10:31 a.m.
This patch implements a demo server for the new -open-hook-fd feature.
It opens any filename given to it by QEMU and therefore adds no true
security. But it serves as a good debugging tool to see what requests
QEMU is making.
$ gcc -o test-fd-passing -Wall test-fd-passing.c
$ ./test-fd-passing path/to/my/vm.img
Try:
(qemu) change ide1-cd0 path/to/a/cdrom.iso
Signed-off-by: Stefan Hajnoczi <stefanha(a)linux.vnet.ibm.com>
---
test-fd-passing.c | 147 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 147 insertions(+)
create mode 100644 test-fd-passing.c
diff --git a/test-fd-passing.c b/test-fd-passing.c
new file mode 100644
index 0000000..43b2e86
--- /dev/null
+++ b/test-fd-passing.c
@@ -0,0 +1,147 @@
+/*
+ * QEMU -open-hook-fd test server
+ *
+ * Copyright IBM, Corp. 2012
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha(a)linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2 or later.
+ * See the COPYING.LIB file in the top-level directory.
+ *
+ * gcc -o test-fd-passing -Wall test-fd-passing.c
+ */
+
+#define _GNU_SOURCE
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <spawn.h>
+
+typedef struct {
+ uint32_t message_len;
+ uint32_t type;
+ uint32_t flags;
+ uint32_t mode;
+ uint32_t filename_len;
+ uint8_t filename[0];
+} OpenRequest;
+
+typedef struct {
+ uint32_t message_len;
+ uint32_t type;
+ int32_t result;
+} OpenResponse;
+
+int main(int argc, char **argv)
+{
+ if (argc != 2) {
+ fprintf(stderr, "usage: %s <image-file>\n", argv[0]);
+ return EXIT_FAILURE;
+ }
+
+ int fds[2];
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, fds) != 0) {
+ perror("socketpair");
+ return EXIT_FAILURE;
+ }
+
+ char *fdstr = NULL;
+ asprintf(&fdstr, "%d", fds[1]);
+
+ char *drivestr = NULL;
+ asprintf(&drivestr, "file=%s,cache=none,if=virtio", argv[1]);
+
+ char *child_argv[] = {
+ "qemu-system-x86_64",
+ "-enable-kvm",
+ "-m", "1024",
+ "-drive", drivestr,
+ "-open-hook-fd", fdstr,
+ NULL,
+ };
+
+ pid_t child_pid;
+ if (posix_spawn(&child_pid, "x86_64-softmmu/qemu-system-x86_64",
+ NULL, NULL, child_argv, environ) != 0) {
+ fprintf(stderr, "posix_spawn failed\n");
+ return EXIT_FAILURE;
+ }
+ free(drivestr);
+ free(fdstr);
+ close(fds[1]);
+
+ for (;;) {
+ OpenRequest req;
+ char filename[1024];
+
+ if (recv(fds[0], &req, sizeof(req), 0) != sizeof(req)) {
+ perror("recv");
+ return EXIT_FAILURE;
+ }
+
+ if (req.type != 1 /* OpenRequest */) {
+ fprintf(stderr, "Expected request type 1, got %u\n", req.type);
+ return EXIT_FAILURE;
+ }
+
+ if (req.filename_len > sizeof(filename) - 1) {
+ fprintf(stderr, "Filename length too large (%u)\n",
+ req.filename_len);
+ return EXIT_FAILURE;
+ }
+
+ if (recv(fds[0], filename, req.filename_len, 0) != req.filename_len) {
+ perror("recv");
+ return EXIT_FAILURE;
+ }
+ filename[req.filename_len] = '\0';
+
+ fprintf(stderr, "open(\"%s\", %#x, %#o) = ",
+ filename, req.flags, req.mode);
+
+ int fd, ret;
+ fd = ret = open(filename, req.flags, req.mode);
+
+ fprintf(stderr, "%d (errno %d)\n", ret, errno);
+
+ OpenResponse resp = {
+ .message_len = sizeof(resp),
+ .type = 1,
+ .result = ret < 0 ? -errno : 0,
+ };
+ struct iovec iov = {
+ .iov_base = &resp,
+ .iov_len = sizeof(resp),
+ };
+ char buf[CMSG_SPACE(sizeof(int))];
+ struct msghdr msg = {
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ };
+ if (ret >= 0) {
+ msg.msg_control = buf;
+ msg.msg_controllen = sizeof(buf);
+
+ struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
+ cmsg->cmsg_level = SOL_SOCKET;
+ cmsg->cmsg_type = SCM_RIGHTS;
+ cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+
+ memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
+ }
+
+ ret = sendmsg(fds[0], &msg, 0);
+ if (ret < 0) {
+ perror("sendmsg");
+ return EXIT_FAILURE;
+ }
+ close(fd);
+ }
+}
--
1.7.10