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     bool deleted;
  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     assert(fd >= 0);
  60
  61     if (!fd_read && !fd_write) {
  62         QLIST_FOREACH(ioh, &io_handlers, next) {
  63             if (ioh->fd == fd) {
  64                 ioh->deleted = 1;
  65                 break;
  66             }
  67         }
  68     } else {
  69         QLIST_FOREACH(ioh, &io_handlers, next) {
  70             if (ioh->fd == fd)
  71                 goto found;
  72         }
  73         ioh = g_malloc0(sizeof(IOHandlerRecord));
  74         QLIST_INSERT_HEAD(&io_handlers, ioh, next);
  75     found:
  76         ioh->fd = fd;
  77         ioh->fd_read_poll = fd_read_poll;
  78         ioh->fd_read = fd_read;
  79         ioh->fd_write = fd_write;
  80         ioh->opaque = opaque;
  81         ioh->deleted = 0;
  82         qemu_notify_event();
  83     }
  84     return 0;
  85 }
  86
  87 int qemu_set_fd_handler(int fd,
  88                         IOHandler *fd_read,
  89                         IOHandler *fd_write,
  90                         void *opaque)
  91 {
  92     return qemu_set_fd_handler2(fd, NULL, fd_read, fd_write, opaque);
  93 }
  94
  95 void qemu_iohandler_fill(int *pnfds, fd_set *readfds, fd_set *writefds, fd_set *xfds)
  96 {
  97     IOHandlerRecord *ioh;
  98
  99     QLIST_FOREACH(ioh, &io_handlers, next) {
 100         if (ioh->deleted)
 101             continue;
 102         if (ioh->fd_read &&
 103             (!ioh->fd_read_poll ||
 104              ioh->fd_read_poll(ioh->opaque) != 0)) {
 105             FD_SET(ioh->fd, readfds);
 106             if (ioh->fd > *pnfds)
 107                 *pnfds = ioh->fd;
 108         }
 109         if (ioh->fd_write) {
 110             FD_SET(ioh->fd, writefds);
 111             if (ioh->fd > *pnfds)
 112                 *pnfds = ioh->fd;
 113         }
 114     }
 115 }
 116
 117 void qemu_iohandler_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds, int ret)
 118 {
 119     if (ret > 0) {
 120         IOHandlerRecord *pioh, *ioh;
 121
 122         QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
 123             if (!ioh->deleted && ioh->fd_read && FD_ISSET(ioh->fd, readfds)) {
 124                 ioh->fd_read(ioh->opaque);
 125             }
 126             if (!ioh->deleted && ioh->fd_write && FD_ISSET(ioh->fd, writefds)) {
 127                 ioh->fd_write(ioh->opaque);
 128             }
 129
 130             /* Do this last in case read/write handlers marked it for deletion */
 131             if (ioh->deleted) {
 132                 QLIST_REMOVE(ioh, next);
 133                 g_free(ioh);
 134             }
 135         }
 136     }
 137 }
 138
 139 /* reaping of zombies.  right now we're not passing the status to
 140    anyone, but it would be possible to add a callback.  */
 141 #ifndef _WIN32
 142 typedef struct ChildProcessRecord {
 143     int pid;
 144     QLIST_ENTRY(ChildProcessRecord) next;
 145 } ChildProcessRecord;
 146
 147 static QLIST_HEAD(, ChildProcessRecord) child_watches =
 148     QLIST_HEAD_INITIALIZER(child_watches);
 149
 150 static QEMUBH *sigchld_bh;
 151
 152 static void sigchld_handler(int signal)
 153 {
 154     qemu_bh_schedule(sigchld_bh);
 155 }
 156
 157 static void sigchld_bh_handler(void *opaque)
 158 {
 159     ChildProcessRecord *rec, *next;
 160
 161     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 162         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 163             QLIST_REMOVE(rec, next);
 164             g_free(rec);
 165         }
 166     }
 167 }
 168
 169 static void qemu_init_child_watch(void)
 170 {
 171     struct sigaction act;
 172     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 173
 174     act.sa_handler = sigchld_handler;
 175     act.sa_flags = SA_NOCLDSTOP;
 176     sigaction(SIGCHLD, &act, NULL);
 177 }
 178
 179 int qemu_add_child_watch(pid_t pid)
 180 {
 181     ChildProcessRecord *rec;
 182
 183     if (!sigchld_bh) {
 184         qemu_init_child_watch();
 185     }
 186
 187     QLIST_FOREACH(rec, &child_watches, next) {
 188         if (rec->pid == pid) {
 189             return 1;
 190         }
 191     }
 192     rec = g_malloc0(sizeof(ChildProcessRecord));
 193     rec->pid = pid;
 194     QLIST_INSERT_HEAD(&child_watches, rec, next);
 195     return 0;
 196 }
 197 #endif