Ignore errors and retry later when in daemon mode

A persistent failure that could lead to a session not being able to be
recovered, or a failure during the login process (which is not covered
by the recovery function), would normally cause the process to
terminate.  This is expected when the configuration is run once, but not
desirable when running in daemon mode.

And thus just after the process has become a daemon, a session that
could not be restored, either because the connection to the server could
not be established or the login and its related negotiations failed, is
now disabled temporarily, and a recoqnection is attempted at the
beginning of the next daemon loop iteration.

There is one exception to that, and that is when there is an
authentication error, for example when a wrong username or password has
been supplied, and in this case the process terminates and a relevant
error is printed.

src/account.lua

@@ -8,6 +8,10 @@ Account._mt = {}
 setmetatable(Account, Account._mt)
 
 
+_imap = {}
+setmetatable(_imap, { __mode = "v" })
+
+
 Account._mt.__call = function (self, arg)
     _check_required(arg.server, 'string')
     _check_required(arg.username, 'string')
@@ -37,7 +41,9 @@ Account._mt.__call = function (self, arg)
     object._mt.__gc = object._logout_user
     setmetatable(object, object._mt)
 
-    object:_login_user()
+    table.insert(_imap, object)
+
+    object._login_user(object)
 
     return object
 end
@@ -45,15 +51,22 @@ end
 
 function Account._check_connection(self)
     if not self._account.session then
-        error('not connected to ' .. self._string, 0)
+        if not _daemon then
+            error('not connected to ' .. self._string, 0)
+        else
+            return false
+        end
     end
+    return true
 end
 
 function Account._check_result(self, request, result)
     if result == nil then
         self._account.session = nil
         self._account.selected = nil
-        error(request .. ' request to ' .. self._string ..  ' failed', 0)
+        if not _daemon then
+            error(request .. ' request to ' .. self._string ..  ' failed', 0)
+        end
     end
 end
 
@@ -70,8 +83,9 @@ function Account._login_user(self)
                               self._account.password)
     self._check_result(self, 'login', r)
     if r == false then
-        error('failed to authenticate to ' .. self._string .. '.', 0)
+        error('authentication to ' .. self._string .. ' failed.', 0)
     end
+    if not r then return false end
 
     self._account.session = s
     self._account.selected = nil
@@ -80,7 +94,7 @@ function Account._login_user(self)
 end
 
 function Account._logout_user(self)
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.logout(self._account.session)
     self._check_result(self, 'logout', r)
     if r == false then return false end
@@ -116,7 +130,7 @@ function Account.list_all(self, folder, mbox)
     end
     if mbox == nil then mbox = '%' end
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r, mailboxes, folders = ifcore.list(self._account.session, '',
                                               folder .. mbox)
     self._check_result(self, 'list', r)
@@ -151,7 +165,7 @@ function Account.list_subscribed(self, folder, mbox)
     end
     if mbox == nil then mbox = '*' end
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r, mailboxes, folders = ifcore.lsub(self._account.session, '',
                                               folder .. mbox)
     self._check_result(self, 'lsub', r)
@@ -174,7 +188,7 @@ end
 function Account.create_mailbox(self, name)
     _check_required(name, 'string')
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.create(self._account.session, name)
     self._check_result(self, 'create', r)
     if r == false then return false end
@@ -189,7 +203,7 @@ end
 function Account.delete_mailbox(self, name)
     _check_required(name, 'string')
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.delete(self._account.session, name)
     self._check_result(self, 'delete', r)
     if r == false then return false end
@@ -205,7 +219,7 @@ function Account.rename_mailbox(self, oldname, newname)
     _check_required(oldname, 'string')
     _check_required(newname, 'string')
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.rename(self._account.session, oldname, newname)
     self._check_result(self, 'rename', r)
     if r == false then return false end
@@ -221,7 +235,7 @@ end
 function Account.subscribe_mailbox(self, name)
     _check_required(name, 'string')
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.subscribe(self._account.session, name)
     self._check_result(self, 'subscribe', r)
     if r == false then return false end
@@ -236,7 +250,7 @@ end
 function Account.unsubscribe_mailbox(self, name)
     _check_required(name, 'string')
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.unsubscribe(self._account.session, name)
     self._check_result(self, 'unsubscribe', r)
     if r == false then return false end

src/auxiliary.lua

@@ -59,8 +59,15 @@ function become_daemon(interval, commands, nochdir, noclose)
     if nochdir == nil then nochdir = false end
     if noclose == nil then noclose = false end
     ifsys.daemon(nochdir, noclose)
+    _daemon = true
     repeat
+        for _, account in pairs(_imap) do
+            if not account._account.session then
+                account:_login_user(account)
+            end
+        end
         commands()
+        collectgarbage()
     until ifsys.sleep(interval) ~= 0
 end
 

src/mailbox.lua

@@ -29,16 +29,23 @@ end
 
 function Mailbox._check_connection(self)
     if not self._account._account.session then
-        error('not connected to ' .. self._account._string, 0)
+        if not _daemon then
+            error('not connected to ' .. self._account._string, 0)
+        else
+            return false
+        end
     end
+    return true
 end
 
 function Mailbox._check_result(self, request, result)
     if result == nil then
         self._account._account.session = nil
         self._account._account.selected = nil
-        error(request .. ' request to ' .. self._account._string ..
+        if not _daemon then
-              ' failed', 0)
+            error(request .. ' request to ' .. self._account._string ..
+                  ' failed', 0)
+        end
     end
 end
 
@@ -57,7 +64,7 @@ function Mailbox._cached_select(self)
     if self._account._account.selected == nil or
         self._account._account.selected ~= self._mailbox then
 
