Asterisk.org: Developer Documentation (28 Oct 2009)

Wed Oct 28 15:47:54 2009

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# io.c

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    00001 /*
    00002  * Asterisk -- An open source telephony toolkit.
    00003  *
    00004  * Copyright (C) 1999 - 2005, Digium, Inc.
    00005  *
    00006  * Mark Spencer <markster@digium.com>
    00007  *
    00008  * See http://www.asterisk.org for more information about
    00009  * the Asterisk project. Please do not directly contact
    00010  * any of the maintainers of this project for assistance;
    00011  * the project provides a web site, mailing lists and IRC
    00012  * channels for your use.
    00013  *
    00014  * This program is free software, distributed under the terms of
    00015  * the GNU General Public License Version 2. See the LICENSE file
    00016  * at the top of the source tree.
    00017  */
    00018
    00019 /*! \file
    00020  *
    00021  * \brief I/O Managment (Derived from Cheops-NG)
    00022  *
    00023  */
    00024
    00025 #include <stdio.h>
    00026 #include <unistd.h>
    00027 #include <stdlib.h>
    00028 #include <termios.h>
    00029 #include <string.h> /* for memset */
    00030 #include <sys/ioctl.h>
    00031
    00032 #include "asterisk.h"
    00033
    00034 ASTERISK_FILE_VERSION(__FILE__, "$Revision: 44168 $")
    00035
    00036 #include "asterisk/io.h"
    00037 #include "asterisk/logger.h"
    00038
    00039 #ifdef DEBUG_IO
    00040 #define DEBUG DEBUG_M
    00041 #else
    00042 #define DEBUG(a)
    00043 #endif
    00044
    00045 /*
    00046  * Kept for each file descriptor
    00047  */
    00048 struct io_rec {
    00049    ast_io_cb callback;     /* What is to be called */
    00050    void *data;             /* Data to be passed */
    00051    int *id;                /* ID number */
    00052 };
    00053
    00054 /* These two arrays are keyed with
    00055    the same index.  it's too bad that
    00056    pollfd doesn't have a callback field
    00057    or something like that.  They grow as
    00058    needed, by GROW_SHRINK_AMOUNT structures
    00059    at once */
    00060
    00061 #define GROW_SHRINK_SIZE 512
    00062
    00063 /* Global variables are now in a struct in order to be
    00064    made threadsafe */
    00065 struct io_context {
    00066    /* Poll structure */
    00067    struct pollfd *fds;
    00068    /* Associated I/O records */
    00069    struct io_rec *ior;
    00070    /* First available fd */
    00071    unsigned int fdcnt;
    00072    /* Maximum available fd */
    00073    unsigned int maxfdcnt;
    00074    /* Currently used io callback */
    00075    int current_ioc;
    00076    /* Whether something has been deleted */
    00077    int needshrink;
    00078 };
    00079
    00080 struct io_context *io_context_create(void)
    00081 {
    00082    /* Create an I/O context */
    00083    struct io_context *tmp;
    00084    tmp = malloc(sizeof(struct io_context));
    00085    if (tmp) {
    00086       tmp->needshrink = 0;
    00087       tmp->fdcnt = 0;
    00088       tmp->maxfdcnt = GROW_SHRINK_SIZE/2;
    00089       tmp->current_ioc = -1;
    00090       tmp->fds = malloc((GROW_SHRINK_SIZE/2) * sizeof(struct pollfd));
    00091       if (!tmp->fds) {
    00092          free(tmp);
    00093          tmp = NULL;
    00094       } else {
    00095          memset(tmp->fds, 0, (GROW_SHRINK_SIZE / 2) * sizeof(struct pollfd));
    00096          tmp->ior =  malloc((GROW_SHRINK_SIZE / 2) * sizeof(struct io_rec));
    00097          if (!tmp->ior) {
    00098             free(tmp->fds);
    00099             free(tmp);
    00100             tmp = NULL;
    00101          } else {
    00102             memset(tmp->ior, 0, (GROW_SHRINK_SIZE / 2) * sizeof(struct io_rec));
    00103          }
    00104       }
    00105    }
    00106    return tmp;
    00107 }
    00108
    00109 void io_context_destroy(struct io_context *ioc)
    00110 {
    00111    /* Free associated memory with an I/O context */
    00112    if (ioc->fds)
    00113       free(ioc->fds);
    00114    if (ioc->ior)
    00115       free(ioc->ior);
    00116    free(ioc);
    00117 }
    00118
    00119 static int io_grow(struct io_context *ioc)
    00120 {
    00121    /*
    00122     * Grow the size of our arrays.  Return 0 on success or
    00123     * -1 on failure
    00124     */
    00125    void *tmp;
    00126    DEBUG(ast_log(LOG_DEBUG, "io_grow()\n"));
    00127    ioc->maxfdcnt += GROW_SHRINK_SIZE;
    00128    tmp = realloc(ioc->ior, (ioc->maxfdcnt + 1) * sizeof(struct io_rec));
    00129    if (tmp) {
    00130       ioc->ior = (struct io_rec *)tmp;
    00131       tmp = realloc(ioc->fds, (ioc->maxfdcnt + 1) * sizeof(struct pollfd));
    00132       if (tmp) {
    00133          ioc->fds = tmp;
    00134       } else {
    00135          /*
    00136           * Not enough memory for the pollfd.  Not really any need
    00137           * to shrink back the iorec's as we'll probably want to
    00138           * grow them again soon when more memory is available, and
    00139           * then they'll already be the right size
    00140           */
    00141          ioc->maxfdcnt -= GROW_SHRINK_SIZE;
    00142          return -1;
    00143       }
    00144    } else {
    00145       /*
    00146        * Out of memory.  We return to the old size, and return a failure
    00147        */
    00148       ioc->maxfdcnt -= GROW_SHRINK_SIZE;
    00149       return -1;
    00150    }
    00151    return 0;
    00152 }
    00153
    00154 int *ast_io_add(struct io_context *ioc, int fd, ast_io_cb callback, short events, void *data)
    00155 {
    00156    /*
    00157     * Add a new I/O entry for this file descriptor
    00158     * with the given event mask, to call callback with
    00159     * data as an argument.  Returns NULL on failure.
