From: Michael Tremer <michael.tremer@ipfire.org>
Date: Fri, 24 Nov 2023 16:49:57 +0000 (+0000)
Subject: path: Add function to compute relative paths
X-Git-Tag: 0.9.30~1295
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=827eca07301c0f67f14f38e060d72b7d13551aec;p=pakfire.git

path: Add function to compute relative paths

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/libpakfire/include/pakfire/path.h b/src/libpakfire/include/pakfire/path.h
index b619bf073..cb2d72a8d 100644
--- a/src/libpakfire/include/pakfire/path.h
+++ b/src/libpakfire/include/pakfire/path.h
@@ -43,4 +43,8 @@ int __pakfire_path_basename(char* buffer, const size_t length, const char* s);
 	__pakfire_path_dirname(path, sizeof(path), s)
 int __pakfire_path_dirname(char* buffer, const size_t length, const char* s);
 
+#define pakfire_path_relative(path, root, s) \
+	__pakfire_path_relative(path, sizeof(path), root, s)
+int __pakfire_path_relative(char* buffer, const size_t length, const char* root, const char* s);
+
 #endif /* PAKFIRE_PATH_H */
diff --git a/src/libpakfire/path.c b/src/libpakfire/path.c
index ee2fdee6e..99edf24cd 100644
--- a/src/libpakfire/path.c
+++ b/src/libpakfire/path.c
@@ -54,9 +54,13 @@ static void pakfire_path_free(struct pakfire_path* path) {
 	free(path);
 }
 
-static int pakfire_path_append_segment(struct pakfire_path* path, const char* segment) {
+static int pakfire_path_insert_segment(struct pakfire_path* path, unsigned int idx, const char* segment) {
 	char* s = NULL;
 
+	// Index must be within range
+	if (idx >= path->num_segments + 1)
+		return -ERANGE;
+
 	// Make space
 	path->segments = reallocarray(path->segments, sizeof(*path->segments),
 		path->num_segments + 2);
@@ -70,12 +74,26 @@ static int pakfire_path_append_segment(struct pakfire_path* path, const char* se
 	if (!s)
 		return -errno;
 
-	// Store the segment in the array
-	path->segments[path->num_segments++] = s;
+	unsigned int i = path->num_segments;
+
+	do {
+		if (i > idx)
+			path->segments[i] = path->segments[i - 1];
+
+		else if (i == idx)
+			path->segments[i] = s;
+	} while (i-- > idx);
+
+	// Increment the number of segments we have
+	path->num_segments++;
 
 	return 0;
 }
 
+static int pakfire_path_append_segment(struct pakfire_path* path, const char* segment) {
+	return pakfire_path_insert_segment(path, path->num_segments, segment);
+}
+
 static int pakfire_path_remove_segment(struct pakfire_path* path, unsigned int idx) {
 	if (idx >= path->num_segments)
 		return -EINVAL;
@@ -411,3 +429,61 @@ ERROR:
 
 	return r;
 }
+
+int __pakfire_path_relative(char* buffer, const size_t length, const char* __root, const char* s) {
+	struct pakfire_path* root = NULL;
+	struct pakfire_path* path = NULL;
+	int r;
+
+	// Parse the root
+	r = pakfire_path_parse(&root, __root);
+	if (r)
+		goto ERROR;
+
+	// Parse the path
+	r = pakfire_path_parse(&path, s);
+	if (r)
+		goto ERROR;
+
+	// Both paths must be absolute
+	if (!root->is_absolute || !path->is_absolute)
+		return -EINVAL;
+
+	// The result is no longer absolute
+	path->is_absolute = 0;
+
+	// Walk through all segments of the root
+	while (root->num_segments && path->num_segments) {
+		// If the first segments match, we drop them both
+		if (strcmp(root->segments[0], path->segments[0]) == 0) {
+			r = pakfire_path_remove_segment(root, 0);
+			if (r)
+				goto ERROR;
+
+			r = pakfire_path_remove_segment(path, 0);
+			if (r)
+				goto ERROR;
+
+		// Otherwise we have reached the end
+		} else {
+			r = pakfire_path_insert_segment(path, 0, "..");
+			if (r)
+				goto ERROR;
+
+			break;
+		}
+	}
+
+	// Write back the path
+	r = pakfire_path_to_string(path, buffer, length);
+	if (r)
+		goto ERROR;
+
+ERROR:
+	if (path)
+		pakfire_path_free(path);
+	if (root)
+		pakfire_path_free(root);
+
+	return r;
+}
diff --git a/tests/libpakfire/path.c b/tests/libpakfire/path.c
index ffc0d51d2..c7214c46f 100644
--- a/tests/libpakfire/path.c
+++ b/tests/libpakfire/path.c
@@ -118,12 +118,37 @@ FAIL:
 	return EXIT_FAILURE;
 }
 
+static int test_path_relative(const struct test* t) {
+	char path[PATH_MAX];
+
+	ASSERT_SUCCESS(pakfire_path_relative(path, "/", "/usr/bin/bash"));
+	ASSERT_STRING_EQUALS(path, "usr/bin/bash");
+
+	ASSERT_SUCCESS(pakfire_path_relative(path, "/usr", "/usr/bin/bash"));
+	ASSERT_STRING_EQUALS(path, "bin/bash");
+
+	ASSERT_SUCCESS(pakfire_path_relative(path, "/usr/bin", "/usr/bin/bash"));
+	ASSERT_STRING_EQUALS(path, "bash");
+
+	ASSERT_SUCCESS(pakfire_path_relative(path, "/usr/sbin", "/usr/bin/bash"));
+	ASSERT_STRING_EQUALS(path, "../bin/bash");
+
+	ASSERT_SUCCESS(pakfire_path_relative(path, "/dev", "/usr/bin/bash"));
+	ASSERT_STRING_EQUALS(path, "../usr/bin/bash");
+
+	return EXIT_SUCCESS;
+
+FAIL:
+	return EXIT_FAILURE;
+}
+
 int main(int argc, const char* argv[]) {
 	testsuite_add_test(test_path_normalize, 0);
 	testsuite_add_test(test_path_append, 0);
 	testsuite_add_test(test_path_merge, 0);
 	testsuite_add_test(test_path_basename, 0);
 	testsuite_add_test(test_path_dirname, 0);
+	testsuite_add_test(test_path_relative, 0);
 
 	return testsuite_run(argc, argv);
 }