procps/sysctl.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
  *
  * Copyright 1999 George Staikos
  *
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  *
  * Changelog:
  * v1.01   - added -p <preload> to preload values from a file
  * v1.01.1 - busybox applet aware by <solar@gentoo.org>
  */
 //config:config BB_SYSCTL
 //config:	bool "sysctl (7.4 kb)"
 //config:	default y
 //config:	help
 //config:	Configure kernel parameters at runtime.

 //applet:IF_BB_SYSCTL(APPLET_NOEXEC(sysctl, sysctl, BB_DIR_SBIN, BB_SUID_DROP, sysctl))

 //kbuild:lib-$(CONFIG_BB_SYSCTL) += sysctl.o

 //usage:#define sysctl_trivial_usage
 //usage:       "-p [-enq] [FILE...] / [-enqaw] [KEY[=VALUE]]..."
 //usage:#define sysctl_full_usage "\n\n"
 //usage:       "Show/set kernel parameters\n"
 //usage:     "\n	-p	Set values from FILEs (default /etc/sysctl.conf)"
 //usage:     "\n	-e	Don't warn about unknown keys"
 //usage:     "\n	-n	Don't show key names"
 //usage:     "\n	-q      Quiet"
 //usage:     "\n	-a	Show all values"
 /* Same as -a, no need to show it */
 /* //usage:     "\n	-A	Show all values in table form" */
 //usage:     "\n	-w	Set values"
 //usage:
 //usage:#define sysctl_example_usage
 //usage:       "sysctl [-n] [-e] variable...\n"
 //usage:       "sysctl [-n] [-e] [-q] -w variable=value...\n"
 //usage:       "sysctl [-n] [-e] -a\n"
 //usage:       "sysctl [-n] [-e] [-q] -p file	(default /etc/sysctl.conf)\n"
 //usage:       "sysctl [-n] [-e] -A\n"

 #include "libbb.h"

 enum {
 	FLAG_SHOW_KEYS       = 1 << 0,
 	FLAG_SHOW_KEY_ERRORS = 1 << 1,
 	FLAG_TABLE_FORMAT    = 1 << 2, /* not implemented */
 	FLAG_SHOW_ALL        = 1 << 3,
 	FLAG_PRELOAD_FILE    = 1 << 4,
 	/* NB: procps 3.2.8 does not require -w for KEY=VAL to work, it only rejects non-KEY=VAL form */
 	FLAG_WRITE           = 1 << 5,
 	FLAG_QUIET           = 1 << 6,
 };
 #define OPTION_STR "neAapwq"

 static void sysctl_dots_to_slashes(char *name)
 {
 	char *cptr, *last_good, *end, *slash;
 	char end_ch;

 	end = strchrnul(name, '=');

 	slash = strchrnul(name, '/');
 	if (slash < end
 	 && strchrnul(name, '.') < slash
 	) {
 		/* There are both dots and slashes, and 1st dot is
 		 * before 1st slash.
 		 * (IOW: not raw, unmangled a/b/c.d format)
 		 *
 		 * procps supports this syntax for names with dots:
 		 *  net.ipv4.conf.eth0/100.mc_forwarding
 		 * (dots and slashes are simply swapped)
 		 */
 		while (end != name) {
 			end--;
 			if (*end == '.') *end = '/';
 			else if (*end == '/') *end = '.';
 		}
 		return;
 	}
 	/* else: use our old behavior: */

 	/* Convert minimum number of '.' to '/' so that
 	 * we end up with existing file's name.
 	 *
 	 * Example from bug 3894:
 	 * net.ipv4.conf.eth0.100.mc_forwarding ->
 	 * net/ipv4/conf/eth0.100/mc_forwarding
 	 * NB: net/ipv4/conf/eth0/mc_forwarding *also exists*,
 	 * therefore we must start from the end, and if
 	 * we replaced even one . -> /, start over again,
 	 * but never replace dots before the position
 	 * where last replacement occurred.
 	 *
 	 * Another bug we later had is that
 	 * net.ipv4.conf.eth0.100
 	 * (without .mc_forwarding) was mishandled.
 	 *
 	 * To set up testing: modprobe 8021q; vconfig add eth0 100
 	 */
 	end_ch = *end;
 	*end = '.'; /* trick the loop into trying full name too */

