Add limit subcommand

.gitignore

@@ -5,5 +5,6 @@
 *.dylib
 launchctl
 a.out
+*.dSYM
 
 compile_commands.json

Makefile

@@ -3,7 +3,7 @@ DESTDIR ?=
 
 SRC    := launchctl.c xpc_helper.c start_stop.c print.c env.c load.c manager.c
 SRC    += enable.c reboot.c bootstrap.c error.c remove.c kickstart.c kill.c blame.c
-SRC    += attach.c plist.c runstats.c userswitch.c
+SRC    += attach.c plist.c runstats.c userswitch.c limit.c
 LDLIBS := 
 
 all: launchctl

TODO.md

@@ -14,7 +14,7 @@
 1. [ ] procinfo
 1. [ ] hostinfo
 1. [ ] resolveport
-1. [ ] limit
+1. [x] limit
 1. [x] runstats
 1. [x] examine
 1. [x] config

launchctl.c

@@ -74,7 +74,7 @@ static const struct {
 	{ "procinfo", "Prints port information about a process.", "<pid>", todo_cmd },
 	{ "hostinfo", "Prints port information about the host.", NULL, todo_cmd },
 	{ "resolveport", "Resolves a port name from a process to an endpoint in launchd.", "<owner-pid> <port-name>", todo_cmd },
-	{ "limit", "Reads or modifies launchd's resource limits.", "[<limit-name> [<both-limits> | <soft-limit> <hard-limit>]", todo_cmd },
+	{ "limit", "Reads or modifies launchd's resource limits.", "[<limit-name> [<both-limits> | <soft-limit> <hard-limit>]", limit_cmd },
 	{ "runstats", "Prints performance statistics for a service.", "<service-target>", runstats_cmd },
 	{ "examine", "Runs the specified analysis tool against launchd in a non-reentrant manner.", "[<tool> [arg0, arg1, ... , @PID, ...]]", examine_cmd },
 	{ "config", "Modifies persistent configuration parameters for launchd domains.", NULL, config_cmd },

launchctl.h

@@ -105,6 +105,9 @@ cmd_main runstats_cmd;
 // userswitch.c
 cmd_main userswitch_cmd;
 
+// limit.c
+cmd_main limit_cmd;
+
 void launchctl_xpc_object_print(xpc_object_t, const char *name, int level);
 int launchctl_send_xpc_to_launchd(uint64_t routine, xpc_object_t msg, xpc_object_t *reply);
 void launchctl_setup_xpc_dict(xpc_object_t dict);

