--- /dev/null
+#include "database-private.h"
+
+static const struct {
+ /* NOTMUCH_FEATURE_* value. */
+ _notmuch_features value;
+ /* Feature name as it appears in the database. This name should
+ * be appropriate for displaying to the user if an older version
+ * of notmuch doesn't support this feature. */
+ const char *name;
+ /* Compatibility flags when this feature is declared. */
+ const char *flags;
+} feature_names[] = {
+ { NOTMUCH_FEATURE_FILE_TERMS,
+ "multiple paths per message", "rw" },
+ { NOTMUCH_FEATURE_DIRECTORY_DOCS,
+ "relative directory paths", "rw" },
+ /* Header values are not required for reading a database because a
+ * reader can just refer to the message file. */
+ { NOTMUCH_FEATURE_FROM_SUBJECT_ID_VALUES,
+ "from/subject/message-ID in database", "w" },
+ { NOTMUCH_FEATURE_BOOL_FOLDER,
+ "exact folder:/path: search", "rw" },
+ { NOTMUCH_FEATURE_GHOSTS,
+ "mail documents for missing messages", "w" },
+ /* Knowledge of the index mime-types are not required for reading
+ * a database because a reader will just be unable to query
+ * them. */
+ { NOTMUCH_FEATURE_INDEXED_MIMETYPES,
+ "indexed MIME types", "w" },
+ { NOTMUCH_FEATURE_LAST_MOD,
+ "modification tracking", "w" },
+ /* Existing databases will work fine for all queries not involving
+ * 'body:' */
+ { NOTMUCH_FEATURE_UNPREFIX_BODY_ONLY,
+ "index body and headers separately", "w" },
+};
+
+char *
+_notmuch_database_print_features (const void *ctx, unsigned int features)
+{
+ unsigned int i;
+ char *res = talloc_strdup (ctx, "");
+
+ for (i = 0; i < ARRAY_SIZE (feature_names); ++i)
+ if (features & feature_names[i].value)
+ res = talloc_asprintf_append_buffer (
+ res, "%s\t%s\n", feature_names[i].name, feature_names[i].flags);
+
+ return res;
+}
+
+
+/* Parse a database features string from the given database version.
+ * Returns the feature bit set.
+ *
+ * For version < 3, this ignores the features string and returns a
+ * hard-coded set of features.
+ *
+ * If there are unrecognized features that are required to open the
+ * database in mode (which should be 'r' or 'w'), return a
+ * comma-separated list of unrecognized but required features in
+ * *incompat_out suitable for presenting to the user. *incompat_out
+ * will be allocated from ctx.
+ */
+_notmuch_features
+_notmuch_database_parse_features (const void *ctx, const char *features, unsigned int version,
+ char mode, char **incompat_out)
+{
+ _notmuch_features res = static_cast<_notmuch_features>(0);
+ unsigned int namelen, i;
+ size_t llen = 0;
+ const char *flags;
+
+ /* Prior to database version 3, features were implied by the
+ * version number. */
+ if (version == 0)
+ return NOTMUCH_FEATURES_V0;
+ else if (version == 1)
+ return NOTMUCH_FEATURES_V1;
+ else if (version == 2)
+ return NOTMUCH_FEATURES_V2;
+
+ /* Parse the features string */
+ while ((features = strtok_len_c (features + llen, "\n", &llen)) != NULL) {
+ flags = strchr (features, '\t');
+ if (! flags || flags > features + llen)
+ continue;
+ namelen = flags - features;
+
+ for (i = 0; i < ARRAY_SIZE (feature_names); ++i) {
+ if (strlen (feature_names[i].name) == namelen &&
+ strncmp (feature_names[i].name, features, namelen) == 0) {
+ res |= feature_names[i].value;
+ break;
+ }
+ }
+
+ if (i == ARRAY_SIZE (feature_names) && incompat_out) {
+ /* Unrecognized feature */
+ const char *have = strchr (flags, mode);
+ if (have && have < features + llen) {
+ /* This feature is required to access this database in
+ * 'mode', but we don't understand it. */
+ if (! *incompat_out)
+ *incompat_out = talloc_strdup (ctx, "");
+ *incompat_out = talloc_asprintf_append_buffer (
+ *incompat_out, "%s%.*s", **incompat_out ? ", " : "",
+ namelen, features);
+ }
+ }
+ }
+
+ return res;
+}