Merge branch 'ci/forbid-unwanted-current-branch-update'
[git] / pager.c
1 #include "cache.h"
2 #include "run-command.h"
3 #include "sigchain.h"
4
5 #ifndef DEFAULT_PAGER
6 #define DEFAULT_PAGER "less"
7 #endif
8
9 /*
10  * This is split up from the rest of git so that we can do
11  * something different on Windows.
12  */
13
14 #ifndef WIN32
15 static void pager_preexec(void)
16 {
17         /*
18          * Work around bug in "less" by not starting it until we
19          * have real input
20          */
21         fd_set in;
22
23         FD_ZERO(&in);
24         FD_SET(0, &in);
25         select(1, &in, NULL, &in, NULL);
26 }
27 #endif
28
29 static const char *pager_argv[] = { NULL, NULL };
30 static struct child_process pager_process;
31
32 static void wait_for_pager(void)
33 {
34         fflush(stdout);
35         fflush(stderr);
36         /* signal EOF to pager */
37         close(1);
38         close(2);
39         finish_command(&pager_process);
40 }
41
42 static void wait_for_pager_signal(int signo)
43 {
44         wait_for_pager();
45         sigchain_pop(signo);
46         raise(signo);
47 }
48
49 const char *git_pager(int stdout_is_tty)
50 {
51         const char *pager;
52
53         if (!stdout_is_tty)
54                 return NULL;
55
56         pager = getenv("GIT_PAGER");
57         if (!pager) {
58                 if (!pager_program)
59                         git_config(git_default_config, NULL);
60                 pager = pager_program;
61         }
62         if (!pager)
63                 pager = getenv("PAGER");
64         if (!pager)
65                 pager = DEFAULT_PAGER;
66         else if (!*pager || !strcmp(pager, "cat"))
67                 pager = NULL;
68
69         return pager;
70 }
71
72 void setup_pager(void)
73 {
74         const char *pager = git_pager(isatty(1));
75
76         if (!pager)
77                 return;
78
79         setenv("GIT_PAGER_IN_USE", "true", 1);
80
81         /* spawn the pager */
82         pager_argv[0] = pager;
83         pager_process.use_shell = 1;
84         pager_process.argv = pager_argv;
85         pager_process.in = -1;
86         if (!getenv("LESS")) {
87                 static const char *env[] = { "LESS=FRSX", NULL };
88                 pager_process.env = env;
89         }
90 #ifndef WIN32
91         pager_process.preexec_cb = pager_preexec;
92 #endif
93         if (start_command(&pager_process))
94                 return;
95
96         /* original process continues, but writes to the pipe */
97         dup2(pager_process.in, 1);
98         if (isatty(2))
99                 dup2(pager_process.in, 2);
100         close(pager_process.in);
101
102         /* this makes sure that the parent terminates after the pager */
103         sigchain_push_common(wait_for_pager_signal);
104         atexit(wait_for_pager);
105 }
106
107 int pager_in_use(void)
108 {
109         const char *env;
110         env = getenv("GIT_PAGER_IN_USE");
111         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
112 }