1 /*
2 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
3 * Use is subject to license terms.
4 */
5
6 /*
7 * Pager: Routines to create a "more" running out of a particular file
8 * descriptor.
9 *
10 * Copyright 1987, 1988 by MIT Student Information Processing Board
11 *
12 * For copyright information, see copyright.h.
13 */
14
15 #include "ss_internal.h"
16 #include "copyright.h"
17 #include <errno.h>
18 #include <stdio.h>
19 #include <sys/types.h>
20 #include <sys/file.h>
21 #include <signal.h>
22
23 static char MORE[] = "more";
24 extern char *_ss_pager_name;
25 extern char *getenv();
26
27 /*
28 * this needs a *lot* of work....
29 *
30 * run in same process
31 * handle SIGINT sensibly
32 * allow finer control -- put-page-break-here
33 */
34
35 #ifndef NO_FORK
ss_pager_create(void)36 int ss_pager_create(void)
37 {
38 int filedes[2];
39
40 if (pipe(filedes) != 0)
41 return(-1);
42
43 switch((int) fork()) {
44 case -1:
45 return(-1);
46 case 0:
47 /*
48 * Child; dup read half to 0, close all but 0, 1, and 2
49 */
50 if (dup2(filedes[0], 0) == -1)
51 exit(1);
52 ss_page_stdin();
53 default:
54 /*
55 * Parent: close "read" side of pipe, return
56 * "write" side.
57 */
58 (void) close(filedes[0]);
59 return(filedes[1]);
60 }
61 }
62 #else /* don't fork */
ss_pager_create(void)63 int ss_pager_create(void)
64 {
65 int fd;
66 fd = open("/dev/tty", O_WRONLY, 0);
67 return fd;
68 }
69 #endif
70
ss_page_stdin(void)71 void ss_page_stdin(void)
72 {
73 int i;
74 #ifdef POSIX_SIGNALS
75 struct sigaction sa;
76 sigset_t mask;
77 #endif
78 /*
79 * Close all fd's, excepting stdin/stdout/stderr
80 */
81 closefrom(3);
82
83 #ifdef POSIX_SIGNALS
84 sa.sa_handler = SIG_DFL;
85 sigemptyset(&sa.sa_mask);
86 sa.sa_flags = 0;
87 sigaction(SIGINT, &sa, NULL);
88 #else
89 (void) signal(SIGINT, SIG_DFL);
90 #endif
91 {
92 #ifdef POSIX_SIGNALS
93 sigemptyset(&mask);
94 sigaddset(&mask, SIGINT);
95 sigprocmask(SIG_UNBLOCK, &mask, NULL);
96 #else
97 int mask = sigblock(0);
98 mask &= ~sigmask(SIGINT);
99 sigsetmask(mask);
100 #endif
101 }
102 if (_ss_pager_name == NULL) {
103 if ((_ss_pager_name = getenv("PAGER")) == NULL)
104 _ss_pager_name = MORE;
105 }
106 (void) execlp(_ss_pager_name, _ss_pager_name, NULL);
107 {
108 /* minimal recovery if pager program isn't found */
109 char buf[80];
110 register int n;
111 while ((n = read(0, buf, 80)) > 0)
112 write(1, buf, (unsigned) n);
113 }
114 exit(errno);
115 }
116