pth_cancel2.c revision e739ac0589b4fb43561f801c4faba8c1b89f8680 
1/********************************************************
2 * An example source module to accompany...
3 *
4 * "Using POSIX Threads: Programming with Pthreads"
5 *     by Brad nichols, Dick Buttlar, Jackie Farrell
6 *     O'Reilly & Associates, Inc.
7 *
8 ********************************************************
9 * async_safe --
10 *
11 * Example showing macro wrappers for calling non-async
12 * safe routines when the caller has asynchronous
13 * cancellation turned on
14 */
15
16#include <stdlib.h>
17#include <stdio.h>
18#include <unistd.h>
19#include <fcntl.h>
20#include <sys/types.h>
21#include <sys/stat.h>
22
23#include <pthread.h>
24
25
26#define async_cancel_safe_read(fd,buf,amt) \
27   { \
28      int oldtype; \
29      pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, &oldtype); \
30      if (read(fd,buf,amt) < 0) \
31         perror("read"),exit(1); \
32      pthread_setcanceltype(oldtype,NULL); \
33      pthread_testcancel(); \
34   }
35
36
37#define async_cancel_safe_write(fd,buf,amt) \
38   { \
39      int oldtype; \
40      pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, &oldtype); \
41      if (write(fd,buf,amt) < 0) \
42         perror("write"), exit(1); \
43      pthread_setcanceltype(oldtype,NULL); \
44      pthread_testcancel(); \
45   }
46
47
48static int fd;
49
50void *io(void *arg)
51{
52   int *fd2=(int *)arg;
53   char buf[20]="String";
54   int amt=20;
55
56   for (;;) {
57      async_cancel_safe_write(*fd2,buf,amt);
58      async_cancel_safe_read(*fd2,buf,amt);
59   }
60   return(NULL);
61}
62
63void *killer(void *arg)
64{
65   pthread_t * target = (pthread_t *)arg;
66   sleep(1);
67   pthread_cancel(*target);
68   return(NULL);
69}
70
71extern int
72main(void)
73{
74   pthread_t io_thread, killer_thread;
75
76   //   extern void *io(void *);
77   // extern void *killer(void  *);
78
79   if ((fd = open(".ktemp",O_CREAT | O_RDWR, 0666)) < 0)
80      perror("open"), exit(1);
81
82   pthread_create(&io_thread,
83		  NULL,
84		  io,
85		  (void *)&fd);
86   pthread_create(&killer_thread,
87		  NULL,
88		  killer,
89		  (void *)&io_thread);
90
91   pthread_join(io_thread, NULL);
92
93   pthread_join(killer_thread,NULL);
94
95   if ((close(fd)) < 0)
96     perror("close"),exit(1);
97   if ((unlink(".ktemp")) < 0)
98     perror("unlink"),exit(1);
99
100   return 0;
101}
102