 	last_good = name - 1;
  again:
 	cptr = end;
 	while (cptr > last_good) {
 		if (*cptr == '.') {
 			*cptr = '\0';
 			//bb_error_msg("trying:'%s'", name);
 			if (access(name, F_OK) == 0) {
 				*cptr = '/';
 				//bb_error_msg("replaced:'%s'", name);
 				last_good = cptr;
 				goto again;
 			}
 			*cptr = '.';
 		}
 		cptr--;
 	}
 	*end = end_ch;
 }

 static int sysctl_act_on_setting(char *setting)
 {
 	int fd, retval = EXIT_SUCCESS;
 	char *cptr, *outname;
 	char *value = value; /* for compiler */
 	bool writing = (option_mask32 & FLAG_WRITE);

 	outname = xstrdup(setting);

 	cptr = outname;
 	while (*cptr) {
 		if (*cptr == '/')
 			*cptr = '.';
 		else if (*cptr == '.')
 			*cptr = '/';
 		cptr++;
 	}

 	cptr = strchr(setting, '=');
 	if (cptr)
 		writing = 1;
 	if (writing) {
 		if (!cptr) {
 			bb_error_msg("error: '%s' must be of the form name=value",
 				outname);
 			retval = EXIT_FAILURE;
 			goto end;
 		}
 		value = cptr + 1;  /* point to the value in name=value */
 		if (setting == cptr /* "name" can't be empty */
 		 /* || !*value - WRONG: "sysctl net.ipv4.ip_local_reserved_ports=" is a valid syntax (clears the value) */
 		) {
 			bb_error_msg("error: malformed setting '%s'", outname);
 			retval = EXIT_FAILURE;
 			goto end;
 		}
 		*cptr = '\0';
 		outname[cptr - setting] = '\0';
 		/* procps 3.2.7 actually uses these flags */
 		fd = open(setting, O_WRONLY|O_CREAT|O_TRUNC, 0666);
 	} else {
 		fd = open(setting, O_RDONLY);
 	}

 	if (fd < 0) {
 		switch (errno) {
 		case ENOENT:
 			if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
 				bb_error_msg("error: '%s' is an unknown key", outname);
 			break;
 		case EACCES:
 			/* Happens for write-only settings, e.g. net.ipv6.route.flush */
 			if (!writing)
 				goto end;
 			/* fall through */
 		default:
 			bb_perror_msg("error %sing key '%s'",
 					writing ?
 						"sett" : "read",
 					outname);
 			break;
 		}
 		retval = EXIT_FAILURE;
 		goto end;
 	}

 	if (writing) {
 //TODO: procps 3.2.7 writes "value\n", note trailing "\n"
 		xwrite_str(fd, value);
 		close(fd);
 		if (!(option_mask32 & FLAG_QUIET)) {
 			if (option_mask32 & FLAG_SHOW_KEYS)
 				printf("%s = ", outname);
 			puts(value);
 		}
 	} else {
 		char c;

 		value = cptr = xmalloc_read(fd, NULL);
 		close(fd);
 		if (value == NULL) {
 			bb_perror_msg("error reading key '%s'", outname);
 			retval = EXIT_FAILURE;
 			goto end;
 		}

 		/* dev.cdrom.info and sunrpc.transports, for example,
 		 * are multi-line. Try "sysctl sunrpc.transports"
 		 */
 		while ((c = *cptr) != '\0') {
 			if (option_mask32 & FLAG_SHOW_KEYS)
 				printf("%s = ", outname);
 			while (1) {
 				fputc(c, stdout);
 				cptr++;
 				if (c == '\n')
 					break;
 				c = *cptr;
 				if (c == '\0')
 					break;
 			}
 		}
 		free(value);
 	}
  end:
 	free(outname);
 	return retval;
 }

