mirror of
https://github.com/freebsd/freebsd-src.git
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fdescfs: descend through /dev/fd/N when mounted linrdlnk
Linux resolves a path below /proc/self/fd/N in the directory the
descriptor names, and linprocfs makes /proc/<pid>/fd a symlink to
/dev/fd. Under linrdlnk the fdescfs node carries only VV_READLINK,
which namei will not walk through, so such a path fails with ENOTDIR.
Return the underlying vnode from fdesc_lookup for a non-final component,
or a trailing slash, reusing the machinery the nodup option already
uses. The last component is untouched, so open("/dev/fd/N") keeps its
dup(2) semantic; a descriptor with no vnode behind it, such as a pipe,
yields ENOTDIR.
Add ATF coverage for traversal, descriptor reuse, and preservation of
last-component and mount-option semantics.
Approved by: adrian (mentor)
Reviewed by: kib, adrian
Differential Revision: https://reviews.freebsd.org/D59393
Signed-off-by: Nick Price <[email protected]>
This commit is contained in:
6 files changed
+406
-2
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@@ -7,6 +7,7 @@ TESTSDIR= ${TESTSBASE}/sys/fs
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TESTSRC= ${SRCTOP}/contrib/netbsd-tests/fs
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TESTS_SUBDIRS+= fdescfs
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#TESTS_SUBDIRS+= nullfs # XXX: needs rump
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# fusefs tests cannot be compiled/used without the googletest infrastructure.
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.if ${COMPILER_FEATURES:Mc++14} && ${MK_GOOGLETEST} != "no"
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@@ -0,0 +1,9 @@
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PACKAGE= tests
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TESTSDIR= ${TESTSBASE}/sys/fs/fdescfs
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ATF_TESTS_C+= fdescfs_test
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LIBADD+= util
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.include <bsd.test.mk>
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@@ -0,0 +1,373 @@
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#include <sys/param.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <atf-c.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <mntopts.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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static const char *const linrdlnk[] = { "linrdlnk", NULL };
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static const char *const nodup_linrdlnk[] = { "nodup", "linrdlnk", NULL };
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static void
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mount_fdescfs(const char *const *opts)
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{
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struct iovec *iov;
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char errmsg[256];
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int error, iovlen;
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ATF_REQUIRE_EQ(0, mkdir("mnt", 0755));
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iov = NULL;
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iovlen = 0;
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build_iovec(&iov, &iovlen, __DECONST(char *, "fstype"),
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__DECONST(char *, "fdescfs"), (size_t)-1);
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build_iovec(&iov, &iovlen, __DECONST(char *, "fspath"),
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__DECONST(char *, "mnt"), (size_t)-1);
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for (; opts != NULL && *opts != NULL; opts++)
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build_iovec(&iov, &iovlen, __DECONST(char *, *opts), NULL,
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(size_t)-1);
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build_iovec(&iov, &iovlen, __DECONST(char *, "errmsg"), errmsg,
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sizeof(errmsg));
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errmsg[0] = '\0';
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error = nmount(iov, iovlen, 0);
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if (error != 0 && errno == ENODEV)
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atf_tc_skip("fdescfs is not available");
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ATF_REQUIRE_MSG(error == 0, "nmount: %s",
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errmsg[0] != '\0' ? errmsg : strerror(errno));
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free_iovec(&iov, &iovlen);
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}
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static void
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fdpath(char *path, size_t size, int fd, const char *suffix)
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{
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int len;
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len = snprintf(path, size, "mnt/%d%s", fd, suffix);
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ATF_REQUIRE(len > 0 && (size_t)len < size);
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}
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static void
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create_directory(const char *path, char marker)
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{
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int dirfd, fd;
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ATF_REQUIRE_EQ(0, mkdir(path, 0755));
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ATF_REQUIRE((dirfd = open(path, O_RDONLY | O_DIRECTORY)) >= 0);
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ATF_REQUIRE(
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(fd = openat(dirfd, "marker", O_WRONLY | O_CREAT, 0644)) >= 0);
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ATF_REQUIRE_EQ(1, write(fd, &marker, 1));
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ATF_REQUIRE_EQ(0, close(fd));
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ATF_REQUIRE_EQ(0, close(dirfd));
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}
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static void
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check_identity(const struct stat *expected, const struct stat *actual)
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{
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ATF_CHECK_EQ(expected->st_dev, actual->st_dev);
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ATF_CHECK_EQ(expected->st_ino, actual->st_ino);
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ATF_CHECK_EQ(expected->st_mode & S_IFMT, actual->st_mode & S_IFMT);
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}
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static void