-        self._check_connection(self)
+        if not self._check_connection(self) then return end
         local r = ifcore.select(self._account._account.session, self._mailbox)
         self._check_result(self, 'select', r)
         if r == false then return false end
@@ -68,7 +75,7 @@ function Mailbox._cached_select(self)
 end
 
 function Mailbox._cached_close(self)
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.close(self._account._account.session)
     self._check_result(self, 'close', r)
     if r == false then return false end
@@ -102,7 +109,7 @@ function Mailbox._send_query(self, criteria, charset)
         end
     end
 
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r, results = ifcore.search(self._account._account.session, query,
                                      charset)
     self._check_result(self, 'search', r)
@@ -134,7 +141,7 @@ function Mailbox._flag_messages(self, mode, flags, messages)
         if n < j then
             j = n
         end
-        self._check_connection(self)
+        if not self._check_connection(self) then return end
         r = ifcore.store(self._account._account.session, table.concat(m, ',',
                          i, j), mode, f)
         self._check_result(self, 'store', r)
@@ -161,7 +168,7 @@ function Mailbox._copy_messages(self, dest, messages)
             if n < j then
                 j = n
             end
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             r = ifcore.copy(self._account._account.session,
                             table.concat(m, ',', i, j), dest._mailbox)
             self._check_result(self, 'copy', r)
@@ -180,7 +187,7 @@ function Mailbox._copy_messages(self, dest, messages)
                 end
             end
 
-            self._check_connection(dest)
+            if not self._check_connection(dest) then return end
             r = ifcore.append(dest._account._account.session, dest._mailbox,
                               mesgs[i], table.concat(fast[i]['flags'], ' '),
                               fast[i]['date'])
@@ -199,7 +206,7 @@ function Mailbox._fetch_fast(self, messages)
 
     local results = {}
     for _, m in ipairs(messages) do
-        self._check_connection(self)
+        if not self._check_connection(self) then return end
         local r, flags, date, size =
             ifcore.fetchfast(self._account._account.session, tostring(m))
         self._check_result(self, 'fetchfast', r)
@@ -228,7 +235,7 @@ function Mailbox._fetch_flags(self, messages)
 
     local results = {}
     for _, m in ipairs(messages) do
-        self._check_connection(self)
+        if not self._check_connection(self) then return end
         local r, flags = ifcore.fetchflags(self._account._account.session,
                                            tostring(m))
         self._check_result(self, 'fetchfast', r)
@@ -258,7 +265,7 @@ function Mailbox._fetch_date(self, messages)
             self[m]._date then
             results[m] = self[m]._date
         else
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             local r, date = ifcore.fetchdate(self._account._account.session,
                                              tostring(m))
             self._check_result(self, 'fetchdate', r)
@@ -286,7 +293,7 @@ function Mailbox._fetch_size(self, messages)
             self[m]._size then
             results[m] = self[m]._size
         else
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             local r, size = ifcore.fetchsize(self._account._account.session,
                                              tostring(m))
             self._check_result(self, 'fetchsize', r)
@@ -314,7 +321,7 @@ function Mailbox._fetch_header(self, messages)
             self[m]._header then
             results[m] = self[m]._header
         else
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             local r, header = ifcore.fetchheader(self._account._account.session,
                                                  tostring(m))
             self._check_result(self, 'fetchheader', r)
@@ -342,7 +349,7 @@ function Mailbox._fetch_body(self, messages)
             self[m]._body then
             results[m] = self[m]._body
         else
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             local r, body = ifcore.fetchbody(self._account._account.session,
                                              tostring(m))
             self._check_result(self, 'fetchbody', r)
@@ -396,7 +403,7 @@ function Mailbox._fetch_fields(self, fields, messages)
                 self[m]._fields[f] then
                 results[m] = results[m] .. self[m]._fields[f]
             else
-                self._check_connection(self)
+                if not self._check_connection(self) then return end
                 local r, field =
                     ifcore.fetchfields(self._account._account.session,
                                        tostring(m), f)
@@ -429,7 +436,7 @@ function Mailbox._fetch_structure(self, messages)
             self[m]._structure then
             results[m] = self[m]._structure
         else
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             local r, structure =
                 ifcore.fetchstructure(self._account._account.session,
                                       tostring(m))
@@ -460,7 +467,7 @@ function Mailbox._fetch_parts(self, parts, message)
             self[message]._parts[part] then
             results[part] = self[message]._parts[part]
         else
-            self._check_connection(self)
+            if not self._check_connection(self) then return end
             local r, bodypart = ifcore.fetchpart(self._account._account.session,
                                                  tostring(message), part)
             self._check_result(self, 'fetchpart', r)
@@ -480,7 +487,7 @@ end
 
 
 function Mailbox.check_status(self)
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r, exist, recent, unseen, uidnext =
         ifcore.status(self._account._account.session,self._mailbox)
     self._check_result(self, 'status', r)
@@ -768,7 +775,7 @@ function Mailbox.append_message(self, message, flags, date)
     _check_optional(date, 'string')
 
     if type(flags) == 'table' then flags = table.concat(flags, ' ') end
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     r = ifcore.append(self._account._account.session, self._mailbox, message,
                       flags, date)
     self._check_result(self, 'append', r)
@@ -1033,7 +1040,7 @@ end
 function Mailbox.enter_idle(self)
     if self._cached_select(self) ~= true then return false end
    
-    self._check_connection(self)
+    if not self._check_connection(self) then return end
     local r = ifcore.idle(self._account._account.session)
     self._check_result(self, 'idle', r)
     if r == false then return false end