/*

 *  event.c - ACPI daemon event handler

 *

 *  Copyright (C) 2000 Andrew Henroid

 *  Copyright (C) 2001 Sun Microsystems (thockin@sun.com)

 *  Copyright (C) 2004 Tim Hockin (thockin@hockin.org)

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  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.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/wait.h>

#include <poll.h>

#include <fcntl.h>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <errno.h>

#include <dirent.h>

#include <ctype.h>

#include <regex.h>

#include <signal.h>

#include "acpid.h"

#include "log.h"

#include "sock.h"

#include "ud_socket.h"

#include "libc_compat.h"

#include "event.h"

/*

 * What is a rule?  It's polymorphic, pretty much.

 */

#define RULE_REGEX_FLAGS (REG_EXTENDED | REG_ICASE | REG_NOSUB | REG_NEWLINE)

struct rule {

	enum {

		RULE_NONE = 0,

		RULE_CMD,

		RULE_CLIENT,

	} type;

	char *origin;

	regex_t *event;

	union {

		char *cmd;

		int fd;

	} action;

	struct rule *next;

	struct rule *prev;

};

struct rule_list {

	struct rule *head;

	struct rule *tail;

};

static struct rule_list drop_list;

static struct rule_list client_list;

static struct rule_list cmd_list;

/* rule routines */

static void enlist_rule(struct rule_list *list, struct rule *r);

static void delist_rule(struct rule_list *list, struct rule *r);

static struct rule *new_rule(void);

static void free_rule(struct rule *r);

/* other helper routines */

static void lock_rules(void);

static void unlock_rules(void);

static sigset_t *signals_handled(void);

static struct rule *parse_file(int fd_rule, const char *file);

static struct rule *parse_client(int client);

static int do_cmd_rule(struct rule *r, const char *event);

static int do_client_rule(struct rule *r, const char *event);

static int safe_write(int fd, const char *buf, int len);

static char *parse_cmd(const char *cmd, const char *event);

static int check_escapes(const char *str);

extern const char *dropaction;

/*

 * read in all the configuration files

 */

int

acpid_read_conf(const char *confdir)

{

	DIR *dir;

	struct dirent *dirent;

	int nrules = 0;

	regex_t preg;

	int rc = 0;

	lock_rules();

	dir = opendir(confdir);

	if (!dir) {

		acpid_log(LOG_ERR, "opendir(%s): %s",

			confdir, strerror(errno));

		unlock_rules();

		return -1;

	}

	/* Compile the regular expression.  This is based on run-parts(8). */

	rc = regcomp(&preg, "^[a-zA-Z0-9_-]+$", RULE_REGEX_FLAGS);

	if (rc) {

		closedir(dir);

		acpid_log(LOG_ERR, "regcomp(): %d", rc);

		unlock_rules();

		return -1;

	}

	/* scan all the files */

	while ((dirent = readdir(dir))) {

		struct rule *r;

		struct stat stat_buf;

        char *file = NULL;  /* rename: filename */

        int fd_rule;

		/* skip "." and ".." */

		if (strncmp(dirent->d_name, ".", sizeof(dirent->d_name)) == 0)

			continue;

		if (strncmp(dirent->d_name, "..", sizeof(dirent->d_name)) == 0)

			continue;

        if (asprintf(&file, "%s/%s", confdir, dirent->d_name) < 0) {

            acpid_log(LOG_ERR, "asprintf: %s", strerror(errno));

            regfree(&preg;;

            closedir(dir);

            unlock_rules();

            return -1;

        }

		/* skip any files that don't match the run-parts convention */

		if (regexec(&preg, dirent->d_name, 0, NULL, 0) != 0) {

			acpid_log(LOG_INFO, "skipping conf file %s", file);

            free(file);

			continue;

