tools/time.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  *
  21  * Copyright (c) 2010, Oracle and/or it's affiliates.  All rights reserved.
  22  */
  23
  24 /*
  25  * This compiles to a module that can be preloaded during a build.  If this
  26  * is preloaded, it interposes on time(2), gettimeofday(3C), and
  27  * clock_gethrtime(3C) and returns a constant number of seconds since epoch
  28  * when the execname matches one of the desired "programs" and TIME_CONSTANT
  29  * contains an integer value to be returned.
  30  */
  31
  32 #include <stdlib.h>
  33 #include <ucontext.h>
  34 #include <dlfcn.h>
  35 #include <strings.h>
  36 #include <time.h>
  37
  38 /* The list of programs that we want to use a constant time. */
  39 static char *programs[] = {
  40         "autogen", "bash", "cpp", "cc1", "date", "doxygen",
  41         "erl", "grops", "gs", "gtroff", "javadoc", "ksh", "ksh93", "ld",
  42         "perl", "perl5.8.4", "perl5.10", "ruby", "sh", NULL
  43 };
  44
  45 static int
  46 stack_info(uintptr_t pc, int signo, void *arg)
  47 {
  48         Dl_info info;
  49         void *sym;
  50
  51         if (dladdr1((void *)pc, &info, &sym, RTLD_DL_SYMENT) != 0) {
  52                 if (strstr(info.dli_fname, ".so") == NULL)
  53                         *(char **)arg = (char *)info.dli_fname;
  54         }
  55
  56         return (0);
  57 }
  58
  59 static char *
  60 my_execname()
  61 {
  62         static char *execname;
  63
  64         if (execname == NULL) {
  65                 ucontext_t ctx;
  66
  67                 if (getcontext(&ctx) == 0)
  68                         walkcontext(&ctx, stack_info, &execname);
  69
  70                 if (execname != NULL) {
  71                         char *s = strrchr(execname, '/');
  72
  73                         if (s != NULL)
  74                                 execname = ++s;
  75                 }
  76         }
  77
  78         return (execname);
  79 }
  80
  81 static time_t
  82 time_constant()
  83 {
  84         char *execname = my_execname();
  85         time_t result = -1;
  86
  87         if (execname != NULL) {
  88                 int i;
  89
  90                 for (i = 0; programs[i] != NULL; i++)
  91                         if (strcmp(execname, programs[i]) == 0) {
  92                                 static char *time_string;
  93
  94                                 if (time_string == NULL)
  95                                         time_string = getenv("TIME_CONSTANT");
  96
  97                                 if (time_string != NULL)
  98                                         result = atoll(time_string);
  99
 100                                 break;
 101                         }
 102         }
 103
 104         return (result);
 105 }
 106
 107 time_t
 108 time(time_t *ptr)
 109 {
 110         time_t result = time_constant();
 111
 112         if (result == (time_t)-1) {
 113                 static time_t (*fptr)(time_t *);
 114
 115                 if (fptr == NULL)
 116                         fptr = (time_t (*)(time_t *))dlsym(RTLD_NEXT, "time");
 117
 118                 result = (fptr)(ptr);
 119         } else if (ptr != NULL)
 120                         *ptr = result;
 121
 122         return (result);
 123 }
 124
 125 int
 126 gettimeofday(struct timeval *tp, void *tzp)
 127 {
 128         static int (*fptr)(struct timeval *, void *);
 129         int result = -1;
 130
 131         if (fptr == NULL)
 132                 fptr = (int (*)(struct timeval *, void *))dlsym(RTLD_NEXT,
 133                                 "gettimeofday");
 134
 135         if ((result = (fptr)(tp, tzp)) == 0) {
 136                 time_t curtime = time_constant();
 137
 138                 if (curtime != (time_t)-1)
 139                         tp->tv_sec = curtime;
 140         }
 141
 142         return (result);
 143 }
 144
 145 int
 146 clock_gettime(clockid_t clock_id, struct timespec *tp)
 147 {
 148         static int (*fptr)(clockid_t, struct timespec *);
 149         int result = -1;
 150
 151         if (fptr == NULL)
 152                 fptr = (int (*)(clockid_t, struct timespec *))dlsym(RTLD_NEXT,
 153                                 "clock_gettime");
 154
 155         if ((result = (fptr)(clock_id, tp)) == 0) {
 156                 time_t curtime = time_constant();
 157
 158                 if (curtime != (time_t)-1)
 159                         tp->tv_sec = curtime;
 160         }
 161
 162         return (result);
 163 }