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