		}

        /* ??? Check for DT_UNKNOWN and do this, then "else if" on not DT_REG

               and do the same as the !S_ISREG() branch below. */

        if (dirent->d_type != DT_REG) { /* may be DT_UNKNOWN ...*/

            /* allow only regular files and symlinks to files */

            if (fstatat(dirfd(dir), dirent->d_name, &stat_buf, 0) != 0) {

			    acpid_log(LOG_ERR, "fstatat(%s): %s", file, strerror(errno));

			    free(file);

			    continue; /* keep trying the rest of the files */

		    }

		    if (!S_ISREG(stat_buf.st_mode)) {

                acpid_log(LOG_INFO, "skipping non-file %s", file);

                free(file);

                continue; /* skip non-regular files */

            }

        }

        /* open the rule file (might want to move this into parse_file()?) */

		if ((fd_rule = openat(dirfd(dir), dirent->d_name, 

                              O_RDONLY|O_CLOEXEC|O_NONBLOCK)) == -1) {

                /* something went _really_ wrong.. Not Gonna Happen(tm) */

                acpid_log(LOG_ERR, "openat(%s): %s", file, strerror(errno));

                free(file);

                /* ??? Too extreme?  Why not just continue? */

                closedir(dir);

                regfree(&preg;;

                unlock_rules();

                return -1;

        }

        /* fd is closed by parse_file() */

		r = parse_file(fd_rule, file);

		if (r) {

			/* if this is a drop rule */

			if (!strcmp(r->action.cmd, dropaction))

				enlist_rule(&drop_list, r);

			else

				enlist_rule(&cmd_list, r);

			nrules++;

		}

		free(file);

	}

    regfree(&preg;;

	closedir(dir);

	unlock_rules();

	acpid_log(LOG_INFO, "%d rule%s loaded", nrules, (nrules == 1)?"":"s");

	return 0;

}

/*

 * cleanup all rules

 */

int

acpid_cleanup_rules(int do_detach)

{

	struct rule *p;

	struct rule *next;

	lock_rules();

	if (debug_level >= 3) {

		acpid_log(LOG_DEBUG, "cleaning up rules");

	}

	if (do_detach) {

		/* tell our clients to buzz off */

		p = client_list.head;

		while (p) {

			next = p->next;

			delist_rule(&client_list, p);

			close(p->action.fd);

			free_rule(p);

			p = next;

		}

	}

	/* clear out our conf rules */

	p = cmd_list.head;

	while (p) {

		next = p->next;

		delist_rule(&cmd_list, p);

		free_rule(p);

		p = next;

	}

	/* drop the drop rules */

	p = drop_list.head;

	while (p) {

		next = p->next;

		delist_rule(&drop_list, p);

		free_rule(p);

		p = next;

	}

	unlock_rules();

	return 0;

}

static struct rule *

parse_file(int fd_rule, const char *file)

{

	FILE *fp;

	char buf[512];

	int line = 0;

	struct rule *r;

	acpid_log(LOG_DEBUG, "parsing conf file %s", file);

    /* r - read-only, e - O_CLOEXEC */

	fp = fdopen(fd_rule, "re");

	if (!fp) {

		acpid_log(LOG_ERR, "fopen(%s): %s", file, strerror(errno));

		return NULL;

	}

	/* make a new rule */

	r = new_rule();

	if (!r) {

		fclose(fp);

		return NULL;

	}

	r->type = RULE_CMD;

	r->origin = strdup(file);

	if (!r->origin) {

		acpid_log(LOG_ERR, "strdup(): %s", strerror(errno));

		free_rule(r);

		fclose(fp);

		return NULL;

	}

	/* read each line */

	while (!feof(fp) && !ferror(fp)) {

		char *p = buf;

		char key[64];

		char val[512];

		int n;

		line++;

		memset(key, 0, sizeof(key));

		memset(val, 0, sizeof(val));

		if (fgets(buf, sizeof(buf)-1, fp) == NULL) {

			continue;

		}

		/* skip leading whitespace */

		while (*p && isspace((int)*p)) {

			p++;

		}

		/* blank lines and comments get ignored */

		if (!*p || *p == '#') {

			continue;

		}

		/* quick parse */

		n = sscanf(p, "%63[^=\n]=%255[^\n]", key, val);

		if (n != 2) {

			acpid_log(LOG_WARNING, "can't parse %s at line %d",

			    file, line);

			continue;

		}

		if (debug_level >= 3) {

			acpid_log(LOG_DEBUG, "    key=\"%s\" val=\"%s\"",

			    key, val);

