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[] = { 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(int stdout_is_tty)
  52 {
  53         const char *pager;
  54
  55         if (!stdout_is_tty)
  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(isatty(1));
  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[0] = pager;
  85         pager_process.use_shell = 1;
  86         pager_process.argv = pager_argv;
  87         pager_process.in = -1;
  88         if (!getenv("LESS")) {
  89                 static const char *env[] = { "LESS=FRSX", NULL };
  90                 pager_process.env = env;
  91         }
  92 #ifndef WIN32
  93         pager_process.preexec_cb = pager_preexec;
  94 #endif
  95         if (start_command(&pager_process))
  96                 return;
  97
  98         /* original process continues, but writes to the pipe */
  99         dup2(pager_process.in, 1);
 100         if (isatty(2))
 101                 dup2(pager_process.in, 2);
 102         close(pager_process.in);
 103
 104         /* this makes sure that the parent terminates after the pager */
 105         sigchain_push_common(wait_for_pager_signal);
 106         atexit(wait_for_pager);
 107 }
 108
 109 int pager_in_use(void)
 110 {
 111         const char *env;
 112
 113         if (spawned_pager)
 114                 return 1;
 115
 116         env = getenv("GIT_PAGER_IN_USE");
 117         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 118 }