/*
 * Sysctl 1.01 - A utility to read and manipulate the sysctl parameters
 *
 * "Copyright 1999 George Staikos
 * This file may be used subject to the terms and conditions of the GNU
 * General Public License Version 2, or any later version at your option, as
 * published by the Free Software Foundation.  This program is distributed in
 * the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 * PURPOSE.  See the GNU General Public License for more details."
 *
 * Changelog:
 *            v1.01:
 *                   - added -p <preload> to preload values from a file
 *            Horms:
 *                   - added -q to be quiet when modifying values
 *
 * Changes by Albert Cahalan, 2002.
 */

#include <dirent.h>
#include <errno.h>
#include <getopt.h>
#include <libgen.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "c.h"
#include "nls.h"
#include "xalloc.h"
#include "proc/procps.h"
#include "proc/version.h"

/* Proof that C++ causes brain damage: */
typedef int bool;
static bool true  = 1;
static bool false = 0;

/*
 *    Globals...
 */
static const char PROC_PATH[] = "/proc/sys/";
static const char DEFAULT_PRELOAD[] = "/etc/sysctl.conf";
static bool NameOnly;
static bool PrintName;
static bool PrintNewline;
static bool IgnoreError;
static bool Quiet;
static char *pattern;

/* Function prototypes. */
static int pattern_match(const char *string, const char *pattern);
static int DisplayAll(const char *restrict const path);

static void slashdot(char *restrict p, char old, char new)
{
	int warned = 1;
	p = strpbrk(p, "/.");
	if (!p)
		/* nothing -- can't be, but oh well */
		return;
	if (*p == new)
		/* already in desired format */
		return;
	while (p) {
		char c = *p;
		if ((*(p + 1) == '/' || *(p + 1) == '.') && warned) {
			xwarnx(_("separators should not be repeated: %s"), p);
			warned = 0;
		}
		if (c == old)
			*p = new;
		if (c == new)
			*p = old;
		p = strpbrk(p + 1, "/.");
	}
}

/*
 * Display the usage format
 */
static void __attribute__ ((__noreturn__))
    Usage(FILE * out)
{
	fputs(USAGE_HEADER, out);
	fprintf(out,
	      _(" %s [options] [variable[=value] ...]\n"),
		program_invocation_short_name);
	fputs(USAGE_OPTIONS, out);
	fputs(_("  -a, --all            display all variables\n"
		"  -A                   alias of -a\n"
		"  -X                   alias of -a\n"
		"  -b, --binary         print value without new line\n"
		"  -e, --ignore         ignore unknown variables errors\n"
		"  -N, --names          print variable names without values\n"
		"  -n, --values         print only values of a variables\n"
		"  -p, --load[=<file>]  read values from file\n"
		"  -f                   alias of -p\n"
		"      --system         read values from all system directories\n"
		"  -r, --pattern <expression>\n"
		"                       select setting that match expression\n"
		"  -q, --quiet          do not echo variable set\n"
		"  -w, --write          enable writing a value to variable\n"
		"  -o                   does nothing\n"
		"  -x                   does nothing\n"
		"  -d                   alias of -h\n"), out);
	fputs(USAGE_SEPARATOR, out);
	fputs(USAGE_HELP, out);
	fputs(USAGE_VERSION, out);
	fprintf(out, USAGE_MAN_TAIL("sysctl(8)"));

	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}

/*
 * Strip the leading and trailing spaces from a string
 */
static char *StripLeadingAndTrailingSpaces(char *oneline)
{
	char *t;

	if (!oneline || !*oneline)
		return oneline;

	t = oneline;
	t += strlen(oneline) - 1;

	while ((*t == ' ' || *t == '\t' || *t == '\n' || *t == '\r') && t != oneline)
		*t-- = 0;

	t = oneline;

	while ((*t == ' ' || *t == '\t') && *t != 0)
		t++;

	return t;
}

/*
 * Read a sysctl setting
 */
static int ReadSetting(const char *restrict const name)
{
	int rc = 0;
	char *restrict tmpname;
	char *restrict outname;
	char inbuf[1025];
	FILE *restrict fp;
	struct stat ts;

	if (!name || !*name) {
		xwarnx(_("\"%s\" is an unknown key"), name);
		return -1;
	}

