X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/0eaf64e8d26c08228401fa89741c63fc2ff064c3..fde67de26e36cf02d5632d934623bbc054a3c1d9:/lib/trackdb.c

diff --git a/lib/trackdb.c b/lib/trackdb.c
index 3647f10..85d38dd 100644
--- a/lib/trackdb.c
+++ b/lib/trackdb.c
@@ -2,20 +2,18 @@
  * This file is part of DisOrder
  * Copyright (C) 2005-2008 Richard Kettlewell
  *
- * This program is free software; you can redistribute it and/or modify
+ * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
+ * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
  * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
- * USA
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 /** @file lib/trackdb.c
  * @brief Track database
@@ -60,6 +58,7 @@
 #include "unicode.h"
 #include "unidata.h"
 #include "base64.h"
+#include "sendmail.h"
 
 #define RESCAN "disorder-rescan"
 #define DEADLOCK "disorder-deadlock"
@@ -83,8 +82,14 @@ int trackdb_existing_database;
 
 /* setup and teardown ********************************************************/
 
-static const char *home;                /* home had better not change */
-DB_ENV *trackdb_env;			/* db environment */
+/** @brief Database home directory
+ *
+ * All database files live below here.  It had better never change.
+ */
+static const char *home;
+
+/** @brief Database environment */
+DB_ENV *trackdb_env;
 
 /** @brief The tracks database
  * - Keys are UTF-8(NFC(unicode(path name)))
@@ -158,11 +163,55 @@ DB *trackdb_scheduledb;
  */
 DB *trackdb_usersdb;
 
-static pid_t db_deadlock_pid = -1;      /* deadlock manager PID */
-static pid_t rescan_pid = -1;           /* rescanner PID */
-static int initialized, opened;         /* state */
+/** @brief The playlists database
+ * - Keys are playlist names
+ * - Values are encoded key-value pairs
+ * - Data is user data and cannot be reconstructed
+ */
+DB *trackdb_playlistsdb;
+
+/** @brief Deadlock manager PID */
+static pid_t db_deadlock_pid = -1;
+
+/** @brief Rescanner PID */
+static pid_t rescan_pid = -1;
+
+/** @brief Set when the database environment exists */
+static int initialized;
+
+/** @brief Set when databases are open */
+static int opened;
+
+/** @brief Current stats subprocess PIDs */
+static hash *stats_pids;
+
+/** @brief PID of current random track chooser (disorder-choose) */
+static pid_t choose_pid = -1;
+
+/** @brief Our end of pipe from disorder-choose */
+static int choose_fd;
+
+/** @brief Callback to supply random track to */
+static random_callback *choose_callback;
+
+/** @brief Accumulator for output from disorder-choose */
+static struct dynstr choose_output;
+
+/** @brief Current completion status of disorder-choose
+ * A bitmap of @ref CHOOSE_READING and @ref CHOOSE_RUNNING.
+ */
+static unsigned choose_complete;
+
+/* @brief Exit status from disorder-choose */
+static int choose_status;
 
-/* comparison function for keys */
+/** @brief disorder-choose process is running */
+#define CHOOSE_RUNNING 1
+
+/** @brief disorder-choose pipe is still open */
+#define CHOOSE_READING 2
+
+/** @brief Comparison function for filename-based keys */
 static int compare(DB attribute((unused)) *db_,
 		   const DBT *a, const DBT *b) {
   return compare_path_raw(a->data, a->size, b->data, b->size);
@@ -256,7 +305,7 @@ void trackdb_init(int flags) {
   D(("initialized database environment"));
 }
 
-/* called when deadlock manager terminates */
+/** @brief Called when deadlock manager terminates */
 static int reap_db_deadlock(ev_source attribute((unused)) *ev,
                             pid_t attribute((unused)) pid,
                             int status,
@@ -271,6 +320,18 @@ static int reap_db_deadlock(ev_source attribute((unused)) *ev,
   return 0;
 }
 
+/** @brief Start a subprogram
+ * @param ev Event loop
+ * @param outputfd File descriptor to redirect @c stdout to, or -1
+ * @param prog Program name
+ * @param ... Arguments
+ * @return PID
+ *
+ * Starts a subprocess.  Adds the following arguments:
+ * - @c --config to ensure the right config file is used
+ * - @c --debug or @c --no-debug to match debug settings
+ * - @c --syslog or @c --no-syslog to match log settings
+ */
 static pid_t subprogram(ev_source *ev, int outputfd, const char *prog,
                         ...) {
   pid_t pid;
@@ -310,7 +371,11 @@ static pid_t subprogram(ev_source *ev, int outputfd, const char *prog,
   return pid;
 }
 
-/* start deadlock manager */
+/** @brief Start deadlock manager
+ * @param ev Event loop
+ *
+ * Called from the main server (only).
+ */
 void trackdb_master(ev_source *ev) {
   assert(db_deadlock_pid == -1);
   db_deadlock_pid = subprogram(ev, -1, DEADLOCK, (char *)0);
@@ -318,8 +383,34 @@ void trackdb_master(ev_source *ev) {
   D(("started deadlock manager"));
 }
 
-/* close environment */
-void trackdb_deinit(void) {
+/** @brief Kill a subprocess and wait for it to terminate
+ * @param ev Event loop or NULL
+ * @param pid Process ID or -1
+ * @param what Description of subprocess
+ *
+ * Used during trackdb_deinit().  This function blocks so don't use it for
+ * normal teardown as that will hang the server.
+ */
+static void terminate_and_wait(ev_source *ev,
+                               pid_t pid,
+                               const char *what) {
+  int err;
+
+  if(pid == -1)
+    return;
+  if(kill(pid, SIGTERM) < 0)
+    fatal(errno, "error killing %s", what);
+  /* wait for the rescanner to finish */
+  while(waitpid(pid, &err, 0) == -1 && errno == EINTR)
+    ;
+  if(ev)
+    ev_child_cancel(ev, pid);
+}
+
+/** @brief Close database environment
+ * @param ev Event loop
+ */
+void trackdb_deinit(ev_source *ev) {
   int err;
 
   /* sanity checks */
@@ -330,32 +421,40 @@ void trackdb_deinit(void) {
   if((err = trackdb_env->close(trackdb_env, 0)))
     fatal(0, "trackdb_env->close: %s", db_strerror(err));
 
