io.c

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/*
 * Asterisk
 * 
 * Mark Spencer <markster@marko.net>
 *
 * Copyright(C) Mark Spencer
 * 
 * Distributed under the terms of the GNU General Public License (GPL) Version 2
 *
 * I/O Managment (Derived from Cheops-NG)
 *
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <termios.h>
#include <string.h> /* for memset */
#include <sys/ioctl.h>
#include <asterisk/io.h>
#include <asterisk/logger.h>

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

/* 
 * 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_AMOUNT structures
   at once */

#define GROW_SHRINK_SIZE 512

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


struct io_context *io_context_create(void)
{
   /* Create an I/O context */
   struct io_context *tmp;
   tmp = malloc(sizeof(struct io_context));
   if (tmp) {
      tmp->needshrink = 0;
      tmp->fdcnt = 0;
      tmp->maxfdcnt = GROW_SHRINK_SIZE/2;
      tmp->current_ioc = -1;
      tmp->fds = malloc((GROW_SHRINK_SIZE/2) * sizeof(struct pollfd));
      if (!tmp->fds) {
         free(tmp);
         tmp = NULL;
      } else {
         memset(tmp->fds, 0, (GROW_SHRINK_SIZE/2) * sizeof(struct pollfd));
         tmp->ior =  malloc((GROW_SHRINK_SIZE/2) * sizeof(struct io_rec));
         if (!tmp->ior) {
            free(tmp->fds);
            free(tmp);
            tmp = NULL;
         } else
            memset(tmp->ior, 0, (GROW_SHRINK_SIZE/2) * sizeof(struct io_rec));
      }
   }
   return tmp;
}

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

static int io_grow(struct io_context *ioc)
{
   /* 
    * Grow the size of our arrays.  Return 0 on success or
    * -1 on failure
    */
   void *tmp;
   DEBUG(ast_log(LOG_DEBUG, "io_grow()\n"));
   ioc->maxfdcnt += GROW_SHRINK_SIZE;
   tmp = realloc(ioc->ior, (ioc->maxfdcnt + 1) * sizeof(struct io_rec));
   if (tmp) {
      ioc->ior = (struct io_rec *)tmp;
      tmp = realloc(ioc->fds, (ioc->maxfdcnt + 1) * sizeof(struct pollfd));
      if (tmp) {
         ioc->fds = tmp;
      } else {
         /*
          * Not 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 {
      /*
       * Out of memory.  We return to the old size, and return a failure
       */
      ioc->maxfdcnt -= GROW_SHRINK_SIZE;
      return -1;
   }
   return 0;
}

int *ast_io_add(struct io_context *ioc, int fd, ast_io_cb callback, short events, void *data)
{
   /*
    * Add a new I/O entry for this file descriptor
    * with the given event mask, to call callback with
    * data as an argument.  Returns NULL on failure.
    */
   int *ret;
   DEBUG(ast_log(LOG_DEBUG, "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->ior[ioc->fdcnt].callback = callback;
   ioc->ior[ioc->fdcnt].data = data;
   ioc->ior[ioc->fdcnt].id = (int *)malloc(sizeof(int));
   /* Bonk if we couldn't allocate an int */
   if (!ioc->ior[ioc->fdcnt].id)
      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 (*id < ioc->fdcnt) {
      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;
   } else return NULL;
}

static int io_shrink(struct io_context *ioc)
{
   int getfrom;
   int 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 */
         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)
            io_shrink(ioc);
         return 0;
      }
   }
   
   ast_log(LOG_NOTICE, "Unable to remove unknown id %p\n", _id);
   return -1;
}

int ast_io_wait(struct io_context *ioc, int howlong)
{
   /*
    * Make the poll call, and call
    * the callbacks for anything that needs
    * to be handled
    */
   int res;
   int x;
   int origcnt;
   DEBUG(ast_log(LOG_DEBUG, "ast_io_wait()\n"));
   res = poll(ioc->fds, ioc->fdcnt, howlong);
   if (res > 0) {
      /*
       * At least one event
       */
      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_log(LOG_DEBUG, "Asterisk IO Dump: %d entries, %d max entries\n", ioc->fdcnt, ioc->maxfdcnt);
   ast_log(LOG_DEBUG, "================================================\n");
   ast_log(LOG_DEBUG, "| ID    FD     Callback    Data        Events  |\n");
   ast_log(LOG_DEBUG, "+------+------+-----------+-----------+--------+\n");
   for (x=0;x<ioc->fdcnt;x++) {
      ast_log(LOG_DEBUG, "| %.4d | %.4d | %p | %p | %.6x |\n", 
            *ioc->ior[x].id,
            ioc->fds[x].fd,
            ioc->ior[x].callback,
            ioc->ior[x].data,
            ioc->fds[x].events);
   }
   ast_log(LOG_DEBUG, "================================================\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;
}

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