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