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