		}

		/* handle the parsed line */

		if (!strcasecmp(key, "event")) {

			int rv;

			r->event = malloc(sizeof(regex_t));

			if (!r->event) {

				acpid_log(LOG_ERR, "malloc(): %s",

					strerror(errno));

				free_rule(r);

				fclose(fp);

				return NULL;

			}

			rv = regcomp(r->event, val, RULE_REGEX_FLAGS);

			if (rv) {

				char rbuf[128];

				regerror(rv, r->event, rbuf, sizeof(rbuf));

				acpid_log(LOG_ERR, "regcomp(): %s", rbuf);

				free_rule(r);

				fclose(fp);

				return NULL;

			}

		} else if (!strcasecmp(key, "action")) {

			if (check_escapes(val) < 0) {

				acpid_log(LOG_ERR, "can't load file %s",

				    file);

				free_rule(r);

				fclose(fp);

				return NULL;

			}

			r->action.cmd = strdup(val);

			if (!r->action.cmd) {

				acpid_log(LOG_ERR, "strdup(): %s",

					strerror(errno));

				free_rule(r);

				fclose(fp);

				return NULL;

			}

		} else {

			acpid_log(LOG_WARNING,

			    "unknown option '%s' in %s at line %d",

			    key, file, line);

			continue;

		}

	}

	if (!r->event || !r->action.cmd) {

		acpid_log(LOG_INFO, "skipping incomplete file %s", file);

		free_rule(r);

		fclose(fp);

		return NULL;

	}

	fclose(fp);

	return r;

}

int

acpid_add_client(int clifd, const char *origin)

{

	struct rule *r;

	int nrules = 0;

	acpid_log(LOG_NOTICE, "client connected from %s", origin);

	r = parse_client(clifd);

	if (r) {

		r->origin = strdup(origin);

		enlist_rule(&client_list, r);

		nrules++;

	}

	acpid_log(LOG_INFO, "%d client rule%s loaded",

	    nrules, (nrules == 1)?"":"s");

	return 0;

}

static struct rule *

parse_client(int client)

{

	struct rule *r;

	int rv;

	/* make a new rule */

	r = new_rule();

	if (!r) {

		return NULL;

	}

	r->type = RULE_CLIENT;

	r->action.fd = client;

	r->event = malloc(sizeof(regex_t));

	if (!r->event) {

		acpid_log(LOG_ERR, "malloc(): %s", strerror(errno));

		free_rule(r);

		return NULL;

	}

	rv = regcomp(r->event, ".*", RULE_REGEX_FLAGS);

	if (rv) {

		char buf[128];

		regerror(rv, r->event, buf, sizeof(buf));

		acpid_log(LOG_ERR, "regcomp(): %s", buf);

		free_rule(r);

		return NULL;

	}

	return r;

}

/*

 * a few rule methods

 */

static void

enlist_rule(struct rule_list *list, struct rule *r)

{

	r->next = r->prev = NULL;

	if (!list->head) {

		list->head = list->tail = r;

	} else {

		list->tail->next = r;

		r->prev = list->tail;

		list->tail = r;

	}

}

static void

delist_rule(struct rule_list *list, struct rule *r)

{

	if (r->next) {

		r->next->prev = r->prev;

	} else {

		list->tail = r->prev;

	}

	if (r->prev) {

		r->prev->next = r->next;

	} else {

		list->head = r->next;;

	}

	r->next = r->prev = NULL;

}

static struct rule *

new_rule(void)

{

	struct rule *r;

	r = malloc(sizeof(*r));

	if (!r) {

		acpid_log(LOG_ERR, "malloc(): %s", strerror(errno));

		return NULL;

	}

	r->type = RULE_NONE;

	r->origin = NULL;

	r->event = NULL;

	r->action.cmd = NULL;

	r->prev = r->next = NULL;

	return r;

}

/* I hope you delisted the rule before you free() it */

static void

free_rule(struct rule *r)

{

	if (r->type == RULE_CMD) {

		if (r->action.cmd) {

			free(r->action.cmd);

		}

	}

	if (r->origin) {

		free(r->origin);

	}

	if (r->event) {

		regfree(r->event);

		free(r->event);

	}

	free(r);

}

static int

client_is_dead(int fd)

