compat: Use libbsd's setproctitle(3)

Linux PRCTL variant, although more light weight, doesn't work on
some kernels.
This weighs in around 1k more, but always works.
It does play around with environ and args but unlike other
similar variants doesn't appear to stamp on what you actually
use in the program.

compat/setproctitle.c

@@ -1,179 +1,331 @@
 /*
- * lxc: linux Container library
+ * Copyright © 2010 William Ahern
+ * Copyright © 2012-2013 Guillem Jover <guillem@hadrons.org>
  *
- * (C) Copyright IBM Corp. 2007, 2008
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to permit
+ * persons to whom the Software is furnished to do so, subject to the
+ * following conditions:
  *
- * Authors:
+ * The above copyright notice and this permission notice shall be included
- * Daniel Lezcano <daniel.lezcano at free.fr>
+ * in all copies or substantial portions of the Software.
  *
- * This library is free software; you can redistribute it and/or
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
- * modify it under the terms of the GNU Lesser General Public
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
- * License as published by the Free Software Foundation; either
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
- * version 2.1 of the License, or (at your option) any later version.
+ * NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
- *
+ * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
- * This library is distributed in the hope that it will be useful,
+ * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * USE OR OTHER DEALINGS IN THE SOFTWARE.
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#endif
-#ifdef __linux__
-#include <sys/prctl.h>
-#include <sys/syscall.h>
-#endif
-
 #include <errno.h>
-#include <fcntl.h>
+#include <stddef.h>
 #include <stdarg.h>
+#include <stdbool.h>
 #include <stdlib.h>
 #include <stdio.h>
-#include <string.h>
+#include <err.h>
 #include <unistd.h>
+#include <string.h>
+//#include "local-link.h"
 
 #include "config.h"
 
-#define prctl_arg(x) ((unsigned long)x)
+static struct {
+	/* Original value. */
+	char *arg0;
 
-static char *setproctitle_argv;
+	/* Title space available. */
+	char *base, *end;
 
-int setproctitle(const char *fmt, ...)
+	 /* Pointer to original nul character within base. */
+	char *nul;
+
+	bool warned;
+	bool reset;
+	int error;
+
+	/* Our copy of args and environment to free. */
+	int argc;
+	char **argv;
+	char **tmp_environ;
+} SPT;
+
+
+static inline size_t
+spt_min(size_t a, size_t b)
 {
-	const char *progname;
+	return a < b ? a : b;
-	char title[1024], *tp;
+}
-	size_t tl, n;
-	va_list args;
-	int ret;
 
-#if 0
+/*
-	progname = getprogname();
+ * For discussion on the portability of the various methods, see
+ * https://lists.freebsd.org/pipermail/freebsd-stable/2008-June/043136.html
+ */
+static int
+spt_clearenv(void)
+{
+#ifdef HAVE_CLEARENV
+	return clearenv();
 #else
-	progname = "dhcpcd";
+	SPT.tmp_environ = malloc(sizeof(*SPT.tmp_environ));
+	if (SPT.tmp_environ == NULL)
+		return errno;
+
+	SPT.tmp_environ[0] = NULL;
+	environ = SPT.tmp_environ;
+
+	return 0;
 #endif
+}
 
-	tp = title;
+static int
-	tl = sizeof(title);
+spt_copyenv(int envc, char *envp[])
-	n = strlcpy(tp, progname, tl);
+{
-	tp += n;
+	char **envcopy;
-	tl -= n;
+	char *eq;
-	n = strlcpy(tp, ": ", tl);
+	size_t envsize;
-	tp += n;
+	int i, error;
-	tl -= n;
-	va_start(args, fmt);
-	vsnprintf(tp, tl, fmt, args);
-	va_end(args);
 
-#if defined(__linux__) && defined(PR_SET_MM_MAP)
+	if (environ != envp)
-	int fd, i;
+		return 0;
-	char *buf_ptr, *tmp_proctitle;
-	char buf[BUFSIZ];
-	ssize_t bytes_read;
-	size_t len;
 
