Add the logging module.

src/Makefile

@@ -48,7 +48,7 @@ HACKERBASE-OBJS=hackerbase.o testing.o listing.o month.o period.o	\
 	 util-set-list.o util-time.o util-tag.o util-io.o		\
 	 util-string.o util-io.o util-list.o util-parser.o texts.o	\
 	 tests.o util-proc.o util-mail.o reminders.o util-format.o	\
-	 brmember-format.o
+	 brmember-format.o logging.o
 
 .PHONY: imports
 imports: $(HACKERBASE-DEPS)
@@ -338,3 +338,8 @@ BRMEMBER-FORMAT-SOURCES=brmember-format.scm util-dict-list.import.scm	\
 
 brmember-format.o: brmember-format.import.scm
 brmember-format.import.scm: $(BRMEMBER-FORMAT-SOURCES)
+
+LOGGING-SOURCES=logging.scm util-string.import.scm
+
+logging.o: logging.import.scm
+logging.import.scm: $(LOGGING-SOURCES)

src/logging.scm

@@ -0,0 +1,87 @@
+;;
+;; logging.scm
+;;
+;; Universal logging module.
+;;
+;; ISC License
+;;
+;; Copyright 2023 Brmlab, z.s.
+;; Dominik Pantůček <dominik.pantucek@trustica.cz>
+;;
+;; Permission to use, copy, modify, and/or distribute this software
+;; for any purpose with or without fee is hereby granted, provided
+;; that the above copyright notice and this permission notice appear
+;; in all copies.
+;; 
+;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
+;; WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
+;; WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
+;; AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
+;; CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+;; OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
+;; NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+;; CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+;;
+
+(declare (unit logging))
+
+(module
+ logging
+ (
+  *log-file*
+  
+  log-debug
+  log-info
+  log-warning
+  log-error
+  )
+
+ (import scheme
+	 (chicken base)
+	 (chicken format)
+	 (chicken time posix)
+	 util-string)
+
+ ;; No logging by default
+ (define *log-file* (make-parameter #f))
+
+ ;; Opened log file
+ (define log-file (make-parameter #f))
+
+ ;; Ensures leading zeroes
+ (define (format-number2 n)
+   (format "~A~A"
+	   (if (< n 10) "0" "")
+	   n))
+
+ ;; Current time for logging
+ (define (format-current-time)
+   (let ((ltime (seconds->local-time)))
+     (format "~A-~A-~A ~A:~A:~A"
+	     (+ 1900 (vector-ref ltime 5))
+	     (format-number2 (add1 (vector-ref ltime 4)))
+	     (format-number2 (vector-ref ltime 3))
+	     (format-number2 (vector-ref ltime 2))
+	     (format-number2 (vector-ref ltime 1))
+	     (format-number2 (vector-ref ltime 0)))))
+
+ ;; Handles the actual logging
+ (define ((log-line level) fmt . args)
+   (when (or (not (*log-file*))
+	     (not (log-file)))
+     (when (not (log-file))
+       (log-file (open-output-file (*log-file*) #:append)))
+     (display (format "~A [~A] ~A"
+		      (format-current-time)
+		      (string-upcase (symbol->string level))
+		      (apply format fmt args))
+	      (log-file))
+     (flush-output (log-file))))
+
+ ;; Specific log procedures
+ (define log-debug (log-line 'debug))
+ (define log-info (log-line 'info))
+ (define log-warning (log-line 'warning))
+ (define log-error (log-line 'error))
+
+ )