-  if(rescan_pid != -1) {
-    /* shut down the rescanner */
-    if(kill(rescan_pid, SIGTERM) < 0)
-      fatal(errno, "error killing rescanner");
-    /* wait for the rescanner to finish */
-    while(waitpid(rescan_pid, &err, 0) == -1 && errno == EINTR)
-      ;
-  }
+  terminate_and_wait(ev, rescan_pid, "disorder-rescan");
+  rescan_pid = -1;
+  terminate_and_wait(ev, choose_pid, "disorder-choose");
+  choose_pid = -1;
 
-  /* TODO kill any stats subprocesses */
+  if(stats_pids) {
+    char **ks = hash_keys(stats_pids);
 
-  /* finally terminate the deadlock manager */
-  if(db_deadlock_pid != -1 && kill(db_deadlock_pid, SIGTERM) < 0)
-    fatal(errno, "error killing deadlock manager");
-  db_deadlock_pid = -1;
+    while(*ks) {
+      pid_t pid = atoi(*ks++);
+      terminate_and_wait(ev, pid, "disorder-stats");
+    }
+    stats_pids = NULL;
+  }
 
+  terminate_and_wait(ev, db_deadlock_pid, "disorder-deadlock");
+  db_deadlock_pid = -1;
   D(("deinitialized database environment"));
 }
 
-/* open a specific database */
+/** @brief Open a specific database
+ * @param path Relative path to database
+ * @param dbflags Database flags: DB_DUP, DB_DUPSORT, etc
+ * @param dbtype Database type: DB_HASH, DB_BTREE, etc
+ * @param openflags Open flags: DB_RDONLY, DB_CREATE, etc
+ * @param mode Permission mask: usually 0666
+ * @return Database handle
+ */
 static DB *open_db(const char *path,
                    u_int32_t dbflags,
                    DBTYPE dbtype,
                    u_int32_t openflags,
                    int mode) {
-  int err;
+  int err, err2;
   DB *db;
 
   D(("open %s", path));
@@ -370,8 +469,14 @@ static DB *open_db(const char *path,
       fatal(0, "db->set_bt_compare %s: %s", path, db_strerror(err));
   if((err = db->open(db, 0, path, 0, dbtype,
                      openflags | DB_AUTO_COMMIT, mode))) {
-    if((openflags & DB_CREATE) || errno != ENOENT)
+    if((openflags & DB_CREATE) || errno != ENOENT) {
+      if((err2 = db->close(db, 0)))
+        error(0, "db->close: %s", db_strerror(err2));
+      trackdb_close();
+      trackdb_env->close(trackdb_env,0);
+      trackdb_env = 0;
       fatal(0, "db->open %s: %s", path, db_strerror(err));
+    }
     db->close(db, 0);
     db = 0;
   }
@@ -467,7 +572,8 @@ void trackdb_open(int flags) {
   trackdb_noticeddb = open_db("noticed.db",
                              DB_DUPSORT, DB_BTREE, dbflags, 0666);
   trackdb_scheduledb = open_db("schedule.db", 0, DB_HASH, dbflags, 0666);
-  if(!trackdb_existing_database) {
+  trackdb_playlistsdb = open_db("playlists.db", 0, DB_HASH, dbflags, 0666);
+  if(!trackdb_existing_database && !(flags & TRACKDB_READ_ONLY)) {
     /* Stash the database version */
     char buf[32];
 
@@ -478,38 +584,39 @@ void trackdb_open(int flags) {
   D(("opened databases"));
 }
 
-/* close track databases */
+/** @brief Close track databases */
 void trackdb_close(void) {
   int err;
 
   /* sanity checks */
   assert(opened == 1);
   --opened;
-  if((err = trackdb_tracksdb->close(trackdb_tracksdb, 0)))
-    fatal(0, "error closing tracks.db: %s", db_strerror(err));
-  if((err = trackdb_searchdb->close(trackdb_searchdb, 0)))
-    fatal(0, "error closing search.db: %s", db_strerror(err));
-  if((err = trackdb_tagsdb->close(trackdb_tagsdb, 0)))
-    fatal(0, "error closing tags.db: %s", db_strerror(err));
-  if((err = trackdb_prefsdb->close(trackdb_prefsdb, 0)))
-    fatal(0, "error closing prefs.db: %s", db_strerror(err));
-  if((err = trackdb_globaldb->close(trackdb_globaldb, 0)))
-    fatal(0, "error closing global.db: %s", db_strerror(err));
-  if((err = trackdb_noticeddb->close(trackdb_noticeddb, 0)))
-    fatal(0, "error closing noticed.db: %s", db_strerror(err));
-  if((err = trackdb_scheduledb->close(trackdb_scheduledb, 0)))
-    fatal(0, "error closing schedule.db: %s", db_strerror(err));
-  if((err = trackdb_usersdb->close(trackdb_usersdb, 0)))
-    fatal(0, "error closing users.db: %s", db_strerror(err));
-  trackdb_tracksdb = trackdb_searchdb = trackdb_prefsdb = 0;
-  trackdb_tagsdb = trackdb_globaldb = 0;
+#define CLOSE(N, V) do {                                        \
+  if(V && (err = V->close(V, 0)))                               \
+    fatal(0, "error closing %s: %s", N, db_strerror(err));      \
+  V = 0;                                                        \
+} while(0)
+  CLOSE("tracks.db", trackdb_tracksdb);
+  CLOSE("search.db", trackdb_searchdb);
+  CLOSE("tags.db", trackdb_tagsdb);
+  CLOSE("prefs.db", trackdb_prefsdb);
+  CLOSE("global.db", trackdb_globaldb);
+  CLOSE("noticed.db", trackdb_noticeddb);
+  CLOSE("schedule.db", trackdb_scheduledb);
+  CLOSE("users.db", trackdb_usersdb);
+  CLOSE("playlists.db", trackdb_playlistsdb);
   D(("closed databases"));
 }
 
