lib: factor out message-id parsing to separate file.

[notmuch] / lib / message-id.c

diff --git a/lib/message-id.c b/lib/message-id.c
new file mode 100644 (file)
index 0000000..d7541d5
--- /dev/null
+++ b/lib/message-id.c
@@ -0,0 +1,96 @@
+#include "notmuch-private.h"
+
+/* Advance 'str' past any whitespace or RFC 822 comments. A comment is
+ * a (potentially nested) parenthesized sequence with '\' used to
+ * escape any character (including parentheses).
+ *
+ * If the sequence to be skipped continues to the end of the string,
+ * then 'str' will be left pointing at the final terminating '\0'
+ * character.
+ */
+static void
+skip_space_and_comments (const char **str)
+{
+    const char *s;
+
+    s = *str;
+    while (*s && (isspace (*s) || *s == '(')) {
+       while (*s && isspace (*s))
+           s++;
+       if (*s == '(') {
+           int nesting = 1;
+           s++;
+           while (*s && nesting) {
+               if (*s == '(') {
+                   nesting++;
+               } else if (*s == ')') {
+                   nesting--;
+               } else if (*s == '\\') {
+                   if (*(s+1))
+                       s++;
+               }
+               s++;
+           }
+       }
+    }
+
+    *str = s;
+}
+
+char *
+_notmuch_message_id_parse (void *ctx, const char *message_id, const char **next)
+{
+    const char *s, *end;
+    char *result;
+
+    if (message_id == NULL || *message_id == '\0')
+       return NULL;
+
+    s = message_id;
+
+    skip_space_and_comments (&s);
+
+    /* Skip any unstructured text as well. */
+    while (*s && *s != '<')
+       s++;
+
+    if (*s == '<') {
+       s++;
+    } else {
+       if (next)
+           *next = s;
+       return NULL;
+    }
+
+    skip_space_and_comments (&s);
+
+    end = s;
+    while (*end && *end != '>')
+       end++;
+    if (next) {
+       if (*end)
+           *next = end + 1;
+       else
+           *next = end;
+    }
+
+    if (end > s && *end == '>')
+       end--;
+    if (end <= s)
+       return NULL;
+
+    result = talloc_strndup (ctx, s, end - s + 1);
+
+    /* Finally, collapse any whitespace that is within the message-id
+     * itself. */
+    {
+       char *r;
+       int len;
+
+       for (r = result, len = strlen (r); *r; r++, len--)
+           if (*r == ' ' || *r == '\t')
+               memmove (r, r+1, len);
+    }
+
+    return result;
+}