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-rw-r--r--libc/string/generic/strncpy.c86
1 files changed, 86 insertions, 0 deletions
diff --git a/libc/string/generic/strncpy.c b/libc/string/generic/strncpy.c
new file mode 100644
index 000000000..214f38430
--- /dev/null
+++ b/libc/string/generic/strncpy.c
@@ -0,0 +1,86 @@
+/* Copyright (C) 1991, 1997, 2003 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
+#include <string.h>
+#include "memcopy.h"
+
+#undef strncpy
+
+char *
+strncpy (s1, s2, n)
+ char *s1;
+ const char *s2;
+ size_t n;
+{
+ reg_char c;
+ char *s = s1;
+
+ --s1;
+
+ if (n >= 4)
+ {
+ size_t n4 = n >> 2;
+
+ for (;;)
+ {
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ break;
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ break;
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ break;
+ c = *s2++;
+ *++s1 = c;
+ if (c == '\0')
+ break;
+ if (--n4 == 0)
+ goto last_chars;
+ }
+ n = n - (s1 - s) - 1;
+ if (n == 0)
+ return s;
+ goto zero_fill;
+ }
+
+ last_chars:
+ n &= 3;
+ if (n == 0)
+ return s;
+
+ do
+ {
+ c = *s2++;
+ *++s1 = c;
+ if (--n == 0)
+ return s;
+ }
+ while (c != '\0');
+
+ zero_fill:
+ do
+ *++s1 = '\0';
+ while (--n > 0);
+
+ return s;
+}