tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2#include <sys/select.h>
3#include <stdlib.h>
4#include <stdio.h>
5#include <string.h>
6#include <signal.h>
7#include <sys/ioctl.h>
8#include "pager.h"
9#include "run-command.h"
10#include "sigchain.h"
11#include "subcmd-config.h"
12
13/*
14 * This is split up from the rest of git so that we can do
15 * something different on Windows.
16 */
17
18static int spawned_pager;
19static int pager_columns;
20
21void pager_init(const char *pager_env)
22{
23 subcmd_config.pager_env = pager_env;
24}
25
26static void pager_preexec(void)
27{
28 /*
29 * Work around bug in "less" by not starting it until we
30 * have real input
31 */
32 fd_set in;
33 fd_set exception;
34
35 FD_ZERO(&in);
36 FD_ZERO(&exception);
37 FD_SET(0, &in);
38 FD_SET(0, &exception);
39 select(1, &in, NULL, &exception, NULL);
40
41 setenv("LESS", "FRSX", 0);
42}
43
44static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
45static struct child_process pager_process;
46
47static void wait_for_pager(void)
48{
49 fflush(stdout);
50 fflush(stderr);
51 /* signal EOF to pager */
52 close(1);
53 close(2);
54 finish_command(&pager_process);
55}
56
57static void wait_for_pager_signal(int signo)
58{
59 wait_for_pager();
60 sigchain_pop(signo);
61 raise(signo);
62}
63
64void setup_pager(void)
65{
66 const char *pager = getenv(subcmd_config.pager_env);
67 struct winsize sz;
68
69 if (!isatty(1))
70 return;
71 if (ioctl(1, TIOCGWINSZ, &sz) == 0)
72 pager_columns = sz.ws_col;
73 if (!pager)
74 pager = getenv("PAGER");
75 if (!(pager || access("/usr/bin/pager", X_OK)))
76 pager = "/usr/bin/pager";
77 if (!(pager || access("/usr/bin/less", X_OK)))
78 pager = "/usr/bin/less";
79 if (!pager)
80 pager = "cat";
81 if (!*pager || !strcmp(pager, "cat"))
82 return;
83
84 spawned_pager = 1; /* means we are emitting to terminal */
85
86 /* spawn the pager */
87 pager_argv[2] = pager;
88 pager_process.argv = pager_argv;
89 pager_process.in = -1;
90 pager_process.preexec_cb = pager_preexec;
91
92 if (start_command(&pager_process))
93 return;
94
95 /* original process continues, but writes to the pipe */
96 dup2(pager_process.in, 1);
97 if (isatty(2))
98 dup2(pager_process.in, 2);
99 close(pager_process.in);
100
101 /* this makes sure that the parent terminates after the pager */
102 sigchain_push_common(wait_for_pager_signal);
103 atexit(wait_for_pager);
104}
105
106int pager_in_use(void)
107{
108 return spawned_pager;
109}
110
111int pager_get_columns(void)
112{
113 char *s;
114
115 s = getenv("COLUMNS");
116 if (s)
117 return atoi(s);
118
119 return (pager_columns ? pager_columns : 80) - 2;
120}