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event.c

/*
 *  event.c - ACPI daemon
 *
 *  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 <sys/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 "ud_socket.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 cmd_list;
static struct rule_list client_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(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);

/*
 * read in all the configuration files
 */
int
acpid_read_conf(const char *confdir)
{
      DIR *dir;
      struct dirent *dirent;
      char *file = NULL;
      int nrules = 0;

      lock_rules();

      dir = opendir(confdir);
      if (!dir) {
            acpid_log(LOG_ERR, "opendir(%s): %s\n",
                  confdir, strerror(errno));
            unlock_rules();
            return -1;
      }

      /* scan all the files */
      while ((dirent = readdir(dir))) {
            int len;
            struct rule *r;
            struct stat stat_buf;

            if (dirent->d_name[0] == '.')
                  continue; /* skip dotfiles */

            len = strlen(dirent->d_name);

            if (dirent->d_name[len - 1] == '~') {
                  continue; /* skip editor backup files */
            }

            len += strlen(confdir) + 2;

            file = malloc(len);
            if (!file) {
                  acpid_log(LOG_ERR, "malloc(): %s\n", strerror(errno));
                  unlock_rules();
                  return -1;
            }
            snprintf(file, len, "%s/%s", confdir, dirent->d_name);

            /* allow only regular files and symlinks to files */
            if (stat(file, &stat_buf) != 0) {
                  acpid_log(LOG_ERR, "stat(%s): %s\n", file,
                        strerror(errno));
                  free(file);
                  continue; /* keep trying the rest of the files */
            }
            if (!S_ISREG(stat_buf.st_mode)) {
                  acpid_log(LOG_DEBUG, "skipping non-file %s\n", file);
                  free(file);
                  continue; /* skip non-regular files */
            }

            r = parse_file(file);
            if (r) {
                  enlist_rule(&cmd_list, r);
                  nrules++;
            }
            free(file);
      }
      closedir(dir);
      unlock_rules();

      acpid_log(LOG_INFO, "%d rule%s loaded\n",
          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 (acpid_debug >= 3) {
            acpid_log(LOG_DEBUG, "cleaning up rules\n");
      }

      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;
      }

      unlock_rules();

      return 0;
}

static struct rule *
parse_file(const char *file)
{
      FILE *fp;
      char buf[512];
      int line = 0;
      struct rule *r;

      if (acpid_debug) {
            acpid_log(LOG_DEBUG, "parsing conf file %s\n", file);
      }

      fp = fopen(file, "r");
      if (!fp) {
            acpid_log(LOG_ERR, "fopen(%s): %s\n", 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\n", 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\n",
                      file, line);
                  continue;
            }
            if (acpid_debug >= 3) {
                  acpid_log(LOG_DEBUG, "    key=\"%s\" val=\"%s\"\n",
                      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\n",
                              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\n", 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\n",
                            file);
                        free_rule(r);
                        fclose(fp);
                        return NULL;
                  }
                  r->action.cmd = strdup(val);
                  if (!r->action.cmd) {
                        acpid_log(LOG_ERR, "strdup(): %s\n",
                              strerror(errno));
                        free_rule(r);
                        fclose(fp);
                        return NULL;
                  }
            } else {
                  acpid_log(LOG_WARNING,
                      "unknown option '%s' in %s at line %d\n",
                      key, file, line);
                  continue;
            }
      }
      if (!r->event || !r->action.cmd) {
            if (acpid_debug) {
                  acpid_log(LOG_DEBUG, "skipping incomplete file %s\n",
                      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\n", 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\n",
          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\n", 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\n", 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\n", 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\n", 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\n", 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 propogating events
 */
int
acpid_handle_event(const char *event)
{
      struct rule *p;
      int nrules = 0;
      struct rule_list *ar[] = { &client_list, &cmd_list, NULL };
      struct rule_list **lp;

      /* make an event be 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 (acpid_debug && logevents) {
                              acpid_log(LOG_DEBUG,
                                  "rule from %s matched\n",
                                  p->origin);
                        }
                        nrules++;
                        if (p->type == RULE_CMD) {
                              do_cmd_rule(p, event);
                        } else if (p->type == RULE_CLIENT) {
                              do_client_rule(p, event);
                        } else {
                              acpid_log(LOG_WARNING,
                                  "unknown rule type: %d\n",
                                  p->type);
                        }
                  } else {
                        if (acpid_debug >= 3 && logevents) {
                              acpid_log(LOG_DEBUG,
                                  "rule from %s did not match\n",
                                  p->origin);
                        }
                  }
                  p = pnext;
            }
      }

      unlock_rules();

      if (acpid_debug && logevents) {
            acpid_log(LOG_DEBUG, "%d total rule%s matched\n",
                  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 (acpid_debug >= 4) {
            acpid_log(LOG_DEBUG, "blocking signals for rule lock\n");
      }
      sigprocmask(SIG_BLOCK, signals_handled(), NULL);
}

static void
unlock_rules(void)
{
      if (acpid_debug >= 4) {
            acpid_log(LOG_DEBUG, "unblocking signals for rule lock\n");
      }
      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;

      pid = fork();
      switch (pid) {
      case -1:
            acpid_log(LOG_ERR, "fork(): %s\n", 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\"\n", 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 (acpid_debug && logevents) {
                  fprintf(stdout, "BEGIN HANDLER MESSAGES\n");
            }
            execl("/bin/sh", "/bin/sh", "-c", action, NULL);
            /* should not get here */
            acpid_log(LOG_ERR, "execl(): %s\n", strerror(errno));
            exit(EXIT_FAILURE);
      }

      /* parent */
      waitpid(pid, &status, 0);
      if (acpid_debug && logevents) {
            fprintf(stdout, "END HANDLER MESSAGES\n");
      }

      if (logevents) {
            if (WIFEXITED(status)) {
                  acpid_log(LOG_INFO, "action exited with status %d\n",
                      WEXITSTATUS(status));
            } else if (WIFSIGNALED(status)) {
                  acpid_log(LOG_INFO, "action exited on signal %d\n",
                      WTERMSIG(status));
            } else {
                  acpid_log(LOG_INFO, "action exited with status %d\n",
                      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\n", 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\n", 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 = write(fd, buf+ttl, len-ttl);
            if (r < 0) {
                  if (errno != EAGAIN && errno != EINTR) {
                        /* 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) {
            /* crap */
            if (acpid_debug >= 2) {
                  acpid_log(LOG_ERR, "uh-oh! safe_write() timed out\n");
            }
            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 (acpid_debug >= 2) {
            acpid_log(LOG_DEBUG, "expanded \"%s\" -> \"%s\"\n", 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\n");
                        return -1;
                  } else if (*p != '%' && *p != 'e') {
                        acpid_log(LOG_WARNING,
                            "invalid escape \"%%%c\"\n", *p);
                        r = -1;
                  }
            }
            p++;
      }
      return r;
}

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