lib: libc: Implement gethostname() + sethostname()

This commit adds the POSIX gethostname() and sethostname() functions to
the Hyra C library.

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 128 insertions, 0 deletions

diff --git a/lib/libc/include/unistd.h b/lib/libc/include/unistd.h
index 8b03b81..21206ad 100644
--- a/lib/libc/include/unistd.h
+++ b/lib/libc/include/unistd.h
@@ -47,6 +47,9 @@ __BEGIN_DECLS
 int sysconf(int name);
 int setuid(uid_t new);
 
+int gethostname(char *name, size_t size);
+int sethostname(const char *name, size_t size);
+
 uid_t getuid(void);
 char *getlogin(void);
 
diff --git a/lib/libc/src/unistd/hostname.c b/lib/libc/src/unistd/hostname.c
new file mode 100644
index 0000000..60df9a0
--- /dev/null
+++ b/lib/libc/src/unistd/hostname.c
@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/sysctl.h>
+#include <unistd.h>
+
+/*
+ * Internal helper to grab a sysctl
+ * variable.
+ *
+ * @name: Name definition of sysctl variable
+ * @buf: Buffer to read data in
+ * @buflen: Length of buffer
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value.
+ */
+static int
+__sysctl_get(int name, char *buf, size_t buflen)
+{
+    struct sysctl_args args;
+    int error;
+
+    args.name = &name;
+    args.nlen = 1;
+    args.oldp = buf;
+    args.oldlenp = &buflen;
+    args.newp = NULL;
+    args.newlen = 0;
+
+    if ((error = sysctl(&args)) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+/*
+ * Internal helper to set a sysctl
+ * variable.
+ *
+ * @name: Name definition of sysctl variable
+ * @buf: Buffer with data to set
+ * @buflen: Length of buffer
+ *
+ * Returns zero on success, otherwise a less than
+ * zero value.
+ */
+static int
+__sysctl_set(int name, const char *buf, size_t buflen)
+{
+    struct sysctl_args args;
+    int error;
+
+    args.name = &name;
+    args.nlen = 1;
+    args.oldp = NULL;
+    args.oldlenp = NULL;
+    args.newp = (void *)buf;
+    args.newlen = buflen;
+
+    if ((error = sysctl(&args)) != 0) {
+        return -1;
+    }
+
+    return 0;
+}
+
+/*
+ * Get the system hostname
+ *
+ * @name: Buffer to read name into
+ * @size: Length of name to read
+ */
+int
+gethostname(char *name, size_t size)
+{
+    if (name == NULL || size == 0) {
+        return -1;
+    }
+
+    return __sysctl_get(KERN_HOSTNAME, name, size);
+}
+
+/*
+ * Set the system hostname
+ *
+ * @name: Name to set
+ * @size: Size of name to set
+ */
+int
+sethostname(const char *name, size_t size)
+{
+    if (name == NULL || size == 0) {
+        return -1;
+    }
+
+    return __sysctl_set(KERN_HOSTNAME, name, size);
+}