Refactor logging logic.

Also, introduce new option 'logger-prefix' to determine the prefix of
each log line.

Closes: #942725.

1 files changed, 13 insertions, 0 deletions

diff --git a/doc/interimap.1.md b/doc/interimap.1.md
index febec28..ee92668 100644
--- a/doc/interimap.1.md
+++ b/doc/interimap.1.md
@@ -290,6 +290,19 @@ Valid options are:
     default these messages are written to the error output.)  This
     option is only available in the default section.
 
+*log-prefix*
+
+:   A `printf`(3)-like format string to use as prefix for each log
+    message.  Interpreted sequences are `%n` and `%m`, expanding
+    respectively to the component name (*local*/*remote*) and to the
+    name of the mailbox relevant for the log entry.  Conditions on a
+    specifier `%X` can be obtained with `%?X?then?` or `%?X?then&else?`,
+    which expands to *then* if the `%X` specifier expands to a non-empty
+    string, and to *else* (or the empty string if there is no else
+    condition) if it doesn't.  Literal `%` characters need to be escaped
+    as `%%`, while `&`, `?` and `\` characters need to be `\`-escaped.
+    (Default: `%?n?%?m?%n(%m)&%n?: ?`.)
+
 *type*
 
 :   One of `imap`, `imaps` or `tunnel`.