string/i386/strncpy.c: fixlet for testing code

string/i386/strchrnul.c: new function, adapted from strchr.c

    text           data     bss     dec     hex filename
- 240604           1759   11960  254323   3e173 lib/libuClibc-0.9.30-svn.so
+ 240449           1759   11960  254168   3e0d8 lib/libuClibc-0.9.30-svn.so

libc/string/i386/strchrnul.c

@@ -0,0 +1,47 @@
+/*
+ * Adapted from strchr.c code
+ *
+ * Copyright (C) 2008 Denys Vlasenko <vda.linux@googlemail.com>
+ *
+ * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball.
+ */
+
+#include <string.h>
+
+#undef strchrnul
+//#define strchrnul TESTING
+char *strchrnul(const char *s, int c)
+{
+	int esi;
+	char *eax;
+	__asm__ __volatile__(
+		"	movb	%%al, %%ah\n"
+		"1:	lodsb\n"
+		"	cmpb	%%ah, %%al\n"
+		"	je	2f\n"
+		"	testb	%%al, %%al\n"
+		"	jnz	1b\n"
+		/* with this, we'd get strchr(): */
+		/* "	movl	$1, %%esi\n" */
+		"2:	leal	-1(%%esi), %%eax\n"
+		: "=a" (eax), "=&S" (esi)
+		: "0" (c), "1" (s)
+		/* no clobbers */
+	);
+	return eax;
+}
+#ifndef strchrnul
+libc_hidden_def(strchrnul)
+#else
+/* Uncomment TESTING, gcc -D_GNU_SOURCE -m32 -Os strchrnul.c -o strchrnul
+ * and run ./strchrnul
+ */
+int main()
+{
+	static const char str[] = "abc.def";
+	printf((char*)strchrnul(str, '.') - str == 3 ? "ok\n" : "BAD!\n");
+	printf((char*)strchrnul(str, '*') - str == 7 ? "ok\n" : "BAD!\n");
+	printf((char*)strchrnul(str,   0) - str == 7 ? "ok\n" : "BAD!\n");
+	printf((char*)strchrnul(str+3, '.') - str == 3 ? "ok\n" : "BAD!\n");
+}
+#endif

libc/string/i386/strncpy.c

@@ -68,7 +68,7 @@ int main()
 	str[4] = '*'; str[5] = '+'; strncpy(str, "abc", 5);
 	printf(strcmp(str, "abc") == 0 && str[4] == 0 && str[5] == '+' ?
 				"ok\n" : "BAD!\n");
-	strncpy(str, "abc", 0); /* should do nothing */
+	strncpy(str, "def", 0); /* should do nothing */
 	printf(strcmp(str, "abc") == 0 && str[4] == 0 && str[5] == '+' ?
 				"ok\n" : "BAD!\n");
 }