From: Michael Tremer <michael.tremer@ipfire.org>
Date: Wed, 3 Mar 2021 00:32:17 +0000 (+0000)
Subject: util: Implement a function that replace patterns in a string
X-Git-Tag: 0.9.28~1285^2~659
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b8377a9fbabc4f197d5072c3148a554510dbb56b;p=pakfire.git

util: Implement a function that replace patterns in a string

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

diff --git a/src/libpakfire/include/pakfire/util.h b/src/libpakfire/include/pakfire/util.h
index 5e107b03d..2f9948986 100644
--- a/src/libpakfire/include/pakfire/util.h
+++ b/src/libpakfire/include/pakfire/util.h
@@ -30,6 +30,7 @@
 
 int pakfire_string_startswith(const char* s, const char* prefix);
 int pakfire_string_partition(const char* s, const char* delim, char** s1, char** s2);
+char* pakfire_string_replace(const char* s, const char* pattern, const char* repl);
 
 char* pakfire_format_size(double size);
 char* pakfire_format_date(time_t t);
diff --git a/src/libpakfire/libpakfire.sym b/src/libpakfire/libpakfire.sym
index a8e259697..ba24d0acf 100644
--- a/src/libpakfire/libpakfire.sym
+++ b/src/libpakfire/libpakfire.sym
@@ -412,6 +412,7 @@ global:
 	pakfire_read_file_into_buffer;
 	pakfire_split_string;
 	pakfire_string_partition;
+	pakfire_string_replace;
 	pakfire_string_startswith;
 	pakfire_string_to_size;
 
diff --git a/src/libpakfire/util.c b/src/libpakfire/util.c
index b894de5e1..70c04da6f 100644
--- a/src/libpakfire/util.c
+++ b/src/libpakfire/util.c
@@ -72,6 +72,87 @@ PAKFIRE_EXPORT int pakfire_string_partition(
 	return 0;
 }
 
+PAKFIRE_EXPORT char* pakfire_string_replace(
+		const char* s, const char* pattern, const char* repl) {
+	char* result = NULL;
+	const char** cache = NULL;
+	unsigned int count = 0;
+
+	const size_t pattern_length = strlen(pattern);
+
+	// Working pointer
+	const char* p = s;
+
+	// Find all occurrences of pattern and store their location
+	while (1) {
+		const char* needle = strstr(p, pattern);
+		if (!needle)
+			break;
+
+		// Make space in the cache
+		cache = reallocarray(cache, sizeof(*cache), count + 1);
+		cache[count++] = needle;
+
+		// Move p forward
+		p = needle + pattern_length;
+	}
+
+	// Copy the string if no occurence was found
+	if (count == 0) {
+		result = strdup(s);
+		goto ERROR;
+	}
+
+	// Store the end pointer
+	cache = reallocarray(cache, sizeof(*cache), count + 1);
+	cache[count] = s + strlen(s);
+
+	const size_t repl_length = strlen(repl);
+
+	// Determine the length of the final string
+	const size_t length = strlen(s) + ((repl_length - pattern_length) * count);
+
+	// Allocate enough memory for the result
+	result = malloc(length + 1);
+	if (!result)
+		goto ERROR;
+
+	// Reset p
+	p = s;
+
+	// Working pointer for the result
+	char* r = result;
+
+	// Copy everything up to the first match
+	ssize_t l = cache[0] - s;
+	memcpy(r, p, l);
+	r += l;
+	p += l;
+
+	for (unsigned int i = 0; i < count; i++) {
+		// Put replacement here
+		memcpy(r, repl, repl_length);
+		r += repl_length;
+		p += pattern_length;
+
+		// Determine the length between two matches
+		l = cache[i+1] - (cache[i] + pattern_length);
+
+		memcpy(r, p, l);
+		r += l;
+		p += l;
+	}
+
+	// Terminate the string
+	result[length] = '\0';
+
+ERROR:
+	if (cache)
+		free(cache);
+
+	return result;
+}
+
 char* pakfire_lstrip(const char* s) {
 	while (*s && isspace(*s))
 		s++;
diff --git a/tests/libpakfire/util.c b/tests/libpakfire/util.c
index 942641c1b..e78b135a4 100644
--- a/tests/libpakfire/util.c
+++ b/tests/libpakfire/util.c
@@ -107,11 +107,21 @@ static int test_string_partition(const struct test* t) {
 	return EXIT_SUCCESS;
 }
 
+static int test_string_replace(const struct test* t) {
+	const char* result = pakfire_string_replace(
+		"ABCABCABCABC", "AB", "CC"
+	);
+	ASSERT_STRING_EQUALS(result, "CCCCCCCCCCCC");
+
+	return EXIT_SUCCESS;
+}
+
 int main(int argc, char** argv) {
 	testsuite_add_test(test_basename);
 	testsuite_add_test(test_dirname);
 	testsuite_add_test(test_string_startswith);
 	testsuite_add_test(test_string_partition);
+	testsuite_add_test(test_string_replace);
 
 	return testsuite_run();
 }