Treat a trailing backslash as an error

Commit a2a5291b3f5 changed the parser to reject unfinished quoted
strings. Unfortunately it introduced an error where a trailing
backslash would case an infinite loop. Of course this must fixed, but
the question is what to to instead. Allowing trailing backslashes and
treating them as normal characters would be one option, but this seems
suboptimal. First, there would be inconsistency between handling of
quoting and of backslashes. Second, a trailing backslash is most
likely an error, at it seems better to point it out to the user than
to try to continue.

Updated rules:
ExecStart=/bin/echo \\ → OK, prints a backslash
ExecStart=/bin/echo \ → error
ExecStart=/bin/echo "x → error
ExecStart=/bin/echo "x"y → error

Signed-off-by: Anthony G. Basile <blueness@gentoo.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index 5dd2b5b4b3..bd16abc8db 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -348,7 +348,7 @@ int safe_atolli(const char *s, long long int *ret_lli) {
 
 static size_t strcspn_escaped(const char *s, const char *reject) {
         bool escaped = false;
-        size_t n;
+        int n;
 
         for (n=0; s[n]; n++) {
                 if (escaped)
@@ -358,6 +358,7 @@ static size_t strcspn_escaped(const char *s, const char *reject) {
                 else if (strchr(reject, s[n]))
                         break;
         }
+
         /* if s ends in \, return index of previous char */
         return n - escaped;
 }
@@ -393,6 +394,11 @@ const char* split(const char **state, size_t *l, const char *separator, bool quo
                 *state = current++ + *l + 2;
         } else if (quoted) {
                 *l = strcspn_escaped(current, separator);
+                if (current[*l] && !strchr(separator, current[*l])) {
+                        /* unfinished escape */
+                        *state = current;
+                        return NULL;
+                }
                 *state = current + *l;
         } else {
                 *l = strcspn(current, separator);