pager.c

   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
  10 static int spawned_pager;
  11
  12 #ifndef __MINGW32__
  13 static void pager_preexec(void)
  14 {
  15         /*
  16          * Work around bug in "less" by not starting it until we
  17          * have real input
  18          */
  19         fd_set in;
  20
  21         FD_ZERO(&in);
  22         FD_SET(0, &in);
  23         select(1, &in, NULL, &in, NULL);
  24
  25         setenv("LESS", "FRSX", 0);
  26 }
  27 #endif
  28
  29 static const char *pager_argv[] = { "sh", "-c", 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 void setup_pager(void)
  50 {
  51         const char *pager = getenv("GIT_PAGER");
  52
  53         if (!isatty(1))
  54                 return;
  55         if (!pager) {
  56                 if (!pager_program)
  57                         git_config(git_default_config, NULL);
  58                 pager = pager_program;
  59         }
  60         if (!pager)
  61                 pager = getenv("PAGER");
  62         if (!pager)
  63                 pager = "less";
  64         else if (!*pager || !strcmp(pager, "cat"))
  65                 return;
  66
  67         spawned_pager = 1; /* means we are emitting to terminal */
  68
  69         /* spawn the pager */
  70         pager_argv[2] = pager;
  71         pager_process.argv = pager_argv;
  72         pager_process.in = -1;
  73 #ifndef __MINGW32__
  74         pager_process.preexec_cb = pager_preexec;
  75 #endif
  76         if (start_command(&pager_process))
  77                 return;
  78
  79         /* original process continues, but writes to the pipe */
  80         dup2(pager_process.in, 1);
  81         if (isatty(2))
  82                 dup2(pager_process.in, 2);
  83         close(pager_process.in);
  84
  85         /* this makes sure that the parent terminates after the pager */
  86         sigchain_push_common(wait_for_pager_signal);
  87         atexit(wait_for_pager);
  88 }
  89
  90 int pager_in_use(void)
  91 {
  92         const char *env;
  93
  94         if (spawned_pager)
  95                 return 1;
  96
  97         env = getenv("GIT_PAGER_IN_USE");
  98         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
  99 }