{

	struct pollfd pfd;

	int r;

	/* check the fd to see if it is dead */

	pfd.fd = fd;

	pfd.events = POLLERR | POLLHUP;

	r = poll(&pfd, 1, 0);

	if (r < 0) {

		acpid_log(LOG_ERR, "poll(): %s", strerror(errno));

		return 0;

	}

	return pfd.revents;

}

void

acpid_close_dead_clients(void)

{

	struct rule *p;

	lock_rules();

	/* scan our client list */

	p = client_list.head;

	while (p) {

		struct rule *next = p->next;

		if (client_is_dead(p->action.fd)) {

			struct ucred cred;

			/* closed */

			acpid_log(LOG_NOTICE,

			    "client %s has disconnected", p->origin);

			delist_rule(&client_list, p);

			ud_get_peercred(p->action.fd, &cred);

			if (cred.uid != 0) {

				non_root_clients--;

			}

			close(p->action.fd);

			free_rule(p);

		}

		p = next;

	}

	unlock_rules();

}

/*

 * the main hook for propagating events

 */

int

acpid_handle_event(const char *event)

{

	struct rule *p;

	int nrules = 0;

	struct rule_list *ar[] = { &drop_list, &client_list, &cmd_list, NULL };

	struct rule_list **lp;

	/* make an event atomic wrt known signals */

	lock_rules();

	/* scan each rule list for any rules that care about this event */

	for (lp = ar; *lp; lp++) {

		struct rule_list *l = *lp;

		p = l->head;

		while (p) {

			/* the list can change underneath us */

			struct rule *pnext = p->next;

			if (!regexec(p->event, event, 0, NULL, 0)) {

				/* a match! */

				if (logevents) {

					acpid_log(LOG_INFO,

					    "rule from %s matched",

					    p->origin);

				}

				nrules++;

				if (p->type == RULE_CMD) {

					if (do_cmd_rule(p, event) == DROP_EVENT) {

						/* Abort processing if event matches drop rule */

						if (logevents)

							acpid_log(LOG_INFO, "event dropped");

						/* Skip the remaining rules. */

						while (*++lp)

							;

						--lp;

						break;

					}

				} else if (p->type == RULE_CLIENT) {

					do_client_rule(p, event);

				} else {

					acpid_log(LOG_WARNING,

					    "unknown rule type: %d",

					    p->type);

				}

			} else {

				if (debug_level >= 3 && logevents) {

					acpid_log(LOG_INFO,

					    "rule from %s did not match",

					    p->origin);

				}

			}

			p = pnext;

		}

	}

	unlock_rules();

	if (logevents) {

		acpid_log(LOG_INFO, "%d total rule%s matched",

			nrules, (nrules == 1)?"":"s");

	}

	return 0;

}

/* helper functions to block signals while iterating */

static sigset_t *

signals_handled(void)

{

	static sigset_t set;

	sigemptyset(&set);

	sigaddset(&set, SIGHUP);

	sigaddset(&set, SIGTERM);

	sigaddset(&set, SIGQUIT);

	sigaddset(&set, SIGINT);

	return &set;

}

static void

lock_rules(void)

{

	if (debug_level >= 4) {

		acpid_log(LOG_DEBUG, "blocking signals for rule lock");

	}

	sigprocmask(SIG_BLOCK, signals_handled(), NULL);

}

static void

unlock_rules(void)

{

	if (debug_level >= 4) {

		acpid_log(LOG_DEBUG, "unblocking signals for rule lock");

	}

	sigprocmask(SIG_UNBLOCK, signals_handled(), NULL);

}

/*

 * the meat of the rules

 */

static int

do_cmd_rule(struct rule *rule, const char *event)

{

	pid_t pid;

	int status;

	const char *action;

	if (!strcmp(rule->action.cmd, dropaction))

		return DROP_EVENT;

	pid = fork();

	switch (pid) {

	case -1:

		acpid_log(LOG_ERR, "fork(): %s", strerror(errno));

		return -1;

	case 0: /* child */

		/* parse the commandline, doing any substitutions needed */

		action = parse_cmd(rule->action.cmd, event);

		if (logevents) {

			acpid_log(LOG_INFO,

			    "executing action \"%s\"", action);

