1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #include <sys/select.h>
3*4882a593Smuzhiyun #include <stdlib.h>
4*4882a593Smuzhiyun #include <stdio.h>
5*4882a593Smuzhiyun #include <string.h>
6*4882a593Smuzhiyun #include <signal.h>
7*4882a593Smuzhiyun #include <sys/ioctl.h>
8*4882a593Smuzhiyun #include "pager.h"
9*4882a593Smuzhiyun #include "run-command.h"
10*4882a593Smuzhiyun #include "sigchain.h"
11*4882a593Smuzhiyun #include "subcmd-config.h"
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun /*
14*4882a593Smuzhiyun * This is split up from the rest of git so that we can do
15*4882a593Smuzhiyun * something different on Windows.
16*4882a593Smuzhiyun */
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun static int spawned_pager;
19*4882a593Smuzhiyun static int pager_columns;
20*4882a593Smuzhiyun
pager_init(const char * pager_env)21*4882a593Smuzhiyun void pager_init(const char *pager_env)
22*4882a593Smuzhiyun {
23*4882a593Smuzhiyun subcmd_config.pager_env = pager_env;
24*4882a593Smuzhiyun }
25*4882a593Smuzhiyun
26*4882a593Smuzhiyun static const char *forced_pager;
27*4882a593Smuzhiyun
force_pager(const char * pager)28*4882a593Smuzhiyun void force_pager(const char *pager)
29*4882a593Smuzhiyun {
30*4882a593Smuzhiyun forced_pager = pager;
31*4882a593Smuzhiyun }
32*4882a593Smuzhiyun
pager_preexec(void)33*4882a593Smuzhiyun static void pager_preexec(void)
34*4882a593Smuzhiyun {
35*4882a593Smuzhiyun /*
36*4882a593Smuzhiyun * Work around bug in "less" by not starting it until we
37*4882a593Smuzhiyun * have real input
38*4882a593Smuzhiyun */
39*4882a593Smuzhiyun fd_set in;
40*4882a593Smuzhiyun fd_set exception;
41*4882a593Smuzhiyun
42*4882a593Smuzhiyun FD_ZERO(&in);
43*4882a593Smuzhiyun FD_ZERO(&exception);
44*4882a593Smuzhiyun FD_SET(0, &in);
45*4882a593Smuzhiyun FD_SET(0, &exception);
46*4882a593Smuzhiyun select(1, &in, NULL, &exception, NULL);
47*4882a593Smuzhiyun
48*4882a593Smuzhiyun setenv("LESS", "FRSX", 0);
49*4882a593Smuzhiyun }
50*4882a593Smuzhiyun
51*4882a593Smuzhiyun static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
52*4882a593Smuzhiyun static struct child_process pager_process;
53*4882a593Smuzhiyun
wait_for_pager(void)54*4882a593Smuzhiyun static void wait_for_pager(void)
55*4882a593Smuzhiyun {
56*4882a593Smuzhiyun fflush(stdout);
57*4882a593Smuzhiyun fflush(stderr);
58*4882a593Smuzhiyun /* signal EOF to pager */
59*4882a593Smuzhiyun close(1);
60*4882a593Smuzhiyun close(2);
61*4882a593Smuzhiyun finish_command(&pager_process);
62*4882a593Smuzhiyun }
63*4882a593Smuzhiyun
wait_for_pager_signal(int signo)64*4882a593Smuzhiyun static void wait_for_pager_signal(int signo)
65*4882a593Smuzhiyun {
66*4882a593Smuzhiyun wait_for_pager();
67*4882a593Smuzhiyun sigchain_pop(signo);
68*4882a593Smuzhiyun raise(signo);
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
setup_pager(void)71*4882a593Smuzhiyun void setup_pager(void)
72*4882a593Smuzhiyun {
73*4882a593Smuzhiyun const char *pager = getenv(subcmd_config.pager_env);
74*4882a593Smuzhiyun struct winsize sz;
75*4882a593Smuzhiyun
76*4882a593Smuzhiyun if (forced_pager)
77*4882a593Smuzhiyun pager = forced_pager;
78*4882a593Smuzhiyun if (!isatty(1) && !forced_pager)
79*4882a593Smuzhiyun return;
80*4882a593Smuzhiyun if (ioctl(1, TIOCGWINSZ, &sz) == 0)
81*4882a593Smuzhiyun pager_columns = sz.ws_col;
82*4882a593Smuzhiyun if (!pager)
83*4882a593Smuzhiyun pager = getenv("PAGER");
84*4882a593Smuzhiyun if (!(pager || access("/usr/bin/pager", X_OK)))
85*4882a593Smuzhiyun pager = "/usr/bin/pager";
86*4882a593Smuzhiyun if (!(pager || access("/usr/bin/less", X_OK)))
87*4882a593Smuzhiyun pager = "/usr/bin/less";
88*4882a593Smuzhiyun if (!pager)
89*4882a593Smuzhiyun pager = "cat";
90*4882a593Smuzhiyun if (!*pager || !strcmp(pager, "cat"))
91*4882a593Smuzhiyun return;
92*4882a593Smuzhiyun
93*4882a593Smuzhiyun spawned_pager = 1; /* means we are emitting to terminal */
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun /* spawn the pager */
96*4882a593Smuzhiyun pager_argv[2] = pager;
97*4882a593Smuzhiyun pager_process.argv = pager_argv;
98*4882a593Smuzhiyun pager_process.in = -1;
99*4882a593Smuzhiyun pager_process.preexec_cb = pager_preexec;
100*4882a593Smuzhiyun
101*4882a593Smuzhiyun if (start_command(&pager_process))
102*4882a593Smuzhiyun return;
103*4882a593Smuzhiyun
104*4882a593Smuzhiyun /* original process continues, but writes to the pipe */
105*4882a593Smuzhiyun dup2(pager_process.in, 1);
106*4882a593Smuzhiyun if (isatty(2))
107*4882a593Smuzhiyun dup2(pager_process.in, 2);
108*4882a593Smuzhiyun close(pager_process.in);
109*4882a593Smuzhiyun
110*4882a593Smuzhiyun /* this makes sure that the parent terminates after the pager */
111*4882a593Smuzhiyun sigchain_push_common(wait_for_pager_signal);
112*4882a593Smuzhiyun atexit(wait_for_pager);
113*4882a593Smuzhiyun }
114*4882a593Smuzhiyun
pager_in_use(void)115*4882a593Smuzhiyun int pager_in_use(void)
116*4882a593Smuzhiyun {
117*4882a593Smuzhiyun return spawned_pager;
118*4882a593Smuzhiyun }
119*4882a593Smuzhiyun
pager_get_columns(void)120*4882a593Smuzhiyun int pager_get_columns(void)
121*4882a593Smuzhiyun {
122*4882a593Smuzhiyun char *s;
123*4882a593Smuzhiyun
124*4882a593Smuzhiyun s = getenv("COLUMNS");
125*4882a593Smuzhiyun if (s)
126*4882a593Smuzhiyun return atoi(s);
127*4882a593Smuzhiyun
128*4882a593Smuzhiyun return (pager_columns ? pager_columns : 80) - 2;
129*4882a593Smuzhiyun }
130