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/*
* gcc time_past.c -o time_past.so -shared -ldl
* LD_PRELOAD=./time_past.so PAST_DAYS=2 ./test
*/
#define _GNU_SOURCE
#include <dlfcn.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdarg.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
typedef time_t (*time_type) (time_t *t);
static time_type next_time;
static int time_past = 0;
static char *past = NULL;
time_t time (time_t *t)
{
time_t res;
if (NULL == next_time)
{
next_time = dlsym (RTLD_NEXT, "time");
assert (NULL != next_time);
}
if (NULL == past) {
const char *past = getenv ("PAST_DAYS");
if (NULL == past) {
fputs ("No PAST_DAYS defined\n", stderr);
}
time_past = atoi (past);
}
res = next_time (t);
res -= 24*60*60*time_past;
if (NULL != t) {
*t = res;
}
return res;
}
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