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