From: Michael Tremer <michael.tremer@ipfire.org>
Date: Mon, 25 Sep 2023 16:54:28 +0000 (+0000)
Subject: string: Refactor replace function
X-Git-Tag: 0.9.30~1644
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0d4e3f69d3029ded9522ecbc96b9802e7ee1f4c0;p=pakfire.git

string: Refactor replace function

The old version was slightly over-engineered and the static analyzer was
not too happy with it. Instead of debugging any problems, I wrote this
version which is a lot easier and should be more bug-free.

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

diff --git a/src/libpakfire/string.c b/src/libpakfire/string.c
index cf04f05b3..db4783aae 100644
--- a/src/libpakfire/string.c
+++ b/src/libpakfire/string.c
@@ -121,93 +121,54 @@ int pakfire_string_partition(const char* s, const char* delim, char** s1, char**
 }
 
 char* pakfire_string_replace(const char* s, const char* pattern, const char* repl) {
-	// Return NULL on no input or no pattern
-	if (!s || !pattern) {
+	const char* m = NULL;
+	char* buffer = "";
+	size_t l = 0;
+	int r;
+
+	// Check inputs
+	if (!s || !pattern || !repl) {
 		errno = EINVAL;
 		return NULL;
 	}
 
-	// Replace with nothing when repl is NULL
-	if (!repl)
-		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;
+	// Walk through the string...
+	for (const char* p = s; *p;) {
+		// Search for the pattern
+		m = strstr(p, pattern);
 
-	// 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;
-	}
+		// Pattern does not exist in the remaining string
+		if (!m) {
+			// Copy the remaining string
+			r = asprintf(&buffer, "%s%s", buffer, p);
+			if (r < 0)
+				goto ERROR;
 
-	// 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;
+			break;
+		}
 
-	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 of the string up to the match
+		l = m - p;
 
-		// Determine the length between two matches
-		l = cache[i+1] - (cache[i] + pattern_length);
+		// Copy the read string up to pattern and the replacement into the buffer
+		r = asprintf(&buffer, "%s%.*s%s", buffer, (int)l, p, repl);
+		if (r < 0)
+			goto ERROR;
 
-		memcpy(r, p, l);
-		r += l;
-		p += l;
+		// Advance p
+		p += l + pattern_length;
 	}
 
-	// Terminate the string
-	result[length] = '\0';
+	// Return the buffer
+	return buffer;
 
 ERROR:
-	if (cache)
-		free(cache);
+	if (buffer)
+		free(buffer);
 
-	return result;
+	return NULL;
 }
 
 static unsigned int pakfire_chrcnt(const char* s, char delim) {