#include "klog_api.h"
#include <linux/slab.h>
#include <linux/module.h>

#define LOG_MSG_SZ   1024
#define MODULE_FMT   "[%s]"

klog_t *g_klog = NULL;

klog_t *klog_init(const char *module_name)
{
    klog_t *log = NULL;
    u32 len = 0;

    if(NULL == module_name) {
        return NULL;
    }

    len = strlen(module_name);
    
    if (len > MAX_MODULE_NAME_SZ) {
        printk(KERN_ERR"The length:%d of module_name must be not more than %d, but input module_name is %s", len, MAX_MODULE_NAME_SZ, module_name);
        return NULL;
    }

    log = (klog_t *)kmalloc(sizeof(*log), GFP_KERNEL);
    if (NULL == log) {
        printk(KERN_ERR"Allocating log memory is failure");
        return NULL;
    }
    memset(log->module_name, '\0', MAX_MODULE_NAME_SZ+1);
    strncpy(log->module_name, module_name, len);

    return log;
}

void klog_close(klog_t *log)
{
    if (log != NULL) {
        kfree(log);
    }
}

void klog_record(const klog_t *log, const char* level_str, const char *fmt, ...)
{
    char log_buf[LOG_MSG_SZ];
    va_list args;
    
    va_start(args, fmt);       
    vsnprintf(log_buf, sizeof(log_buf), fmt, args);
    va_end(args);

    if (NULL != log) {
        printk("%s"MODULE_FMT" %s", level_str, log->module_name, log_buf) ; 
    }
    else {
        printk("%s %s", level_str, log_buf) ; 
    }
}

EXPORT_SYMBOL_GPL(klog_init);
EXPORT_SYMBOL_GPL(klog_close);
EXPORT_SYMBOL_GPL(klog_record);


static int __init klog_api_init(void)
{
    g_klog = klog_init("klog_api");

    KLOG_INFO(g_klog, "Klog is initiated");

    return 0;
}

static void __exit klog_api_exit(void)
{
    KLOG_INFO(g_klog, "Klog is exited");

    klog_close(g_klog);
}

module_init(klog_api_init);
module_exit(klog_api_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Klog_api process module");
MODULE_AUTHOR("zhangtao");