	/* used to display the output */
	outname = xstrdup(name);
	/* change / to . */
	slashdot(outname, '/', '.');

	/* used to open the file */
	tmpname = xmalloc(strlen(name) + strlen(PROC_PATH) + 2);
	strcpy(tmpname, PROC_PATH);
	strcat(tmpname, name);
	/* change . to / */
	slashdot(tmpname + strlen(PROC_PATH), '.', '/');

	/* used to display the output */
	outname = xstrdup(name);
	/* change / to . */
	slashdot(outname, '/', '.');

	if (stat(tmpname, &ts) < 0) {
		if (!IgnoreError) {
			xwarn(_("cannot stat %s"), tmpname);
			rc = -1;
		}
		goto out;
	}
	if ((ts.st_mode & S_IRUSR) == 0)
		goto out;

	if (S_ISDIR(ts.st_mode)) {
		size_t len;
		len = strlen(tmpname);
		tmpname[len] = '/';
		tmpname[len + 1] = '\0';
		rc = DisplayAll(tmpname);
		goto out;
	}

	if (pattern && !pattern_match(outname, pattern)) {
		free(outname);
		return 0;
	}

	fp = fopen(tmpname, "r");

	if (!fp) {
		switch (errno) {
		case ENOENT:
			if (!IgnoreError) {
				xwarnx(_("\"%s\" is an unknown key"), outname);
				rc = -1;
			}
			break;
		case EACCES:
			xwarnx(_("permission denied on key '%s'"), outname);
			rc = -1;
			break;
		default:
			xwarn(_("reading key \"%s\""), outname);
			rc = -1;
			break;
		}
	} else {
		errno = 0;
		if (fgets(inbuf, sizeof inbuf - 1, fp)) {
			/* this loop is required, see
			 * /sbin/sysctl -a | egrep -6 dev.cdrom.info
			 */
			do {
				if (NameOnly) {
					fprintf(stdout, "%s\n", outname);
				} else {
					/* already has the \n in it */
					if (PrintName) {
						fprintf(stdout, "%s = %s",
							outname, inbuf);
					} else {
						if (!PrintNewline) {
							char *nlptr =
							    strchr(inbuf, '\n');
							if (nlptr)
								*nlptr = '\0';
						}
						fprintf(stdout, "%s", inbuf);
					}
				}
			} while (fgets(inbuf, sizeof inbuf - 1, fp));
		} else {
			switch (errno) {
			case EACCES:
				xwarnx(_("permission denied on key '%s'"),
				       outname);
				rc = -1;
				break;
			case EISDIR: {
					size_t len;
					len = strlen(tmpname);
					tmpname[len] = '/';
					tmpname[len + 1] = '\0';
					fclose(fp);
					rc = DisplayAll(tmpname);
					goto out;
				}
			default:
				xwarnx(_("reading key \"%s\""), outname);
				rc = -1;
			case 0:
				break;
			}
		}
		fclose(fp);
	}
      out:
	free(tmpname);
	free(outname);
	return rc;
}

/*
 * Display all the sysctl settings
 */
static int DisplayAll(const char *restrict const path)
{
	int rc = 0;
	int rc2;
	DIR *restrict dp;
	struct dirent *restrict de;
	struct stat ts;

	dp = opendir(path);

	if (!dp) {
		xwarnx(_("unable to open directory \"%s\""), path);
		rc = -1;
	} else {
		readdir(dp);	/* skip .  */
		readdir(dp);	/* skip .. */
		while ((de = readdir(dp))) {
			char *restrict tmpdir;
			tmpdir =
			    (char *restrict) xmalloc(strlen(path) +
						     strlen(de->d_name) +
						     2);
			sprintf(tmpdir, "%s%s", path, de->d_name);
			rc2 = stat(tmpdir, &ts);
			if (rc2 != 0) {
				xwarn(_("cannot stat %s"), tmpdir);
			} else {
				if (S_ISDIR(ts.st_mode)) {
					strcat(tmpdir, "/");
					DisplayAll(tmpdir);
				} else {
					rc |=
					    ReadSetting(tmpdir +
							strlen(PROC_PATH));
				}
			}
			free(tmpdir);
		}
		closedir(dp);
	}
	return rc;
}