 /* generic db routines *******************************************************/
 
-/* fetch and decode a database entry.  Returns 0, DB_NOTFOUND or
- * DB_LOCK_DEADLOCK. */
+/** @brief Fetch and decode a database entry
+ * @param db Database
+ * @param track Track name
+ * @param kp Where to put decoded list (or NULL if you don't care)
+ * @param tid Owning transaction
+ * @return 0, @c DB_NOTFOUND or @c DB_LOCK_DEADLOCK
+ */
 int trackdb_getdata(DB *db,
                     const char *track,
                     struct kvp **kp,
@@ -520,10 +627,12 @@ int trackdb_getdata(DB *db,
   switch(err = db->get(db, tid, make_key(&key, track),
                        prepare_data(&data), 0)) {
   case 0:
-    *kp = kvp_urldecode(data.data, data.size);
+    if(kp)
+      *kp = kvp_urldecode(data.data, data.size);
     return 0;
   case DB_NOTFOUND:
-    *kp = 0;
+    if(kp)
+      *kp = 0;
     return err;
   case DB_LOCK_DEADLOCK:
     error(0, "error querying database: %s", db_strerror(err));
@@ -533,8 +642,14 @@ int trackdb_getdata(DB *db,
   }
 }
 
-/* encode and store a database entry.  Returns 0, DB_KEYEXIST or
- * DB_LOCK_DEADLOCK. */
+/** @brief Encode and store a database entry
+ * @param db Database
+ * @param track Track name
+ * @param k List of key/value pairs to store
+ * @param tid Owning transaction
+ * @param flags DB flags e.g. DB_NOOVERWRITE
+ * @return 0, DB_KEYEXIST or DB_LOCK_DEADLOCK
+ */
 int trackdb_putdata(DB *db,
                     const char *track,
                     const struct kvp *k,
@@ -580,7 +695,11 @@ int trackdb_delkey(DB *db,
   }
 }
 
-/* open a database cursor */
+/** @brief Open a database cursor
+ * @param db Database
+ * @param tid Owning transaction
+ * @return Cursor
+ */
 DBC *trackdb_opencursor(DB *db, DB_TXN *tid) {
   int err;
   DBC *c;
@@ -592,7 +711,10 @@ DBC *trackdb_opencursor(DB *db, DB_TXN *tid) {
   return c;
 }
 
-/* close a database cursor; returns 0 or DB_LOCK_DEADLOCK */
+/** @brief Close a database cursor
+ * @param c Cursor
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 int trackdb_closecursor(DBC *c) {
   int err;
 
@@ -608,7 +730,16 @@ int trackdb_closecursor(DBC *c) {
   }
 }
 
-/* delete a (key,data) pair.  Returns 0, DB_NOTFOUND or DB_LOCK_DEADLOCK. */
+/** @brief Delete a key/data pair
+ * @param db Database
+ * @param word Key
+ * @param track Data
+ * @param tid Owning transaction
+ * @return 0, DB_NOTFOUND or DB_LOCK_DEADLOCK
+ *
+ * Used by the search and tags databases, hence the odd parameter names.
+ * See also register_word().
+ */
 int trackdb_delkeydata(DB *db,
                        const char *word,
                        const char *track,
@@ -646,7 +777,9 @@ int trackdb_delkeydata(DB *db,
   return err;
 }
 
-/* start a transaction */
+/** @brief Start a transaction
+ * @return Transaction
+ */
 DB_TXN *trackdb_begin_transaction(void) {
   DB_TXN *tid;
   int err;
@@ -656,7 +789,11 @@ DB_TXN *trackdb_begin_transaction(void) {
   return tid;
 }
 
-/* abort transaction */
+/** @brief Abort transaction
+ * @param tid Transaction (or NULL)
+ *
+ * If @p tid is NULL then nothing happens.
+ */
 void trackdb_abort_transaction(DB_TXN *tid) {
   int err;
 
@@ -665,7 +802,9 @@ void trackdb_abort_transaction(DB_TXN *tid) {
       fatal(0, "tid->abort: %s", db_strerror(err));
 }
 
-/* commit transaction */
+/** @brief Commit transaction
+ * @param tid Transaction (must not be NULL)
+ */
 void trackdb_commit_transaction(DB_TXN *tid) {
   int err;
 
@@ -675,12 +814,26 @@ void trackdb_commit_transaction(DB_TXN *tid) {
 
 /* search/tags shared code ***************************************************/
 
-/* comparison function used by dedupe() */
+/** @brief Comparison function used by dedupe()
+ * @param a Pointer to first key
+ * @param b Pointer to second key
+ * @return -1, 0 or 1
+ *
+ * Passed to qsort().
+ */
 static int wordcmp(const void *a, const void *b) {
   return strcmp(*(const char **)a, *(const char **)b);
 }
 
-/* sort and de-dupe VEC */
+/** @brief Sort and de-duplicate @p vec
+ * @param vec Vector to sort
+ * @param nvec Length of @p vec
+ * @return @p vec
+ *
+ * The returned vector is NULL-terminated, and there must be room for this NULL
+ * even if there are no duplicates (i.e. it must have more than @p nvec
+ * elements.)
+ */
 static char **dedupe(char **vec, int nvec) {
   int m, n;
 
@@ -696,7 +849,17 @@ static char **dedupe(char **vec, int nvec) {
   return vec;
 }
 
-/* update a key/track database.  Returns 0 or DB_DEADLOCK. */
+/** @brief Store a key/data pair
+ * @param db Database
+ * @param what Description
+ * @param track Data
+ * @param word Key
+ * @param tid Owning transaction
+ * @return 0 or DB_DEADLOCK
+ *
+ * Used by the search and tags databases, hence the odd parameter names.
+ * See also trackdb_delkeydata().
+ */
 static int register_word(DB *db, const char *what,
                          const char *track, const char *word,
                          DB_TXN *tid) {
@@ -718,13 +881,22 @@ static int register_word(DB *db, const char *what,
 
 /* search primitives *********************************************************/
 
-/* return true iff NAME is a trackname_display_ pref */
+/** @brief Return true iff @p name is a trackname_display_ pref
+ * @param name Preference name
+ * @return Non-zero iff @p name is a trackname_display_ pref
+ */
 static int is_display_pref(const char *name) {
   static const char prefix[] = "trackname_display_";
   return !strncmp(name, prefix, (sizeof prefix) - 1);
 }
 
-/** @brief Word_Break property tailor that treats underscores as spaces */
+/** @brief Word_Break property tailor that treats underscores as spaces
+ * @param c Code point
+ * @return Tailored property or -1 to use standard value
+ *
+ * Passed to utf32_word_split() when splitting a track name into words.
+ * See word_split() and @ref unicode_property_tailor.
+ */
 static int tailor_underscore_Word_Break_Other(uint32_t c) {
   switch(c) {
   default:
@@ -750,7 +922,20 @@ static size_t remove_combining_chars(uint32_t *s, size_t ns) {
   return t - start;
 }
 