 static int sysctl_act_recursive(const char *path)
 {
 	struct stat buf;
 	int retval = 0;

 	if (!(option_mask32 & FLAG_WRITE)
 	 && !strchr(path, '=')  /* do not try to resurse on "var=val" */
 	 && stat(path, &buf) == 0
 	 && S_ISDIR(buf.st_mode)
 	) {
 		struct dirent *entry;
 		DIR *dirp;

 		dirp = opendir(path);
 		if (dirp == NULL)
 			return -1;
 		while ((entry = readdir(dirp)) != NULL) {
 			char *next = concat_subpath_file(path, entry->d_name);
 			if (next == NULL)
 				continue; /* d_name is "." or ".." */
 			/* if path was ".", drop "./" prefix: */
 			retval |= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
 					next + 2 : next);
 			free(next);
 		}
 		closedir(dirp);
 	} else {
 		char *name = xstrdup(path);
 		retval |= sysctl_act_on_setting(name);
 		free(name);
 	}

 	return retval;
 }

 /* Set sysctl's from a conf file. Format example:
  * # Controls IP packet forwarding
  * net.ipv4.ip_forward = 0
  */
 static int sysctl_handle_preload_file(const char *filename)
 {
 	char *token[2];
 	parser_t *parser;
 	int parse_flags;

 	parser = config_open(filename);
 	/* Must do it _after_ config_open(): */
 	xchdir("/proc/sys");

 	parse_flags = 0;
 	parse_flags &= ~PARSE_COLLAPSE;   // NO (var==val is not var=val) - treat consecutive delimiters as one
 	parse_flags &= ~PARSE_TRIM;       // NO - trim leading and trailing delimiters
 	parse_flags |= PARSE_GREEDY;      // YES - last token takes entire remainder of the line
 	parse_flags &= ~PARSE_MIN_DIE;    // NO - die if < min tokens found
 	parse_flags &= ~PARSE_EOL_COMMENTS; // NO (only first char) - comments are recognized even if not first char
 	parse_flags |= PARSE_ALT_COMMENTS;// YES - two comment chars: ';' and '#'
 	/* <space><tab><space>#comment is also comment, not strictly 1st char only */
 	parse_flags |= PARSE_WS_COMMENTS; // YES - comments are recognized even if there is whitespace before
 	while (config_read(parser, token, 2, 2, ";#=", parse_flags)) {
 		char *tp;

 		trim(token[1]);
 		tp = trim(token[0]);
 		sysctl_dots_to_slashes(token[0]);
 		/* ^^^converted in-place. tp still points to NUL */
 		/* now, add "=TOKEN1" */
 		*tp++ = '=';
 		overlapping_strcpy(tp, token[1]);

 		sysctl_act_on_setting(token[0]);
 	}
 	if (ENABLE_FEATURE_CLEAN_UP)
 		config_close(parser);
 	return 0;
 }

 int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int sysctl_main(int argc UNUSED_PARAM, char **argv)
 {
 	int retval;
 	int opt;

 	opt = getopt32(argv, "+" OPTION_STR); /* '+' - stop on first non-option */
 	argv += optind;
 	opt ^= (FLAG_SHOW_KEYS | FLAG_SHOW_KEY_ERRORS);
 	option_mask32 = opt;

 	if (opt & FLAG_PRELOAD_FILE) {
 		int cur_dir_fd;
 		option_mask32 |= FLAG_WRITE;
 		if (!*argv)
 			*--argv = (char*)"/etc/sysctl.conf";
 		cur_dir_fd = xopen(".", O_RDONLY | O_DIRECTORY);
 		do {
 			/* xchdir("/proc/sys") is inside */
 			sysctl_handle_preload_file(*argv);
 			xfchdir(cur_dir_fd); /* files can be relative, must restore cwd */
 		} while (*++argv);
 		return 0; /* procps-ng 3.3.10 does not flag parse errors */
 	}
 	xchdir("/proc/sys");
 	if (opt & (FLAG_TABLE_FORMAT | FLAG_SHOW_ALL)) {
 		return sysctl_act_recursive(".");
 	}