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check_directory(int dirfd, const char *suffix)
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{
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struct stat expected, actual;
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char path[64];
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int fd;
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fdpath(path, sizeof(path), dirfd, suffix);
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ATF_REQUIRE_EQ(0, fstat(dirfd, &expected));
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ATF_REQUIRE_MSG(stat(path, &actual) == 0, "stat(%s): %s", path,
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strerror(errno));
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check_identity(&expected, &actual);
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ATF_REQUIRE_MSG((fd = open(path, O_RDONLY | O_DIRECTORY)) >= 0,
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"open(%s): %s", path, strerror(errno));
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ATF_REQUIRE_EQ(0, fstat(fd, &actual));
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check_identity(&expected, &actual);
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ATF_REQUIRE_EQ(0, close(fd));
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}
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static void
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check_marker(int dirfd, char expected)
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{
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char path[64], actual;
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int fd;
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fdpath(path, sizeof(path), dirfd, "/marker");
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ATF_REQUIRE_MSG((fd = open(path, O_RDONLY)) >= 0, "open(%s): %s", path,
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strerror(errno));
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ATF_REQUIRE_EQ(1, read(fd, &actual, 1));
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ATF_CHECK_EQ(expected, actual);
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ATF_REQUIRE_EQ(0, close(fd));
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}
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static void
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check_bare(int fd, const char *target)
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{
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struct stat sb;
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char path[64], expected[PATH_MAX], actual[PATH_MAX];
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ssize_t len;
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int copy, flags, actual_flags;
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fdpath(path, sizeof(path), fd, "");
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ATF_REQUIRE_EQ(0, lstat(path, &sb));
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ATF_CHECK(S_ISLNK(sb.st_mode));
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ATF_REQUIRE(realpath(target, expected) != NULL);
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ATF_REQUIRE((len = readlink(path, actual, sizeof(actual))) >= 0);
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ATF_REQUIRE_EQ(strlen(expected), (size_t)len);
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ATF_CHECK_EQ(0, memcmp(expected, actual, len));
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ATF_REQUIRE((copy = open(path, O_RDONLY)) >= 0);
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ATF_REQUIRE((flags = fcntl(fd, F_GETFL)) >= 0);
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ATF_REQUIRE_EQ(0, fcntl(copy, F_SETFL, flags ^ O_NONBLOCK));
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ATF_REQUIRE((actual_flags = fcntl(fd, F_GETFL)) >= 0);
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ATF_CHECK_EQ((flags ^ O_NONBLOCK) & O_NONBLOCK,
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actual_flags & O_NONBLOCK);
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ATF_REQUIRE_EQ(0, fcntl(fd, F_SETFL, flags));
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ATF_REQUIRE_EQ(0, close(copy));
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}
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static void
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check_open_offset(bool duplicate)
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{
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char path[64], buf[2], byte;
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int fd, copy;
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ATF_REQUIRE((fd = open("file", O_RDWR | O_CREAT, 0644)) >= 0);
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ATF_REQUIRE_EQ(6, write(fd, "abcdef", 6));
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ATF_REQUIRE_EQ(0, lseek(fd, 0, SEEK_SET));
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ATF_REQUIRE_EQ(2, read(fd, buf, sizeof(buf)));
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ATF_REQUIRE_EQ(0, memcmp(buf, "ab", sizeof(buf)));
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fdpath(path, sizeof(path), fd, "");
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ATF_REQUIRE((copy = open(path, O_RDONLY)) >= 0);
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ATF_CHECK_EQ(duplicate ? 2 : 0, lseek(copy, 0, SEEK_CUR));
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ATF_REQUIRE_EQ(1, read(copy, &byte, 1));
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ATF_CHECK_EQ(duplicate ? 'c' : 'a', byte);
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ATF_CHECK_EQ(duplicate ? 3 : 2, lseek(fd, 0, SEEK_CUR));
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ATF_REQUIRE_EQ(0, close(copy));
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ATF_REQUIRE_EQ(0, close(fd));
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}
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static void
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check_notdir(int fd)
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{
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const char *suffixes[] = { "/child", "/" };
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char path[64];
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size_t i;
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for (i = 0; i < nitems(suffixes); i++) {
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fdpath(path, sizeof(path), fd, suffixes[i]);
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ATF_REQUIRE_ERRNO(ENOTDIR, open(path, O_RDONLY) == -1);
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}
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}
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static void
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check_traverse(int flags)