-/** @brief Normalize and split a string using a given tailoring */
+/** @brief Normalize and split a string using a given tailoring
+ * @param v Where to store words from string
+ * @param s Input string
+ * @param pt Word_Break property tailor, or NULL
+ *
+ * The output words will be:
+ * - case-folded
+ * - have any combination characters stripped
+ * - not include any word break code points (as tailored)
+ *
+ * Used by track_to_words(), with @p pt set to @ref
+ * tailor_underscore_Word_Break_Other, and by normalize_tag() with no
+ * tailoring.
+ */
 static void word_split(struct vector *v,
                        const char *s,
                        unicode_property_tailor *pt) {
@@ -806,7 +991,11 @@ static char *normalize_tag(const char *s, size_t ns) {
   return d->vec;
 }
 
-/* compute the words of a track name */
+/** @brief Compute the words of a track name
+ * @param track Track name
+ * @param p Preferences (for display prefs)
+ * @return NULL-terminated, de-duplicated list or words
+ */
 static char **track_to_words(const char *track,
                              const struct kvp *p) {
   struct vector v;
@@ -824,7 +1013,10 @@ static char **track_to_words(const char *track,
   return dedupe(v.vec, v.nvec);
 }
 
-/* return nonzero iff WORD is a stopword */
+/** @brief Test for a stopword
+ * @param word Word
+ * @return Non-zero if @p word is a stopword
+ */
 static int stopword(const char *word) {
   int n;
 
@@ -834,7 +1026,12 @@ static int stopword(const char *word) {
   return n < config->stopword.n;
 }
 
-/* record that WORD appears in TRACK.  Returns 0 or DB_LOCK_DEADLOCK. */
+/** @brief Register a search term
+ * @param track Track name
+ * @param word A word that appears in the name of @p track
+ * @param tid Owning transaction
+ * @return  0 or DB_LOCK_DEADLOCK
+ */
 static int register_search_word(const char *track, const char *word,
                                 DB_TXN *tid) {
   if(stopword(word)) return 0;
@@ -843,7 +1040,13 @@ static int register_search_word(const char *track, const char *word,
 
 /* Tags **********************************************************************/
 
-/* Return nonzero if C is a valid tag character */
+/** @brief Test for tag characters
+ * @param c Character
+ * @return Non-zero if @p c is a tag character
+ *
+ * The current rule is that commas and the control characters 0-31 are not
+ * allowed but anything else is permitted.  This is arguably a bit loose.
+ */
 static int tagchar(int c) {
   switch(c) {
   case ',':
@@ -853,7 +1056,12 @@ static int tagchar(int c) {
   }
 }
 
-/* Parse and de-dupe a tag list.  If S=0 then assumes "". */
+/** @brief Parse a tag list
+ * @param s Tag list or NULL (equivalent to "")
+ * @return Parsed tag list
+ *
+ * The tags will be normalized (as per normalize_tag()) and de-duplicated.
+ */
 char **parsetags(const char *s) {
   const char *t;
   struct vector v;
@@ -882,15 +1090,38 @@ char **parsetags(const char *s) {
   return dedupe(v.vec, v.nvec);
 }
 
-/* Record that TRACK has TAG.  Returns 0 or DB_LOCK_DEADLOCK. */
+/** @brief Register a tag
+ * @param track Track name
+ * @param tag Tag name
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 static int register_tag(const char *track, const char *tag, DB_TXN *tid) {
   return register_word(trackdb_tagsdb, "tags", track, tag, tid);
 }
 
 /* aliases *******************************************************************/
 
-/* compute the alias and store at aliasp.  Returns 0 or DB_LOCK_DEADLOCK.  If
- * there is no alias sets *aliasp to 0. */
+/** @brief Compute an alias
+ * @param aliasp Where to put alias (gets NULL if none)
+ * @param track Track to find alias for
+ * @param p Prefs for @p track
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ *
+ * This function looks up the track name parts for @p track.  By default these
+ * amount to the original values from the track name but are overridden by
+ * preferences.
+ *
+ * These values are then substituted into the pattern defined by the @b alias
+ * command; see disorder_config(5) for the syntax.
+ *
+ * The track is only considered to have an alias if all of the following are
+ * true:
+ * - a preference was used for at least one name part
+ * - the result differs from the original track name
+ * - the result does not match any existing track or alias
+ */
 static int compute_alias(char **aliasp,
                          const char *track,
                          const struct kvp *p,
@@ -953,15 +1184,28 @@ static int compute_alias(char **aliasp,
   }
 }
 
-/* get track and prefs data (if tp/pp not null pointers).  Returns 0 on
- * success, DB_NOTFOUND if the track does not exist or DB_LOCK_DEADLOCK.
- * Always sets the return values, even if only to null pointers. */
+/** @brief Assert that no alias is allowed for gettrackdata() */
+#define GTD_NOALIAS 0x0001
+
+/** @brief Get all track data
+ * @param track Track to look up; aliases allowed unless @ref GTD_NOALIAS
+ * @param tp Where to put track data (if not NULL)
+ * @param pp Where to put preferences (if not NULL)
+ * @param actualp Where to put real (i.e. non-alias) path (if not NULL)
+ * @param flags Flag values, see below
+ * @param tid Owning transaction
+ * @return 0, DB_NOTFOUND (track doesn't exist) or DB_LOCK_DEADLOCK
+ *
+ * Possible flags values are:
+ * - @ref GTD_NOALIAS to assert that an alias is not allowed
+ *
+ * The return values are always set (even if to NULL).
+ */
 static int gettrackdata(const char *track,
                         struct kvp **tp,
                         struct kvp **pp,
                         const char **actualp,
                         unsigned flags,
-#define GTD_NOALIAS 0x0001
                         DB_TXN *tid) {
   int err;
   const char *actual = track;
@@ -991,8 +1235,12 @@ done:
 
