util: add shell_maybe_quote() call for preparing a string for shell cmdline inclusion

If necessary the passed string is enclosed in "", and all special
characters escapes.

This also ports over usage in bus-util.c and job.c to use this, instead
of a incorrect local implementation that forgets to properly escape.

2 files changed, 45 insertions, 2 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index da75667c80..3a80f264ca 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -1332,7 +1332,8 @@ char *cescape(const char *s) {
 
         assert(s);
 
-        /* Does C style string escaping. */
+        /* Does C style string escaping. May be be reversed with
+         * cunescape(). */
 
         r = new(char, strlen(s)*4 + 1);
         if (!r)
@@ -1542,7 +1543,7 @@ char *xescape(const char *s, const char *bad) {
 
         /* Escapes all chars in bad, in addition to \ and all special
          * chars, in \xFF style escaping. May be reversed with
-         * cunescape. */
+         * cunescape(). */
 
         r = new(char, strlen(s) * 4 + 1);
         if (!r)
@@ -8035,3 +8036,43 @@ int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char
 
         return 0;
 }
+
+char *shell_maybe_quote(const char *s) {
+        const char *p;
+        char *r, *t;
+
+        assert(s);
+
+        /* Encloses a string in double quotes if necessary to make it
+         * OK as shell string. */
+
+        for (p = s; *p; p++)
+                if (*p <= ' ' ||
+                    *p >= 127 ||
+                    strchr(SHELL_NEED_QUOTES, *p))
+                        break;
+
+        if (!*p)
+                return strdup(s);
+
+        r = new(char, 1+strlen(s)*2+1+1);
+        if (!r)
+                return NULL;
+
+        t = r;
+        *(t++) = '"';
+        t = mempcpy(t, s, p - s);
+
+        for (; *p; p++) {
+
+                if (strchr(SHELL_NEED_ESCAPE, *p))
+                        *(t++) = '\\';
+
+                *(t++) = *p;
+        }
+
+        *(t++)= '"';
+        *t = 0;
+
+        return r;
+}
diff --git a/src/shared/util.h b/src/shared/util.h
index b41090bf70..737a3f3280 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -1090,3 +1090,5 @@ int syslog_parse_priority(const char **p, int *priority, bool with_facility);
 void cmsg_close_all(struct msghdr *mh);
 
 int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char *newpath);
+
+char *shell_maybe_quote(const char *s);