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{
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struct stat expected, actual;
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char path[64];
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int fd;
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mount_fdescfs(linrdlnk);
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ATF_REQUIRE_EQ(0, mkdir("parent", 0755));
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create_directory("parent/target", 'a');
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ATF_REQUIRE((fd = open("parent/target", flags | O_DIRECTORY)) >= 0);
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fdpath(path, sizeof(path), fd, "/..");
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ATF_REQUIRE_EQ(0, stat("parent", &expected));
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ATF_REQUIRE_MSG(stat(path, &actual) == 0, "stat(%s): %s", path,
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strerror(errno));
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check_identity(&expected, &actual);
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check_marker(fd, 'a');
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fdpath(path, sizeof(path), fd, "/child");
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ATF_REQUIRE_MSG(mkdir(path, 0755) == 0, "mkdir(%s): %s", path,
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strerror(errno));
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ATF_REQUIRE_EQ(0, stat("parent/target/child", &expected));
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ATF_REQUIRE_EQ(0, stat(path, &actual));
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ATF_CHECK(S_ISDIR(actual.st_mode));
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check_identity(&expected, &actual);
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ATF_REQUIRE_EQ(0, close(fd));
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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#define FDESCFS_TC(name, description) \
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ATF_TC_WITH_CLEANUP(name); \
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ATF_TC_HEAD(name, tc) \
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{ \
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atf_tc_set_md_var(tc, "descr", description); \
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atf_tc_set_md_var(tc, "require.user", "root"); \
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atf_tc_set_md_var(tc, "timeout", "30"); \
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} \
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ATF_TC_CLEANUP(name, tc) \
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{ \
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(void)unmount("mnt", 0); \
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}
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FDESCFS_TC(traverse_dir, "Traverse a directory descriptor under linrdlnk");
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ATF_TC_BODY(traverse_dir, tc)
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{
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check_traverse(O_RDONLY);
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}
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FDESCFS_TC(traverse_path, "Traverse an O_PATH descriptor under linrdlnk");
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ATF_TC_BODY(traverse_path, tc)
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{
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check_traverse(O_PATH);
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}
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FDESCFS_TC(trailing_slash,
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"Trailing slashes resolve to the referenced directory");
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ATF_TC_BODY(trailing_slash, tc)
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{
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const int flags[] = { O_RDONLY, O_PATH };
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size_t i;
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int fd;
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mount_fdescfs(linrdlnk);
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create_directory("target", 'a');
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for (i = 0; i < nitems(flags); i++) {
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ATF_REQUIRE((fd = open("target", flags[i] | O_DIRECTORY)) >= 0);
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check_directory(fd, "/");
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ATF_REQUIRE_EQ(0, close(fd));
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}
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(last_component_dups,
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"Bare linrdlnk opens share the original offset");
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ATF_TC_BODY(last_component_dups, tc)
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{
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mount_fdescfs(linrdlnk);
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check_open_offset(true);
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(lookup_order,
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"Bare and traversing lookups do not affect each other");
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ATF_TC_BODY(lookup_order, tc)
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{
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int first, second;
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mount_fdescfs(linrdlnk);
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create_directory("target", 'a');
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ATF_REQUIRE((first = open("target", O_RDONLY | O_DIRECTORY)) >= 0);
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ATF_REQUIRE((second = open("target", O_RDONLY | O_DIRECTORY)) >= 0);
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check_bare(first, "target");
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check_marker(first, 'a');
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check_directory(first, "/");
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check_bare(first, "target");
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check_marker(second, 'a');
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check_directory(second, "/");
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check_bare(second, "target");
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check_marker(second, 'a');
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ATF_REQUIRE_EQ(0, close(second));
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ATF_REQUIRE_EQ(0, close(first));
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(descriptor_reuse, "Reusing a descriptor selects its current target");