 //TODO: if(!argv[0]) bb_show_usage() ?

 	retval = 0;
 	while (*argv) {
 		sysctl_dots_to_slashes(*argv);
 		retval |= sysctl_act_recursive(*argv);
 		argv++;
 	}

 	return retval;
 }
	/* vi: set sw=4 ts=4: */
	/*
	* Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
	*
	* Copyright 1999 George Staikos
	*
	* Licensed under GPLv2 or later, see file LICENSE in this source tree.
	*
	* Changelog:
	* v1.01 - added -p <preload> to preload values from a file
	* v1.01.1 - busybox applet aware by <solar@gentoo.org>
	*/
	//config:config BB_SYSCTL
	//config: bool "sysctl (7.4 kb)"
	//config: default y
	//config: help
	//config: Configure kernel parameters at runtime.

	//applet:IF_BB_SYSCTL(APPLET_NOEXEC(sysctl, sysctl, BB_DIR_SBIN, BB_SUID_DROP, sysctl))

	//kbuild:lib-$(CONFIG_BB_SYSCTL) += sysctl.o

	//usage:#define sysctl_trivial_usage
	//usage: "-p [-enq] [FILE...] / [-enqaw] [KEY[=VALUE]]..."
	//usage:#define sysctl_full_usage "\n\n"
	//usage: "Show/set kernel parameters\n"
	//usage: "\n -p Set values from FILEs (default /etc/sysctl.conf)"
	//usage: "\n -e Don't warn about unknown keys"
	//usage: "\n -n Don't show key names"
	//usage: "\n -q Quiet"
	//usage: "\n -a Show all values"
	/* Same as -a, no need to show it */
	/* //usage: "\n -A Show all values in table form" */
	//usage: "\n -w Set values"
	//usage:
	//usage:#define sysctl_example_usage
	//usage: "sysctl [-n] [-e] variable...\n"
	//usage: "sysctl [-n] [-e] [-q] -w variable=value...\n"
	//usage: "sysctl [-n] [-e] -a\n"
	//usage: "sysctl [-n] [-e] [-q] -p file (default /etc/sysctl.conf)\n"
	//usage: "sysctl [-n] [-e] -A\n"

	#include "libbb.h"

	enum {
	FLAG_SHOW_KEYS = 1 << 0,
	FLAG_SHOW_KEY_ERRORS = 1 << 1,
	FLAG_TABLE_FORMAT = 1 << 2, /* not implemented */
	FLAG_SHOW_ALL = 1 << 3,
	FLAG_PRELOAD_FILE = 1 << 4,
	/* NB: procps 3.2.8 does not require -w for KEY=VAL to work, it only rejects non-KEY=VAL form */
	FLAG_WRITE = 1 << 5,
	FLAG_QUIET = 1 << 6,
	};
	#define OPTION_STR "neAapwq"

	static void sysctl_dots_to_slashes(char *name)
	{
	char cptr, last_good, end, slash;
	char end_ch;

	end = strchrnul(name, '=');

	slash = strchrnul(name, '/');
	if (slash < end
	&& strchrnul(name, '.') < slash
	) {
	/* There are both dots and slashes, and 1st dot is
	* before 1st slash.
	* (IOW: not raw, unmangled a/b/c.d format)
	*
	* procps supports this syntax for names with dots:
	* net.ipv4.conf.eth0/100.mc_forwarding
	* (dots and slashes are simply swapped)
	*/
	while (end != name) {
	end--;
	if (end == '.') end = '/';
	else if (end == '/') end = '.';
	}
	return;
	}
	/* else: use our old behavior: */