 /* trackdb_notice() **********************************************************/
 
-/** @brief notice a possibly new track
+/** @brief Notice a possibly new track
+ * @param track NFC UTF-8 track name
+ * @param path Raw path name (i.e. the bytes that came out of readdir())
  * @return @c DB_NOTFOUND if new, 0 if already known
+ *
+ * @c disorder-rescan is responsible for normalizing the track name.
  */
 int trackdb_notice(const char *track,
                    const char *path) {
@@ -1011,11 +1259,13 @@ int trackdb_notice(const char *track,
   return err;
 }
 
-/** @brief notice a possibly new track
+/** @brief Notice a possibly new track
  * @param track NFC UTF-8 track name
- * @param path Raw path name
- * @param tid Transaction ID
+ * @param path Raw path name (i.e. the bytes that came out of readdir())
+ * @param tid Owning transaction
  * @return @c DB_NOTFOUND if new, 0 if already known, @c DB_LOCK_DEADLOCK also
+ *
+ * @c disorder-rescan is responsible for normalizing the track name.
  */
 int trackdb_notice_tid(const char *track,
                        const char *path,
@@ -1035,7 +1285,7 @@ int trackdb_notice_tid(const char *track,
   /* this is a real track */
   t_changed += kvp_set(&t, "_alias_for", 0);
   t_changed += kvp_set(&t, "_path", path);
-  time(&now);
+  xtime(&now);
   if(ret == DB_NOTFOUND) {
     /* It's a new track; record the time */
     byte_xasprintf(&noticed, "%lld", (long long)now);
@@ -1084,7 +1334,14 @@ int trackdb_notice_tid(const char *track,
 
 /* trackdb_obsolete() ********************************************************/
 
-/* obsolete a track */
+/** @brief Obsolete a track
+ * @param track Track name
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ *
+ * Discards a track from the database when it's known not to exist any more.
+ * Returns 0 even if it wasn't recorded.
+ */
 int trackdb_obsolete(const char *track, DB_TXN *tid) {
   int err, n;
   struct kvp *p;
@@ -1168,7 +1425,14 @@ static const struct statinfo {
   B(bt_over_pgfree),
 };
 
-/* look up stats for DB */
+/** @brief Look up DB statistics
+ * @param v Where to store stats
+ * @param database Database
+ * @param si Pointer to table of stats
+ * @param nsi Size of @p si
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 static int get_stats(struct vector *v,
                      DB *database,
                      const struct statinfo *si,
@@ -1235,7 +1499,12 @@ static int register_search_entry(struct search_entry *se,
   return nse;
 }
 
-/* find the top COUNT words in the search database */
+/** @brief Find the top @p count words in the search database
+ * @param v Where to format the result
+ * @param count Maximum number of words
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 static int search_league(struct vector *v, int count, DB_TXN *tid) {
   struct search_entry *se;
   DBT k, d;
@@ -1284,7 +1553,13 @@ static int search_league(struct vector *v, int count, DB_TXN *tid) {
 #define SI(what) statinfo_##what, \
                  sizeof statinfo_##what / sizeof (struct statinfo)
 
-/* return a list of database stats */
+/** @brief Return a list of database stats
+ * @param nstatsp Where to store number of lines (or NULL)
+ * @return Database stats output
+ *
+ * This is called by @c disorder-stats.  Don't call it directly from elsewhere
+ * as it can take unreasonably long.
+ */
 char **trackdb_stats(int *nstatsp) {
   DB_TXN *tid;
   struct vector v;
@@ -1313,6 +1588,7 @@ fail:
   return v.vec;
 }
 
+/** @brief State structure tracking @c disorder-stats */
 struct stats_details {
   void (*done)(char *data, void *u);
   void *u;
@@ -1322,6 +1598,12 @@ struct stats_details {
   struct dynstr data[1];                /* data read from pipe */
 };
 
+/** @brief Called when @c disorder-stats may have completed
+ * @param d Pointer to state structure
+ *
+ * Called from stats_finished() and stats_read().  Only proceeds when the
+ * process has terminated and the output is complete.
+ */
 static void stats_complete(struct stats_details *d) {
   char *s;
 
@@ -1338,8 +1620,16 @@ static void stats_complete(struct stats_details *d) {
   d->done(d->data->vec, d->u);
 }
 
+/** @brief Called when @c disorder-stats exits
+ * @param ev Event loop
+ * @param pid Process ID
+ * @param status Exit status
+ * @param rusage Resource usage
+ * @param u Pointer to state structure (@ref stats_details)
+ * @return 0
+ */
 static int stats_finished(ev_source attribute((unused)) *ev,
-                          pid_t attribute((unused)) pid,
+                          pid_t pid,
                           int status,
                           const struct rusage attribute((unused)) *rusage,
                           void *u) {
@@ -1349,9 +1639,21 @@ static int stats_finished(ev_source attribute((unused)) *ev,
   if(status)
     error(0, "disorder-stats %s", wstat(status));
   stats_complete(d);
+  char *k;
+  byte_xasprintf(&k, "%lu", (unsigned long)pid);
+  hash_remove(stats_pids, k);
   return 0;
 }
 
+/** @brief Called when pipe from @c disorder-stats is readable
+ * @param ev Event loop
+ * @param reader Reader state
+ * @param ptr Pointer to bytes read
+ * @param bytes Number of bytes available
+ * @param eof Set at end of file
+ * @param u Pointer to state structure (@ref stats_details)
+ * @return 0
+ */
 static int stats_read(ev_source attribute((unused)) *ev,
                       ev_reader *reader,
                       void *ptr,
@@ -1368,6 +1670,12 @@ static int stats_read(ev_source attribute((unused)) *ev,
   return 0;
 }
 
+/** @brief Called when pipe from @c disorder-stats errors
+ * @param ev Event loop
+ * @param errno_value Error code
+ * @param u Pointer to state structure (@ref stats_details)
+ * @return 0
+ */
 static int stats_error(ev_source attribute((unused)) *ev,
                        int errno_value,
                        void *u) {
@@ -1379,6 +1687,14 @@ static int stats_error(ev_source attribute((unused)) *ev,
   return 0;
 }
 
