diff --git a/c/tools/log/log.c b/c/tools/log/log.c
index 3b9fc09..b271844 100644
--- a/c/tools/log/log.c
+++ b/c/tools/log/log.c
@@ -9,6 +9,34 @@
 #include <fcntl.h>
 #include <string.h>
 
+int write_into_block(char *writein,char *org,int *length,int maxlength,char *logname)
+{
+    if(writein == NULL||org == NULL||length == NULL||logname == NULL)
+        return -1;
+    if(*length+strlen(org)<maxlength-1)
+    {
+        strcpy(&writein[*length],org);
+        *length +=strlen(org);//栈内存充足
+    }
+    else
+    {
+        int n = *length + strlen(org) - maxlength;
+        strncpy(&writein[*length],org,strlen(org)-n);//栈内存不足
+        writein[maxlength-1] = '\0';
+        int fd = open(logname,O_CREAT | O_WRONLY | O_APPEND, 0644);
+        if(fd != -1)
+        {
+            write(fd,writein,maxlength);
+            close(fd);
+        }
+        else if(fd == -1)
+            perror("log:");//仅警告
+        *length = n;
+        strcpy(writein,&org[*length]);//剩余部分拷贝 
+    }
+    return 0;
+}
+
 int in_log(logs *log,log_manager *self)
 {
     if(log == NULL||self == NULL)
@@ -102,7 +130,7 @@ int cleanup(log_manager *self)
     char failback[MAX_LOG_LENGTH];
     logbuf = (char*)malloc(1);
     logbuf[0] = '\0';
-    size_t buf_length,buf_lengthbk = 0;
+    size_t buf_length = 0,buf_lengthbk = 0;
     int fd;
     while(loc->next !=NULL)
     {
@@ -120,7 +148,8 @@ int cleanup(log_manager *self)
                 close(fd);
             }
             free(logbufbk);
-            logbuf = failback;//降级策略，堆空间不足时，使用预分配栈空间，保留最后一条日志
+            logbuf = failback;//降级策略，堆空间不足时，使用预分配栈空间
+            buf_length = 0;
         }
         if(logbuf != failback){
             buf_lengthbk = buf_length;
@@ -129,7 +158,7 @@ int cleanup(log_manager *self)
         }
         else
         {
-            buf_length = MAX_LOG_LENGTH;
+            write_into_block(logbuf,tobeclean->log,&buf_length,MAX_LOG_LENGTH,"log.txt");
         }
         free(tobeclean);
     }
@@ -151,8 +180,7 @@ int cleanup(log_manager *self)
         }
     }
     else{
-        strcpy(logbuf,loc->log);
-        buf_length = strlen(logbuf);
+        write_into_block(logbuf,loc->log,&buf_length,MAX_LOG_LENGTH,"log.txt");
     }
     if(logbuf == failback&&buf_length>MAX_LOG_LENGTH)
         logbuf[MAX_LOG_LENGTH-1] = '\0';