	/* Convert minimum number of '.' to '/' so that
	* we end up with existing file's name.
	*
	* Example from bug 3894:
	* net.ipv4.conf.eth0.100.mc_forwarding ->
	* net/ipv4/conf/eth0.100/mc_forwarding
	* NB: net/ipv4/conf/eth0/mc_forwarding also exists,
	* therefore we must start from the end, and if
	* we replaced even one . -> /, start over again,
	* but never replace dots before the position
	* where last replacement occurred.
	*
	* Another bug we later had is that
	* net.ipv4.conf.eth0.100
	* (without .mc_forwarding) was mishandled.
	*
	* To set up testing: modprobe 8021q; vconfig add eth0 100
	*/
	end_ch = *end;
	end = '.'; / trick the loop into trying full name too */

	last_good = name - 1;
	again:
	cptr = end;
	while (cptr > last_good) {
	if (*cptr == '.') {
	*cptr = '\0';
	//bb_error_msg("trying:'%s'", name);
	if (access(name, F_OK) == 0) {
	*cptr = '/';
	//bb_error_msg("replaced:'%s'", name);
	last_good = cptr;
	goto again;
	}
	*cptr = '.';
	}
	cptr--;
	}
	*end = end_ch;
	}

	static int sysctl_act_on_setting(char *setting)
	{
	int fd, retval = EXIT_SUCCESS;
	char cptr, outname;
	char value = value; / for compiler */
	bool writing = (option_mask32 & FLAG_WRITE);

	outname = xstrdup(setting);

	cptr = outname;
	while (*cptr) {
	if (*cptr == '/')
	*cptr = '.';
	else if (*cptr == '.')
	*cptr = '/';
	cptr++;
	}

	cptr = strchr(setting, '=');
	if (cptr)
	writing = 1;
	if (writing) {
	if (!cptr) {
	bb_error_msg("error: '%s' must be of the form name=value",
	outname);
	retval = EXIT_FAILURE;
	goto end;
	}
	value = cptr + 1; /* point to the value in name=value */
	if (setting == cptr /* "name" can't be empty */
	/* \|\| !value - WRONG: "sysctl net.ipv4.ip_local_reserved_ports=" is a valid syntax (clears the value) /
	) {
	bb_error_msg("error: malformed setting '%s'", outname);
	retval = EXIT_FAILURE;
	goto end;
	}
	*cptr = '\0';
	outname[cptr - setting] = '\0';
	/* procps 3.2.7 actually uses these flags */
	fd = open(setting, O_WRONLY\|O_CREAT\|O_TRUNC, 0666);
	} else {
	fd = open(setting, O_RDONLY);
	}

	if (fd < 0) {
	switch (errno) {
	case ENOENT:
	if (option_mask32 & FLAG_SHOW_KEY_ERRORS)
	bb_error_msg("error: '%s' is an unknown key", outname);
	break;
	case EACCES:
	/* Happens for write-only settings, e.g. net.ipv6.route.flush */
	if (!writing)
	goto end;
	/* fall through */
	default:
	bb_perror_msg("error %sing key '%s'",
	writing ?
	"sett" : "read",
	outname);
	break;
	}
	retval = EXIT_FAILURE;
	goto end;
	}

	if (writing) {
	//TODO: procps 3.2.7 writes "value\n", note trailing "\n"
	xwrite_str(fd, value);
	close(fd);
	if (!(option_mask32 & FLAG_QUIET)) {
	if (option_mask32 & FLAG_SHOW_KEYS)
	printf("%s = ", outname);
	puts(value);
	}
	} else {
	char c;

	value = cptr = xmalloc_read(fd, NULL);
	close(fd);
	if (value == NULL) {
	bb_perror_msg("error reading key '%s'", outname);
	retval = EXIT_FAILURE;
	goto end;
	}

	/* dev.cdrom.info and sunrpc.transports, for example,
	* are multi-line. Try "sysctl sunrpc.transports"
	*/
	while ((c = *cptr) != '\0') {
	if (option_mask32 & FLAG_SHOW_KEYS)
	printf("%s = ", outname);
	while (1) {
	fputc(c, stdout);
	cptr++;
	if (c == '\n')
	break;
	c = *cptr;
	if (c == '\0')
	break;
	}
	}
	free(value);
	}
	end:
	free(outname);
	return retval;
	}

	static int sysctl_act_recursive(const char *path)
	{
	struct stat buf;
	int retval = 0;

