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