iohandler.c

   1 /*
   2  * QEMU System Emulator - managing I/O handler
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "config-host.h"
  26 #include "qemu-common.h"
  27 #include "qemu-char.h"
  28 #include "qemu-queue.h"
  29
  30 typedef struct IOHandlerRecord {
  31     int fd;
  32     IOCanReadHandler *fd_read_poll;
  33     IOHandler *fd_read;
  34     IOHandler *fd_write;
  35     int deleted;
  36     void *opaque;
  37     QLIST_ENTRY(IOHandlerRecord) next;
  38 } IOHandlerRecord;
  39
  40 static QLIST_HEAD(, IOHandlerRecord) io_handlers =
  41     QLIST_HEAD_INITIALIZER(io_handlers);
  42
  43
  44 /* XXX: fd_read_poll should be suppressed, but an API change is
  45    necessary in the character devices to suppress fd_can_read(). */
  46 int qemu_set_fd_handler2(int fd,
  47                          IOCanReadHandler *fd_read_poll,
  48                          IOHandler *fd_read,
  49                          IOHandler *fd_write,
  50                          void *opaque)
  51 {
  52     IOHandlerRecord *ioh;
  53
  54     if (!fd_read && !fd_write) {
  55         QLIST_FOREACH(ioh, &io_handlers, next) {
  56             if (ioh->fd == fd) {
  57                 ioh->deleted = 1;
  58                 break;
  59             }
  60         }
  61     } else {
  62         QLIST_FOREACH(ioh, &io_handlers, next) {
  63             if (ioh->fd == fd)
  64                 goto found;
  65         }
  66         ioh = qemu_mallocz(sizeof(IOHandlerRecord));
  67         QLIST_INSERT_HEAD(&io_handlers, ioh, next);
  68     found:
  69         ioh->fd = fd;
  70         ioh->fd_read_poll = fd_read_poll;
  71         ioh->fd_read = fd_read;
  72         ioh->fd_write = fd_write;
  73         ioh->opaque = opaque;
  74         ioh->deleted = 0;
  75     }
  76     return 0;
  77 }
  78
  79 int qemu_set_fd_handler(int fd,
  80                         IOHandler *fd_read,
  81                         IOHandler *fd_write,
  82                         void *opaque)
  83 {
  84     return qemu_set_fd_handler2(fd, NULL, fd_read, fd_write, opaque);
  85 }
  86
  87 void qemu_iohandler_fill(int *pnfds, fd_set *readfds, fd_set *writefds, fd_set *xfds)
  88 {
  89     IOHandlerRecord *ioh;
  90
  91     QLIST_FOREACH(ioh, &io_handlers, next) {
  92         if (ioh->deleted)
  93             continue;
  94         if (ioh->fd_read &&
  95             (!ioh->fd_read_poll ||
  96              ioh->fd_read_poll(ioh->opaque) != 0)) {
  97             FD_SET(ioh->fd, readfds);
  98             if (ioh->fd > *pnfds)
  99                 *pnfds = ioh->fd;
 100         }
 101         if (ioh->fd_write) {
 102             FD_SET(ioh->fd, writefds);
 103             if (ioh->fd > *pnfds)
 104                 *pnfds = ioh->fd;
 105         }
 106     }
 107 }
 108
 109 void qemu_iohandler_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds, int ret)
 110 {
 111     if (ret > 0) {
 112         IOHandlerRecord *pioh, *ioh;
 113
 114         QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
 115             if (!ioh->deleted && ioh->fd_read && FD_ISSET(ioh->fd, readfds)) {
 116                 ioh->fd_read(ioh->opaque);
 117             }
 118             if (!ioh->deleted && ioh->fd_write && FD_ISSET(ioh->fd, writefds)) {
 119                 ioh->fd_write(ioh->opaque);
 120             }
 121
 122             /* Do this last in case read/write handlers marked it for deletion */
 123             if (ioh->deleted) {
 124                 QLIST_REMOVE(ioh, next);
 125                 qemu_free(ioh);
 126             }
 127         }
 128     }
 129 }