Update COPYING with GPLv2 with new FSF address
[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 static int spawned_pager;
15
16 #ifndef WIN32
17 static void pager_preexec(void)
18 {
19         /*
20          * Work around bug in "less" by not starting it until we
21          * have real input
22          */
23         fd_set in;
24
25         FD_ZERO(&in);
26         FD_SET(0, &in);
27         select(1, &in, NULL, &in, NULL);
28 }
29 #endif
30
31 static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
32 static struct child_process pager_process;
33
34 static void wait_for_pager(void)
35 {
36         fflush(stdout);
37         fflush(stderr);
38         /* signal EOF to pager */
39         close(1);
40         close(2);
41         finish_command(&pager_process);
42 }
43
44 static void wait_for_pager_signal(int signo)
45 {
46         wait_for_pager();
47         sigchain_pop(signo);
48         raise(signo);
49 }
50
51 const char *git_pager(void)
52 {
53         const char *pager;
54
55         if (!isatty(1))
56                 return NULL;
57
58         pager = getenv("GIT_PAGER");
59         if (!pager) {
60                 if (!pager_program)
61                         git_config(git_default_config, NULL);
62                 pager = pager_program;
63         }
64         if (!pager)
65                 pager = getenv("PAGER");
66         if (!pager)
67                 pager = DEFAULT_PAGER;
68         else if (!*pager || !strcmp(pager, "cat"))
69                 pager = NULL;
70
71         return pager;
72 }
73
74 void setup_pager(void)
75 {
76         const char *pager = git_pager();
77
78         if (!pager)
79                 return;
80
81         spawned_pager = 1; /* means we are emitting to terminal */
82
83         /* spawn the pager */
84         pager_argv[2] = pager;
85         pager_process.argv = pager_argv;
86         pager_process.in = -1;
87         if (!getenv("LESS")) {
88                 static const char *env[] = { "LESS=FRSX", NULL };
89                 pager_process.env = env;
90         }
91 #ifndef WIN32
92         pager_process.preexec_cb = pager_preexec;
93 #endif
94         if (start_command(&pager_process))
95                 return;
96
97         /* original process continues, but writes to the pipe */
98         dup2(pager_process.in, 1);
99         if (isatty(2))
100                 dup2(pager_process.in, 2);
101         close(pager_process.in);
102
103         /* this makes sure that the parent terminates after the pager */
104         sigchain_push_common(wait_for_pager_signal);
105         atexit(wait_for_pager);
106 }
107
108 int pager_in_use(void)
109 {
110         const char *env;
111
112         if (spawned_pager)
113                 return 1;
114
115         env = getenv("GIT_PAGER_IN_USE");
116         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
117 }