+/** @brief Get database statistics via background process
+ * @param ev Event loop
+ * @param done Called on completion
+ * @param u Passed to @p done
+ *
+ * Within the main server use this instead of trackdb_stats(), which can take
+ * unreasonably long.
+ */
 void trackdb_stats_subprocess(ev_source *ev,
                               void (*done)(char *data, void *u),
                               void *u) {
@@ -1393,7 +1709,15 @@ void trackdb_stats_subprocess(ev_source *ev,
   pid = subprogram(ev, p[1], "disorder-stats", (char *)0);
   xclose(p[1]);
   ev_child(ev, pid, 0, stats_finished, d);
-  ev_reader_new(ev, p[0], stats_read, stats_error, d, "disorder-stats reader");
+  if(!ev_reader_new(ev, p[0], stats_read, stats_error, d,
+                    "disorder-stats reader"))
+    fatal(0, "ev_reader_new for disorder-stats reader failed");
+  /* Remember the PID */
+  if(!stats_pids)
+    stats_pids = hash_new(1);
+  char *k;
+  byte_xasprintf(&k, "%lu", (unsigned long)pid);
+  hash_add(stats_pids, k, "", HASH_INSERT);
 }
 
 /** @brief Parse a track name part preference
@@ -1450,7 +1774,12 @@ static const char *trackdb__default(const char *track, const char *name) {
   return 0;
 }
 
-/* set a pref (remove if value=0) */
+/** @brief Set a preference
+ * @param track Track to modify
+ * @param name Preference name
+ * @param value New value, or NULL to erase any existing value
+ * @return 0 on success or non-zero if not allowed to set preference
+ */
 int trackdb_set(const char *track,
                 const char *name,
                 const char *value) {
@@ -1547,13 +1876,20 @@ fail:
   return err == 0 ? 0 : -1;
 }
 
-/* get a pref */
+/** @brief Get the value of a preference
+ * @param track Track name
+ * @param name Preference name
+ * @return Preference value or NULL if it's not set
+ */
 const char *trackdb_get(const char *track,
                         const char *name) {
   return kvp_get(trackdb_get_all(track), name);
 }
 
-/* get all prefs as a 0-terminated array */
+/** @brief Get all preferences for a track
+ * @param track Track name
+ * @return Linked list of preferences
+ */
 struct kvp *trackdb_get_all(const char *track) {
   struct kvp *t, *p, **pp;
   DB_TXN *tid;
@@ -1573,7 +1909,10 @@ fail:
   return p;
 }
 
-/* resolve alias */
+/** @brief Resolve an alias
+ * @param track Track name (might be an alias)
+ * @return Real track name (definitely not an alias) or NULL if no such track
+ */
 const char *trackdb_resolve(const char *track) {
   DB_TXN *tid;
   const char *actual;
@@ -1590,13 +1929,20 @@ fail:
   return actual;
 }
 
+/** @brief Detect an alias
+ * @param track Track name
+ * @return Nonzero if @p track exists and is an alias
+ */
 int trackdb_isalias(const char *track) {
   const char *actual = trackdb_resolve(track);
 
   return strcmp(actual, track);
 }
 
-/* test whether a track exists (perhaps an alias) */
+/** @brief Detect whether a track exists
+ * @param track Track name (can be an alias)
+ * @return Nonzero if @p track exists (whether or not it's an alias)
+ */
 int trackdb_exists(const char *track) {
   DB_TXN *tid;
   int err;
@@ -1614,7 +1960,9 @@ fail:
   return (err == 0);
 }
 
-/* return the list of tags */
+/** @brief Return list of all known tags
+ * @return NULL-terminated tag list
+ */
 char **trackdb_alltags(void) {
   int e;
   struct vector v[1];
@@ -1654,6 +2002,13 @@ int trackdb_listkeys(DB *db, struct vector *v, DB_TXN *tid) {
 }
 
 /* return 1 iff sorted tag lists A and B have at least one member in common */
+/** @brief Detect intersecting tag lists
+ * @param a First list of tags (NULL-terminated)
+ * @param b Second list of tags (NULL-terminated)
+ * @return 1 if @p a and @p b have at least one member in common
+ *
+ * @p a and @p must be sorted.
+ */
 int tag_intersection(char **a, char **b) {
   int cmp;
 
@@ -1666,15 +2021,13 @@ int tag_intersection(char **a, char **b) {
   return 0;
 }
 
-static pid_t choose_pid = -1;
-static int choose_fd;
-static random_callback *choose_callback;
-static struct dynstr choose_output;
-static unsigned choose_complete;
-static int choose_status;
-#define CHOOSE_RUNNING 1
-#define CHOOSE_READING 2
-
+/** @brief Called when disorder-choose might have completed
+ * @param ev Event loop
+ * @param which @ref CHOOSE_RUNNING or @ref CHOOSE_READING
+ *
+ * Once called with both @p which values, @ref choose_callback is called
+ * (usually chosen_random_track()).
+ */
 static void choose_finished(ev_source *ev, unsigned which) {
   choose_complete |= which;
   if(choose_complete != (CHOOSE_RUNNING|CHOOSE_READING))
@@ -1687,7 +2040,14 @@ static void choose_finished(ev_source *ev, unsigned which) {
     choose_callback(ev, 0);
 }
 
-/** @brief Called when @c disorder-choose terminates */
+/** @brief Called when @c disorder-choose terminates
+ * @param ev Event loop
+ * @param pid Process ID
+ * @param status Exit status
+ * @param rusage Resource usage
+ * @param u User data
+ * @return 0
+ */
 static int choose_exited(ev_source *ev,
                          pid_t attribute((unused)) pid,
                          int status,
@@ -1700,7 +2060,15 @@ static int choose_exited(ev_source *ev,
   return 0;
 }
 
-/** @brief Called with data from @c disorder-choose pipe */
+/** @brief Called with data from @c disorder-choose pipe
+ * @param ev Event loop
+ * @param reader Reader state
+ * @param ptr Data read
+ * @param bytes Number of bytes read
+ * @param eof Set at end of file
+ * @param u User data
+ * @return 0
+ */
 static int choose_readable(ev_source *ev,
                            ev_reader *reader,
                            void *ptr,
@@ -1714,6 +2082,12 @@ static int choose_readable(ev_source *ev,
   return 0;
 }
 