    00160     */
    00161    int *ret;
    00162    DEBUG(ast_log(LOG_DEBUG, "ast_io_add()\n"));
    00163    if (ioc->fdcnt >= ioc->maxfdcnt) {
    00164       /*
    00165        * We don't have enough space for this entry.  We need to
    00166        * reallocate maxfdcnt poll fd's and io_rec's, or back out now.
    00167        */
    00168       if (io_grow(ioc))
    00169          return NULL;
    00170    }
    00171
    00172    /*
    00173     * At this point, we've got sufficiently large arrays going
    00174     * and we can make an entry for it in the pollfd and io_r
    00175     * structures.
    00176     */
    00177    ioc->fds[ioc->fdcnt].fd = fd;
    00178    ioc->fds[ioc->fdcnt].events = events;
    00179    ioc->fds[ioc->fdcnt].revents = 0;
    00180    ioc->ior[ioc->fdcnt].callback = callback;
    00181    ioc->ior[ioc->fdcnt].data = data;
    00182    ioc->ior[ioc->fdcnt].id = (int *)malloc(sizeof(int));
    00183    /* Bonk if we couldn't allocate an int */
    00184    if (!ioc->ior[ioc->fdcnt].id)
    00185       return NULL;
    00186    *(ioc->ior[ioc->fdcnt].id) = ioc->fdcnt;
    00187    ret = ioc->ior[ioc->fdcnt].id;
    00188    ioc->fdcnt++;
    00189    return ret;
    00190 }
    00191
    00192 int *ast_io_change(struct io_context *ioc, int *id, int fd, ast_io_cb callback, short events, void *data)
    00193 {
    00194    if (*id < ioc->fdcnt) {
    00195       if (fd > -1)
    00196          ioc->fds[*id].fd = fd;
    00197       if (callback)
    00198          ioc->ior[*id].callback = callback;
    00199       if (events)
    00200          ioc->fds[*id].events = events;
    00201       if (data)
    00202          ioc->ior[*id].data = data;
    00203       return id;
    00204    }
    00205    return NULL;
    00206 }
    00207
    00208 static int io_shrink(struct io_context *ioc)
    00209 {
    00210    int getfrom;
    00211    int putto = 0;
    00212    /*
    00213     * Bring the fields from the very last entry to cover over
    00214     * the entry we are removing, then decrease the size of the
    00215     * arrays by one.
