From 85b7ea33088fa16d319adbd228fc152f5b9da730 Mon Sep 17 00:00:00 2001 From: David A Ramos Date: Tue, 27 Jul 2010 13:10:15 +0200 Subject: Fix ctime() standard compliance bug fixes issue2209: ctime() was updated in 0.9.31 to call localtime_r() instead of localtime() to avoid using a static buffer. Unfortunately, this change replaces the static buffer (which is zeroed out on initialization) with an uninitialized local buffer. In the common case, this has no effect. However, with a sufficiently large time_t value, the value returned differs from that returned by asctime(localtime(t)), and thus violates the ANSI/ISO standard. An example input is (on a 64-bit machine): time_t t = 0x7ffffffffff6c600; Signed-off-by: Bernhard Reutner-Fischer --- libc/misc/time/time.c | 1 + test/time/tst-ctime.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 45 insertions(+) create mode 100644 test/time/tst-ctime.c diff --git a/libc/misc/time/time.c b/libc/misc/time/time.c index 758a737fd..ff44892a8 100644 --- a/libc/misc/time/time.c +++ b/libc/misc/time/time.c @@ -479,6 +479,7 @@ char *ctime(const time_t *t) * localtime's static buffer: */ struct tm xtm; + memset(&xtm, 0, sizeof(xtm)); return asctime(localtime_r(t, &xtm)); } diff --git a/test/time/tst-ctime.c b/test/time/tst-ctime.c new file mode 100644 index 000000000..91d827aa2 --- /dev/null +++ b/test/time/tst-ctime.c @@ -0,0 +1,44 @@ +/* vi: set sw=4 ts=4: */ +/* testcase for ctime(3) with large time + * Copyright (C) 2010 David A Ramos + * Licensed under the LGPL v2.1, see the file COPYING.LIB in this tarball. + */ + +#include +#include +#include +#include + +#define MAX_POSITIVE(type) (~0 & ~((type) 1 << (sizeof(type)*8 - 1))) + +int do_test(int argc, char **argv) { + char *correct = 0, *s; + int status; + + /* need a very high positive number (e.g., max - 1024) */ + time_t test = MAX_POSITIVE(time_t) - 1024; + + s = asctime(localtime(&test)); + + if (s) { + // copy static buffer to heap + correct = malloc(strlen(s)+1); + strcpy(correct, s); + } + + s = ctime(&test); + + printf("ANSI:\t%suClibc:\t%s", correct, s); + + if (s != correct && strcmp(correct, s)) + status = EXIT_FAILURE; + else + status = EXIT_SUCCESS; + + if (correct) + free(correct); + + return status; +} + +#include -- cgit v1.2.3