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/queue.h"
  28 #include "block/aio.h"
  29 #include "qemu/main-loop.h"
  30
  31 #ifndef _WIN32
  32 #include <sys/wait.h>
  33 #endif
  34
  35 typedef struct IOHandlerRecord {
  36     IOCanReadHandler *fd_read_poll;
  37     IOHandler *fd_read;
  38     IOHandler *fd_write;
  39     void *opaque;
  40     QLIST_ENTRY(IOHandlerRecord) next;
  41     int fd;
  42     int pollfds_idx;
  43     bool deleted;
  44 } IOHandlerRecord;
  45
  46 static QLIST_HEAD(, IOHandlerRecord) io_handlers =
  47     QLIST_HEAD_INITIALIZER(io_handlers);
  48
  49
  50 /* XXX: fd_read_poll should be suppressed, but an API change is
  51    necessary in the character devices to suppress fd_can_read(). */
  52 int qemu_set_fd_handler2(int fd,
  53                          IOCanReadHandler *fd_read_poll,
  54                          IOHandler *fd_read,
  55                          IOHandler *fd_write,
  56                          void *opaque)
  57 {
  58     IOHandlerRecord *ioh;
  59
  60     assert(fd >= 0);
  61
  62     if (!fd_read && !fd_write) {
  63         QLIST_FOREACH(ioh, &io_handlers, next) {
  64             if (ioh->fd == fd) {
  65                 ioh->deleted = 1;
  66                 break;
  67             }
  68         }
  69     } else {
  70         QLIST_FOREACH(ioh, &io_handlers, next) {
  71             if (ioh->fd == fd)
  72                 goto found;
  73         }
  74         ioh = g_malloc0(sizeof(IOHandlerRecord));
  75         QLIST_INSERT_HEAD(&io_handlers, ioh, next);
  76     found:
  77         ioh->fd = fd;
  78         ioh->fd_read_poll = fd_read_poll;
  79         ioh->fd_read = fd_read;
  80         ioh->fd_write = fd_write;
  81         ioh->opaque = opaque;
  82         ioh->pollfds_idx = -1;
  83         ioh->deleted = 0;
  84         qemu_notify_event();
  85     }
  86     return 0;
  87 }
  88
  89 int qemu_set_fd_handler(int fd,
  90                         IOHandler *fd_read,
  91                         IOHandler *fd_write,
  92                         void *opaque)
  93 {
  94     return qemu_set_fd_handler2(fd, NULL, fd_read, fd_write, opaque);
  95 }
  96
  97 void qemu_iohandler_fill(GArray *pollfds)
  98 {
  99     IOHandlerRecord *ioh;
 100
 101     QLIST_FOREACH(ioh, &io_handlers, next) {
 102         int events = 0;
 103
 104         if (ioh->deleted)
 105             continue;
 106         if (ioh->fd_read &&
 107             (!ioh->fd_read_poll ||
 108              ioh->fd_read_poll(ioh->opaque) != 0)) {
 109             events |= G_IO_IN | G_IO_HUP | G_IO_ERR;
 110         }
 111         if (ioh->fd_write) {
 112             events |= G_IO_OUT | G_IO_ERR;
 113         }
 114         if (events) {
 115             GPollFD pfd = {
 116                 .fd = ioh->fd,
 117                 .events = events,
 118             };
 119             ioh->pollfds_idx = pollfds->len;
 120             g_array_append_val(pollfds, pfd);
 121         } else {
 122             ioh->pollfds_idx = -1;
 123         }
 124     }
 125 }
 126
 127 void qemu_iohandler_poll(GArray *pollfds, int ret)
 128 {
 129     if (ret > 0) {
 130         IOHandlerRecord *pioh, *ioh;
 131
 132         QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
 133             int revents = 0;
 134
 135             if (!ioh->deleted && ioh->pollfds_idx != -1) {
 136                 GPollFD *pfd = &g_array_index(pollfds, GPollFD,
 137                                               ioh->pollfds_idx);
 138                 revents = pfd->revents;
 139             }
 140
 141             if (!ioh->deleted && ioh->fd_read &&
 142                 (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR))) {
 143                 ioh->fd_read(ioh->opaque);
 144             }
 145             if (!ioh->deleted && ioh->fd_write &&
 146                 (revents & (G_IO_OUT | G_IO_ERR))) {
 147                 ioh->fd_write(ioh->opaque);
 148             }
 149
 150             /* Do this last in case read/write handlers marked it for deletion */
 151             if (ioh->deleted) {
 152                 QLIST_REMOVE(ioh, next);
 153                 g_free(ioh);
 154             }
 155         }
 156     }
 157 }
 158
 159 /* reaping of zombies.  right now we're not passing the status to
 160    anyone, but it would be possible to add a callback.  */
 161 #ifndef _WIN32
 162 typedef struct ChildProcessRecord {
 163     int pid;
 164     QLIST_ENTRY(ChildProcessRecord) next;
 165 } ChildProcessRecord;
 166
 167 static QLIST_HEAD(, ChildProcessRecord) child_watches =
 168     QLIST_HEAD_INITIALIZER(child_watches);
 169
 170 static QEMUBH *sigchld_bh;
 171
 172 static void sigchld_handler(int signal)
 173 {
 174     qemu_bh_schedule(sigchld_bh);
 175 }
 176
 177 static void sigchld_bh_handler(void *opaque)
 178 {
 179     ChildProcessRecord *rec, *next;
 180
 181     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 182         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 183             QLIST_REMOVE(rec, next);
 184             g_free(rec);
 185         }
 186     }
 187 }
 188
 189 static void qemu_init_child_watch(void)
 190 {
 191     struct sigaction act;
 192     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 193
 194     act.sa_handler = sigchld_handler;
 195     act.sa_flags = SA_NOCLDSTOP;
 196     sigaction(SIGCHLD, &act, NULL);
 197 }
 198
 199 int qemu_add_child_watch(pid_t pid)
 200 {
 201     ChildProcessRecord *rec;
 202
 203     if (!sigchld_bh) {
 204         qemu_init_child_watch();
 205     }
 206
 207     QLIST_FOREACH(rec, &child_watches, next) {
 208         if (rec->pid == pid) {
 209             return 1;
 210         }
 211     }
 212     rec = g_malloc0(sizeof(ChildProcessRecord));
 213     rec->pid = pid;
 214     QLIST_INSERT_HEAD(&child_watches, rec, next);
 215     return 0;
 216 }
 217 #endif