unittest: add some tests for get_relative_path helper

v2: let's also mock kerndat_s.sysctl_nr_open field, to make aarch64
clang ci happy

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>

criu/Makefile

@@ -87,6 +87,7 @@ $(obj)/criu: $(PROGRAM-BUILTINS)
 	$(call msg-link, $@)
 	$(Q) $(CC) $(CFLAGS) $^ $(LIBS) $(WRAPFLAGS) $(LDFLAGS) $(GMONLDOPT) -rdynamic -o $@
 
+UNIT-BUILTINS		+= $(obj)/util.o
 UNIT-BUILTINS		+= $(obj)/config.o
 UNIT-BUILTINS		+= $(obj)/log.o
 UNIT-BUILTINS		+= $(obj)/string.o

criu/unittest/mock.c

@@ -97,3 +97,42 @@ int close_service_fd(int type)
 void compel_log_init(int log_fn, unsigned int level)
 {
 }
+
+void set_cr_errno(int new_err)
+{
+}
+
+struct ns_desc {
+};
+struct ns_desc user_ns_desc;
+int switch_ns(int pid, struct ns_desc *nd, int *rst)
+{
+	return -1;
+}
+
+enum script_actions { ACT_FAKE };
+int run_scripts(enum script_actions act)
+{
+	return -1;
+}
+
+typedef struct VmaEntry VmaEntry;
+struct VmaEntry {
+};
+void vma_entry__init(VmaEntry *message)
+{
+}
+
+int clone_noasan(int (*fn)(void *), int flags, void *arg)
+{
+	return -1;
+}
+
+struct kerndat_s {
+	unsigned int sysctl_nr_open;
+};
+struct kerndat_s kdat = {};
+
+int service_fd_rlim_cur;
+
+unsigned __page_size;

criu/unittest/unit.c

@@ -3,6 +3,7 @@
 #include <assert.h>
 
 #include "log.h"
+#include "util.h"
 #include "criu-log.h"
 
 int parse_statement(int i, char *line, char **configuration);
@@ -100,6 +101,48 @@ int main(int argc, char *argv[], char *envp[])
 	i = parse_statement(0, "a b c d e f g h i\n", configuration);
 	assert(i == -1);
 
+	/* get_relative_path */
+	/* different kinds of representation of "/" */
+	assert(!strcmp(get_relative_path("/", "/"), ""));
+	assert(!strcmp(get_relative_path("/", ""), ""));
+	assert(!strcmp(get_relative_path("", "/"), ""));
+	assert(!strcmp(get_relative_path(".", "/"), ""));
+	assert(!strcmp(get_relative_path("/", "."), ""));
+	assert(!strcmp(get_relative_path("/", "./"), ""));
+	assert(!strcmp(get_relative_path("./", "/"), ""));
+	assert(!strcmp(get_relative_path("/.", "./"), ""));
+	assert(!strcmp(get_relative_path("./", "/."), ""));
+	assert(!strcmp(get_relative_path(".//////.", ""), ""));
+	assert(!strcmp(get_relative_path("/./", ""), ""));
+
+	/* all relative paths given are assumed relative to "/" */
+	assert(!strcmp(get_relative_path("/a/b/c", "a/b/c"), ""));
+
+	/* multiple slashes are ignored, only directory names matter */
+	assert(!strcmp(get_relative_path("///alfa///beta///gamma///", "//alfa//beta//gamma//"), ""));
+
+	/* returned path is always relative */
+	assert(!strcmp(get_relative_path("/a/b/c", "/"), "a/b/c"));
+	assert(!strcmp(get_relative_path("/a/b/c", "/a/b"), "c"));
+
+	/* single dots supported */
+	assert(!strcmp(get_relative_path("./a/b", "a/"), "b"));
+
+	/* double dots are partially supported */
+	assert(!strcmp(get_relative_path("a/../b", "a"), "../b"));
+	assert(!strcmp(get_relative_path("a/../b", "a/.."), "b"));
+	assert(!get_relative_path("a/../b/c", "b"));
+
+	/* if second path is not subpath - NULL returned */
+	assert(!get_relative_path("/a/b/c", "/a/b/d"));
+	assert(!get_relative_path("/a/b", "/a/b/c"));
+	assert(!get_relative_path("/a/b/c/d", "b/c/d"));
+
+	assert(!strcmp(get_relative_path("./a////.///./b//././c", "///./a/b"), "c"));
+
+	/* leaves punctuation in returned string as is */
+	assert(!strcmp(get_relative_path("./a////.///./b//././c", "a"), "b//././c"));
+
 	pr_msg("OK\n");
 	return 0;
 }