tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#include <sys/select.h>
2#include <stdlib.h>
3#include <stdio.h>
4#include <string.h>
5#include <signal.h>
6#include <sys/ioctl.h>
7#include "pager.h"
8#include "run-command.h"
9#include "sigchain.h"
10#include "subcmd-config.h"
11
12/*
13 * This is split up from the rest of git so that we can do
14 * something different on Windows.
15 */
16
17static int spawned_pager;
18static int pager_columns;
19
20void pager_init(const char *pager_env)
21{
22 subcmd_config.pager_env = pager_env;
23}
24
25static void pager_preexec(void)
26{
27 /*
28 * Work around bug in "less" by not starting it until we
29 * have real input
30 */
31 fd_set in;
32
33 FD_ZERO(&in);
34 FD_SET(0, &in);
35 select(1, &in, NULL, &in, NULL);
36
37 setenv("LESS", "FRSX", 0);
38}
39
40static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
41static struct child_process pager_process;
42
43static void wait_for_pager(void)
44{
45 fflush(stdout);
46 fflush(stderr);
47 /* signal EOF to pager */
48 close(1);
49 close(2);
50 finish_command(&pager_process);
51}
52
53static void wait_for_pager_signal(int signo)
54{
55 wait_for_pager();
56 sigchain_pop(signo);
57 raise(signo);
58}
59
60void setup_pager(void)
61{
62 const char *pager = getenv(subcmd_config.pager_env);
63 struct winsize sz;
64
65 if (!isatty(1))
66 return;
67 if (ioctl(1, TIOCGWINSZ, &sz) == 0)
68 pager_columns = sz.ws_col;
69 if (!pager)
70 pager = getenv("PAGER");
71 if (!(pager || access("/usr/bin/pager", X_OK)))
72 pager = "/usr/bin/pager";
73 if (!(pager || access("/usr/bin/less", X_OK)))
74 pager = "/usr/bin/less";
75 if (!pager)
76 pager = "cat";
77 if (!*pager || !strcmp(pager, "cat"))
78 return;
79
80 spawned_pager = 1; /* means we are emitting to terminal */
81
82 /* spawn the pager */
83 pager_argv[2] = pager;
84 pager_process.argv = pager_argv;
85 pager_process.in = -1;
86 pager_process.preexec_cb = pager_preexec;
87
88 if (start_command(&pager_process))
89 return;
90
91 /* original process continues, but writes to the pipe */
92 dup2(pager_process.in, 1);
93 if (isatty(2))
94 dup2(pager_process.in, 2);
95 close(pager_process.in);
96
97 /* this makes sure that the parent terminates after the pager */
98 sigchain_push_common(wait_for_pager_signal);
99 atexit(wait_for_pager);
100}
101
102int pager_in_use(void)
103{
104 return spawned_pager;
105}
106
107int pager_get_columns(void)
108{
109 char *s;
110
111 s = getenv("COLUMNS");
112 if (s)
113 return atoi(s);
114
115 return (pager_columns ? pager_columns : 80) - 2;
116}