Closes #131, replace sprintf with snprintf (#134)

deps/common/lang/string.cpp

@@ -194,7 +194,7 @@ char *bin_to_hex(const char *s, const int len, char *hex_buff)
   int new_len = 0;
   unsigned char *end = (unsigned char *)s + len;
   for (unsigned char *p = (unsigned char *)s; p < end; p++) {
-    new_len += sprintf(hex_buff + new_len, "%02x", *p);
+    new_len += snprintf(hex_buff + new_len, 2, "%02x", *p);
   }
 
   hex_buff[new_len] = '\0';

deps/common/log/log.h

@@ -157,14 +157,16 @@ extern Log *g_log;
 #define __FILE_NAME__ (strrchr(__FILE__, '/') ? strrchr(__FILE__, '/') + 1 : __FILE__)
 #endif
 
+#define LOG_HEAD_SIZE 64
+
 #define LOG_HEAD(prefix, level)                                            \
   if (common::g_log) {                                                     \
     time_t now_time;                                                       \
     time(&now_time);                                                       \
     struct tm *p = localtime(&now_time);                                   \
-    char sz_head[64] = {0};                                                \
+    char sz_head[LOG_HEAD_SIZE] = {0};                                     \
     if (p) {                                                               \
-      sprintf(sz_head,                                                     \
+      snprintf(sz_head, LOG_HEAD_SIZE,                                     \
           "%d-%d-%d %d:%d:%u pid:%u tid:%llx ",                            \
           p->tm_year + 1900,                                               \
           p->tm_mon + 1,                                                   \