/*
 * Write a sysctl setting
 */
static int WriteSetting(const char *setting)
{
	int rc = 0;
	const char *name = setting;
	const char *value;
	const char *equals;
	char *tmpname;
	char *outname;
	FILE *fp;
	struct stat ts;

	if (!name)
		/* probably don't want to display this err */
		return 0;

	equals = strchr(setting, '=');

	if (!equals) {
		xwarnx(_("\"%s\" must be of the form name=value"),
		       setting);
		return -1;
	}

	/* point to the value in name=value */
	value = equals + 1;

	if (!*name || !*value || name == equals) {
		xwarnx(_("malformed setting \"%s\""), setting);
		return -2;
	}

	/* used to open the file */
	tmpname = xmalloc(equals - name + 1 + strlen(PROC_PATH));
	strcpy(tmpname, PROC_PATH);
	strncat(tmpname, name, (int) (equals - name));
	tmpname[equals - name + strlen(PROC_PATH)] = 0;
	/* change . to / */
	slashdot(tmpname + strlen(PROC_PATH), '.', '/');

	/* used to display the output */
	outname = xmalloc(equals - name + 1);
	strncpy(outname, name, (int) (equals - name));
	outname[equals - name] = 0;
	/* change / to . */
	slashdot(outname, '/', '.');

	if (stat(tmpname, &ts) < 0) {
		if (!IgnoreError) {
			xwarn(_("cannot stat %s"), tmpname);
			rc = -1;
		}
		goto out;
	}

	if ((ts.st_mode & S_IWUSR) == 0) {
		xwarn(_("setting key \"%s\""), outname);
		goto out;
	}

	if (S_ISDIR(ts.st_mode)) {
		xwarn(_("setting key \"%s\""), outname);
		goto out;
	}

	fp = fopen(tmpname, "w");

	if (!fp) {
		switch (errno) {
		case ENOENT:
			if (!IgnoreError) {
				xwarnx(_("\"%s\" is an unknown key"), outname);
				rc = -1;
			}
			break;
		case EACCES:
			xwarnx(_("permission denied on key '%s'"), outname);
			rc = -1;
			break;
		default:
			xwarn(_("setting key \"%s\""), outname);
			rc = -1;
			break;
		}
	} else {
		rc = fprintf(fp, "%s\n", value);
		if (rc < 0) {
			xwarn(_("setting key \"%s\""), outname);
			fclose(fp);
		} else {
			rc = fclose(fp);
			if (rc != 0)
				xwarn(_("setting key \"%s\""), outname);
		}
		if (rc == 0 && !Quiet) {
			if (NameOnly) {
				fprintf(stdout, "%s\n", outname);
			} else {
				if (PrintName) {
					fprintf(stdout, "%s = %s\n",
						outname, value);
				} else {
					if (PrintNewline)
						fprintf(stdout, "%s\n", value);
					else
						fprintf(stdout, "%s", value);
				}
			}
		}
	}
      out:
	free(tmpname);
	free(outname);
	return rc;
}

static int pattern_match(const char *string, const char *pattern)
{
	int status;
	regex_t re;

	if (regcomp(&re, pattern, REG_EXTENDED | REG_NOSUB) != 0)
		return (0);
	status = regexec(&re, string, (size_t) 0, NULL, 0);
	regfree(&re);
	if (status != 0)
		return (0);
	return (1);
}

