From 766ba5cc06b45439cd3987aa782147041dab65c4 Mon Sep 17 00:00:00 2001
From: rsc <rsc>
Date: Fri, 24 Aug 2007 21:00:02 +0000
Subject: [PATCH] first ever correct use of strncpy
---
defs.h | 1 +
fs.c | 24 ++----------------------
string.c | 16 ++++++++++++++--
3 files changed, 17 insertions(+), 24 deletions(-)
diff --git a/defs.h b/defs.h
index cbe0dd4..cbacf61 100644
--- a/defs.h
+++ b/defs.h
@@ -127,6 +127,7 @@ void* memset(void*, int, uint);
char* safestrcpy(char*, const char*, int);
int strlen(const char*);
int strncmp(const char*, const char*, uint);
+char* strncpy(char*, const char*, int);
// syscall.c
int argint(int, int*);
diff --git a/fs.c b/fs.c
index bc3cccd..eef20e8 100644
--- a/fs.c
+++ b/fs.c
@@ -455,15 +455,7 @@ writei(struct inode *ip, char *src, uint off, uint n)
int
namecmp(const char *s, const char *t)
{
- int i;
-
- for(i=0; i<DIRSIZ; i++){
- if(s[i] != t[i])
- return s[i] - t[i];
- if(s[i] == 0)
- break;
- }
- return 0;
+ return strncmp(s, t, DIRSIZ);
}
// Look for a directory entry in a directory.
@@ -500,18 +492,6 @@ dirlookup(struct inode *dp, char *name, uint *poff)
return 0;
}
-// Copy one name to another.
-static void
-namecpy(char *s, const char *t)
-{
- int i;
-
- for(i=0; i<DIRSIZ && t[i]; i++)
- s[i] = t[i];
- for(; i<DIRSIZ; i++)
- s[i] = 0;
-}
-
// Write a new directory entry (name, ino) into the directory dp.
int
dirlink(struct inode *dp, char *name, uint ino)
@@ -534,7 +514,7 @@ dirlink(struct inode *dp, char *name, uint ino)
break;
}
- namecpy(de.name, name);
+ strncpy(de.name, name, DIRSIZ);
de.inum = ino;
if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
panic("dirwrite");
diff --git a/string.c b/string.c
index 0a92cca..2f9fc25 100644
--- a/string.c
+++ b/string.c
@@ -56,8 +56,20 @@ strncmp(const char *p, const char *q, uint n)
n--, p++, q++;
if(n == 0)
return 0;
- else
- return (int) ((uchar) *p - (uchar) *q);
+ return (uchar)*p - (uchar)*q;
+}
+
+char*
+strncpy(char *s, const char *t, int n)
+{
+ char *os;
+
+ os = s;
+ while(n-- > 0 && (*s++ = *t++) != 0)
+ ;
+ while(n-- > 0)
+ *s++ = 0;
+ return os;
}
// Like strncpy but guaranteed to NUL-terminate.
--
GitLab