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Subject[PATCH 07/14] VFS: Add a sample program for fsopen/fsmount [ver #6]
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Add a sample program for driving fsopen/fsmount.

Signed-off-by: David Howells <dhowells@redhat.com>
---

samples/fsmount/test-fsmount.c | 94 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 94 insertions(+)
create mode 100644 samples/fsmount/test-fsmount.c

diff --git a/samples/fsmount/test-fsmount.c b/samples/fsmount/test-fsmount.c
new file mode 100644
index 000000000000..75f91d272a19
--- /dev/null
+++ b/samples/fsmount/test-fsmount.c
@@ -0,0 +1,94 @@
+/* fd-based mount test.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/prctl.h>
+#include <sys/wait.h>
+
+#define PR_ERRMSG_ENABLE 48
+#define PR_ERRMSG_READ 49
+
+#define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0)
+
+static __attribute__((noreturn))
+void mount_error(int fd, const char *s)
+{
+ char buf[4096];
+ int err, n, perr;
+
+ do {
+ err = errno;
+ errno = 0;
+ n = prctl(PR_ERRMSG_READ, buf, sizeof(buf));
+ perr = errno;
+ errno = err;
+ if (n > 0) {
+ fprintf(stderr, "Error: '%s': %*.*s: %m\n", s, n, n, buf);
+ } else {
+ fprintf(stderr, "%s: %m\n", s);
+ }
+ } while (perr == 0);
+ exit(1);
+}
+
+#define E_write(fd, s) \
+ do { \
+ if (write(fd, s, sizeof(s) - 1) == -1) \
+ mount_error(fd, s); \
+ } while (0)
+
+static inline int fsopen(const char *fs_name, int flags,
+ void *reserved3, void *reserved4, void *reserved5);
+
+{
+ return syscall(333, fs_name, flags, reserved3, reserved4, reserved5);
+}
+
+static inline int fsmount(int fsfd, int dfd, const char *path,
+ unsigned int at_flags, unsigned int flags)
+{
+ return syscall(334, fsfd, dfd, path, at_flags, flags);
+}
+
+int main()
+{
+ int mfd;
+
+ if (prctl(PR_ERRMSG_ENABLE, 1) < 0) {
+ perror("prctl/en");
+ exit(1);
+ }
+
+ /* Mount an NFS filesystem */
+ mfd = fsopen("nfs4", 0, NULL, NULL, NULL);
+ if (mfd == -1) {
+ perror("fsopen");
+ exit(1);
+ }
+
+ E_write(mfd, "s warthog:/data");
+ E_write(mfd, "o fsc");
+ E_write(mfd, "o sync");
+ E_write(mfd, "o intr");
+ E_write(mfd, "o vers=4.2");
+ E_write(mfd, "o addr=90.155.74.18");
+ E_write(mfd, "o clientaddr=90.155.74.21");
+ E_write(mfd, "x create");
+ if (fsmount(mfd, AT_FDCWD, "/mnt", 0, 0) < 0)
+ mount_error(mfd, "fsmount");
+ E(close(mfd));
+
+ exit(0);
+}
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