/*
 * Preload the sysctl's from the conf file.  We parse the file and then
 * reform it (strip out whitespace).
 */
static int Preload(const char *restrict const filename)
{
	char oneline[256];
	char buffer[256];
	FILE *fp;
	char *t;
	int n = 0;
	int rc = 0;
	char *name, *value;

	fp = (filename[0] == '-' && !filename[1])
	    ? stdin : fopen(filename, "r");

	if (!fp) {
		xwarn(_("cannot open \"%s\""), filename);
		return -1;
	}

	while (fgets(oneline, sizeof oneline, fp)) {
		n++;
		t = StripLeadingAndTrailingSpaces(oneline);

		if (strlen(t) < 2)
			continue;

		if (*t == '#' || *t == ';')
			continue;

		name = strtok(t, "=");
		if (!name || !*name) {
			xwarnx(_("%s(%d): invalid syntax, continuing..."),
			       filename, n);
			continue;
		}

		StripLeadingAndTrailingSpaces(name);

		if (pattern && !pattern_match(name, pattern))
			continue;

		value = strtok(NULL, "\n\r");
		if (!value || !*value) {
			xwarnx(_("%s(%d): invalid syntax, continuing..."),
			       filename, n);
			continue;
		}

		while ((*value == ' ' || *value == '\t') && *value != 0)
			value++;

		/* should NameOnly affect this? */
		sprintf(buffer, "%s=%s", name, value);
		rc |= WriteSetting(buffer);
	}

	fclose(fp);
	return rc;
}

struct pair {
	char *name;
	char *value;
};

static int sortpairs(const void *A, const void *B)
{
	const struct pair *a = *(struct pair * const *) A;
	const struct pair *b = *(struct pair * const *) B;
	return strcmp(a->name, b->name);
}

static int PreloadSystem(void)
{
	unsigned di, i;
	const char *dirs[] = {
		"/run/sysctl.d",
		"/etc/sysctl.d",
		"/usr/local/lib/sysctl.d",
		"/usr/lib/sysctl.d",
		"/lib/sysctl.d",
	};
	struct pair **cfgs = NULL;
	unsigned ncfgs = 0;
	enum { nprealloc = 16 };

	for (di = 0; di < sizeof(dirs) / sizeof(dirs[0]); ++di) {
		struct dirent *de;
		DIR *dp = opendir(dirs[di]);
		if (!dp)
			continue;

		while ((de = readdir(dp))) {
			if (!strcmp(de->d_name, ".")
			    || !strcmp(de->d_name, ".."))
				continue;
			if (strlen(de->d_name) < 6
			    || !strcmp(de->d_name + strlen(de->d_name) - 6, ".conf"))
				continue;
			/* check if config already known */
			for (i = 0; i < ncfgs; ++i) {
				if (!strcmp(cfgs[i]->name, de->d_name))
					break;
			}
			if (i < ncfgs)
				/* already in */
				continue;

			if (ncfgs % nprealloc == 0)
				cfgs = xrealloc(cfgs, sizeof(struct pair *) * (ncfgs + nprealloc));
			cfgs[ncfgs] =
			    xmalloc(sizeof(struct pair) + strlen(de->d_name) * 2 + 2 +
				    strlen(dirs[di]) + 1);
			cfgs[ncfgs]->name = (char *) cfgs[ncfgs] + sizeof(struct pair);
			strcpy(cfgs[ncfgs]->name, de->d_name);
			cfgs[ncfgs]->value =
			    (char *) cfgs[ncfgs] + sizeof(struct pair) + strlen(cfgs[ncfgs]->name) +
			    1;
			sprintf(cfgs[ncfgs]->value, "%s/%s", dirs[di], de->d_name);
			ncfgs++;

		}
		closedir(dp);
	}

	qsort(cfgs, ncfgs, sizeof(struct cfg *), sortpairs);

	for (i = 0; i < ncfgs; ++i) {
		if (!Quiet)
			printf(_("* Applying %s ...\n"), cfgs[i]->value);
		Preload(cfgs[i]->value);
	}

	if (!Quiet)
		printf(_("* Applying %s ...\n"), DEFAULT_PRELOAD);
	return Preload(DEFAULT_PRELOAD);
}

