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 #ifndef _WIN32
  31 #include <sys/wait.h>
  32 #endif
  33
  34 typedef struct IOHandlerRecord {
  35     int fd;
  36     IOCanReadHandler *fd_read_poll;
  37     IOHandler *fd_read;
  38     IOHandler *fd_write;
  39     int deleted;
  40     void *opaque;
  41     QLIST_ENTRY(IOHandlerRecord) next;
  42 } IOHandlerRecord;
  43
  44 static QLIST_HEAD(, IOHandlerRecord) io_handlers =
  45     QLIST_HEAD_INITIALIZER(io_handlers);
  46
  47
  48 /* XXX: fd_read_poll should be suppressed, but an API change is
  49    necessary in the character devices to suppress fd_can_read(). */
  50 int qemu_set_fd_handler2(int fd,
  51                          IOCanReadHandler *fd_read_poll,
  52                          IOHandler *fd_read,
  53                          IOHandler *fd_write,
  54                          void *opaque)
  55 {
  56     IOHandlerRecord *ioh;
  57
  58     if (!fd_read && !fd_write) {
  59         QLIST_FOREACH(ioh, &io_handlers, next) {
  60             if (ioh->fd == fd) {
  61                 ioh->deleted = 1;
  62                 break;
  63             }
  64         }
  65     } else {
  66         QLIST_FOREACH(ioh, &io_handlers, next) {
  67             if (ioh->fd == fd)
  68                 goto found;
  69         }
  70         ioh = g_malloc0(sizeof(IOHandlerRecord));
  71         QLIST_INSERT_HEAD(&io_handlers, ioh, next);
  72     found:
  73         ioh->fd = fd;
  74         ioh->fd_read_poll = fd_read_poll;
  75         ioh->fd_read = fd_read;
  76         ioh->fd_write = fd_write;
  77         ioh->opaque = opaque;
  78         ioh->deleted = 0;
  79     }
  80     return 0;
  81 }
  82
  83 typedef struct IOTrampoline
  84 {
  85     GIOChannel *chan;
  86     IOHandler *fd_read;
  87     IOHandler *fd_write;
  88     void *opaque;
  89     guint tag;
  90 } IOTrampoline;
  91
  92 static gboolean fd_trampoline(GIOChannel *chan, GIOCondition cond, gpointer opaque)
  93 {
  94     IOTrampoline *tramp = opaque;
  95
  96     if ((cond & G_IO_IN) && tramp->fd_read) {
  97         tramp->fd_read(tramp->opaque);
  98     }
  99
 100     if ((cond & G_IO_OUT) && tramp->fd_write) {
 101         tramp->fd_write(tramp->opaque);
 102     }
 103
 104     return TRUE;
 105 }
 106
 107 int qemu_set_fd_handler(int fd,
 108                         IOHandler *fd_read,
 109                         IOHandler *fd_write,
 110                         void *opaque)
 111 {
 112     static IOTrampoline fd_trampolines[FD_SETSIZE];
 113     IOTrampoline *tramp = &fd_trampolines[fd];
 114
 115     if (tramp->tag != 0) {
 116         g_io_channel_unref(tramp->chan);
 117         g_source_remove(tramp->tag);
 118         tramp->tag = 0;
 119     }
 120
 121     if (fd_read || fd_write || opaque) {
 122         GIOCondition cond = 0;
 123
 124         tramp->fd_read = fd_read;
 125         tramp->fd_write = fd_write;
 126         tramp->opaque = opaque;
 127
 128         if (fd_read) {
 129             cond |= G_IO_IN | G_IO_ERR;
 130         }
 131
 132         if (fd_write) {
 133             cond |= G_IO_OUT | G_IO_ERR;
 134         }
 135
 136         tramp->chan = g_io_channel_unix_new(fd);
 137         tramp->tag = g_io_add_watch(tramp->chan, cond, fd_trampoline, tramp);
 138     }
 139
 140     return 0;
 141 }
 142
 143 void qemu_iohandler_fill(int *pnfds, fd_set *readfds, fd_set *writefds, fd_set *xfds)
 144 {
 145     IOHandlerRecord *ioh;
 146
 147     QLIST_FOREACH(ioh, &io_handlers, next) {
 148         if (ioh->deleted)
 149             continue;
 150         if (ioh->fd_read &&
 151             (!ioh->fd_read_poll ||
 152              ioh->fd_read_poll(ioh->opaque) != 0)) {
 153             FD_SET(ioh->fd, readfds);
 154             if (ioh->fd > *pnfds)
 155                 *pnfds = ioh->fd;
 156         }
 157         if (ioh->fd_write) {
 158             FD_SET(ioh->fd, writefds);
 159             if (ioh->fd > *pnfds)
 160                 *pnfds = ioh->fd;
 161         }
 162     }
 163 }
 164
 165 void qemu_iohandler_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds, int ret)
 166 {
 167     if (ret > 0) {
 168         IOHandlerRecord *pioh, *ioh;
 169
 170         QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
 171             if (!ioh->deleted && ioh->fd_read && FD_ISSET(ioh->fd, readfds)) {
 172                 ioh->fd_read(ioh->opaque);
 173             }
 174             if (!ioh->deleted && ioh->fd_write && FD_ISSET(ioh->fd, writefds)) {
 175                 ioh->fd_write(ioh->opaque);
 176             }
 177
 178             /* Do this last in case read/write handlers marked it for deletion */
 179             if (ioh->deleted) {
 180                 QLIST_REMOVE(ioh, next);
 181                 g_free(ioh);
 182             }
 183         }
 184     }
 185 }
 186
 187 /* reaping of zombies.  right now we're not passing the status to
 188    anyone, but it would be possible to add a callback.  */
 189 #ifndef _WIN32
 190 typedef struct ChildProcessRecord {
 191     int pid;
 192     QLIST_ENTRY(ChildProcessRecord) next;
 193 } ChildProcessRecord;
 194
 195 static QLIST_HEAD(, ChildProcessRecord) child_watches =
 196     QLIST_HEAD_INITIALIZER(child_watches);
 197
 198 static QEMUBH *sigchld_bh;
 199
 200 static void sigchld_handler(int signal)
 201 {
 202     qemu_bh_schedule(sigchld_bh);
 203 }
 204
 205 static void sigchld_bh_handler(void *opaque)
 206 {
 207     ChildProcessRecord *rec, *next;
 208
 209     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 210         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 211             QLIST_REMOVE(rec, next);
 212             g_free(rec);
 213         }
 214     }
 215 }
 216
 217 static void qemu_init_child_watch(void)
 218 {
 219     struct sigaction act;
 220     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 221
 222     act.sa_handler = sigchld_handler;
 223     act.sa_flags = SA_NOCLDSTOP;
 224     sigaction(SIGCHLD, &act, NULL);
 225 }
 226
 227 int qemu_add_child_watch(pid_t pid)
 228 {
 229     ChildProcessRecord *rec;
 230
 231     if (!sigchld_bh) {
 232         qemu_init_child_watch();
 233     }
 234
 235     QLIST_FOREACH(rec, &child_watches, next) {
 236         if (rec->pid == pid) {
 237             return 1;
 238         }
 239     }
 240     rec = g_malloc0(sizeof(ChildProcessRecord));
 241     rec->pid = pid;
 242     QLIST_INSERT_HEAD(&child_watches, rec, next);
 243     return 0;
 244 }
 245 #endif