	if (!(option_mask32 & FLAG_WRITE)
	&& !strchr(path, '=') /* do not try to resurse on "var=val" */
	&& stat(path, &buf) == 0
	&& S_ISDIR(buf.st_mode)
	) {
	struct dirent *entry;
	DIR *dirp;

	dirp = opendir(path);
	if (dirp == NULL)
	return -1;
	while ((entry = readdir(dirp)) != NULL) {
	char *next = concat_subpath_file(path, entry->d_name);
	if (next == NULL)
	continue; /* d_name is "." or ".." */
	/* if path was ".", drop "./" prefix: */
	retval \|= sysctl_act_recursive((next[0] == '.' && next[1] == '/') ?
	next + 2 : next);
	free(next);
	}
	closedir(dirp);
	} else {
	char *name = xstrdup(path);
	retval \|= sysctl_act_on_setting(name);
	free(name);
	}

	return retval;
	}

	/* Set sysctl's from a conf file. Format example:
	* # Controls IP packet forwarding
	* net.ipv4.ip_forward = 0
	*/
	static int sysctl_handle_preload_file(const char *filename)
	{
	char *token[2];
	parser_t *parser;
	int parse_flags;

	parser = config_open(filename);
	/* Must do it _after_ config_open(): */
	xchdir("/proc/sys");

	parse_flags = 0;
	parse_flags &= ~PARSE_COLLAPSE; // NO (var==val is not var=val) - treat consecutive delimiters as one
	parse_flags &= ~PARSE_TRIM; // NO - trim leading and trailing delimiters
	parse_flags \|= PARSE_GREEDY; // YES - last token takes entire remainder of the line
	parse_flags &= ~PARSE_MIN_DIE; // NO - die if < min tokens found
	parse_flags &= ~PARSE_EOL_COMMENTS; // NO (only first char) - comments are recognized even if not first char
	parse_flags \|= PARSE_ALT_COMMENTS;// YES - two comment chars: ';' and '#'
	/* <space><tab><space>#comment is also comment, not strictly 1st char only */
	parse_flags \|= PARSE_WS_COMMENTS; // YES - comments are recognized even if there is whitespace before
	while (config_read(parser, token, 2, 2, ";#=", parse_flags)) {
	char *tp;

	trim(token[1]);
	tp = trim(token[0]);
	sysctl_dots_to_slashes(token[0]);
	/* ^^^converted in-place. tp still points to NUL */
	/* now, add "=TOKEN1" */
	*tp++ = '=';
	overlapping_strcpy(tp, token[1]);

	sysctl_act_on_setting(token[0]);
	}
	if (ENABLE_FEATURE_CLEAN_UP)
	config_close(parser);
	return 0;
	}

	int sysctl_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
	int sysctl_main(int argc UNUSED_PARAM, char **argv)
	{
	int retval;
	int opt;

	opt = getopt32(argv, "+" OPTION_STR); /* '+' - stop on first non-option */
	argv += optind;
	opt ^= (FLAG_SHOW_KEYS \| FLAG_SHOW_KEY_ERRORS);
	option_mask32 = opt;

	if (opt & FLAG_PRELOAD_FILE) {
	int cur_dir_fd;
	option_mask32 \|= FLAG_WRITE;
	if (!*argv)
	--argv = (char)"/etc/sysctl.conf";
	cur_dir_fd = xopen(".", O_RDONLY \| O_DIRECTORY);
	do {
	/* xchdir("/proc/sys") is inside */
	sysctl_handle_preload_file(*argv);
	xfchdir(cur_dir_fd); /* files can be relative, must restore cwd */
	} while (*++argv);
	return 0; /* procps-ng 3.3.10 does not flag parse errors */
	}
	xchdir("/proc/sys");
	if (opt & (FLAG_TABLE_FORMAT \| FLAG_SHOW_ALL)) {
	return sysctl_act_recursive(".");
	}

	//TODO: if(!argv[0]) bb_show_usage() ?

	retval = 0;
	while (*argv) {
	sysctl_dots_to_slashes(*argv);
	retval \|= sysctl_act_recursive(*argv);
	argv++;
	}

	return retval;
	}