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Commit f176eb4c authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Linus Torvalds
Browse files

lib/test_printf.c: test precision quirks 



The kernel's printf doesn't follow the standards in a few corner cases
(which are probably mostly irrelevant).  Add tests that document the
current behaviour.

Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Maurizio Lombardi <mlombard@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 331e4deb

lib/test_printf.c

+15 −6
Original line number Original line Diff line number Diff line
@@ -166,14 +166,23 @@ test_string(void) 
	test("", "%s%.0s", "", "123");

	test("", "%s%.0s", "", "123");

	test("ABCD|abc|123", "%s|%.3s|%.*s", "ABCD", "abcdef", 3, "123456");

	test("ABCD|abc|123", "%s|%.3s|%.*s", "ABCD", "abcdef", 3, "123456");

	test("1  |  2|3  |  4|5  ", "%-3s|%3s|%-*s|%*s|%*s", "1", "2", 3, "3", 3, "4", -3, "5");

	test("1  |  2|3  |  4|5  ", "%-3s|%3s|%-*s|%*s|%*s", "1", "2", 3, "3", 3, "4", -3, "5");

	test("1234      ", "%-10.4s", "123456");

	test("      1234", "%10.4s", "123456");

	/*

	/*

	 * POSIX and C99 say that a missing precision should be

	 * POSIX and C99 say that a negative precision (which is only

	 * treated as a precision of 0. However, the kernel's printf

	 * possible to pass via a * argument) should be treated as if

	 * implementation treats this case as if the . wasn't

	 * the precision wasn't present, and that if the precision is

	 * present. Let's add a test case documenting the current

	 * omitted (as in %.s), the precision should be taken to be

	 * behaviour; should anyone ever feel the need to follow the

	 * 0. However, the kernel's printf behave exactly opposite,

	 * standards more closely, this can be revisited.

	 * treating a negative precision as 0 and treating an omitted

	 * precision specifier as if no precision was given.

	 *

	 * These test cases document the current behaviour; should

	 * anyone ever feel the need to follow the standards more

	 * closely, this can be revisited.

	 */

	 */

	test("    ", "%4.*s", -5, "123456");

	test("123456", "%.s", "123456");

	test("a||", "%.s|%.0s|%.*s", "a", "b", 0, "c");

	test("a||", "%.s|%.0s|%.*s", "a", "b", 0, "c");

	test("a  |   |   ", "%-3.s|%-3.0s|%-3.*s", "a", "b", 0, "c");

	test("a  |   |   ", "%-3.s|%-3.0s|%-3.*s", "a", "b", 0, "c");

}

}