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