Reject invalid quoted strings

String which ended in an unfinished quote were accepted, potentially
with bad memory accesses.

Reject anything which ends in a unfished quote, or contains
non-whitespace characters right after the closing quote.

_FOREACH_WORD now returns the invalid character in *state. But this return
value is not checked anywhere yet.

Also, make 'word' and 'state' variables const pointers, and rename 'w'
to 'word' in various places. Things are easier to read if the same name
is used consistently.

mbiebl_> am I correct that something like this doesn't work
mbiebl_> ExecStart=/usr/bin/encfs --extpass='/bin/systemd-ask-passwd "Unlock EncFS"'
mbiebl_> systemd seems to strip of the quotes
mbiebl_> systemctl status shows
mbiebl_> ExecStart=/usr/bin/encfs --extpass='/bin/systemd-ask-password Unlock EncFS  $RootDir $MountPoint
mbiebl_> which is pretty weird

1 files changed, 5 insertions, 4 deletions

diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index 7c47f6ecd2..ddf1c371a0 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -395,7 +395,7 @@ static int parse_argv(int argc, char *argv[]) {
 
                 case ARG_CAPABILITY:
                 case ARG_DROP_CAPABILITY: {
-                        char *state, *word;
+                        const char *state, *word;
                         size_t length;
 
                         FOREACH_WORD_SEPARATOR(word, length, optarg, ",", state) {
@@ -2602,7 +2602,8 @@ static int spawn_getent(const char *database, const char *key, pid_t *rpid) {
 }
 
 static int change_uid_gid(char **_home) {
-        char line[LINE_MAX], *w, *x, *state, *u, *g, *h;
+        char line[LINE_MAX], *x, *u, *g, *h;
+        const char *word, *state;
         _cleanup_free_ uid_t *uids = NULL;
         _cleanup_free_ char *home = NULL;
         _cleanup_fclose_ FILE *f = NULL;
@@ -2752,10 +2753,10 @@ static int change_uid_gid(char **_home) {
         x += strcspn(x, WHITESPACE);
         x += strspn(x, WHITESPACE);
 
-        FOREACH_WORD(w, l, x, state) {
+        FOREACH_WORD(word, l, x, state) {
                 char c[l+1];
 
-                memcpy(c, w, l);
+                memcpy(c, word, l);
                 c[l] = 0;
 
                 if (!GREEDY_REALLOC(uids, sz, n_uids+1))