util/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 "qemu/osdep.h"
  26 #include "qapi/error.h"
  27 #include "qemu-common.h"
  28 #include "qemu/queue.h"
  29 #include "block/aio.h"
  30 #include "qemu/main-loop.h"
  31
  32 #ifndef _WIN32
  33 #include <sys/wait.h>
  34 #endif
  35
  36 /* This context runs on top of main loop. We can't reuse qemu_aio_context
  37  * because iohandlers mustn't be polled by aio_poll(qemu_aio_context). */
  38 static AioContext *iohandler_ctx;
  39
  40 static void iohandler_init(void)
  41 {
  42     if (!iohandler_ctx) {
  43         iohandler_ctx = aio_context_new(&error_abort);
  44     }
  45 }
  46
  47 AioContext *iohandler_get_aio_context(void)
  48 {
  49     iohandler_init();
  50     return iohandler_ctx;
  51 }
  52
  53 GSource *iohandler_get_g_source(void)
  54 {
  55     iohandler_init();
  56     return aio_get_g_source(iohandler_ctx);
  57 }
  58
  59 void qemu_set_fd_handler(int fd,
  60                          IOHandler *fd_read,
  61                          IOHandler *fd_write,
  62                          void *opaque)
  63 {
  64     iohandler_init();
  65     aio_set_fd_handler(iohandler_ctx, fd, false,
  66                        fd_read, fd_write, NULL, opaque);
  67 }
  68
  69 void event_notifier_set_handler(EventNotifier *e,
  70                                 EventNotifierHandler *handler)
  71 {
  72     iohandler_init();
  73     aio_set_event_notifier(iohandler_ctx, e, false,
  74                            handler, NULL);
  75 }
  76
  77 /* reaping of zombies.  right now we're not passing the status to
  78    anyone, but it would be possible to add a callback.  */
  79 #ifndef _WIN32
  80 typedef struct ChildProcessRecord {
  81     int pid;
  82     QLIST_ENTRY(ChildProcessRecord) next;
  83 } ChildProcessRecord;
  84
  85 static QLIST_HEAD(, ChildProcessRecord) child_watches =
  86     QLIST_HEAD_INITIALIZER(child_watches);
  87
  88 static QEMUBH *sigchld_bh;
  89
  90 static void sigchld_handler(int signal)
  91 {
  92     qemu_bh_schedule(sigchld_bh);
  93 }
  94
  95 static void sigchld_bh_handler(void *opaque)
  96 {
  97     ChildProcessRecord *rec, *next;
  98
  99     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
 100         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
 101             QLIST_REMOVE(rec, next);
 102             g_free(rec);
 103         }
 104     }
 105 }
 106
 107 static void qemu_init_child_watch(void)
 108 {
 109     struct sigaction act;
 110     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
 111
 112     memset(&act, 0, sizeof(act));
 113     act.sa_handler = sigchld_handler;
 114     act.sa_flags = SA_NOCLDSTOP;
 115     sigaction(SIGCHLD, &act, NULL);
 116 }
 117
 118 int qemu_add_child_watch(pid_t pid)
 119 {
 120     ChildProcessRecord *rec;
 121
 122     if (!sigchld_bh) {
 123         qemu_init_child_watch();
 124     }
 125
 126     QLIST_FOREACH(rec, &child_watches, next) {
 127         if (rec->pid == pid) {
 128             return 1;
 129         }
 130     }
 131     rec = g_malloc0(sizeof(ChildProcessRecord));
 132     rec->pid = pid;
 133     QLIST_INSERT_HEAD(&child_watches, rec, next);
 134     return 0;
 135 }
 136 #endif