io.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <[email protected]>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief I/O Managment (Derived from Cheops-NG)
 *
 * \author Mark Spencer <[email protected]>
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#include <termios.h>
#include <sys/ioctl.h>

#include "asterisk/io.h"
#include "asterisk/utils.h"
#ifdef HAVE_SYSTEMD
#include <systemd/sd-daemon.h>

#ifndef SD_LISTEN_FDS_START
#define SD_LISTEN_FDS_START 3
#endif
#endif

#ifdef DEBUG_IO
#define DEBUG DEBUG_M
#else
#define DEBUG(a)
#endif

/*! \brief
 * Kept for each file descriptor
 */
struct io_rec {
   ast_io_cb callback;     /*!< What is to be called */
   void *data;       /*!< Data to be passed */
   int *id;       /*!< ID number */
};

/* These two arrays are keyed with
   the same index.  it's too bad that
   pollfd doesn't have a callback field
   or something like that.  They grow as
   needed, by GROW_SHRINK_SIZE structures
   at once */

#define GROW_SHRINK_SIZE 512

/*! \brief Global IO variables are now in a struct in order to be
   made threadsafe */
struct io_context {
   struct pollfd *fds;           /*!< Poll structure */
   struct io_rec *ior;           /*!< Associated I/O records */
   unsigned int fdcnt;           /*!< First available fd */
   unsigned int maxfdcnt;        /*!< Maximum available fd */
   int current_ioc;              /*!< Currently used io callback */
   int needshrink;               /*!< Whether something has been deleted */
};

/*! \brief Create an I/O context */
struct io_context *io_context_create(void)
{
   struct io_context *tmp = NULL;

   if (!(tmp = ast_malloc(sizeof(*tmp))))
      return NULL;

   tmp->needshrink = 0;
   tmp->fdcnt = 0;
   tmp->maxfdcnt = GROW_SHRINK_SIZE/2;
   tmp->current_ioc = -1;

   if (!(tmp->fds = ast_calloc(1, (GROW_SHRINK_SIZE / 2) * sizeof(*tmp->fds)))) {
      ast_free(tmp);
      tmp = NULL;
   } else {
      if (!(tmp->ior = ast_calloc(1, (GROW_SHRINK_SIZE / 2) * sizeof(*tmp->ior)))) {
         ast_free(tmp->fds);
         ast_free(tmp);
         tmp = NULL;
      }
   }

   return tmp;
}

void io_context_destroy(struct io_context *ioc)
{
   /* Free associated memory with an I/O context */
   if (ioc->fds)
      ast_free(ioc->fds);
   if (ioc->ior)
      ast_free(ioc->ior);

   ast_free(ioc);
}

/*! \brief
 * Grow the size of our arrays.
 * \return 0 on success or -1 on failure
 */
static int io_grow(struct io_context *ioc)
{
   void *tmp;

   DEBUG(ast_debug(1, "io_grow()\n"));

   ioc->maxfdcnt += GROW_SHRINK_SIZE;

   if ((tmp = ast_realloc(ioc->ior, (ioc->maxfdcnt + 1) * sizeof(*ioc->ior)))) {
      ioc->ior = tmp;
      if ((tmp = ast_realloc(ioc->fds, (ioc->maxfdcnt + 1) * sizeof(*ioc->fds)))) {
         ioc->fds = tmp;
      } else {
         /*
          * Failed to allocate enough memory for the pollfd.  Not
          * really any need to shrink back the iorec's as we'll
          * probably want to grow them again soon when more memory
          * is available, and then they'll already be the right size
          */
         ioc->maxfdcnt -= GROW_SHRINK_SIZE;
         return -1;
      }
   } else {
      /*
       * Memory allocation failure.  We return to the old size, and
       * return a failure
       */
      ioc->maxfdcnt -= GROW_SHRINK_SIZE;
      return -1;
   }

   return 0;
}

/*! \brief
 * Add a new I/O entry for this file descriptor
 * with the given event mask, to call callback with
 * data as an argument.
 * \return Returns NULL on failure.
 */
int *ast_io_add(struct io_context *ioc, int fd, ast_io_cb callback, short events, void *data)
{
   int *ret;

   DEBUG(ast_debug(1, "ast_io_add()\n"));

   if (ioc->fdcnt >= ioc->maxfdcnt) {
      /*
       * We don't have enough space for this entry.  We need to
       * reallocate maxfdcnt poll fd's and io_rec's, or back out now.
       */
      if (io_grow(ioc))
         return NULL;
   }

