[log] add log.c example

log/README.md

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+# 日志模块
+
+- [zlog](https://github.com/HardySimpson/zlog)
+- [glog](https://github.com/google/glog)
+- [log.c](https://github.com/rxi/log.c)
+

log/log.c/LICENSE

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+Copyright (c) 2020 rxi
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

log/log.c/README.md

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+# log.c
+A simple logging library implemented in C99
+
+![screenshot](https://cloud.githubusercontent.com/assets/3920290/23831970/a2415e96-0723-11e7-9886-f8f5d2de60fe.png)
+
+
+## Usage
+**[log.c](src/log.c?raw=1)** and **[log.h](src/log.h?raw=1)** should be dropped
+into an existing project and compiled along with it. The library provides 6
+function-like macros for logging:
+
+```c
+log_trace(const char *fmt, ...);
+log_debug(const char *fmt, ...);
+log_info(const char *fmt, ...);
+log_warn(const char *fmt, ...);
+log_error(const char *fmt, ...);
+log_fatal(const char *fmt, ...);
+```
+
+Each function takes a printf format string followed by additional arguments:
+
+```c
+log_trace("Hello %s", "world")
+```
+
+Resulting in a line with the given format printed to stderr:
+
+```
+20:18:26 TRACE src/main.c:11: Hello world
+```
+
+
+#### log_set_quiet(bool enable)
+Quiet-mode can be enabled by passing `true` to the `log_set_quiet()` function.
+While this mode is enabled the library will not output anything to `stderr`, but
+will continue to write to files and callbacks if any are set.
+
+
+#### log_set_level(int level)
+The current logging level can be set by using the `log_set_level()` function.
+All logs below the given level will not be written to `stderr`. By default the
+level is `LOG_TRACE`, such that nothing is ignored.
+
+
+#### log_add_fp(FILE *fp, int level)
+One or more file pointers where the log will be written can be provided to the
+library by using the `log_add_fp()` function. The data written to the file
+output is of the following format:
+
+```
+2047-03-11 20:18:26 TRACE src/main.c:11: Hello world
+```
+
+Any messages below the given `level` are ignored. If the library failed to add a
+file pointer a value less-than-zero is returned.
+
+
+#### log_add_callback(log_LogFn fn, void *udata, int level)
+One or more callback functions which are called with the log data can be
+provided to the library by using the `log_add_callback()` function. A callback
+function is passed a `log_Event` structure containing the `line` number,
+`filename`, `fmt` string, `va` printf va\_list, `level` and the given `udata`.
+
+
+#### log_set_lock(log_LockFn fn, void *udata)
+If the log will be written to from multiple threads a lock function can be set.
+The function is passed the boolean `true` if the lock should be acquired or
+`false` if the lock should be released and the given `udata` value.
+
+
+#### const char* log_level_string(int level)
+Returns the name of the given log level as a string.
+
+
+#### LOG_USE_COLOR
+If the library is compiled with `-DLOG_USE_COLOR` ANSI color escape codes will
+be used when printing.
+
+
+## License
+This library is free software; you can redistribute it and/or modify it under
+the terms of the MIT license. See [LICENSE](LICENSE) for details.

