LXR qemu/util/compatfd.c

   1/*
   2 * signalfd/eventfd compatibility
   3 *
   4 * Copyright IBM, Corp. 2008
   5 *
   6 * Authors:
   7 *  Anthony Liguori   <aliguori@us.ibm.com>
   8 *
   9 * This work is licensed under the terms of the GNU GPL, version 2.  See
  10 * the COPYING file in the top-level directory.
  11 *
  12 * Contributions after 2012-01-13 are licensed under the terms of the
  13 * GNU GPL, version 2 or (at your option) any later version.
  14 */
  15
  16#include "qemu/osdep.h"
  17#include "qemu/thread.h"
  18
  19#if defined(CONFIG_SIGNALFD)
  20#include <sys/syscall.h>
  21#endif
  22
  23struct sigfd_compat_info {
  24    sigset_t mask;
  25    int fd;
  26};
  27
  28static void *sigwait_compat(void *opaque)
  29{
  30    struct sigfd_compat_info *info = opaque;
  31
  32    while (1) {
  33        int sig;
  34        int err;
  35
  36        err = sigwait(&info->mask, &sig);
  37        if (err != 0) {
  38            if (errno == EINTR) {
  39                continue;
  40            } else {
  41                return NULL;
  42            }
  43        } else {
  44            struct qemu_signalfd_siginfo buffer;
  45            size_t offset = 0;
  46
  47            memset(&buffer, 0, sizeof(buffer));
  48            buffer.ssi_signo = sig;
  49
  50            while (offset < sizeof(buffer)) {
  51                ssize_t len;
  52
  53                len = write(info->fd, (char *)&buffer + offset,
  54                            sizeof(buffer) - offset);
  55                if (len == -1 && errno == EINTR) {
  56                    continue;
  57                }
  58
  59                if (len <= 0) {
  60                    return NULL;
  61                }
  62
  63                offset += len;
  64            }
  65        }
  66    }
  67}
  68
  69static int qemu_signalfd_compat(const sigset_t *mask)
  70{
  71    struct sigfd_compat_info *info;
  72    QemuThread thread;
  73    int fds[2];
  74
  75    info = g_malloc(sizeof(*info));
  76
  77    if (pipe(fds) == -1) {
  78        g_free(info);
  79        return -1;
  80    }
  81
  82    qemu_set_cloexec(fds[0]);
  83    qemu_set_cloexec(fds[1]);
  84
  85    memcpy(&info->mask, mask, sizeof(*mask));
  86    info->fd = fds[1];
  87
  88    qemu_thread_create(&thread, "signalfd_compat", sigwait_compat, info,
  89                       QEMU_THREAD_DETACHED);
  90
  91    return fds[0];
  92}
  93
  94int qemu_signalfd(const sigset_t *mask)
  95{
  96#if defined(CONFIG_SIGNALFD)
  97    int ret;
  98
  99    ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
 100    if (ret != -1) {
 101        qemu_set_cloexec(ret);
 102        return ret;
 103    }
 104#endif
 105
 106    return qemu_signalfd_compat(mask);
 107}
 108