feat: add simple logging library

src/cli.c

@@ -4,24 +4,37 @@
 #include <getopt.h>
 #include "cli.h"
 
-struct cli_options new_options() {
-    struct cli_options result;
+cli_options new_options() {
+    cli_options result;
     result.file.has_value = false;
+    result.file.value = NULL;
+
     result.verbosity = 1;
+
     result.help = false;
+
     result.version = false;
+
+    char *no_color = getenv("NO_COLOR");
+	bool color = true;
+	if(no_color != NULL && no_color[0] != '\0')
+		color = false;
+    result.use_colors = color;
+
+    result.log_file.has_value = false;
+    result.log_file.value = NULL;
     return result;
 }
 
-void free_options(struct cli_options v) {
+void free_options(cli_options v) {
     if(v.file.has_value)
         free(v.file.value);
 }
 
 //                                                         <max
-const char* optstring = "f:v:hV";
+const char* optstring = "f:v:Cl:hV";
 const char* help_msg = 
-    "Usage: %s [-v level] [-h] [-V]\n"
+    "Usage: %s [-v level] [-C] [-l file] [-h] [-V]\n"
     "\n"
     SCI_DESCRIPTION "\n"
     "\n"
@@ -30,7 +43,9 @@ const char* help_msg =
     "\n"
     "OPTIONS:\n"
     "  -f file     set file\n"
-    "  -v level    Set verbosity level [0-3]\n"
+    "  -v level    Set verbosity level [0-4]\n"
+    "  -C          Force color output, ignoring $NO_COLOR\n"
+    "  -l file     Set log to output to a file\n"
     "  -h          Show this message and exit\n"
     "  -V          Show version and exit\n"
     ;
@@ -40,8 +55,8 @@ void print_help(FILE * out, char* prog_name) {
     fprintf(out, help_msg, prog_name);
 }
 
-struct cli_options parse(int argc, char** argv) {
-    struct cli_options options = new_options();
+cli_options parse(int argc, char** argv) {
+    cli_options options = new_options();
     int opt;
     while((opt = getopt(argc, argv, optstring)) != -1) {
         switch(opt) {
@@ -52,6 +67,13 @@ struct cli_options parse(int argc, char** argv) {
             case 'v':
                 options.verbosity = atoi(optarg);
                 break;
+            case 'C':
+                options.use_colors = true;
+                break;
+            case 'l':
+                options.log_file.value = strdup(optarg);
+                options.log_file.has_value = true;
+                break;
             case 'V':
                 options.version = true;
                 break;

src/log.c

@@ -0,0 +1,78 @@
+#include "log.h"
+#include <stdbool.h>
+#include <assert.h>
+#include <time.h>
+
+log_settings g_log_settings;
+bool g_log_initialized = false;
+
+void log_init(log_settings settings) {
+    g_log_settings.level = settings.level;
+    g_log_settings.use_colors = settings.use_colors;
+    g_log_settings.out_file = settings.out_file;
+    g_log_initialized = true;
+}
+
+#define COLOR_TRACE "\x1b[94m"
+#define COLOR_INFO "\x1b[32m"
+#define COLOR_WARN "\x1b[33m"
+#define COLOR_ERROR "\x1b[31m"
+#define COLOR_RESET "\x1b[0m"
+#define COLOR_FILE "\x1b[90m"
+
+const char* get_level_color(int level) {
+    switch(level) {
+        case LOG_TRACE:
+            return COLOR_TRACE;
+        case LOG_INFO:
+            return COLOR_INFO;
+        case LOG_WARN:
+            return COLOR_WARN;
+        case LOG_ERROR:
+            return COLOR_ERROR;
+        default:
+            return COLOR_INFO;
+    }
+}
+
+const char* get_level_name(int level) {
+    switch(level) {
+        case LOG_TRACE:
+            return "TRACE";
+        case LOG_INFO:
+            return "INFO";
+        case LOG_WARN:
+            return "WARN";
+        case LOG_ERROR:
+            return "ERROR";
+        default:
+            return "LOG";
+    }
+}
+
+struct tm* g_log_tm = NULL;
+void log_log(const char* file, int line, int level, const char* fmt, ...) {
+    if(level > g_log_settings.level)
+        return;
+    char timestamp[16];
+    if(g_log_tm == NULL) {
+        time_t t = time(NULL);
+        g_log_tm = localtime(&t);
+    }
+    strftime(timestamp, sizeof(timestamp), "%H:%M:%S", g_log_tm);
+
+    const char* level_color = get_level_color(level);
+    const char* level_name = get_level_name(level);
+
+    if(g_log_settings.use_colors)
+        fprintf(g_log_settings.out_file, "%s %s%-5s"COLOR_RESET" "COLOR_FILE"%s:%d:"COLOR_RESET" ", timestamp, 
+                level_color, level_name, file, line);
+    else
+        fprintf(g_log_settings.out_file, "%s %-5s %s:%d: ", timestamp, level_name, file, line);
+    va_list args;
+    va_start(args, format);
+    vfprintf(g_log_settings.out_file, fmt, args);
+    va_end(args);
+    fprintf(g_log_settings.out_file, "\n");
+    fflush(g_log_settings.out_file);
+}

src/main.c

@@ -1,19 +1,29 @@
 #include "cli.h"
+#include "log.h"
 #include "notify.h"
+#include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
 
-void on_notify_event(struct inotify_event* const e) {
-    fprintf(stdout, "got an event:\n");
-    fprintf(stdout, "  wd: %d\n", e->wd);
-    fprintf(stdout, "  mask: %d\n", e->mask);
-    fprintf(stdout, "  cookie: %d\n", e->cookie);
-    fprintf(stdout, "  len: %d\n", e->len);
-    fprintf(stdout, "  name: %s\n", e->name);
+void on_event(struct inotify_event* const e) {
+    const char* msg =
+        "got an event:\n"
+        "  wd: %d\n"
+        "  mask: %d\n"
+        "  cookie: %d\n"
+        "  len: %d\n"
+        "  name: %s"
+        ;
+    log_info(msg, e->wd, e->mask, e->cookie, e->len, e->name);
 }
 
 int main(int argc, char** argv) {
-    struct cli_options args = parse(argc, argv);
+    cli_options args = parse(argc, argv);
+    log_settings settings;
+    settings.level = args.verbosity;
+    settings.use_colors = args.use_colors;
+    settings.out_file = args.log_file.has_value ? fopen(args.log_file.value, "w+") : stdout;
+    log_init(settings);
 
     if(args.help) {
         print_help(stdout, argv[0]);
@@ -30,7 +40,7 @@ int main(int argc, char** argv) {
             fprintf(stderr, "no such file or directory %s\n", args.file.value);
             exit(EXIT_FAILURE);
         }
-        listen_for_changes(args.file.value, &on_notify_event);
+        listen_for_changes(args.file.value, &on_event);
     }
 
     free_options(args);

src/notify.c

@@ -1,5 +1,6 @@
 #include "notify.h"
 #include "util.h"
+#include "log.h"
 
 #define EV_SIZE sizeof(struct inotify_event)
 #define BUF_LEN EV_SIZE * 32
@@ -9,7 +10,7 @@ void listen_for_changes(const char* filename, notify_callback callback) {
     ASSERT_SYSCALL_SUCCESS(fd);
     inotify_add_watch(fd, filename, IN_ATTRIB);
 
-    fprintf(stdout, "listening for changes in file: %s\n", filename);
+    log_info("listening for changes in file: %s", filename);
 
     char buffer[BUF_LEN];
     int r = read(fd, buffer, BUF_LEN);