pager.c revision e6817ec1d8ab31fc7b01906e305f848542df6413 
1#include "cache.h"
2#include "run-command.h"
3#include "sigchain.h"
4
5/*
6 * This is split up from the rest of git so that we can do
7 * something different on Windows.
8 */
9
10static int spawned_pager;
11
12static void pager_preexec(void)
13{
14	/*
15	 * Work around bug in "less" by not starting it until we
16	 * have real input
17	 */
18	fd_set in;
19
20	FD_ZERO(&in);
21	FD_SET(0, &in);
22	select(1, &in, NULL, &in, NULL);
23
24	setenv("LESS", "FRSX", 0);
25}
26
27static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
28static struct child_process pager_process;
29
30static void wait_for_pager(void)
31{
32	fflush(stdout);
33	fflush(stderr);
34	/* signal EOF to pager */
35	close(1);
36	close(2);
37	finish_command(&pager_process);
38}
39
40static void wait_for_pager_signal(int signo)
41{
42	wait_for_pager();
43	sigchain_pop(signo);
44	raise(signo);
45}
46
47void setup_pager(void)
48{
49	const char *pager = getenv("PERF_PAGER");
50
51	if (!isatty(1))
52		return;
53	if (!pager) {
54		if (!pager_program)
55			perf_config(perf_default_config, NULL);
56		pager = pager_program;
57	}
58	if (!pager)
59		pager = getenv("PAGER");
60	if (!pager)
61		pager = "less";
62	else if (!*pager || !strcmp(pager, "cat"))
63		return;
64
65	spawned_pager = 1; /* means we are emitting to terminal */
66
67	/* spawn the pager */
68	pager_argv[2] = pager;
69	pager_process.argv = pager_argv;
70	pager_process.in = -1;
71	pager_process.preexec_cb = pager_preexec;
72
73	if (start_command(&pager_process))
74		return;
75
76	/* original process continues, but writes to the pipe */
77	dup2(pager_process.in, 1);
78	if (isatty(2))
79		dup2(pager_process.in, 2);
80	close(pager_process.in);
81
82	/* this makes sure that the parent terminates after the pager */
83	sigchain_push_common(wait_for_pager_signal);
84	atexit(wait_for_pager);
85}
86
87int pager_in_use(void)
88{
89	const char *env;
90
91	if (spawned_pager)
92		return 1;
93
94	env = getenv("PERF_PAGER_IN_USE");
95	return env ? perf_config_bool("PERF_PAGER_IN_USE", env) : 0;
96}
97