1 files changed, 54 insertions, 19 deletions

diff --git a/src/string.c b/src/string.c
index c14f1b5..ae19271 100644
--- a/src/string.c
+++ b/src/string.c
@@ -27,6 +27,7 @@
  * 			all others pass through
  */
 enum HX_quote_selector {
+	HXQUOTE_ALWAYS,
 	HXQUOTE_ACCEPT,
 	HXQUOTE_REJECT,
 };
@@ -211,6 +212,8 @@ EXPORT_SYMBOL char **HX_split(const char *str, const char *delim,
 		*cp = max;
 
 	ret = malloc(sizeof(char *) * (*cp + 1));
+	if (ret == nullptr)
+		return nullptr;
 	ret[*cp] = NULL;
 
 	{
@@ -378,20 +381,48 @@ EXPORT_SYMBOL char *HX_stpltrim(const char *p)
 	return const_cast1(char *, p);
 }
 
+/**
+ * Helper for substr() function for dealing with negative off/len values
+ * @z:		total length of string
+ * @offset:	n>=0 specifies offset from the start,
+ * 		n<0 specifies offset from the end
+ * @len:	"length"; n>=0 specifies length to copy (from @offset),
+ * 		n<0 specifies the byte relative to the end at which to stop
+ *
+ * @abstart:	(result) absolute start
+ * @retval:	(result) absolute length to copy (from *@abstart)
+ */
+size_t HX_substr_helper(size_t z, long offset, long len, size_t *start)
+{
+	if (offset >= 0)
+		*start = offset;
+	else if (offset == LONG_MIN)
+		*start = z + -static_cast(size_t, LONG_MIN);
+	else
+		*start = z >= static_cast(unsigned long, -offset) ? z + offset : z;
+
+	size_t end;
+	if (len >= 0)
+		end = *start < SIZE_MAX - len ? *start + len : SIZE_MAX;
+	else if (len == LONG_MIN)
+		end = z + -static_cast(unsigned long, LONG_MIN);
+	else
+		end = z >= static_cast(unsigned long, -len) ? z + len : 0;
+	if (end > z)
+		end = z;
+	return end > *start ? end - *start : 0;
+}
+
 /* supports negative offsets like scripting languages */
 EXPORT_SYMBOL char *HX_strmid(const char *expr, long offset, long length)
 {
-	char *buffer;
-
-	if (offset < 0)
-		offset = strlen(expr) + offset;
-	if (length < 0)
-		length = strlen(expr) - offset + length;
-	if ((buffer = malloc(length + 1)) == NULL)
+	size_t start = 0, tocopy = HX_substr_helper(strlen(expr), offset, length, &start);
+	char *buffer = malloc(tocopy + 1);
+	if (buffer == nullptr)
 		return NULL;
-
-	expr += offset;
-	return HX_strlcpy(buffer, expr, length + 1);
+	memcpy(buffer, &expr[start], tocopy);
+	buffer[tocopy] = '\0';
+	return buffer;
 }
 
 EXPORT_SYMBOL char *HX_strndup(const char *src, size_t size)
@@ -773,7 +804,7 @@ static size_t HX_quoted_size(const char *s, unsigned int type)
 EXPORT_SYMBOL char *HX_strquote(const char *src, unsigned int type,
     char **free_me)
 {
-	const struct HX_quote_rule *rule;
+	const struct HX_quote_rule *rule = nullptr;
 	bool do_quote;
 	char *tmp;
 
@@ -782,15 +813,19 @@ EXPORT_SYMBOL char *HX_strquote(const char *src, unsigned int type,
 		return NULL;
 	}
 	/* If quote_chars is NULL, it is clear all chars are to be encoded. */
-	rule = &HX_quote_rules[type];
-	if (type >= ARRAY_SIZE(HX_quote_rules) || rule->chars == NULL)
+	if (type >= ARRAY_SIZE(HX_quote_rules)) {
 		do_quote = true;
-	else if (rule->selector == HXQUOTE_REJECT)
-		do_quote = strpbrk(src, rule->chars) != NULL;
-	else if (rule->selector == HXQUOTE_ACCEPT)
-		do_quote = HX_strchr2(src, rule->chars) != NULL;
-	else
-		do_quote = false;
+	} else {
+		rule = &HX_quote_rules[type];
+		if (rule->selector == HXQUOTE_ALWAYS)
+			do_quote = true;
+		else if (rule->selector == HXQUOTE_REJECT)
+			do_quote = strpbrk(src, rule->chars) != NULL;
+		else if (rule->selector == HXQUOTE_ACCEPT)
+			do_quote = HX_strchr2(src, rule->chars) != NULL;
+		else
+			do_quote = false;
+	}
 	/*
 	 * free_me == NULL implies that we always allocate, even if
 	 * there is nothing to quote.