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ATF_TC_BODY(descriptor_reuse, tc)
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{
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int fd, replacement;
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mount_fdescfs(linrdlnk);
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create_directory("first", 'a');
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create_directory("second", 'b');
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ATF_REQUIRE((fd = open("first", O_RDONLY | O_DIRECTORY)) >= 0);
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check_bare(fd, "first");
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check_marker(fd, 'a');
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ATF_REQUIRE(
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(replacement = open("second", O_RDONLY | O_DIRECTORY)) >= 0);
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ATF_REQUIRE_EQ(fd, dup2(replacement, fd));
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ATF_REQUIRE_EQ(0, close(replacement));
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check_marker(fd, 'b');
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check_directory(fd, "/");
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check_bare(fd, "second");
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ATF_REQUIRE((replacement = open("second/marker", O_RDONLY)) >= 0);
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ATF_REQUIRE_EQ(fd, dup2(replacement, fd));
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ATF_REQUIRE_EQ(0, close(replacement));
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check_notdir(fd);
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check_bare(fd, "second/marker");
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ATF_REQUIRE_EQ(0, close(fd));
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(traverse_nondir, "Files and pipes reject traversal");
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ATF_TC_BODY(traverse_nondir, tc)
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{
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int fd, pipes[2];
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mount_fdescfs(linrdlnk);
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ATF_REQUIRE((fd = open("file", O_RDONLY | O_CREAT, 0644)) >= 0);
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check_notdir(fd);
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ATF_REQUIRE_EQ(0, close(fd));
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ATF_REQUIRE_EQ(0, pipe(pipes));
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check_notdir(pipes[0]);
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ATF_REQUIRE_EQ(0, close(pipes[0]));
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ATF_REQUIRE_EQ(0, close(pipes[1]));
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(plain_mount, "Plain mounts reject traversal");
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ATF_TC_BODY(plain_mount, tc)
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{
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int fd;
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mount_fdescfs(NULL);
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create_directory("target", 'a');
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ATF_REQUIRE((fd = open("target", O_RDONLY | O_DIRECTORY)) >= 0);
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check_notdir(fd);
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ATF_REQUIRE_EQ(0, close(fd));
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(nodup_linrdlnk_mount, "Linrdlnk preserves nodup behavior");
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ATF_TC_BODY(nodup_linrdlnk_mount, tc)
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{
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int fd;
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mount_fdescfs(nodup_linrdlnk);
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create_directory("target", 'a');
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ATF_REQUIRE((fd = open("target", O_RDONLY | O_DIRECTORY)) >= 0);
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check_marker(fd, 'a');
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check_directory(fd, "/");
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ATF_REQUIRE_EQ(0, close(fd));
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check_open_offset(false);
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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FDESCFS_TC(root_reference,
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"Traverse a descriptor referencing the fdescfs root");
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ATF_TC_BODY(root_reference, tc)
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{
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char suffix[32];
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int fd, len;
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mount_fdescfs(linrdlnk);
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ATF_REQUIRE((fd = open("mnt", O_RDONLY | O_DIRECTORY)) >= 0);
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check_directory(fd, "/");
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len = snprintf(suffix, sizeof(suffix), "/%d/", fd);
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ATF_REQUIRE(len > 0 && (size_t)len < sizeof(suffix));
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check_directory(fd, suffix);
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ATF_REQUIRE_EQ(0, close(fd));
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ATF_REQUIRE_EQ(0, unmount("mnt", 0));
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}
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ATF_TP_ADD_TCS(tp)
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{
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ATF_TP_ADD_TC(tp, traverse_dir);
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ATF_TP_ADD_TC(tp, traverse_path);
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ATF_TP_ADD_TC(tp, trailing_slash);
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ATF_TP_ADD_TC(tp, last_component_dups);
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ATF_TP_ADD_TC(tp, lookup_order);
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ATF_TP_ADD_TC(tp, descriptor_reuse);
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ATF_TP_ADD_TC(tp, traverse_nondir);
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ATF_TP_ADD_TC(tp, plain_mount);
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ATF_TP_ADD_TC(tp, nodup_linrdlnk_mount);
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ATF_TP_ADD_TC(tp, root_reference);
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return (atf_no_error());
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}
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