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 WIN32
  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 #endif
  26
  27 static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  28 static struct child_process pager_process;
  29
  30 static void wait_for_pager(void)
  31 {
  32         fflush(stdout);
  33         fflush(stderr);
  34         /* signal EOF to pager */
  35         close(1);
  36         close(2);
  37         finish_command(&pager_process);
  38 }
  39
  40 static void wait_for_pager_signal(int signo)
  41 {
  42         wait_for_pager();
  43         sigchain_pop(signo);
  44         raise(signo);
  45 }
  46
  47 const char *git_pager(void)
  48 {
  49         const char *pager;
  50
  51         if (!isatty(1))
  52                 return NULL;
  53
  54         pager = getenv("GIT_PAGER");
  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                 pager = NULL;
  66
  67         return pager;
  68 }
  69
  70 void setup_pager(void)
  71 {
  72         const char *pager = git_pager();
  73
  74         if (!pager)
  75                 return;
  76
  77         spawned_pager = 1; /* means we are emitting to terminal */
  78
  79         /* spawn the pager */
  80         pager_argv[2] = pager;
  81         pager_process.argv = pager_argv;
  82         pager_process.in = -1;
  83         if (!getenv("LESS")) {
  84                 static const char *env[] = { "LESS=FRSX", NULL };
  85                 pager_process.env = env;
  86         }
  87 #ifndef WIN32
  88         pager_process.preexec_cb = pager_preexec;
  89 #endif
  90         if (start_command(&pager_process))
  91                 return;
  92
  93         /* original process continues, but writes to the pipe */
  94         dup2(pager_process.in, 1);
  95         if (isatty(2))
  96                 dup2(pager_process.in, 2);
  97         close(pager_process.in);
  98
  99         /* this makes sure that the parent terminates after the pager */
 100         sigchain_push_common(wait_for_pager_signal);
 101         atexit(wait_for_pager);
 102 }
 103
 104 int pager_in_use(void)
 105 {
 106         const char *env;
 107
 108         if (spawned_pager)
 109                 return 1;
 110
 111         env = getenv("GIT_PAGER_IN_USE");
 112         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 113 }