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     IOHandler *fd_read;
  37     IOHandler *fd_write;
  38     void *opaque;
  39     QLIST_ENTRY(IOHandlerRecord) next;
  40     int fd;
  41     int pollfds_idx;
  42     bool deleted;
  43 } IOHandlerRecord;
  44
  45 static QLIST_HEAD(, IOHandlerRecord) io_handlers =
  46     QLIST_HEAD_INITIALIZER(io_handlers);
  47
  48 void qemu_set_fd_handler(int fd,
  49                          IOHandler *fd_read,
  50                          IOHandler *fd_write,
  51                          void *opaque)
  52 {
  53     IOHandlerRecord *ioh;
  54
  55     assert(fd >= 0);
  56
  57     if (!fd_read && !fd_write) {
  58         QLIST_FOREACH(ioh, &io_handlers, next) {
  59             if (ioh->fd == fd) {
  60                 ioh->deleted = 1;
  61                 break;
  62             }
  63         }
  64     } else {
  65         QLIST_FOREACH(ioh, &io_handlers, next) {
  66             if (ioh->fd == fd)
  67                 goto found;
  68         }
  69         ioh = g_malloc0(sizeof(IOHandlerRecord));
  70         QLIST_INSERT_HEAD(&io_handlers, ioh, next);
  71     found:
  72         ioh->fd = fd;
  73         ioh->fd_read = fd_read;
  74         ioh->fd_write = fd_write;
  75         ioh->opaque = opaque;
  76         ioh->pollfds_idx = -1;
  77         ioh->deleted = 0;
  78         qemu_notify_event();
  79     }
  80 }
  81
  82 void qemu_iohandler_fill(GArray *pollfds)
  83 {
  84     IOHandlerRecord *ioh;
  85
  86     QLIST_FOREACH(ioh, &io_handlers, next) {
  87         int events = 0;
  88
  89         if (ioh->deleted)
  90             continue;
  91         if (ioh->fd_read) {
  92             events |= G_IO_IN | G_IO_HUP | G_IO_ERR;
  93         }
  94         if (ioh->fd_write) {
  95             events |= G_IO_OUT | G_IO_ERR;
  96         }
  97         if (events) {
  98             GPollFD pfd = {
  99                 .fd = ioh->fd,
 100                 .events = events,
 101             };
 102             ioh->pollfds_idx = pollfds->len;
 103             g_array_append_val(pollfds, pfd);
 104         } else {
 105             ioh->pollfds_idx = -1;
 106         }
 107     }
 108 }
 109
 110 void qemu_iohandler_poll(GArray *pollfds, int ret)
 111 {
 112     if (ret > 0) {
 113         IOHandlerRecord *pioh, *ioh;
 114
 115         QLIST_FOREACH_SAFE(ioh, &io_handlers, next, pioh) {
 116             int revents = 0;
 117
 118             if (!ioh->deleted && ioh->pollfds_idx != -1) {
 119                 GPollFD *pfd = &g_array_index(pollfds, GPollFD,
 120                                               ioh->pollfds_idx);
 121                 revents = pfd->revents;
 122             }
 123
 124             if (!ioh->deleted && ioh->fd_read &&
 125                 (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR))) {
 126                 ioh->fd_read(ioh->opaque);
 127             }
 128             if (!ioh->deleted && ioh->fd_write &&
 129                 (revents & (G_IO_OUT | G_IO_ERR))) {
 130                 ioh->fd_write(ioh->opaque);
 131             }
 132
 133             /* Do this last in case read/write handlers marked it for deletion */
 134             if (ioh->deleted) {
 135                 QLIST_REMOVE(ioh, next);
 136                 g_free(ioh);
 137             }
 138         }
 139     }
 140 }
 141
 142 /* reaping of zombies.  right now we're not passing the status to
 143    anyone, but it would be possible to add a callback.  */
 144 #ifndef _WIN32
 145 typedef struct ChildProcessRecord {
 146     int pid;
 147     QLIST_ENTRY(ChildProcessRecord) next;
 148 } ChildProcessRecord;
 149
 150 static QLIST_HEAD(, ChildProcessRecord) child_watches =
 151     QLIST_HEAD_INITIALIZER(child_watches);
 152
 153 static QEMUBH *sigchld_bh;
 154
 155 static void sigchld_handler(int signal)
 156 {
 157     qemu_bh_schedule(sigchld_bh);
 158 }
 159
 160 static void sigchld_bh_handler(void *opaque)
 161 {
 162     ChildProcessRecord *rec, *next;
 163
 164     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 165         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 166             QLIST_REMOVE(rec, next);
 167             g_free(rec);
 168         }
 169     }
 170 }
 171
 172 static void qemu_init_child_watch(void)
 173 {
 174     struct sigaction act;
 175     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 176
 177     memset(&act, 0, sizeof(act));
 178     act.sa_handler = sigchld_handler;
 179     act.sa_flags = SA_NOCLDSTOP;
 180     sigaction(SIGCHLD, &act, NULL);
 181 }
 182
 183 int qemu_add_child_watch(pid_t pid)
 184 {
 185     ChildProcessRecord *rec;
 186
 187     if (!sigchld_bh) {
 188         qemu_init_child_watch();
 189     }
 190
 191     QLIST_FOREACH(rec, &child_watches, next) {
 192         if (rec->pid == pid) {
 193             return 1;
 194         }
 195     }
 196     rec = g_malloc0(sizeof(ChildProcessRecord));
 197     rec->pid = pid;
 198     QLIST_INSERT_HEAD(&child_watches, rec, next);
 199     return 0;
 200 }
 201 #endif