1 files changed, 138 insertions, 0 deletions
diff --git a/util/compatfd.c b/util/compatfd.c
new file mode 100644
index 0000000000..9cf3f2834d
--- /dev/null
+++ b/util/compatfd.c
@@ -0,0 +1,138 @@
+/*
+ * signalfd/eventfd compatibility
+ *
+ * Copyright IBM, Corp. 2008
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+
+#include "qemu-common.h"
+#include "qemu/compatfd.h"
+
+#include <sys/syscall.h>
+#include <pthread.h>
+
+struct sigfd_compat_info
+{
+    sigset_t mask;
+    int fd;
+};
+
+static void *sigwait_compat(void *opaque)
+{
+    struct sigfd_compat_info *info = opaque;
+    sigset_t all;
+
+    sigfillset(&all);
+    pthread_sigmask(SIG_BLOCK, &all, NULL);
+
+    while (1) {
+        int sig;
+        int err;
+
+        err = sigwait(&info->mask, &sig);
+        if (err != 0) {
+            if (errno == EINTR) {
+                continue;
+            } else {
+                return NULL;
+            }
+        } else {
+            struct qemu_signalfd_siginfo buffer;
+            size_t offset = 0;
+
+            memset(&buffer, 0, sizeof(buffer));
+            buffer.ssi_signo = sig;
+
+            while (offset < sizeof(buffer)) {
+                ssize_t len;
+
+                len = write(info->fd, (char *)&buffer + offset,
+                            sizeof(buffer) - offset);
+                if (len == -1 && errno == EINTR)
+                    continue;
+
+                if (len <= 0) {
+                    return NULL;
+                }
+
+                offset += len;
+            }
+        }
+    }
+}
+
+static int qemu_signalfd_compat(const sigset_t *mask)
+{
+    pthread_attr_t attr;
+    pthread_t tid;
+    struct sigfd_compat_info *info;
+    int fds[2];
+
+    info = malloc(sizeof(*info));
+    if (info == NULL) {
+        errno = ENOMEM;
+        return -1;
+    }
+
+    if (pipe(fds) == -1) {
+        free(info);
+        return -1;
+    }
+
+    qemu_set_cloexec(fds[0]);
+    qemu_set_cloexec(fds[1]);
+
+    memcpy(&info->mask, mask, sizeof(*mask));
+    info->fd = fds[1];
+
+    pthread_attr_init(&attr);
+    pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
+
+    pthread_create(&tid, &attr, sigwait_compat, info);
+
+    pthread_attr_destroy(&attr);
+
+    return fds[0];
+}
+
+int qemu_signalfd(const sigset_t *mask)
+{
+#if defined(CONFIG_SIGNALFD)
+    int ret;
+
+    ret = syscall(SYS_signalfd, -1, mask, _NSIG / 8);
+    if (ret != -1) {
+        qemu_set_cloexec(ret);
+        return ret;
+    }
+#endif
+
+    return qemu_signalfd_compat(mask);
+}
+
+bool qemu_signalfd_available(void)
+{
+#ifdef CONFIG_SIGNALFD
+    sigset_t mask;
+    int fd;
+    bool ok;
+    sigemptyset(&mask);
+    errno = 0;
+    fd = syscall(SYS_signalfd, -1, &mask, _NSIG / 8);
+    ok = (errno != ENOSYS);
+    if (fd >= 0) {
+        close(fd);
+    }
+    return ok;
+#else
+    return false;
+#endif
+}