[tty]修复多次scanf之后,导致丢数据的问题 (#7640)

guoguozi123456 · web-flow · commit 1d239db59e58 · 2023-06-09T09:09:50.000+08:00
diff --git a/components/drivers/tty/n_tty.c b/components/drivers/tty/n_tty.c
@@ -1436,14 +1436,15 @@ static int canon_copy_from_read_buf(struct tty_struct *tty, char *b, size_t nr)
 
     size_t buf_size = RT_TTY_BUF - tail;
     const void *from = read_buf_addr(ldata, tail);
+    size_t temp_n = n;
     if (n > buf_size)
     {
         rt_memcpy(b, from, buf_size);
         b += buf_size;
-        n -= buf_size;
+        temp_n -= buf_size;
         from = ldata->read_buf;
     }
-    rt_memcpy(b, from, n);
+    rt_memcpy(b, from, temp_n);
 
     if (found)
     {

Original file line number	Diff line number	Diff line change
`@@ -1436,14 +1436,15 @@ static int canon_copy_from_read_buf(struct tty_struct tty, char b, size_t nr)`
`1436`	`1436`
`1437`	`1437`	`size_t buf_size = RT_TTY_BUF - tail;`
`1438`	`1438`	`const void *from = read_buf_addr(ldata, tail);`
	`1439`	`+ size_t temp_n = n;`
`1439`	`1440`	`if (n > buf_size)`
`1440`	`1441`	`{`
`1441`	`1442`	`rt_memcpy(b, from, buf_size);`
`1442`	`1443`	`b += buf_size;`
`1443`		`- n -= buf_size;`
	`1444`	`+ temp_n -= buf_size;`
`1444`	`1445`	`from = ldata->read_buf;`
`1445`	`1446`	`}`
`1446`		`- rt_memcpy(b, from, n);`
	`1447`	`+ rt_memcpy(b, from, temp_n);`
`1447`	`1448`
`1448`	`1449`	`if (found)`
`1449`	`1450`	`{`