log/log.c/log.c

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+/*
+ * Copyright (c) 2020 rxi
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "log.h"
+
+#define MAX_CALLBACKS 32
+
+typedef struct {
+  log_LogFn fn;
+  void *udata;
+  int level;
+} Callback;
+
+static struct {
+  void *udata;
+  log_LockFn lock;
+  int level;
+  bool quiet;
+  Callback callbacks[MAX_CALLBACKS];
+} L;
+
+
+static const char *level_strings[] = {
+  "TRACE", "DEBUG", "INFO", "WARN", "ERROR", "FATAL"
+};
+
+#ifdef LOG_USE_COLOR
+static const char *level_colors[] = {
+  "\x1b[94m", "\x1b[36m", "\x1b[32m", "\x1b[33m", "\x1b[31m", "\x1b[35m"
+};
+#endif
+
+
+static void stdout_callback(log_Event *ev) {
+  char buf[16];
+  buf[strftime(buf, sizeof(buf), "%H:%M:%S", ev->time)] = '\0';
+#ifdef LOG_USE_COLOR
+  fprintf(
+    ev->udata, "%s %s%-5s\x1b[0m \x1b[90m%s:%d:\x1b[0m ",
+    buf, level_colors[ev->level], level_strings[ev->level],
+    ev->file, ev->line);
+#else
+  fprintf(
+    ev->udata, "%s %-5s %s:%d: ",
+    buf, level_strings[ev->level], ev->file, ev->line);
+#endif
+  vfprintf(ev->udata, ev->fmt, ev->ap);
+  fprintf(ev->udata, "\n");
+  fflush(ev->udata);
+}
+
+
+static void file_callback(log_Event *ev) {
+  char buf[64];
+  buf[strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", ev->time)] = '\0';
+  fprintf(
+    ev->udata, "%s %-5s %s:%d: ",
+    buf, level_strings[ev->level], ev->file, ev->line);
+  vfprintf(ev->udata, ev->fmt, ev->ap);
+  fprintf(ev->udata, "\n");
+  fflush(ev->udata);
+}
+
+
+static void lock(void)   {
+  if (L.lock) { L.lock(true, L.udata); }
+}
+
+
+static void unlock(void) {
+  if (L.lock) { L.lock(false, L.udata); }
+}
+
+
+const char* log_level_string(int level) {
+  return level_strings[level];
+}
+
+
+void log_set_lock(log_LockFn fn, void *udata) {
+  L.lock = fn;
+  L.udata = udata;
+}
+
+
+void log_set_level(int level) {
+  L.level = level;
+}
+
+
+void log_set_quiet(bool enable) {
+  L.quiet = enable;
+}
+
+
+int log_add_callback(log_LogFn fn, void *udata, int level) {
+  for (int i = 0; i < MAX_CALLBACKS; i++) {
+    if (!L.callbacks[i].fn) {
+      L.callbacks[i] = (Callback) { fn, udata, level };
+      return 0;
+    }
+  }
+  return -1;
+}
+
+
+int log_add_fp(FILE *fp, int level) {
+  return log_add_callback(file_callback, fp, level);
+}
+
+
+static void init_event(log_Event *ev, void *udata) {
+  if (!ev->time) {
+    time_t t = time(NULL);
+    ev->time = localtime(&t);
+  }
+  ev->udata = udata;
+}
+
+
+void log_log(int level, const char *file, int line, const char *fmt, ...) {
+  log_Event ev = {
+    .fmt   = fmt,
+    .file  = file,
+    .line  = line,
+    .level = level,
+  };
+
+  lock();
+
+  if (!L.quiet && level >= L.level) {
+    init_event(&ev, stderr);
+    va_start(ev.ap, fmt);
+    stdout_callback(&ev);
+    va_end(ev.ap);
+  }
+
+  for (int i = 0; i < MAX_CALLBACKS && L.callbacks[i].fn; i++) {
+    Callback *cb = &L.callbacks[i];
+    if (level >= cb->level) {
+      init_event(&ev, cb->udata);
+      va_start(ev.ap, fmt);
+      cb->fn(&ev);
+      va_end(ev.ap);
+    }
+  }
+
+  unlock();
+}

log/log.c/log.h

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+/**
+ * Copyright (c) 2020 rxi
+ *
+ * This library is free software; you can redistribute it and/or modify it
+ * under the terms of the MIT license. See `log.c` for details.
+ */
+
+#ifndef LOG_H
+#define LOG_H
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <time.h>
+
+#define LOG_VERSION "0.1.0"
+
+typedef struct {
+  va_list ap;
+  const char *fmt;
+  const char *file;
+  struct tm *time;
+  void *udata;
+  int line;
+  int level;
+} log_Event;
+
+typedef void (*log_LogFn)(log_Event *ev);
+typedef void (*log_LockFn)(bool lock, void *udata);
+
+enum { LOG_TRACE, LOG_DEBUG, LOG_INFO, LOG_WARN, LOG_ERROR, LOG_FATAL };
+
+#define log_trace(...) log_log(LOG_TRACE, __FILE__, __LINE__, __VA_ARGS__)
+#define log_debug(...) log_log(LOG_DEBUG, __FILE__, __LINE__, __VA_ARGS__)
+#define log_info(...)  log_log(LOG_INFO,  __FILE__, __LINE__, __VA_ARGS__)
+#define log_warn(...)  log_log(LOG_WARN,  __FILE__, __LINE__, __VA_ARGS__)
+#define log_error(...) log_log(LOG_ERROR, __FILE__, __LINE__, __VA_ARGS__)
+#define log_fatal(...) log_log(LOG_FATAL, __FILE__, __LINE__, __VA_ARGS__)
+
+const char* log_level_string(int level);
+void log_set_lock(log_LockFn fn, void *udata);
+void log_set_level(int level);
+void log_set_quiet(bool enable);
+int log_add_callback(log_LogFn fn, void *udata, int level);
+int log_add_fp(FILE *fp, int level);
+
+void log_log(int level, const char *file, int line, const char *fmt, ...);
+
+#endif

log/log.c/main.c

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+#include "log.h"
+
+int main(void)
+{
+    log_set_quiet(false);
+
+    log_trace("Hello GetIoT.tech");
+    log_debug("Hello GetIoT.tech");
+    log_info("Hello GetIoT.tech");
+    log_warn("Hello GetIoT.tech");
+    log_error("Hello GetIoT.tech");
+    log_fatal("Hello GetIoT.tech");
+
+    return 0;
+}

log/log.c/makefile

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+all:
+	gcc main.c log.c -DLOG_USE_COLOR -o log-test
+
+clean:
+	rm log-test