-	/*
+	/* Make a copy of the old environ array of pointers, in case
-	 * We don't really need to know all of this stuff, but unfortunately
+	 * clearenv() or setenv() is implemented to free the internal
-	 * PR_SET_MM_MAP requires us to set it all at once, so we have to
+	 * environ array, because we will need to access the old environ
-	 * figure it out anyway.
+	 * contents to make the new copy. */
-	 */
+	envsize = (size_t)(envc + 1) * sizeof(char *);
-	unsigned long start_data, end_data, start_brk, start_code, end_code,
+	envcopy = malloc(envsize);
-	    start_stack, arg_start, arg_end, env_start, env_end;
+	if (envcopy == NULL)
-	long brk_val;
+		return errno;
-	struct prctl_mm_map prctl_map;
+	memcpy(envcopy, envp, envsize);
 
-	fd = open("/proc/self/stat", O_RDONLY);
+	error = spt_clearenv();
-	if (fd == -1)
+	if (error) {
-		return -1;
+		environ = envp;
-	bytes_read = read(fd, buf, sizeof(buf) - 1);
+		free(envcopy);
-	close(fd);
+		return error;
-	if (bytes_read == -1)
-		return -1;
-
-	buf[bytes_read] = '\0';
-
-	/* Skip the first 25 fields, column 26-28 are start_code, end_code,
-	 * and start_stack */
-	buf_ptr = strchr(buf, ' ');
-	for (i = 0; i < 24; i++) {
-		if (!buf_ptr)
-			return -1;
-		buf_ptr = strchr(buf_ptr + 1, ' ');
-	}
-	if (!buf_ptr)
-		return -1;
-
-	i = sscanf(buf_ptr, "%lu %lu %lu", &start_code, &end_code, &start_stack);
-	if (i != 3)
-		return -1;
-
-	/* Skip the next 19 fields, column 45-51 are start_data to arg_end */
-	for (i = 0; i < 19; i++) {
-		if (!buf_ptr)
-			return -1;
-		buf_ptr = strchr(buf_ptr + 1, ' ');
 	}
 
-	if (!buf_ptr)
+	for (i = 0; envcopy[i]; i++) {
-		return -1;
+		eq = strchr(envcopy[i], '=');
+		if (eq == NULL)
+			continue;
 
-	i = sscanf(buf_ptr, "%lu %lu %lu %*u %*u %lu %lu", &start_data,
+		*eq = '\0';
-		   &end_data, &start_brk, &env_start, &env_end);
+		if (setenv(envcopy[i], eq + 1, 1) < 0)
-	if (i != 5)
+			error = errno;
-		return -1;
+		*eq = '=';
 
