Fix segfaults caused by faulty command parsing

This patch fixes faulty command parsing introduced by
f0f5de9a9e87ca1f0d74e7cbf82ffceba51ffbe6. When that commit allowed
criteria reset on ';' delimeters in commands lists, it failed to account
for its inner ','-parsing loop eating threw the entire rest of the
string.

This patch refactors argsep to use a list of multiple separators, and
(optionally) return the separator that it matched against in this
iteration via a pointer. This allows it to hint at the command parser
which separator was used at the end of the last command, allowing it to
trigger a potential secondary read of the criteria.

Fixes #4239

1 files changed, 40 insertions, 16 deletions

diff --git a/common/stringop.c b/common/stringop.c
index dea152cc..ac7df296 100644
--- a/common/stringop.c
+++ b/common/stringop.c
@@ -251,37 +251,61 @@ char *join_args(char **argv, int argc) {
 	return res;
 }
 
-char *argsep(char **stringp, const char *delim) {
+static inline char *argsep_next_interesting(const char *src, const char *delim) {
+	char *special = strpbrk(src, "\"'\\");
+	char *next_delim = strpbrk(src, delim);
+	if (!special) {
+		return next_delim;
+	}
+	if (!next_delim) {
+		return special;
+	}
+	return (next_delim < special) ? next_delim : special;
+}
+
+char *argsep(char **stringp, const char *delim, char *matched) {
 	char *start = *stringp;
 	char *end = start;
 	bool in_string = false;
 	bool in_char = false;
 	bool escaped = false;
-	while (1) {
-		if (*end == '"' && !in_char && !escaped) {
+	char *interesting = NULL;
+
+	while ((interesting = argsep_next_interesting(end, delim))) {
+		if (escaped && interesting != end) {
+			escaped = false;
+		}
+		if (*interesting == '"' && !in_char && !escaped) {
 			in_string = !in_string;
-		} else if (*end == '\'' && !in_string && !escaped) {
+			end = interesting + 1;
+		} else if (*interesting == '\'' && !in_string && !escaped) {
 			in_char = !in_char;
-		} else if (*end == '\\') {
+			end = interesting + 1;
+		} else if (*interesting == '\\') {
 			escaped = !escaped;
-		} else if (*end == '\0') {
-			*stringp = NULL;
-			break;
-		} else if (!in_string && !in_char && !escaped && strchr(delim, *end)) {
+			end = interesting + 1;
+		} else if (!in_string && !in_char && !escaped) {
+			// We must have matched a separator
+			end = interesting;
+			if (matched) {
+				*matched = *end;
+			}
 			if (end - start) {
 				*(end++) = 0;
-				*stringp = end + strspn(end, delim);;
-				if (!**stringp) *stringp = NULL;
+				*stringp = end;
 				break;
 			} else {
-				++start;
-				end = start;
+				end = ++start;
 			}
+		} else {
+			end++;
 		}
-		if (*end != '\\') {
-			escaped = false;
+	}
+	if (!interesting) {
+		*stringp = NULL;
+		if (matched) {
+			*matched = '\0';
 		}
-		++end;
 	}
 	return start;
 }