fstab-generator: also convert % → %% for What=

Same reasons as the previous patch.

src/fstab-generator/fstab-generator.c

@@ -74,6 +74,17 @@ static int write_options(FILE *f, const char *options) {
         return 1;
 }
 
+static int write_what(FILE *f, const char *what) {
+        _cleanup_free_ char *w = NULL;
+
+        w = strreplace(what, "%", "%%");
+        if (!w)
+                return log_oom();
+
+        fprintf(f, "What=%s\n", w);
+        return 1;
+}
+
 static int add_swap(
                 const char *what,
                 struct mntent *me,
@@ -113,14 +124,15 @@ static int add_swap(
                                        "Failed to create unit file %s: %m",
                                        unit);
 
-        fprintf(f,
-                "# Automatically generated by systemd-fstab-generator\n\n"
-                "[Unit]\n"
-                "SourcePath=/etc/fstab\n"
-                "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n\n"
-                "[Swap]\n"
-                "What=%s\n",
-                what);
+        fputs("# Automatically generated by systemd-fstab-generator\n\n"
+              "[Unit]\n"
+              "SourcePath=/etc/fstab\n"
+              "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n\n"
+              "[Swap]\n", f);
+
+        r = write_what(f, what);
+        if (r < 0)
+                return r;
 
         r = write_options(f, me->mnt_opts);
         if (r < 0)
@@ -349,11 +361,13 @@ static int add_mount(
         fprintf(f,
                 "\n"
                 "[Mount]\n"
-                "What=%s\n"
                 "Where=%s\n",
-                what,
                 where);
 
+        r = write_what(f, what);
+        if (r < 0)
+                return r;
+
         if (!isempty(fstype) && !streq(fstype, "auto"))
                 fprintf(f, "Type=%s\n", fstype);