   /*
    * At this point, we've got sufficiently large arrays going
    * and we can make an entry for it in the pollfd and io_r
    * structures.
    */
   ioc->fds[ioc->fdcnt].fd = fd;
   ioc->fds[ioc->fdcnt].events = events;
   ioc->fds[ioc->fdcnt].revents = 0;
   ioc->ior[ioc->fdcnt].callback = callback;
   ioc->ior[ioc->fdcnt].data = data;

   if (!(ioc->ior[ioc->fdcnt].id = ast_malloc(sizeof(*ioc->ior[ioc->fdcnt].id)))) {
      /* Bonk if we couldn't allocate an int */
      return NULL;
   }

   *(ioc->ior[ioc->fdcnt].id) = ioc->fdcnt;
   ret = ioc->ior[ioc->fdcnt].id;
   ioc->fdcnt++;

   return ret;
}

int *ast_io_change(struct io_context *ioc, int *id, int fd, ast_io_cb callback, short events, void *data)
{
   /* If this id exceeds our file descriptor count it doesn't exist here */
   if (*id > ioc->fdcnt)
      return NULL;

   if (fd > -1)
      ioc->fds[*id].fd = fd;
   if (callback)
      ioc->ior[*id].callback = callback;
   if (events)
      ioc->fds[*id].events = events;
   if (data)
      ioc->ior[*id].data = data;

   return id;
}

static int io_shrink(struct io_context *ioc)
{
   int getfrom, putto = 0;

   /*
    * Bring the fields from the very last entry to cover over
    * the entry we are removing, then decrease the size of the
    * arrays by one.
    */
   for (getfrom = 0; getfrom < ioc->fdcnt; getfrom++) {
      if (ioc->ior[getfrom].id) {
         /* In use, save it */
         if (getfrom != putto) {
            ioc->fds[putto] = ioc->fds[getfrom];
            ioc->ior[putto] = ioc->ior[getfrom];
            *(ioc->ior[putto].id) = putto;
         }
         putto++;
      }
   }
   ioc->fdcnt = putto;
   ioc->needshrink = 0;
   /* FIXME: We should free some memory if we have lots of unused
      io structs */
   return 0;
}

int ast_io_remove(struct io_context *ioc, int *_id)
{
   int x;

   if (!_id) {
      ast_log(LOG_WARNING, "Asked to remove NULL?\n");
      return -1;
   }

   for (x = 0; x < ioc->fdcnt; x++) {
      if (ioc->ior[x].id == _id) {
         /* Free the int immediately and set to NULL so we know it's unused now */
         ast_free(ioc->ior[x].id);
         ioc->ior[x].id = NULL;
         ioc->fds[x].events = 0;
         ioc->fds[x].revents = 0;
         ioc->needshrink = 1;
         if (ioc->current_ioc == -1)
            io_shrink(ioc);
         return 0;
      }
   }

   ast_log(LOG_NOTICE, "Unable to remove unknown id %p\n", _id);

   return -1;
}

/*! \brief
 * Make the poll call, and call
 * the callbacks for anything that needs
 * to be handled
 */
int ast_io_wait(struct io_context *ioc, int howlong)
{
   int res, x, origcnt;

   DEBUG(ast_debug(1, "ast_io_wait()\n"));

   if ((res = ast_poll(ioc->fds, ioc->fdcnt, howlong)) <= 0) {
      return res;
   }

   /* At least one event tripped */
   origcnt = ioc->fdcnt;
   for (x = 0; x < origcnt; x++) {
      /* Yes, it is possible for an entry to be deleted and still have an
         event waiting if it occurs after the original calling id */
      if (ioc->fds[x].revents && ioc->ior[x].id) {
         /* There's an event waiting */
         ioc->current_ioc = *ioc->ior[x].id;
         if (ioc->ior[x].callback) {
            if (!ioc->ior[x].callback(ioc->ior[x].id, ioc->fds[x].fd, ioc->fds[x].revents, ioc->ior[x].data)) {
               /* Time to delete them since they returned a 0 */
               ast_io_remove(ioc, ioc->ior[x].id);
            }
         }
         ioc->current_ioc = -1;
      }
   }

   if (ioc->needshrink)
      io_shrink(ioc);

   return res;
}

void ast_io_dump(struct io_context *ioc)
{
   /*
    * Print some debugging information via
    * the logger interface
    */
   int x;

