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 "qemu-aio.h"
  30 #include "main-loop.h"
  31
  32 #ifndef _WIN32
  33 #include <sys/wait.h>
  34 #endif
  35
  36 typedef struct IOHandlerRecord {
  37     IOCanReadHandler *fd_read_poll;
  38     IOHandler *fd_read;
  39     IOHandler *fd_write;
  40     void *opaque;
  41     QLIST_ENTRY(IOHandlerRecord) next;
  42     int fd;
  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->deleted = 0;
  83         qemu_notify_event();
  84     }
  85     return 0;
  86 }
  87
  88 int qemu_set_fd_handler(int fd,
  89                         IOHandler *fd_read,
  90                         IOHandler *fd_write,
  91                         void *opaque)
  92 {
  93     return qemu_set_fd_handler2(fd, NULL, fd_read, fd_write, opaque);
  94 }
  95
  96 void qemu_iohandler_fill(int *pnfds, fd_set *readfds, fd_set *writefds, fd_set *xfds)
  97 {
  98     IOHandlerRecord *ioh;
  99
 100     QLIST_FOREACH(ioh, &io_handlers, next) {
 101         if (ioh->deleted)
 102             continue;
 103         if (ioh->fd_read &&
 104             (!ioh->fd_read_poll ||
 105              ioh->fd_read_poll(ioh->opaque) != 0)) {
 106             FD_SET(ioh->fd, readfds);
 107             if (ioh->fd > *pnfds)
 108                 *pnfds = ioh->fd;
 109         }
 110         if (ioh->fd_write) {
 111             FD_SET(ioh->fd, writefds);
 112             if (ioh->fd > *pnfds)
 113                 *pnfds = ioh->fd;
 114         }
 115     }
 116 }
 117
 118 void qemu_iohandler_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds, int ret)
 119 {
 120     if (ret > 0) {
 121         IOHandlerRecord *pioh, *ioh;
 122
 123         QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
 124             if (!ioh->deleted && ioh->fd_read && FD_ISSET(ioh->fd, readfds)) {
 125                 ioh->fd_read(ioh->opaque);
 126             }
 127             if (!ioh->deleted && ioh->fd_write && FD_ISSET(ioh->fd, writefds)) {
 128                 ioh->fd_write(ioh->opaque);
 129             }
 130
 131             /* Do this last in case read/write handlers marked it for deletion */
 132             if (ioh->deleted) {
 133                 QLIST_REMOVE(ioh, next);
 134                 g_free(ioh);
 135             }
 136         }
 137     }
 138 }
 139
 140 /* reaping of zombies.  right now we're not passing the status to
 141    anyone, but it would be possible to add a callback.  */
 142 #ifndef _WIN32
 143 typedef struct ChildProcessRecord {
 144     int pid;
 145     QLIST_ENTRY(ChildProcessRecord) next;
 146 } ChildProcessRecord;
 147
 148 static QLIST_HEAD(, ChildProcessRecord) child_watches =
 149     QLIST_HEAD_INITIALIZER(child_watches);
 150
 151 static QEMUBH *sigchld_bh;
 152
 153 static void sigchld_handler(int signal)
 154 {
 155     qemu_bh_schedule(sigchld_bh);
 156 }
 157
 158 static void sigchld_bh_handler(void *opaque)
 159 {
 160     ChildProcessRecord *rec, *next;
 161
 162     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 163         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 164             QLIST_REMOVE(rec, next);
 165             g_free(rec);
 166         }
 167     }
 168 }
 169
 170 static void qemu_init_child_watch(void)
 171 {
 172     struct sigaction act;
 173     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 174
 175     act.sa_handler = sigchld_handler;
 176     act.sa_flags = SA_NOCLDSTOP;
 177     sigaction(SIGCHLD, &act, NULL);
 178 }
 179
 180 int qemu_add_child_watch(pid_t pid)
 181 {
 182     ChildProcessRecord *rec;
 183
 184     if (!sigchld_bh) {
 185         qemu_init_child_watch();
 186     }
 187
 188     QLIST_FOREACH(rec, &child_watches, next) {
 189         if (rec->pid == pid) {
 190             return 1;
 191         }
 192     }
 193     rec = g_malloc0(sizeof(ChildProcessRecord));
 194     rec->pid = pid;
 195     QLIST_INSERT_HEAD(&child_watches, rec, next);
 196     return 0;
 197 }
 198 #endif