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-common.h"
  18#include "qemu/compatfd.h"
  19#include "qemu/thread.h"
  20
  21#include <sys/syscall.h>
  22
  23struct sigfd_compat_info
  24{
  25    sigset_t mask;
  26    int fd;
  27};
  28
  29static void *sigwait_compat(void *opaque)
  30{
  31    struct sigfd_compat_info *info = opaque;
  32
  33    while (1) {
  34        int sig;
  35        int err;
  36
  37        err = sigwait(&info->mask, &sig);
  38        if (err != 0) {
  39            if (errno == EINTR) {
  40                continue;
  41            } else {
  42                return NULL;
  43            }
  44        } else {
  45            struct qemu_signalfd_siginfo buffer;
  46            size_t offset = 0;
  47
  48            memset(&buffer, 0, sizeof(buffer));
  49            buffer.ssi_signo = sig;
  50
  51            while (offset < sizeof(buffer)) {
  52                ssize_t len;
  53
  54                len = write(info->fd, (char *)&buffer + offset,
  55                            sizeof(buffer) - offset);
  56                if (len == -1 && errno == EINTR)
  57                    continue;
  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 = malloc(sizeof(*info));
  76    if (info == NULL) {
  77        errno = ENOMEM;
  78        return -1;
  79    }
  80
  81    if (pipe(fds) == -1) {
  82        free(info);
  83        return -1;
  84    }
  85
  86    qemu_set_cloexec(fds[0]);
  87    qemu_set_cloexec(fds[1]);
  88
  89    memcpy(&info->mask, mask, sizeof(*mask));
  90    info->fd = fds[1];
  91
  92    qemu_thread_create(&thread, "signalfd_compat", sigwait_compat, info,
  93                       QEMU_THREAD_DETACHED);
  94
  95    return fds[0];
  96}
  97
  98int qemu_signalfd(const sigset_t *mask)
  99{
 100#if defined(CONFIG_SIGNALFD)
 101    int ret;
 102
 103    ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
 104    if (ret != -1) {
 105        qemu_set_cloexec(ret);
 106        return ret;
 107    }
 108#endif
 109
 110    return qemu_signalfd_compat(mask);
 111}
 112