Make sys/vfs/lookup_cap_dotdot actually work with "kyua test"

The tests don't work when reading/writing to file descriptors in the
sandbox after entering capability mode (and wouldn't have, regardless
of the framework), so adjust the tests so they function within the
framework.

For tests that enter capability mode over the course of the test, the
following is now done:

  1. Fork child process for capability mode test.
  2. In child...
     i.   Enter capability mode.
     ii.  Test invariants.
     iii. Exit after calling test function.
  3. Collect status for child and determine whether or not it completed
     successfully.

In order to test the invariants in the child process, they now use assert(3)
instead of ATF_REQUIRE*, as the atf-c-api functions right to results files
in the directories in order to determine where and how tests fail.

While in the area, fix several -Wshadow and -Wunused warnings found when I
bumped WARNS up to 6, and fix some minor style(9) issues with indentation
and type alignment.

PR:	215690

tests/sys/vfs/lookup_cap_dotdot.c

@@ -31,23 +31,27 @@ __FBSDID("$FreeBSD$");
 #include <sys/capsicum.h>
 #include <sys/sysctl.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 
 #include <atf-c.h>
+#include <assert.h>
 #include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "freebsd_test_suite/macros.h"
 
-static int dirfd = -1;
-static char *abspath;
+static char	*abspath;
+static int	dirfd = -1;
+
+typedef	void (*child_test_fn_t)(void);
 
 static void
-touchat(int dirfd, const char *name)
+touchat(int _dirfd, const char *name)
 {
 	int fd;
 
-	ATF_REQUIRE((fd = openat(dirfd, name, O_CREAT | O_TRUNC | O_WRONLY,
+	ATF_REQUIRE((fd = openat(_dirfd, name, O_CREAT | O_TRUNC | O_WRONLY,
 	    0777)) >= 0);
 	ATF_REQUIRE(close(fd) == 0);
 }
@@ -78,10 +82,43 @@ prepare_dotdot_tests(void)
 static void
 check_capsicum(void)
 {
+
 	ATF_REQUIRE_FEATURE("security_capabilities");
 	ATF_REQUIRE_FEATURE("security_capability_mode");
 }
 
+static void
+run_capsicum_test(child_test_fn_t test_func)
+{
+	int child_exit_code, child_status;
+	pid_t child_pid;
+
+	check_capsicum();
+	prepare_dotdot_tests();
+
+	ATF_REQUIRE_MSG((child_pid = fork()) != -1,
+	    "fork failed: %s", strerror(errno));
+
+	if (child_pid == 0) {
+		test_func();
+		_exit(0);
+	}
+
+	ATF_REQUIRE_MSG(waitpid(child_pid, &child_status, 0) != -1,
+	    "waitpid failed: %s", strerror(errno));
+	if (WIFEXITED(child_status)) {
+		child_exit_code = WEXITSTATUS(child_status);
+		ATF_REQUIRE_MSG(child_exit_code == 0,
+		    "child exited with non-zero exit code: %d",
+		    child_exit_code);
+	} else if (WIFSIGNALED(child_status))
+		atf_tc_fail("child exited with signal: %d",
+		    WTERMSIG(child_status));
+	else
+		atf_tc_fail("child exited with unexpected status: %d",
+		    child_status);
+}
+
 /*
  * Positive tests
  */
@@ -93,6 +130,7 @@ ATF_TC_HEAD(openat__basic_positive, tc)
 
 ATF_TC_BODY(openat__basic_positive, tc)
 {
+
 	prepare_dotdot_tests();
 
 	ATF_REQUIRE(openat(dirfd, "d1/d2/d3/f3", O_RDONLY) >= 0);
@@ -114,21 +152,22 @@ ATF_TC_HEAD(lookup_cap_dotdot__basic, tc)
 	    "Validate cap-mode (testdir)/d1/.. lookup");
 }
 
-ATF_TC_BODY(lookup_cap_dotdot__basic, tc)
+static void
+lookup_cap_dotdot__basic_child(void)
 {
 	cap_rights_t rights;
-	int fd;
-
-	check_capsicum();
-	prepare_dotdot_tests();
 
 	cap_rights_init(&rights, CAP_LOOKUP, CAP_READ);
-	ATF_REQUIRE(cap_rights_limit(dirfd, &rights) >= 0);
 
-	ATF_REQUIRE(cap_enter() >= 0);
+	assert(cap_rights_limit(dirfd, &rights) >= 0);
+	assert(cap_enter() >= 0);
+	assert(openat(dirfd, "d1/..", O_RDONLY) >= 0);
+}
 
-	ATF_REQUIRE_MSG(openat(dirfd, "d1/..", O_RDONLY) >= 0, "%s",
-	    strerror(errno));
+ATF_TC_BODY(lookup_cap_dotdot__basic, tc)
+{
+
+	run_capsicum_test(lookup_cap_dotdot__basic_child);
 }
 
 ATF_TC(lookup_cap_dotdot__advanced);
@@ -138,23 +177,26 @@ ATF_TC_HEAD(lookup_cap_dotdot__advanced, tc)
 	    "Validate cap-mode (testdir)/d1/.. lookup");
 }
 
-ATF_TC_BODY(lookup_cap_dotdot__advanced, tc)
+static void
+lookup_cap_dotdot__advanced_child(void)
 {
 	cap_rights_t rights;
-	int fd;
-
-	check_capsicum();
-	prepare_dotdot_tests();
 
 	cap_rights_init(&rights, CAP_LOOKUP, CAP_READ);
-	ATF_REQUIRE(cap_rights_limit(dirfd, &rights) >= 0);
+	assert(cap_rights_limit(dirfd, &rights) >= 0);
 