-	/* Include the null byte here, because in the calculations below we
+		if (error) {
-	 * want to have room for it. */
+#ifdef HAVE_CLEARENV
-	len = strlen(title) + 1;
+			/* Because the old environ might not be available
-
+			 * anymore we will make do with the shallow copy. */
-	tmp_proctitle = realloc(setproctitle_argv, len);
+			environ = envcopy;
-	if (!tmp_proctitle)
-		return -1;
-
-	setproctitle_argv = tmp_proctitle;
-
-	arg_start = (unsigned long)setproctitle_argv;
-	arg_end = arg_start + len;
-
-	brk_val = syscall(__NR_brk, 0);
-
-	prctl_map = (struct prctl_mm_map){
-	    .start_code = start_code,
-	    .end_code = end_code,
-	    .start_stack = start_stack,
-	    .start_data = start_data,
-	    .end_data = end_data,
-	    .start_brk = start_brk,
-	    .brk = (unsigned long long)brk_val,
-	    .arg_start = arg_start,
-	    .arg_end = arg_end,
-	    .env_start = env_start,
-	    .env_end = env_end,
-	    .auxv = NULL,
-	    .auxv_size = 0,
-	    .exe_fd = (unsigned int)-1,
-	};
-
-	ret = prctl(PR_SET_MM, prctl_arg(PR_SET_MM_MAP), prctl_arg(&prctl_map),
-		    prctl_arg(sizeof(prctl_map)), prctl_arg(0));
-	if (ret == 0)
-		(void)strlcpy((char *)arg_start, title, len);
 #else
-	/* Solaris doesn't work with the ARGV stamping approach.
+			environ = envp;
-	 * Is there any other way? */
+			free(envcopy);
-	ret = -1;
-	errno = ENOTSUP;
 #endif
-	return ret;
+			return error;
+		}
+	}
+
+	/* Dispose of the shallow copy, now that we've finished transfering
+	 * the old environment. */
+	free(envcopy);
+
+	return 0;
+}
+
+static int
+spt_copyargs(int argc, char *argv[])
+{
+	char *tmp;
+	int i;
+
+	for (i = 1; i < argc || (i >= argc && argv[i]); i++) {
+		if (argv[i] == NULL)
+			continue;
+
+		tmp = strdup(argv[i]);
+		if (tmp == NULL)
+			return errno;
+
+		argv[i] = tmp;
+	}
+
+	return 0;
 }
 
 void
-setproctitle_free(void)
+setproctitle_init(int argc, char *argv[], char *envp[])
 {
+	char *base, *end, *nul, *tmp;
+	int i, envc, error;
 
-	free(setproctitle_argv);
+	/* Try to make sure we got called with main() arguments. */
+	if (argc < 0)
+		return;
+
+	base = argv[0];
+	if (base == NULL)
+		return;
+
+	nul = &base[strlen(base)];
+	end = nul + 1;
+
+	for (i = 0; i < argc || (i >= argc && argv[i]); i++) {
+		if (argv[i] == NULL || argv[i] != end)
+			continue;
+
+		end = argv[i] + strlen(argv[i]) + 1;
+	}
+
+	for (i = 0; envp[i]; i++) {
+		if (envp[i] != end)
+			continue;
+
+		end = envp[i] + strlen(envp[i]) + 1;
+	}
+	envc = i;
+
+	SPT.arg0 = strdup(argv[0]);
+	if (SPT.arg0 == NULL) {
+		SPT.error = errno;
+		return;
+	}
+
+	tmp = strdup(getprogname());
+	if (tmp == NULL) {
+		SPT.error = errno;
+		return;
+	}
+	setprogname(tmp);
+
+	error = spt_copyenv(envc, envp);
+	if (error) {
+		SPT.error = error;
+		return;
+	}
+
+	error = spt_copyargs(argc, argv);
+	if (error) {
+		SPT.error = error;
+		return;
+	}
+
+	SPT.argc = argc;
+	SPT.argv = argv;
+
+	SPT.nul  = nul;
+	SPT.base = base;
+	SPT.end  = end;
 }
+
+void
+setproctitle_fini(void)
+{
+	int i;
+
+	free(SPT.arg0);
+	SPT.arg0 = NULL;
+
+	for (i = 1; i < SPT.argc; i++) {
+		if (SPT.argv[i] != NULL)
+			free(SPT.argv[i]);
+	}
+	SPT.argc = 0;
+
+	free(SPT.tmp_environ);
+	SPT.tmp_environ = NULL;
+}
+
+#ifndef SPT_MAXTITLE
+#define SPT_MAXTITLE 255
+#endif
+
+__printflike(1, 2) static void
+setproctitle_impl(const char *fmt, ...)
+{
+	/* Use buffer in case argv[0] is passed. */
+	char buf[SPT_MAXTITLE + 1];
+	va_list ap;
+	char *nul;
+	int l;
+	size_t len, base_len;
+
+	if (SPT.base == NULL) {
+		if (!SPT.warned) {
+			warnx("setproctitle not initialized, please either call "
+			      "setproctitle_init() or link against libbsd-ctor.");
+			SPT.warned = true;
+		}
+		return;
+	}
+
+	if (fmt) {
+		if (fmt[0] == '-') {
+			/* Skip program name prefix. */
+			fmt++;
+			len = 0;
+		} else {
+			/* Print program name heading for grep. */
+			l = snprintf(buf, sizeof(buf), "%s: ", getprogname());
+			if (l <= 0)
+				return;
+			len = (size_t)l;
+		}
+
+		va_start(ap, fmt);
+		l = vsnprintf(buf + len, sizeof(buf) - len, fmt, ap);
+		va_end(ap);
+	} else {
+		len = 0;
+		l = snprintf(buf, sizeof(buf), "%s", SPT.arg0);
+	}
+
+	if (l <= 0) {
+		SPT.error = errno;
+		return;
+	}
+	len += (size_t)l;
+
+	base_len = (size_t)(SPT.end - SPT.base);
+	if (!SPT.reset) {
+		memset(SPT.base, 0, base_len);
+		SPT.reset = true;
+	} else {
+		memset(SPT.base, 0, spt_min(sizeof(buf), base_len));
+	}
+
+	len = spt_min(len, spt_min(sizeof(buf), base_len) - 1);
+	memcpy(SPT.base, buf, len);
+	nul = &SPT.base[len];
+
+	if (nul < SPT.nul) {
+		*SPT.nul = '.';
+	} else if (nul == SPT.nul && &nul[1] < SPT.end) {
+		*SPT.nul = ' ';
+		*++nul = '\0';
+	}
+}
+libbsd_symver_default(setproctitle, setproctitle_impl, LIBBSD_0.5);
+
+/* The original function introduced in 0.2 was a stub, it only got implemented
+ * in 0.5, make the implementation available in the old version as an alias
+ * for code linking against that version, and change the default to use the
+ * new version, so that new code depends on the implemented version. */
+#ifdef HAVE_TYPEOF
+extern __typeof__(setproctitle_impl)
+setproctitle_stub
+	__attribute__((__alias__("setproctitle_impl")));
+#else
+void
+setproctitle_stub(const char *fmt, ...)
+	__attribute__((__alias__("setproctitle_impl")));
+#endif
+libbsd_symver_variant(setproctitle, setproctitle_stub, LIBBSD_0.2);

