Initial implementation of logging library

Signed-off-by: Aidan Hahn <aidan@aidanis.online>

alog.h

@@ -0,0 +1,94 @@
+/*  ALOG: A Logger
+ *  Copyright (C) 2022 Aidan Hahn
+ *  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 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.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program. If not, see https://www.gnu.org/licenses/.
+ */
+
+#ifndef ALOG_H
+#define ALOG_H
+
+// gimmie booleans
+#ifndef true
+#define true 1
+#endif
+
+#ifndef false
+#define false 0
+#endif
+
+struct _global_logging_state {
+  // if set calls to alog will print to all fds in both err and out lists
+  int broadcast_to_all_fds : 1;
+  // if set messages with severity DEBUG will be logged
+  int log_debug_messages : 1;
+};
+
+/* I know its in poor taste to exose a global like this as part of the user
+ * facing API for this library but I find it way nicer than implementing and
+ * using getters and setters. Since this was meant to serve my personal projects
+ * I am sticking with it here.
+ *
+ * Alloc'ed/Initialized by a call to init_alog()*/
+struct _global_logging_state *ALOG_LOGGING_STATE;
+
+/* alternative impl I didnt want to write
+ * it would have required a bunch of getters and setters
+ * and been a PITA in general.
+ * keeping it around for basically no reason.
+
+#define LOGGING_INIT_FIELD = 0;
+#define BROADCAST_TO_ALL_FIELD = 1;
+#define LOG_DEBUG_MSGS_FIELD = 2;
+int flags = 0; */
+
+int _alog_num_out_fds;
+int *_alog_out_fds;
+int _alog_num_err_fds;
+int *_alog_err_fds;
+
+typedef enum {
+  // Not printed by default. Useful for debug info
+  DEBUG,
+  // Default non-err message level. Prints to _alog_out_fds
+  INFO,
+  // Same as INFO but will get printed without the time or sev
+  PRINT,
+  // Default err message level. Prints to _alog_err_fds
+  ERROR
+} alog_sev;
+
+/* global state is initialized with the following defaults:
+ *   broadcast_to_all_fds = 0
+ *   log_debug_messages = 0
+ *   out fds: stdout
+ *   err fds: stderr
+ */
+void _init_alog();
+
+/* deinitializes all global state memory used in this library */
+void deinit_alog();
+
+/* adds an fd to out fds or (iff char arg is set to 0x01) err fds */
+void alog_add_target(int, char);
+
+/* removes an fd from both out fds and err fds */
+void alog_remove_target(int);
+
+/* call to log a message. Takes a severity, a message, and format stuff */
+void alog(alog_sev, const char *, ...);
+
+/* overrides all calls to printf with a call to alog */
+#ifdef ALOG_HIJACK_PRINTF
+int printf(const char *format, ...);
+#endif // ALOG_HIJACK_PRINTF
+#endif // ALOG_H