+/** @brief Called when @c disorder-choose pipe errors
+ * @param ev Event loop
+ * @param errno_value Error code
+ * @param u User data
+ * @return 0
+ */
 static int choose_read_error(ev_source *ev,
                              int errno_value,
                              void attribute((unused)) *u) {
@@ -1749,14 +2123,23 @@ int trackdb_request_random(ev_source *ev,
   choose_callback = callback;
   choose_output.nvec = 0;
   choose_complete = 0;
-  ev_reader_new(ev, p[0], choose_readable, choose_read_error, 0,
-                "disorder-choose reader"); /* owns p[0] */
+  if(!ev_reader_new(ev, p[0], choose_readable, choose_read_error, 0,
+                    "disorder-choose reader")) /* owns p[0] */
+    fatal(0, "ev_reader_new for disorder-choose reader failed");
   ev_child(ev, choose_pid, 0, choose_exited, 0); /* owns the subprocess */
   return 0;
 }
 
-/* get a track name given the prefs.  Set *used_db to 1 if we got the answer
- * from the prefs. */
+/** @brief Get a track name part, using prefs
+ * @param track Track name
+ * @param context Context ("display" etc)
+ * @param part Part ("album" etc)
+ * @param p Preference
+ * @param used_db Set if a preference is used
+ * @return Name part (never NULL)
+ *
+ * Used by compute_alias() and trackdb_getpart().
+ */
 static const char *getpart(const char *track,
                            const char *context,
                            const char *part,
@@ -1774,8 +2157,14 @@ static const char *getpart(const char *track,
   return result;
 }
 
-/* get a track name part, like trackname_part(), but taking the database into
- * account. */
+/** @brief Get a track name part
+ * @param track Track name
+ * @param context Context ("display" etc)
+ * @param part Part ("album" etc)
+ * @return Name part (never NULL)
+ *
+ * This is interface used by c_part().
+ */
 const char *trackdb_getpart(const char *track,
                             const char *context,
                             const char *part) {
@@ -1799,7 +2188,12 @@ fail:
   return getpart(actual, context, part, p, &used_db);
 }
 
-/* get the raw path name for @track@ (might be an alias) */
+/** @brief Get the raw (filesystem) path for @p track
+ * @param track track Track name (can be an alias)
+ * @return Raw path (never NULL)
+ *
+ * The raw path is the actual bytes that came out of readdir() etc.
+ */
 const char *trackdb_rawpath(const char *track) {
   DB_TXN *tid;
   struct kvp *t;
@@ -1825,6 +2219,19 @@ fail:
 
 /* return true if the basename of TRACK[0..TL-1], as defined by DL, matches RE.
  * If RE is a null pointer then it matches everything. */
+/** @brief Match a track against a rgeexp
+ * @param dl Length of directory part of track
+ * @param track Track name
+ * @param tl Length of track name
+ * @param re Regular expression or NULL
+ * @return Nonzero on match
+ *
+ * @p tl is the total length of @p track, @p dl is the length of the directory
+ * part (the index of the final "/").  The subject of the regexp match is the
+ * basename, i.e. the part after @p dl.
+ *
+ * If @p re is NULL then always matches.
+ */
 static int track_matches(size_t dl, const char *track, size_t tl,
 			 const pcre *re) {
   int ovec[3], rc;
@@ -1844,6 +2251,14 @@ static int track_matches(size_t dl, const char *track, size_t tl,
   }
 }
 
+/** @brief Generate a list of tracks and/or directories in @p dir
+ * @param v Where to put results
+ * @param dir Directory to list
+ * @param what Bitmap of objects to return
+ * @param re Regexp to filter matches (or NULL to accept all)
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 static int do_list(struct vector *v, const char *dir,
                    enum trackdb_listable what, const pcre *re, DB_TXN *tid) {
   DBC *cursor;
@@ -1935,7 +2350,13 @@ deadlocked:
   return err;
 }
 
-/* return the directories or files below @dir@ */
+/** @brief Get the directories or files below @p dir
+ * @param dir Directory to list
+ * @param np Where to put number of results (or NULL)
+ * @param what Bitmap of objects to return
+ * @param re Regexp to filter matches (or NULL to accept all)
+ * @return List of tracks
+ */
 char **trackdb_list(const char *dir, int *np, enum trackdb_listable what,
                     const pcre *re) {
   DB_TXN *tid;
@@ -1965,7 +2386,12 @@ fail:
   return v.vec;
 }
 
-/* If S is tag:something, return something.  Else return 0. */
+/** @brief Detect a tag element in a search string
+ * @param s Element of search string
+ * @return Pointer to tag name (in @p s) if this is a tag: search, else NULL
+ *
+ * Tag searches take the form "tag:TAG".
+ */
 static const char *checktag(const char *s) {
   if(!strncmp(s, "tag:", 4))
     return s + 4;
@@ -2105,6 +2531,17 @@ char **trackdb_search(char **wordlist, int nwordlist, int *ntracks) {
 
 /* trackdb_scan **************************************************************/
 
+/** @brief Visit every track
+ * @param root Root to scan or NULL for all
+ * @param callback Callback for each track
+ * @param u Passed to @p callback
+ * @param tid Owning transaction
+ * @return 0, DB_LOCK_DEADLOCK or EINTR
+ *
+ * Visits every track and calls @p callback.  @p callback will get the track
+ * data and preferences and should return 0 to continue scanning or EINTR to
+ * stop.
+ */
 int trackdb_scan(const char *root,
                  int (*callback)(const char *track,
                                  struct kvp *data,
@@ -2240,7 +2677,7 @@ static int reap_rescan(ev_source attribute((unused)) *ev,
  * @param ev Event loop or 0 to block
  * @param recheck 1 to recheck lengths, 0 to suppress check
  * @param rescanned Called on completion (if not NULL)
- * @param u Passed to @p rescanned
+ * @param ru Passed to @p rescanned
  */
 void trackdb_rescan(ev_source *ev, int recheck,
                     void (*rescanned)(void *ru),
@@ -2267,6 +2704,9 @@ void trackdb_rescan(ev_source *ev, int recheck,
   }
 }
 
+/** @brief Cancel a rescan
+ * @return Nonzero if a rescan was cancelled
+ */
 int trackdb_rescan_cancel(void) {
   if(rescan_pid == -1) return 0;
   if(kill(rescan_pid, SIGTERM) < 0)
@@ -2282,6 +2722,11 @@ int trackdb_rescan_underway(void) {
 
 /* global prefs **************************************************************/
 
+/** @brief Set a global preference
+ * @param name Global preference name
+ * @param value New value
+ * @param who Who is setting it
+ */
 void trackdb_set_global(const char *name,
                         const char *value,
                         const char *who) {
@@ -2313,6 +2758,11 @@ void trackdb_set_global(const char *name,
   }
 }
 