   ast_debug(1, "Asterisk IO Dump: %u entries, %u max entries\n", ioc->fdcnt, ioc->maxfdcnt);
   ast_debug(1, "================================================\n");
   ast_debug(1, "| ID    FD     Callback    Data        Events  |\n");
   ast_debug(1, "+------+------+-----------+-----------+--------+\n");
   for (x = 0; x < ioc->fdcnt; x++) {
      ast_debug(1, "| %.4d | %.4d | %p | %p | %.6x |\n",
            *ioc->ior[x].id,
            ioc->fds[x].fd,
            ioc->ior[x].callback,
            ioc->ior[x].data,
            (unsigned)ioc->fds[x].events);
   }
   ast_debug(1, "================================================\n");
}

/* Unrelated I/O functions */

int ast_hide_password(int fd)
{
   struct termios tios;
   int res;
   int old;
   if (!isatty(fd))
      return -1;
   res = tcgetattr(fd, &tios);
   if (res < 0)
      return -1;
   old = tios.c_lflag & (ECHO | ECHONL);
   tios.c_lflag &= ~ECHO;
   tios.c_lflag |= ECHONL;
   res = tcsetattr(fd, TCSAFLUSH, &tios);
   if (res < 0)
      return -1;
   return old;
}

int ast_restore_tty(int fd, int oldstate)
{
   int res;
   struct termios tios;
   if (oldstate < 0)
      return 0;
   res = tcgetattr(fd, &tios);
   if (res < 0)
      return -1;
   tios.c_lflag &= ~(ECHO | ECHONL);
   tios.c_lflag |= oldstate;
   res = tcsetattr(fd, TCSAFLUSH, &tios);
   if (res < 0)
      return -1;
   return 0;
}

int ast_get_termcols(int fd)
{
   struct winsize win;
   int cols = 0;

   if (!isatty(fd))
      return -1;

   if ( ioctl(fd, TIOCGWINSZ, &win) != -1 ) {
      if ( !cols && win.ws_col > 0 )
         cols = (int) win.ws_col;
   } else {
      /* assume 80 characters if the ioctl fails for some reason */
      cols = 80;
   }

   return cols;
}

int ast_sd_notify(const char *state) {
#ifdef HAVE_SYSTEMD
   return sd_notify(0, state);
#else
   return 0;
#endif
}

/*!
 * \internal \brief Check the type and sockaddr of a file descriptor.
 * \param fd File Descriptor to check.
 * \param type SOCK_STREAM or SOCK_DGRAM
 * \param addr The socket address to match.
 * \retval 0 if matching
 * \retval -1 if not matching
 */
#ifdef HAVE_SYSTEMD
static int ast_sd_is_socket_sockaddr(int fd, int type, const struct ast_sockaddr* addr)
{
   int canretry = 1;
   struct ast_sockaddr fd_addr;
   struct sockaddr ss;
   socklen_t ss_len;

   if (sd_is_socket(fd, AF_UNSPEC, type, 1) <= 0) {
      return -1;
   }

doretry:
   if (getsockname(fd, &ss, &ss_len) != 0) {
      return -1;
   }

   if (ss.sa_family == AF_UNSPEC && canretry) {
      /* An unknown bug can cause silent failure from
       * the first call to getsockname. */
      canretry = 0;
      goto doretry;
   }

   ast_sockaddr_copy_sockaddr(&fd_addr, &ss, ss_len);

   return ast_sockaddr_cmp(addr, &fd_addr);
}
#endif

int ast_sd_get_fd(int type, const struct ast_sockaddr *addr)
{
#ifdef HAVE_SYSTEMD
   int count = sd_listen_fds(0);
   int idx;

   for (idx = 0; idx < count; idx++) {
      if (!ast_sd_is_socket_sockaddr(idx + SD_LISTEN_FDS_START, type, addr)) {
         return idx + SD_LISTEN_FDS_START;
      }
   }
#endif

   return -1;
}

int ast_sd_get_fd_un(int type, const char *path)
{
#ifdef HAVE_SYSTEMD
   int count = sd_listen_fds(0);
   int idx;

   for (idx = 0; idx < count; idx++) {
      if (sd_is_socket_unix(idx + SD_LISTEN_FDS_START, type, 1, path, 0) > 0) {
         return idx + SD_LISTEN_FDS_START;
      }
   }
#endif

   return -1;
}