    00216     */
    00217    for (getfrom = 0; getfrom < ioc->fdcnt; getfrom++) {
    00218       if (ioc->ior[getfrom].id) {
    00219          /* In use, save it */
    00220          if (getfrom != putto) {
    00221             ioc->fds[putto] = ioc->fds[getfrom];
    00222             ioc->ior[putto] = ioc->ior[getfrom];
    00223             *(ioc->ior[putto].id) = putto;
    00224          }
    00225          putto++;
    00226       }
    00227    }
    00228    ioc->fdcnt = putto;
    00229    ioc->needshrink = 0;
    00230    /* FIXME: We should free some memory if we have lots of unused
    00231       io structs */
    00232    return 0;
    00233 }
    00234
    00235 int ast_io_remove(struct io_context *ioc, int *_id)
    00236 {
    00237    int x;
    00238    if (!_id) {
    00239       ast_log(LOG_WARNING, "Asked to remove NULL?\n");
    00240       return -1;
    00241    }
    00242    for (x = 0; x < ioc->fdcnt; x++) {
    00243       if (ioc->ior[x].id == _id) {
    00244          /* Free the int immediately and set to NULL so we know it's unused now */
    00245          free(ioc->ior[x].id);
    00246          ioc->ior[x].id = NULL;
    00247          ioc->fds[x].events = 0;
    00248          ioc->fds[x].revents = 0;
    00249          ioc->needshrink = 1;
    00250          if (ioc->current_ioc == -1)
    00251             io_shrink(ioc);
    00252          return 0;
    00253       }
    00254    }
    00255
    00256    ast_log(LOG_NOTICE, "Unable to remove unknown id %p\n", _id);
    00257    return -1;
    00258 }
    00259
    00260 int ast_io_wait(struct io_context *ioc, int howlong)
    00261 {
    00262    /*
    00263     * Make the poll call, and call
    00264     * the callbacks for anything that needs
    00265     * to be handled
    00266     */
    00267    int res;
    00268    int x;
    00269    int origcnt;
    00270    DEBUG(ast_log(LOG_DEBUG, "ast_io_wait()\n"));
    00271    res = poll(ioc->fds, ioc->fdcnt, howlong);
    00272    if (res > 0) {
    00273       /*
    00274        * At least one event
    00275        */
    00276       origcnt = ioc->fdcnt;
    00277       for(x = 0; x < origcnt; x++) {
    00278          /* Yes, it is possible for an entry to be deleted and still have an
    00279             event waiting if it occurs after the original calling id */
    00280          if (ioc->fds[x].revents && ioc->ior[x].id) {
    00281             /* There's an event waiting */
    00282             ioc->current_ioc = *ioc->ior[x].id;
    00283             if (ioc->ior[x].callback) {
    00284                if (!ioc->ior[x].callback(ioc->ior[x].id, ioc->fds[x].fd, ioc->fds[x].revents, ioc->ior[x].data)) {
    00285                   /* Time to delete them since they returned a 0 */
    00286                   ast_io_remove(ioc, ioc->ior[x].id);
    00287                }
    00288             }
    00289             ioc->current_ioc = -1;
    00290          }
    00291       }
    00292       if (ioc->needshrink)
    00293          io_shrink(ioc);
    00294    }
    00295    return res;
    00296 }
    00297
    00298 void ast_io_dump(struct io_context *ioc)
    00299 {
    00300    /*
    00301     * Print some debugging information via
    00302     * the logger interface
    00303     */
    00304    int x;
    00305    ast_log(LOG_DEBUG, "Asterisk IO Dump: %d entries, %d max entries\n", ioc->fdcnt, ioc->maxfdcnt);
    00306    ast_log(LOG_DEBUG, "================================================\n");
    00307    ast_log(LOG_DEBUG, "| ID    FD     Callback    Data        Events  |\n");
    00308    ast_log(LOG_DEBUG, "+------+------+-----------+-----------+--------+\n");
    00309    for (x = 0; x < ioc->fdcnt; x++) {
    00310       ast_log(LOG_DEBUG, "| %.4d | %.4d | %p | %p | %.6x |\n",
    00311             *ioc->ior[x].id,
    00312             ioc->fds[x].fd,
    00313             ioc->ior[x].callback,
    00314             ioc->ior[x].data,
    00315             ioc->fds[x].events);
    00316    }
    00317    ast_log(LOG_DEBUG, "================================================\n");
    00318 }
    00319
    00320 /* Unrelated I/O functions */
    00321
    00322 int ast_hide_password(int fd)
    00323 {
    00324    struct termios tios;
    00325    int res;
    00326    int old;
    00327    if (!isatty(fd))
    00328       return -1;
    00329    res = tcgetattr(fd, &tios);
    00330    if (res < 0)
    00331       return -1;
    00332    old = tios.c_lflag & (ECHO | ECHONL);
    00333    tios.c_lflag &= ~ECHO;
    00334    tios.c_lflag |= ECHONL;
    00335    res = tcsetattr(fd, TCSAFLUSH, &tios);
    00336    if (res < 0)
    00337       return -1;
    00338    return old;
    00339 }
    00340
    00341 int ast_restore_tty(int fd, int oldstate)
    00342 {
    00343    int res;
    00344    struct termios tios;
    00345    if (oldstate < 0)
    00346       return 0;
    00347    res = tcgetattr(fd, &tios);
    00348    if (res < 0)
    00349       return -1;
    00350    tios.c_lflag &= ~(ECHO | ECHONL);
    00351    tios.c_lflag |= oldstate;
    00352    res = tcsetattr(fd, TCSAFLUSH, &tios);
    00353    if (res < 0)
    00354       return -1;
    00355    return 0;
    00356 }
    00357
    00358 int ast_get_termcols(int fd)
    00359 {
    00360    struct winsize win;
    00361    int cols = 0;
    00362
    00363    if (!isatty(fd))
    00364       return -1;
    00365
    00366    if ( ioctl(fd, TIOCGWINSZ, &win) != -1 ) {
    00367       if ( !cols && win.ws_col > 0 )
    00368          cols = (int) win.ws_col;
    00369    } else {
    00370       /* assume 80 characters if the ioctl fails for some reason */
    00371       cols = 80;
    00372    }
    00373
    00374    return cols;
    00375 }
    00376