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 /* 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 GSource *iohandler_get_g_source(void)
  47 {
  48     iohandler_init();
  49     return aio_get_g_source(iohandler_ctx);
  50 }
  51
  52 void qemu_set_fd_handler(int fd,
  53                          IOHandler *fd_read,
  54                          IOHandler *fd_write,
  55                          void *opaque)
  56 {
  57     iohandler_init();
  58     aio_set_fd_handler(iohandler_ctx, fd, fd_read, fd_write, opaque);
  59 }
  60
  61 /* reaping of zombies.  right now we're not passing the status to
  62    anyone, but it would be possible to add a callback.  */
  63 #ifndef _WIN32
  64 typedef struct ChildProcessRecord {
  65     int pid;
  66     QLIST_ENTRY(ChildProcessRecord) next;
  67 } ChildProcessRecord;
  68
  69 static QLIST_HEAD(, ChildProcessRecord) child_watches =
  70     QLIST_HEAD_INITIALIZER(child_watches);
  71
  72 static QEMUBH *sigchld_bh;
  73
  74 static void sigchld_handler(int signal)
  75 {
  76     qemu_bh_schedule(sigchld_bh);
  77 }
  78
  79 static void sigchld_bh_handler(void *opaque)
  80 {
  81     ChildProcessRecord *rec, *next;
  82
  83     QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {
  84         if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {
  85             QLIST_REMOVE(rec, next);
  86             g_free(rec);
  87         }
  88     }
  89 }
  90
  91 static void qemu_init_child_watch(void)
  92 {
  93     struct sigaction act;
  94     sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);
  95
  96     memset(&act, 0, sizeof(act));
  97     act.sa_handler = sigchld_handler;
  98     act.sa_flags = SA_NOCLDSTOP;
  99     sigaction(SIGCHLD, &act, NULL);
 100 }
 101
 102 int qemu_add_child_watch(pid_t pid)
 103 {
 104     ChildProcessRecord *rec;
 105
 106     if (!sigchld_bh) {
 107         qemu_init_child_watch();
 108     }
 109
 110     QLIST_FOREACH(rec, &child_watches, next) {
 111         if (rec->pid == pid) {
 112             return 1;
 113         }
 114     }
 115     rec = g_malloc0(sizeof(ChildProcessRecord));
 116     rec->pid = pid;
 117     QLIST_INSERT_HEAD(&child_watches, rec, next);
 118     return 0;
 119 }
 120 #endif