1 /*

     2  * Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.

     3  *

     4  * Permission is hereby granted, free of charge, to any person obtaining a

     5  * copy of this software and associated documentation files (the "Software"),

     6  * to deal in the Software without restriction, including without limitation

     7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,

     8  * and/or sell copies of the Software, and to permit persons to whom the

     9  * Software is furnished to do so, subject to the following conditions:

    10  *

    11  * The above copyright notice and this permission notice (including the next

    12  * paragraph) shall be included in all copies or substantial portions of the

    13  * Software.

    14  *

    15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

    16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

    17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

    18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

    19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

    20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

    21  * DEALINGS IN THE SOFTWARE.

    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[] = { "autogen", "bash", "cpp", "cc1", "date", "doxygen",

    40 	"erl", "javadoc", "ksh", "ksh93", "ld", "perl", "perl5.8.4", "perl5.10",

    41 	"ruby", "sh", "uil", NULL };

    42 

    43 static int

    44 stack_info(uintptr_t pc, int signo, void *arg)

    45 {

    46 	Dl_info info;

    47 	void *sym;

    48 

    49 	if (dladdr1((void *)pc, &info, &sym, RTLD_DL_SYMENT) != NULL) {

    50 		if (strstr(info.dli_fname, ".so") == NULL)

    51 			*(char **)arg = (char *)info.dli_fname;

    52 	}

    53 

    54 	return (0);

    55 }

    56 

    57 static char *

    58 my_execname()

    59 {

    60 	static char *execname;

    61 

    62 	if (execname == NULL) {

    63 		ucontext_t ctx;

    64 

    65 		if (getcontext(&ctx) == 0)

    66 			walkcontext(&ctx, stack_info, &execname);

    67 

    68 		if (execname != NULL) {

    69 			char *s = strrchr(execname, '/');

    70 

    71 			if (s != NULL)

    72 				execname = ++s;

    73 		}

    74 	}

    75 

    76 	return (execname);

    77 }

    78 

    79 static time_t

    80 time_constant()

    81 {

    82 	char *execname = my_execname();

    83 	time_t result = -1;

    84 

    85 	if (execname != NULL) {

    86 		int i;

    87 

    88 		for (i = 0; programs[i] != NULL; i++)

    89 			if (strcmp(execname, programs[i]) == 0) {

    90 				static char *time_string;

    91 

    92 				if (time_string == NULL)

    93 					time_string = getenv("TIME_CONSTANT");

    94 

    95 				if (time_string != NULL)

    96 					result = atoll(time_string);

    97 

    98 				break;

    99 			}

   100 	}

   101 

   102 	return (result);

   103 }

   104 

   105 time_t

   106 time(time_t *ptr)

   107 {

   108 	time_t result = time_constant();

   109 

   110 	if (result == (time_t)-1) {

   111 		static time_t (*fptr)(time_t *);

   112 

   113 		if (fptr == NULL)

   114 			fptr = (time_t (*)(time_t *))dlsym(RTLD_NEXT, "time");

   115 

   116 		result = (fptr)(ptr);

   117 	} else if (ptr != NULL)

   118 			*ptr = result;

   119 

   120 	return (result);

   121 }

   122 

   123 int

   124 gettimeofday(struct timeval *tp, void *tzp)

   125 {

   126 	static int (*fptr)(struct timeval *, void *);

   127 	int result = -1;

   128 

   129 	if (fptr == NULL)

   130 		fptr = (int (*)(struct timeval *, void *))dlsym(RTLD_NEXT,

   131 				"gettimeofday");

   132 

   133 	if ((result = (fptr)(tp, tzp)) == 0) {

   134 		time_t curtime = time_constant();

   135 

   136 		if (curtime != (time_t)-1)

   137 			tp->tv_sec = curtime;

   138 	}

   139 

   140 	return (result);

   141 }

   142 

   143 int

   144 clock_gettime(clockid_t clock_id, struct timespec *tp)

   145 {

   146 	static int (*fptr)(clockid_t, struct timespec *);

   147 	int result = -1;

   148 

   149 	if (fptr == NULL)

   150 		fptr = (int (*)(clockid_t, struct timespec *))dlsym(RTLD_NEXT,

   151 				"clock_gettime");

   152 

   153 	if ((result = (fptr)(clock_id, tp)) == 0) {

   154 		time_t curtime = time_constant();

   155 

   156 		if (curtime != (time_t)-1)

   157 			tp->tv_sec = curtime;

   158 	}

   159 

   160 	return (result);

   161 }