[balsa/port-to-pcre2: 9/10] gmime-gpgme-signature: Use a custom parser

[Peter Bloomfield <peterb src gnome org>]

commit 2455c91878192ad180a4cc609a35db23989ad0d9
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Wed Dec 9 13:58:49 2020 -0500

    gmime-gpgme-signature: Use a custom parser
    
    instead of libbalsa_regex_split().

 libbalsa/gmime-gpgme-signature.c | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)
---
diff --git a/libbalsa/gmime-gpgme-signature.c b/libbalsa/gmime-gpgme-signature.c
index 659d2c2e6..3360cc6a2 100644
--- a/libbalsa/gmime-gpgme-signature.c
+++ b/libbalsa/gmime-gpgme-signature.c
@@ -342,6 +342,34 @@ hex_decode(const gchar *hexstr)
     return result;
 }
 
+/*
+ * Simple parser: split the subject at every unescaped '=' or ','
+ */
+static char **
+split_subject(const char *subject)
+{
+    GPtrArray *result = g_ptr_array_new();
+    const char *p = subject;
+    const char *start = subject;
+
+    while (*p != '\0') {
+        int c = *p++;
+
+        if (c == '\\') {
+            if (*p != '\0')
+                p++;
+        } else if (c == '=' || c == ',') {
+            g_ptr_array_add(result, g_strndup(start, (p - start) - 1));
+            start = p;
+        }
+    }
+
+    g_ptr_array_add(result, g_strndup(start, p - start));
+    g_ptr_array_add(result, NULL);
+
+    return (char **) g_ptr_array_free(result, FALSE);
+}
+
 /** \brief Split a S/MIME certificate subject string into tokens
  *
  * \param subject certificate subject string
@@ -354,21 +382,13 @@ hex_decode(const gchar *hexstr)
  *
  * If the string starts with a '<', it contains an email address, and is returned untouched in the array.
  */
+
 static gchar **
 tokenize_subject(const gchar *subject,
                                 gboolean     unescape)
 {
-       static LibBalsaRegex *split_re = NULL;
-       static volatile guint initialized = 0U;
        gchar **result;
 
-       /* create the reqular expression when called for teh first time */
-       if (g_atomic_int_or(&initialized, 1U) == 0U) {
-               /* split a DN string at unescaped ',' and '=' chars */
-               split_re = libbalsa_regex_new("(?<!\\\\)[,=]", 0, NULL);
-               g_assert(split_re != NULL);
-       }
-
        /* catch empty string */
        if (subject == NULL) {
                return NULL;
@@ -380,7 +400,7 @@ tokenize_subject(const gchar *subject,
                result[0] = g_strdup(subject);
        } else {
                /* split into (oid, value) pairs */
-               result = libbalsa_regex_split(split_re, subject, 0);
+               result = split_subject(subject);
                if (result != NULL) {
                        gint n;