+/** @brief Set a global preference
+ * @param name Global preference name
+ * @param value New value
+ * @param tid Owning transaction
+ */
 int trackdb_set_global_tid(const char *name,
                            const char *value,
                            DB_TXN *tid) {
@@ -2337,6 +2787,10 @@ int trackdb_set_global_tid(const char *name,
   return 0;
 }
 
+/** @brief Get a global preference
+ * @param name Global preference name
+ * @return Value of global preference, or NULL if it's not set
+ */
 const char *trackdb_get_global(const char *name) {
   DB_TXN *tid;
   int err;
@@ -2352,6 +2806,12 @@ const char *trackdb_get_global(const char *name) {
   return r;
 }
 
+/** @brief Get a global preference
+ * @param name Global preference name
+ * @param tid Owning transaction
+ * @param rp Where to store value (will get NULL if preference not set)
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 int trackdb_get_global_tid(const char *name,
                            DB_TXN *tid,
                            const char **rp) {
@@ -2406,9 +2866,6 @@ char **trackdb_new(int *ntracksp,
  * @return null-terminated array of track names, or NULL on deadlock
  *
  * The most recently added track is first in the array.
- *
- * TODO: exclude tracks that have been deleted again.
- *
  */
 static char **trackdb_new_tid(int *ntracksp,
                               int maxtracks,
@@ -2417,12 +2874,24 @@ static char **trackdb_new_tid(int *ntracksp,
   DBT k, d;
   int err = 0;
   struct vector tracks[1];
+  hash *h = hash_new(1);
 
   vector_init(tracks);
   c = trackdb_opencursor(trackdb_noticeddb, tid);
   while((maxtracks <= 0 || tracks->nvec < maxtracks)
-        && !(err = c->c_get(c, prepare_data(&k), prepare_data(&d), DB_PREV)))
-    vector_append(tracks, xstrndup(d.data, d.size));
+        && !(err = c->c_get(c, prepare_data(&k), prepare_data(&d), DB_PREV))) {
+    char *const track = xstrndup(d.data, d.size);
+    /* Don't add any track more than once */
+    if(hash_add(h, track, "", HASH_INSERT))
+      continue;
+    /* See if the track still exists */
+    err = trackdb_getdata(trackdb_tracksdb, track, NULL/*kp*/, tid);
+    if(err == DB_NOTFOUND)
+      continue;                         /* It doesn't, skip it */
+    if(err == DB_LOCK_DEADLOCK)
+      break;                            /* Doh */
+    vector_append(tracks, track);
+  }
   switch(err) {
   case 0:                               /* hit maxtracks */
   case DB_NOTFOUND:                     /* ran out of tracks */
@@ -2500,6 +2969,10 @@ static int trackdb_expire_noticed_tid(time_t earliest, DB_TXN *tid) {
 
 /* tidying up ****************************************************************/
 
+/** @brief Do database garbage collection
+ *
+ * Called form periodic_database_gc().
+ */
 void trackdb_gc(void) {
   int err;
   char **logfiles;
@@ -2519,7 +2992,12 @@ void trackdb_gc(void) {
 
 /* user database *************************************************************/
 
-/** @brief Return true if @p user is trusted */
+/** @brief Return true if @p user is trusted
+ * @param user User to look up
+ * @return Nonzero if they are in the 'trusted' list
+ *
+ * Now used only in upgrade from old versions.
+ */
 static int trusted(const char *user) {
   int n;
 
@@ -2530,12 +3008,16 @@ static int trusted(const char *user) {
 }
 
 /** @brief Return non-zero for a valid username
+ * @param user Candidate username
+ * @return Nonzero if it's valid
  *
  * Currently we only allow the letters and digits in ASCII.  We could be more
  * liberal than this but it is a nice simple test.  It is critical that
  * semicolons are never allowed.
+ *
+ * NB also used by playlist_parse_name() to validate playlist names!
  */
-static int valid_username(const char *user) {
+int valid_username(const char *user) {
   if(!*user)
     return 0;
   while(*user) {
@@ -2551,7 +3033,16 @@ static int valid_username(const char *user) {
   return 1;
 }
 
-/** @brief Add a user */
+/** @brief Add a user
+ * @param user Username
+ * @param password Initial password or NULL
+ * @param rights Initial rights
+ * @param email Email address or NULL
+ * @param confirmation Confirmation string to require
+ * @param tid Owning transaction
+ * @param flags DB flags e.g. DB_NOOVERWRITE
+ * @return 0, DB_KEYEXIST or DB_LOCK_DEADLOCK
+ */
 static int create_user(const char *user,
                        const char *password,
                        const char *rights,
@@ -2579,12 +3070,19 @@ static int create_user(const char *user,
     kvp_set(&k, "email", email);
   if(confirmation)
     kvp_set(&k, "confirmation", confirmation);
-  snprintf(s, sizeof s, "%jd", (intmax_t)time(0));
+  snprintf(s, sizeof s, "%jd", (intmax_t)xtime(0));
   kvp_set(&k, "created", s);
   return trackdb_putdata(trackdb_usersdb, user, k, tid, flags);
 }
 
-/** @brief Add one pre-existing user */
+/** @brief Add one pre-existing user 
+ * @param user Username
+ * @param password password
+ * @param tid Owning transaction
+ * @return 0, DB_KEYEXIST or DB_LOCK_DEADLOCK
+ *
+ * Used only in upgrade from old versions.
+ */
 static int one_old_user(const char *user, const char *password,
                         DB_TXN *tid) {
   const char *rights;
@@ -2611,6 +3109,10 @@ static int one_old_user(const char *user, const char *password,
                      tid, DB_NOOVERWRITE);
 }
 
+/** @brief Upgrade old users
+ * @param tid Owning transaction
+ * @return 0 or DB_LOCK_DEADLOCK
+ */
 static int trackdb_old_users_tid(DB_TXN *tid) {
   int n;
 
@@ -2784,8 +3286,8 @@ int trackdb_edituserinfo(const char *user,
     }
   } else if(!strcmp(key, "email")) {
     if(*value) {
-      if(!strchr(value, '@')) {
-        error(0, "invalid email address '%s' for user '%s'", user, value);
+      if(!email_valid(value)) {
+        error(0, "invalid email address '%s' for user '%s'", value, user);
         return -1;
       }
     } else