gid, &gr, gr_line_buf, sizeof(gr_line_buf), &result);
+	if (ret != 0) {
+		errno = ret;
+		return NULL;
+	}
+
+	return result;
+}
+
+struct group *getgrnam(const char *name)
+{
+	int ret;
+	struct group *result;
+
+	if (name == NULL) {
+		return NULL;
+	}
+
+	ret = __getgr_r(name, -1, &gr, gr_line_buf, sizeof(gr_line_buf), &result);
+	if (ret != 0) {
+		errno = ret;
+		return NULL;
+	}
+
+	return result;
+}
+
+struct passwd *getpwnam(const char *name)
+{
+	int ret;
+	struct passwd *result;
+
+	if (name == NULL) {
+		return NULL;
+	}
+
+	ret = __getpw_r(name, -1, &pw, pw_line_buf, sizeof(pw_line_buf), &result);
+	if (ret != 0) {
+		errno = ret;
+		return NULL;
+	}
+
+	return result;
+}
+
+struct passwd *getpwuid(uid_t uid)
+{
+	int ret;
+	struct passwd *result;
+
+	ret = __getpw_r(NULL, uid, &pw, pw_line_buf, sizeof(pw_line_buf), &result);
+	if (ret != 0) {
+		errno = ret;
+		return NULL;
+	}
+
+	return result;
+}