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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 12:06:34 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 12:06:34 +0000 |
commit | 5e61585d76ae77fd5e9e96ebabb57afa4d74880d (patch) | |
tree | 2b467823aaeebc7ef8bc9e3cabe8074eaef1666d /src/util/timecmp.c | |
parent | Initial commit. (diff) | |
download | postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.tar.xz postfix-5e61585d76ae77fd5e9e96ebabb57afa4d74880d.zip |
Adding upstream version 3.5.24.upstream/3.5.24upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/util/timecmp.c')
-rw-r--r-- | src/util/timecmp.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/src/util/timecmp.c b/src/util/timecmp.c new file mode 100644 index 0000000..607a9ae --- /dev/null +++ b/src/util/timecmp.c @@ -0,0 +1,93 @@ +/*++ +/* NAME +/* timecmp 3 +/* SUMMARY +/* compare two time_t values +/* SYNOPSIS +/* #include <timecmp.h> +/* +/* int timecmp(t1, t2) +/* time_t t1; +/* time_t t2; +/* DESCRIPTION +/* The timecmp() function return an integer greater than, equal to, or +/* less than 0, according as the time t1 is greater than, equal to, or +/* less than the time t2. The comparison is made in a manner that is +/* insensitive to clock wrap-around, provided the underlying times are +/* within half of the time interval between the smallest and largest +/* representable time values. +/* LICENSE +/* .ad +/* .fi +/* The Secure Mailer license must be distributed with this software. +/* AUTHOR(S) +/* Wietse Venema +/* IBM T.J. Watson Research +/* P.O. Box 704 +/* Yorktown Heights, NY 10598, USA +/* +/* Viktor Dukhovni +/*--*/ + +#include "timecmp.h" + +/* timecmp - wrap-safe time_t comparison */ + +int timecmp(time_t t1, time_t t2) +{ + time_t delta = t1 - t2; + + if (delta == 0) + return 0; + +#define UNSIGNED(type) ( ((type)-1) > ((type)0) ) + + /* + * With a constant switch value, the compiler will emit only the code for + * the correct case, so the signed/unsigned test happens at compile time. + */ + switch (UNSIGNED(time_t) ? 0 : 1) { + case 0: + return ((2 * delta > delta) ? 1 : -1); + case 1: + return ((delta > (time_t) 0) ? 1 : -1); + } +} + +#ifdef TEST +#include <assert.h> + + /* + * Bit banging!! There is no official constant that defines the INT_MAX + * equivalent of the off_t type. Wietse came up with the following macro + * that works as long as off_t is some two's complement number. + * + * Note, however, that C99 permits signed integer representations other than + * two's complement. + */ +#include <limits.h> +#define __MAXINT__(T) ((T) (((((T) 1) << ((sizeof(T) * CHAR_BIT) - 1)) ^ ((T) -1)))) + +int main(void) +{ + time_t now = time((time_t *) 0); + + /* Test that it works for normal times */ + assert(timecmp(now + 10, now) > 0); + assert(timecmp(now, now) == 0); + assert(timecmp(now - 10, now) < 0); + + /* Test that it works at a boundary time */ + if (UNSIGNED(time_t)) + now = (time_t) -1; + else + now = __MAXINT__(time_t); + + assert(timecmp(now + 10, now) > 0); + assert(timecmp(now, now) == 0); + assert(timecmp(now - 10, now) < 0); + + return (0); +} + +#endif |