-	ATF_REQUIRE(cap_enter() >= 0);
+	assert(cap_enter() >= 0);
 
-	ATF_REQUIRE(openat(dirfd, "d1/d2/d3/../../f1", O_RDONLY) >= 0);
-	ATF_REQUIRE(openat(dirfd, "l3/../../f1", O_RDONLY) >= 0);
-	ATF_REQUIRE(openat(dirfd, "l3/ld1", O_RDONLY) >= 0);
-	ATF_REQUIRE(openat(dirfd, "l3/lf1", O_RDONLY) >= 0);
+	assert(openat(dirfd, "d1/d2/d3/../../f1", O_RDONLY) >= 0);
+	assert(openat(dirfd, "l3/../../f1", O_RDONLY) >= 0);
+	assert(openat(dirfd, "l3/ld1", O_RDONLY) >= 0);
+	assert(openat(dirfd, "l3/lf1", O_RDONLY) >= 0);
+}
+
+ATF_TC_BODY(lookup_cap_dotdot__advanced, tc)
+{
+
+	run_capsicum_test(lookup_cap_dotdot__advanced_child);
 }
 
 /*
@@ -168,6 +210,7 @@ ATF_TC_HEAD(openat__basic_negative, tc)
 
 ATF_TC_BODY(openat__basic_negative, tc)
 {
+
 	prepare_dotdot_tests();
 
 	ATF_REQUIRE_ERRNO(ENOENT,
@@ -182,32 +225,43 @@ ATF_TC_HEAD(capmode__negative, tc)
 	atf_tc_set_md_var(tc, "descr", "Negative Capability mode testcases");
 }
 
-ATF_TC_BODY(capmode__negative, tc)
+static void
+capmode__negative_child(void)
 {
 	int subdirfd;
 
-	check_capsicum();
-	prepare_dotdot_tests();
-
-	ATF_REQUIRE(cap_enter() == 0);
+	assert(cap_enter() == 0);
 
 	/* open() not permitted in capability mode */
-	ATF_REQUIRE_ERRNO(ECAPMODE, open("testdir", O_RDONLY) < 0);
+	assert(open("testdir", O_RDONLY) < 0);
+	assert(errno == ECAPMODE);
 
 	/* AT_FDCWD not permitted in capability mode */
-	ATF_REQUIRE_ERRNO(ECAPMODE, openat(AT_FDCWD, "d1/f1", O_RDONLY) < 0);
+	assert(openat(AT_FDCWD, "d1/f1", O_RDONLY) < 0);
+	assert(errno == ECAPMODE);
 
 	/* Relative path above dirfd not capable */
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE, openat(dirfd, "..", O_RDONLY) < 0);
-	ATF_REQUIRE((subdirfd = openat(dirfd, "l3", O_RDONLY)) >= 0);
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE,
-	    openat(subdirfd, "../../f1", O_RDONLY) < 0);
+	assert(openat(dirfd, "..", O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
+
+	assert((subdirfd = openat(dirfd, "l3", O_RDONLY)) >= 0);
+	assert(openat(subdirfd, "../../f1", O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
+	(void)close(subdirfd);
 
 	/* Absolute paths not capable */
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE, openat(dirfd, abspath, O_RDONLY) < 0);
+	assert(openat(dirfd, abspath, O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
 
 	/* Symlink above dirfd */
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE, openat(dirfd, "lup/f1", O_RDONLY) < 0);
+	assert(openat(dirfd, "lup/f1", O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
+}
+
+ATF_TC_BODY(capmode__negative, tc)
+{
+
+	run_capsicum_test(capmode__negative_child);
 }
 
 ATF_TC(lookup_cap_dotdot__negative);
@@ -217,22 +271,30 @@ ATF_TC_HEAD(lookup_cap_dotdot__negative, tc)
 	    "Validate cap-mode (testdir)/.. lookup fails");
 }
 
-ATF_TC_BODY(lookup_cap_dotdot__negative, tc)
+static void
+lookup_cap_dotdot__negative_child(void)
 {
 	cap_rights_t rights;
-	int fd;
-
-	check_capsicum();
-	prepare_dotdot_tests();
 
 	cap_rights_init(&rights, CAP_LOOKUP, CAP_READ);
-	ATF_REQUIRE(cap_rights_limit(dirfd, &rights) >= 0);
+	assert(cap_rights_limit(dirfd, &rights) >= 0);
 
-	ATF_REQUIRE(cap_enter() >= 0);
+	assert(cap_enter() >= 0);
 
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE, openat(dirfd, "..", O_RDONLY) < 0);
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE, openat(dirfd, "d1/../..", O_RDONLY) < 0);
-	ATF_REQUIRE_ERRNO(ENOTCAPABLE, openat(dirfd, "../testdir/d1/f1", O_RDONLY) < 0);
+	assert(openat(dirfd, "..", O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
+
+	assert(openat(dirfd, "d1/../..", O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
+
+	assert(openat(dirfd, "../testdir/d1/f1", O_RDONLY) < 0);
+	assert(errno == ENOTCAPABLE);
+}
+
+ATF_TC_BODY(lookup_cap_dotdot__negative, tc)
+{
+
+	run_capsicum_test(lookup_cap_dotdot__negative_child);
 }
 
 ATF_TP_ADD_TCS(tp)