add safestrcpy

7e89fb90 · rsc · cd08e6e0 · 7e89fb90 · 7e89fb90
--- a/defs.h
+++ b/defs.h
@@ -39,6 +39,7 @@ void* memset(void*, int, uint);
 int memcmp(const void*, const void*, uint);
 void* memmove(void*, const void*, uint);
 int strncmp(const char*, const char*, uint);
+char* safestrcpy(char*, const char*, int);

 // syscall.c
 void syscall(void);

--- a/string.c
+++ b/string.c
@@ -57,3 +57,19 @@ strncmp(const char *p, const char *q, uint n)
  else
    return (int) ((uchar) *p - (uchar) *q);
 }
+
+// Like strncpy but guaranteed to NUL-terminate.
+char*
+safestrcpy(char *s, const char *t, int n)
+{
+  char *os;
+  
+  os = s;
+  if(n <= 0)
+    return os;
+  while(--n > 0 && (*s++ = *t++) != 0)
+    ;
+  *s = 0;
+  return os;
+}
+