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;
 }