		}

		/* reset signals */

		signal(SIGHUP, SIG_DFL);

		signal(SIGTERM, SIG_DFL);

		signal(SIGINT, SIG_DFL);

		signal(SIGQUIT, SIG_DFL);

		signal(SIGPIPE, SIG_DFL);

		sigprocmask(SIG_UNBLOCK, signals_handled(), NULL);

		if (debug_level && logevents) {

			fprintf(stdout, "BEGIN HANDLER MESSAGES\n");

		}

		umask(0077);

		execl("/bin/sh", "/bin/sh", "-c", action, NULL);

		/* should not get here */

		acpid_log(LOG_ERR, "execl(): %s", strerror(errno));

		_exit(EXIT_FAILURE);

	}

	/* parent */

	waitpid(pid, &status, 0);

	if (debug_level && logevents) {

		fprintf(stdout, "END HANDLER MESSAGES\n");

	}

	if (logevents) {

		if (WIFEXITED(status)) {

			acpid_log(LOG_INFO, "action exited with status %d",

			    WEXITSTATUS(status));

		} else if (WIFSIGNALED(status)) {

			acpid_log(LOG_INFO, "action exited on signal %d",

			    WTERMSIG(status));

		} else {

			acpid_log(LOG_INFO, "action exited with status %d",

			    status);

		}

	}

	return 0;

}

static int

do_client_rule(struct rule *rule, const char *event)

{

	int r;

	int client = rule->action.fd;

	if (logevents) {

		acpid_log(LOG_INFO, "notifying client %s", rule->origin);

	}

	r = safe_write(client, event, strlen(event));

	if (r < 0 && errno == EPIPE) {

		struct ucred cred;

		/* closed */

		acpid_log(LOG_NOTICE,

		    "client %s has disconnected", rule->origin);

		delist_rule(&client_list, rule);

		ud_get_peercred(rule->action.fd, &cred);

		if (cred.uid != 0) {

			non_root_clients--;

		}

		close(rule->action.fd);

		free_rule(rule);

		return -1;

	}

	safe_write(client, "\n", 1);

	return 0;

}

#define NTRIES 100

static int

safe_write(int fd, const char *buf, int len)

{

	int r;

	int ttl = 0;

	int ntries = NTRIES;

	do {

		r = TEMP_FAILURE_RETRY (write(fd, buf+ttl, len-ttl) );

		if (r < 0) {

			if (errno != EAGAIN) {

				/* a legit error */

				return r;

			}

			ntries--;

		} else if (r > 0) {

			/* as long as we make forward progress, reset ntries */

			ntries = NTRIES;

			ttl += r;

		}

	} while (ttl < len && ntries);

	if (!ntries) {

		if (debug_level >= 2) {

			acpid_log(LOG_ERR, "safe_write() timed out");

		}

		return r;

	}

	return ttl;

}

static char *

parse_cmd(const char *cmd, const char *event)

{

	static char buf[4096];

	size_t i;

	const char *p;

	p = cmd;

	i = 0;

	memset(buf, 0, sizeof(buf));

	while (i < (sizeof(buf)-1)) {

		if (*p == '%') {

			p++;

			if (*p == 'e') {

				/* handle an event expansion */

				size_t size = sizeof(buf) - i;

				size = snprintf(buf+i, size, "%s", event);

				i += size;

				p++;

				continue;

			}

		}

		if (!*p) {

			break;

		}

		buf[i++] = *p++;

	}

	if (debug_level >= 2) {

		acpid_log(LOG_DEBUG, "expanded \"%s\" -> \"%s\"", cmd, buf);

	}

	return buf;

}

static int

check_escapes(const char *str)

{

	const char *p;

	int r = 0;

	p = str;

	while (*p) {

		/* found an escape */

		if (*p == '%') {

			p++;

			if (!*p) {

				acpid_log(LOG_WARNING,

				    "invalid escape at EOL");

				return -1;

			} else if (*p != '%' && *p != 'e') {

				acpid_log(LOG_WARNING,

				    "invalid escape \"%%%c\"", *p);

				r = -1;

			}

		}

		p++;

	}

	return r;

}