/*
 * Main...
 */
int main(int argc, char *argv[])
{
	bool SwitchesAllowed = true;
	bool WriteMode = false;
	bool DisplayAllOpt = false;
	bool preloadfileOpt = false;
	int ReturnCode = 0;
	int c;
	const char *preloadfile = DEFAULT_PRELOAD;

	enum {
		SYSTEM_OPTION = CHAR_MAX + 1
	};
	static const struct option longopts[] = {
		{"all", no_argument, NULL, 'a'},
		{"binary", no_argument, NULL, 'b'},
		{"ignore", no_argument, NULL, 'e'},
		{"names", no_argument, NULL, 'N'},
		{"values", no_argument, NULL, 'n'},
		{"load", optional_argument, NULL, 'p'},
		{"quiet", no_argument, NULL, 'q'},
		{"write", no_argument, NULL, 'w'},
		{"system", no_argument, NULL, SYSTEM_OPTION},
		{"pattern", required_argument, NULL, 'r'},
		{"help", no_argument, NULL, 'h'},
		{"version", no_argument, NULL, 'V'},
		{NULL, 0, NULL, 0}
	};

	program_invocation_name = program_invocation_short_name;
	setlocale(LC_ALL, "");
	bindtextdomain(PACKAGE, LOCALEDIR);
	textdomain(PACKAGE);

	PrintName = true;
	PrintNewline = true;
	IgnoreError = false;
	Quiet = false;

	if (argc < 2)
		Usage(stderr);

	while ((c =
		getopt_long(argc, argv, "bneNwfp::qoxaAXr:Vdh", longopts,
			    NULL)) != -1)
		switch (c) {
		case 'b':
			/* This is "binary" format, which means more for BSD. */
			PrintNewline = false;
			/* FALL THROUGH */
		case 'n':
			PrintName = false;
			break;
		case 'e':
			/*
			 * For FreeBSD, -e means a "%s=%s\n" format.
			 * ("%s: %s\n" default). We (and NetBSD) use
			 * "%s = %s\n" always, and -e to ignore errors.
			 */
			IgnoreError = true;
			break;
		case 'N':
			NameOnly = true;
			break;
		case 'w':
			SwitchesAllowed = false;
			WriteMode = true;
			break;
		case 'f':	/* the NetBSD way */
		case 'p':
			preloadfileOpt = true;
			if (optarg)
				preloadfile = optarg;
			break;
		case 'q':
			Quiet = true;
			break;
		case 'o':	/* BSD: binary values too, 1st 16 bytes in hex */
		case 'x':	/* BSD: binary values too, whole thing in hex */
			/* does nothing */ ;
			break;
		case 'a':	/* string and integer values (for Linux, all of them) */
		case 'A':	/* same as -a -o */
		case 'X':	/* same as -a -x */
			DisplayAllOpt = true;
			break;
		case SYSTEM_OPTION:
			IgnoreError = true;
			return PreloadSystem();
		case 'r':
			pattern = xstrdup(optarg);
			break;
		case 'V':
			printf(PROCPS_NG_VERSION);
			return EXIT_SUCCESS;
		case 'd':	/* BSD: print description ("vm.kvm_size: Size of KVM") */
		case 'h':	/* BSD: human-readable (did FreeBSD 5 make -e default?) */
		case '?':
			Usage(stdout);
		default:
			Usage(stderr);
		}
	if (DisplayAllOpt)
		return DisplayAll(PROC_PATH);
	if (preloadfileOpt)
		return Preload(preloadfile);

	argc -= optind;
	argv += optind;

	if (argc < 1)
		xerrx(EXIT_FAILURE, _("no variables specified\n"
				      "Try `%s --help' for more information."),
		      program_invocation_short_name);
	if (NameOnly && Quiet)
		xerrx(EXIT_FAILURE, _("options -N and -q cannot coexist\n"
				      "Try `%s --help' for more information."),
		      program_invocation_short_name);

	if (WriteMode || index(*argv, '='))
		ReturnCode = WriteSetting(*argv);
	else
		ReturnCode = ReadSetting(*argv);

	return ReturnCode;
}