pager.c

   1 #include "cache.h"
   2
   3 /*
   4  * This is split up from the rest of git so that we can do
   5  * something different on Windows.
   6  */
   7
   8 static int spawned_pager;
   9
  10 #ifndef __MINGW32__
  11 static void run_pager(const char *pager)
  12 {
  13         /*
  14          * Work around bug in "less" by not starting it until we
  15          * have real input
  16          */
  17         fd_set in;
  18
  19         FD_ZERO(&in);
  20         FD_SET(0, &in);
  21         select(1, &in, NULL, &in, NULL);
  22
  23         execlp(pager, pager, NULL);
  24         execl("/bin/sh", "sh", "-c", pager, NULL);
  25 }
  26 #else
  27 #include "run-command.h"
  28
  29 static const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  30 static struct child_process pager_process = {
  31         .argv = pager_argv,
  32         .in = -1
  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 #endif
  44
  45 void setup_pager(void)
  46 {
  47 #ifndef __MINGW32__
  48         pid_t pid;
  49         int fd[2];
  50 #endif
  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);
  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 #ifndef __MINGW32__
  70         if (pipe(fd) < 0)
  71                 return;
  72         pid = fork();
  73         if (pid < 0) {
  74                 close(fd[0]);
  75                 close(fd[1]);
  76                 return;
  77         }
  78
  79         /* return in the child */
  80         if (!pid) {
  81                 dup2(fd[1], 1);
  82                 dup2(fd[1], 2);
  83                 close(fd[0]);
  84                 close(fd[1]);
  85                 return;
  86         }
  87
  88         /* The original process turns into the PAGER */
  89         dup2(fd[0], 0);
  90         close(fd[0]);
  91         close(fd[1]);
  92
  93         setenv("LESS", "FRSX", 0);
  94         run_pager(pager);
  95         die("unable to execute pager '%s'", pager);
  96         exit(255);
  97 #else
  98         /* spawn the pager */
  99         pager_argv[2] = pager;
 100         if (start_command(&pager_process))
 101                 return;
 102
 103         /* original process continues, but writes to the pipe */
 104         dup2(pager_process.in, 1);
 105         dup2(pager_process.in, 2);
 106         close(pager_process.in);
 107
 108         /* this makes sure that the parent terminates after the pager */
 109         atexit(wait_for_pager);
 110 #endif
 111 }
 112
 113 int pager_in_use(void)
 114 {
 115         const char *env;
 116
 117         if (spawned_pager)
 118                 return 1;
 119
 120         env = getenv("GIT_PAGER_IN_USE");
 121         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 122 }