1 .\" 2 .\" This file and its contents are supplied under the terms of the 3 .\" Common Development and Distribution License ("CDDL"), version 1.0. 4 .\" You may only use this file in accordance with the terms of version 5 .\" 1.0 of the CDDL. 6 .\" 7 .\" A full copy of the text of the CDDL should have accompanied this 8 .\" source. A copy of the CDDL is also available via the Internet at 9 .\" http://www.illumos.org/license/CDDL. 10 .\" 11 .\" 12 .\" Copyright 2016 Joyent, Inc. 13 .\" 14 .Dd Feb 07, 2015 15 .Dt PTHREAD_ATTR_GET_NP 3C 16 .Os 17 .Sh NAME 18 .Nm pthread_attr_get_np 19 .Nd get pthread attributes of a running thread 20 .Sh SYNOPSIS 21 .In pthread.h 22 .Ft int 23 .Fo pthread_attr_get_np 24 .Fa "pthread_t thread" 25 .Fa "pthread_attr_t *attr" 26 .Fc 27 .Sh DESCRIPTION 28 The 29 .Fn pthread_attr_get_np 30 function provides a way to get the attributes of the thread 31 .Fa thread 32 after it has been created. 33 This function is most commonly used to obtain the actual location and size of a 34 thread's stack. 35 .Pp 36 The attributes pointer, 37 .Fa attr , 38 will be filled in with the current attributes for the thread. 39 The attributes should be allocated by a call to 40 .Xr pthread_attr_init 3C 41 prior to calling the 42 .Fn pthrad_attr_get_np 43 function. 44 When 45 .Fa attr 46 is done being used, it should be destroyed through a call to 47 .Xr pthread_attr_destroy 3C . 48 .Pp 49 The attributes of the thread 50 .Fa thread 51 will be the same as those passed in at the time 52 .Xr pthread_create 3C 53 was called (or the default set if none were specified), except that the 54 following values will be updated: 55 .Bl -tag -width Sy 56 .It Sy Thread Stack Size 57 If no explicit stack size was specified, then 58 .Fa attr 59 will contain the actual size of the stack. 60 .Pp 61 If the size of the stack was specified, then it may have been changed to 62 ensure that the required alignment of the platform is satisfied. 63 .It Sy The Stack Address 64 If no stack address was specified, then 65 .Fa attr 66 will contain the actual address of the stack that the system allocated 67 for the thread. 68 .It Sy Thread Detach State 69 The detach state, whether or not the thread may be joined by a call to 70 .Xr pthread_join 3C , 71 may have changed since the process was created due to a call to 72 .Xr pthread_detach 3C . 73 .Fa attr 74 will reflect the current setting of 75 .Fa thread . 76 .It Sy Thread Scheduling Parameter 77 The scheduling parameter attribute will be updated with the current 78 scheduling parameter of 79 .Fa thread . 80 This is the same information as available through 81 .Xr pthread_getschedparam 3C 82 and it is the preferred interface for obtaining that information. 83 .It Sy Thread Scheduling Policy 84 The scheduling policy attribute of 85 .Fa attr 86 will be updated with the current scheduling policy being applied to the 87 thread. 88 This may have changed, for example, due to a call to 89 .Xr pthread_setschedparam 3C . 90 As with the thread's scheduling parameter, the preferred interface for 91 obtaining this information is by using 92 .Xr pthread_getschedparam 3C . 93 .It Sy Thread Guard Size 94 The value of the guard size attribute for the thread will be updated to 95 reflect the actual size of the guard installed for 96 .Fa thread . 97 For more information on the guard size of a thread and its purpose, see 98 .Xr pthread_attr_getguardsize 3C . 99 .El 100 .Sh RETURN VALUES 101 Upon successful completion, the 102 .Fn pthread_attr_get_np 103 and 104 .Fn pthread_getattr_np 105 functions return 106 .Sy 0 . 107 Otherwise, an error number is returned to indicate the error. 108 .Sh EXAMPLES 109 The following program demonstrates how to use these functions to get 110 the location and stack size of a newly created thread. 111 .Bd -literal 112 #include <assert.h> 113 #include <errno.h> 114 #include <pthread.h> 115 #include <stdio.h> 116 #include <stdlib.h> 117 #include <string.h> 118 119 static pthread_t g_thr; 120 121 void * 122 print_stackinfo(void *arg) 123 { 124 int ret; 125 pthread_attr_t attr; 126 pthread_t *thrp = arg; 127 void *stk; 128 size_t stksize; 129 130 if (pthread_attr_init(&attr) != 0) { 131 fprintf(stderr, "failed to init attr: %s\\n", 132 strerror(errno)); 133 exit(1); 134 } 135 136 if (pthread_attr_get_np(*thrp, &attr) != 0) { 137 fprintf(stderr, "failed to get thread attributes: %s\\n", 138 strerror(errno)); 139 exit(1); 140 } 141 142 ret = pthread_attr_getstackaddr(&attr, &stk); 143 assert(ret == 0); 144 ret = pthread_attr_getstacksize(&attr, &stksize); 145 assert(ret == 0); 146 (void) printf("stack base is at %p, it is %d bytes large\\n", 147 stk, stksize); 148 return (NULL); 149 } 150 151 int 152 main(void) 153 { 154 int ret; 155 156 if ((ret = pthread_create(&g_thr, NULL, print_stackinfo, 157 &g_thr) != 0)) { 158 fprintf(stderr, "failed to create a thread: %s\\n", 159 strerror(errno)); 160 exit(1); 161 } 162 163 pthread_join(g_thr, NULL); 164 return (0); 165 } 166 .Ed 167 .Sh ERRORS 168 The 169 .Fn pthread_attr_get_np 170 function will fail if: 171 .Bl -tag -width Er 172 .It Er EINVAL 173 The pthread_attr_t object 174 .Fa attr 175 was not properly initialized with a call to 176 .Xr pthread_attr_init 3C . 177 .It Er ESRCH 178 No thread could be found corresponding to the specified thread ID, 179 .Fa thread . 180 .El 181 .Sh INTERFACE STABILITY 182 .Sy Committed 183 .Sh MT-LEVEL 184 .Sy MT-Safe 185 .Sh SEE ALSO 186 .Xr pthread_attr_destroy 3C , 187 .Xr pthread_attr_getdetachstate 3C , 188 .Xr pthread_attr_getguardsize 3C , 189 .Xr pthread_attr_getinheritsched 3C , 190 .Xr pthread_attr_getschedparam 3C , 191 .Xr pthread_attr_getschedpolicy 3C , 192 .Xr pthread_attr_getscope 3C , 193 .Xr pthread_attr_getstackaddr 3C , 194 .Xr pthread_attr_getstacksize 3C , 195 .Xr pthread_attr_init 3C , 196 .Xr pthread_create 3C , 197 .Xr pthread_detach 3C , 198 .Xr pthread_getschedparam 3C , 199 .Xr pthread_setschedparam 3C , 200 .Xr attributes 5 , 201 .Xr threads 5