mkrundir

commit 3313f639d9e4984ae6e16115976ff6bac9fa4bdf
Author: Robert Russell <robertrussell.72001@gmail.com>
Date:   Sat,  9 Sep 2023 10:33:00 -0700

Initial commit

Diffstat:
A
.gitignore
 | 
2
++
A
Makefile
 | 
20
++++++++++++++++++++
A
README
 | 
7
+++++++
A
config.mk
 | 
5
+++++
A
mkrundir.c
 | 
30
++++++++++++++++++++++++++++++

5 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+mkrundir
+\ No newline at end of file
diff --git a/Makefile b/Makefile
@@ -0,0 +1,20 @@
+.POSIX:
+
+include config.mk
+
+mkrundir: mkrundir.c config.mk
+	$(CC) $(CFLAGS) -o $@ mkrundir.c
+
+install: mkrundir
+	mkdir -p $(DESTDIR)$(PREFIX)/bin
+	cp -f mkrundir $(DESTDIR)$(PREFIX)/bin/
+	chown root:root $(DESTDIR)$(PREFIX)/bin/mkrundir
+	chmod a+rx,u+ws $(DESTDIR)$(PREFIX)/bin/mkrundir
+
+uninstall:
+	rm -f $(DESTDIR)$(PREFIX)/bin/mkrundir
+
+clean:
+	rm -f mkrundir
+
+.PHONY: install uninstall clean
diff --git a/README b/README
@@ -0,0 +1,7 @@
+mkrundir is a simple setuid program for creating XDG_RUNTIME_DIRs in /run/user.
+Installation and usage:
+	# make install
+	# echo 'export XDG_RUNTIME_DIR=$(mkrundir)' >/etc/profile.d/xdg_runtime_dir.sh
+Note that the directory won't be removed when a user fully logs out, contrary
+to the XDG specification. Actually, it won't be removed at all, so your /run
+directory should be a tmpfs.
diff --git a/config.mk b/config.mk
@@ -0,0 +1,5 @@
+PREFIX = /usr/local
+
+CFLAGS = -Wall
+
+CC = cc
diff --git a/mkrundir.c b/mkrundir.c
@@ -0,0 +1,30 @@
+#include <errno.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#define PARENT "/run/user/"  // Must end with '/'.
+
+int
+main(void) {
+	uintmax_t uid = getuid();
+	uintmax_t gid = getgid();
+
+	// This should always be big enough.
+	char path[sizeof PARENT + sizeof(uintmax_t)*CHAR_BIT];
+	int n = snprintf(path, sizeof path, PARENT"%ju", uid);
+	if (n < 0 || n >= sizeof path) return 1;
+
+	if (mkdir(path, S_IRWXU) < 0) {
+		if (errno != EEXIST) return 1;
+		// If it already exists, make sure the mode is correct.
+		if (chmod(path, S_IRWXU) < 0) return 1;
+	}
+	if (chown(path, uid, gid) < 0) return 1;
+
+	puts(path);
+
+	return 0;
+}