compat/setproctitle.h

@@ -32,6 +32,26 @@
 #endif
 #endif /* !__printflike */
 
-__printflike(1, 2) int setproctitle(const char *, ...);
+/* WEXITSTATUS is defined in stdlib.h which defines free() */
-void setproctitle_free(void);
+#ifdef WEXITSTATUS
+static inline const char *
+getprogname(void)
+{
+	return "dhcpcd";
+}
+static inline void
+setprogname(char *name)
+{
+	free(name);
+}
+#endif
+
+void setproctitle_init(int, char *[], char *[]);
+__printflike(1, 2) void setproctitle(const char *, ...);
+void setproctitle_fini(void);
+
+#define libbsd_symver_default(alias, symbol, version) \
+    extern __typeof(symbol) alias __attribute__((__alias__(#symbol)))
+
+#define libbsd_symver_variant(alias, symbol, version)
 #endif

src/dhcpcd.c

@@ -1787,6 +1787,10 @@ main(int argc, char **argv)
 	size_t si;
 #endif
 
+#ifdef SETPROCTITLE_H
+	setproctitle_init(argc, argv, environ);
+#endif
+
 	/* Test for --help and --version */
 	if (argc > 1) {
 		if (strcmp(argv[1], "--help") == 0) {
@@ -2566,7 +2570,7 @@ exit1:
 	free(ctx.logfile);
 	free(ctx.ctl_buf);
 #ifdef SETPROCTITLE_H
-	setproctitle_free();
+	setproctitle_fini();
 #endif
 #ifdef USE_SIGNALS
 	if (ctx.options & DHCPCD_STARTED) {