limit.c

@@ -0,0 +1,151 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2023 Procursus Team <[email protected]>
+ * 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.
+ *
+ * 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 HOLDER 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 <errno.h>
+
+#include <xpc/xpc.h>
+#include "xpc_private.h"
+
+#include "launchctl.h"
+
+static int64_t
+limit_index(const char *name)
+{
+	const char *limitnames[9] = {
+		"cpu",
+		"filesize",
+		"data",
+		"stack",
+		"core",
+		"rss",
+		"memlock",
+		"maxproc",
+		"maxfiles"
+	};
+	for (int i = 0; i < (sizeof(limitnames) / sizeof(limitnames[0])); i++) {
+		if (strcmp(name, limitnames[i]) == 0) {
+			return i;
+		}
+	}
+	return -1;
+}
+
+static long long
+parse_limit(const char *name)
+{
+	long long num;
+	char *end;
+
+	if (strcmp(name, "unlimited") == 0) {
+		errno = 0;
+		return -1;
+	}
+
+	num = strtoll(name, &end, 0);
+
+	if (end[0] != '\0') {
+		errno = EINVAL;
+		return -1;
+	}
+
+	return num;
+}
+
+int
+limit_cmd(xpc_object_t *msg, int argc, char **argv, char **envp, char **apple)
+{
+	if (argc > 4)
+		return EUSAGE;
+
+	xpc_object_t dict, reply;
+	int err = 0;
+	vm_address_t addr;
+	vm_size_t sz = 0x100000;
+	long long softlimit, hardlimit, idx;
+
+	dict = xpc_dictionary_create(NULL, NULL, 0);
+	*msg = dict;
+
+	launchctl_setup_xpc_dict_for_service_name("system", dict, NULL);
+
+	if (argc < 2) {
+printlimits:
+		xpc_dictionary_set_bool(dict, "print", true);
+
+		if (__isPlatformVersionAtLeast(2, 15, 0, 0)) {
+			addr = launchctl_create_shmem(dict, sz);
+		} else {
+			xpc_dictionary_set_fd(dict, "file", STDOUT_FILENO);
+		}
+
+		err = launchctl_send_xpc_to_launchd(XPC_ROUTINE_LIMIT, dict, &reply);
+		if (err != 0) {
+			fprintf(stderr, "Could not print resource limits: %d: %s\n", err, xpc_strerror(err));
+		}
+
+		if (__isPlatformVersionAtLeast(2, 15, 0, 0)) {
+			launchctl_print_shmem(reply, addr, sz, stdout);
+			vm_deallocate(mach_task_self(), addr, sz);
+		}
+	} else {
+		if ((idx = limit_index(argv[1])) == -1) {
+			fprintf(stderr, "%s is not a valid limit name.\n", argv[1]);
+			return EUSAGE;
+		}
+
+		xpc_dictionary_set_int64(dict, "which", idx);
+
+		if (argc < 3) {
+			goto printlimits;
+		}
+
+		softlimit = parse_limit(argv[2]);
+		if (softlimit == -1 && errno != 0) {
+			fprintf(stderr, "%s is not a valid limit.\n", argv[2]);
+			return EUSAGE;
+		}
+		hardlimit = softlimit;
+
+		if (argc > 3) {
+			hardlimit = parse_limit(argv[3]);
+			if (hardlimit == -1 && errno != 0) {
+				fprintf(stderr, "%s is not a valid limit.\n", argv[3]);
+				return EUSAGE;
+			}
+		}
+
+		xpc_dictionary_set_int64(dict, "softlimit", softlimit);
+		xpc_dictionary_set_int64(dict, "hardlimit", hardlimit);
+
+		err = launchctl_send_xpc_to_launchd(XPC_ROUTINE_LIMIT, dict, &reply);
+		if (err != 0) {
+			fprintf(stderr, "Could not set resource limits: %d: %s\n", err, xpc_strerror(err));
+		}
+	}
+
+	return err;
+}

xpc_helper.c

@@ -1,7 +1,7 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
- * Copyright (c) 2022 Procursus Team <[email protected]>
+ * Copyright (c) 2022-2023 Procursus Team <[email protected]>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -132,7 +132,9 @@ launchctl_setup_xpc_dict(xpc_object_t dict)
 int
 launchctl_setup_xpc_dict_for_service_name(char *servicetarget, xpc_object_t dict, const char **name)
 {
-	*name = NULL;
+	if (name != NULL) {
+		*name = NULL;
+	}
 	const char *split[3] = {NULL, NULL, NULL};
 	for (int i = 0; i < 3; i++) {
 		char *var = strsep(&servicetarget, "/");
@@ -147,7 +149,9 @@ launchctl_setup_xpc_dict_for_service_name(char *servicetarget, xpc_object_t dict
 		xpc_dictionary_set_uint64(dict, "handle", 0);
 		if (split[1] != NULL && split[1][0] != '\0') {
 			xpc_dictionary_set_string(dict, "name", split[1]);
-			*name = split[1];
+			if (name != NULL) {
+				*name = split[1];
+			}
 		}
 		return 0;
 	} else if (strcmp(split[0], "user") == 0) {
@@ -164,7 +168,9 @@ launchctl_setup_xpc_dict_for_service_name(char *servicetarget, xpc_object_t dict
 		xpc_dictionary_set_uint64(dict, "handle", handle);
 		if (split[2] != NULL && split[2][0] != '\0') {
 			xpc_dictionary_set_string(dict, "name", split[2]);
-			*name = split[2];
+			if (name != NULL) {
+				*name = split[2];
+			}
 		}
 		return 0;
 	}

xpc_private.h

@@ -1,7 +1,7 @@
 /*-
  * SPDX-License-Identifier: BSD-2-Clause
  *
- * Copyright (c) 2022 Procursus Team <[email protected]>
+ * Copyright (c) 2022-2023 Procursus Team <[email protected]>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -50,6 +50,7 @@ enum {
 	XPC_ROUTINE_REMOVE = 816,
 	XPC_ROUTINE_SETENV = 819,
 	XPC_ROUTINE_GETENV = 820,
+	XPC_ROUTINE_LIMIT = 825,
 	XPC_ROUTINE_EXAMINE = 826,
 	XPC_ROUTINE_PRINT = 828,
 	XPC_ROUTINE_DUMPSTATE = 834,