pager.c

   1 #include "cache.h"
   2
   3 /*
   4  * This is split up from the rest of git so that we might do
   5  * something different on Windows, for example.
   6  */
   7
   8 #ifndef __MINGW32__
   9 static void run_pager(const char *pager)
  10 {
  11         /*
  12          * Work around bug in "less" by not starting it until we
  13          * have real input
  14          */
  15         fd_set in;
  16
  17         FD_ZERO(&in);
  18         FD_SET(0, &in);
  19         select(1, &in, NULL, &in, NULL);
  20
  21         execlp(pager, pager, NULL);
  22         execl("/bin/sh", "sh", "-c", pager, NULL);
  23 }
  24 #else
  25 #include "run-command.h"
  26
  27 const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  28 static struct child_process pager_process = {
  29         .argv = pager_argv,
  30         .in = -1
  31 };
  32 static void collect_pager(void)
  33 {
  34         fflush(stdout);
  35         close(1);       /* signals EOF to pager */
  36         finish_command(&pager_process);
  37 }
  38 #endif
  39
  40 void setup_pager(void)
  41 {
  42 #ifndef __MINGW32__
  43         pid_t pid;
  44         int fd[2];
  45 #endif
  46         const char *pager = getenv("GIT_PAGER");
  47
  48         if (!isatty(1))
  49                 return;
  50         if (!pager) {
  51                 if (!pager_program)
  52                         git_config(git_default_config);
  53                 pager = pager_program;
  54         }
  55         if (!pager)
  56                 pager = getenv("PAGER");
  57         if (!pager)
  58                 pager = "less";
  59         else if (!*pager || !strcmp(pager, "cat"))
  60                 return;
  61
  62         pager_in_use = 1; /* means we are emitting to terminal */
  63
  64 #ifndef __MINGW32__
  65         if (pipe(fd) < 0)
  66                 return;
  67         pid = fork();
  68         if (pid < 0) {
  69                 close(fd[0]);
  70                 close(fd[1]);
  71                 return;
  72         }
  73
  74         /* return in the child */
  75         if (!pid) {
  76                 dup2(fd[1], 1);
  77                 close(fd[0]);
  78                 close(fd[1]);
  79                 return;
  80         }
  81
  82         /* The original process turns into the PAGER */
  83         dup2(fd[0], 0);
  84         close(fd[0]);
  85         close(fd[1]);
  86
  87         setenv("LESS", "FRSX", 0);
  88         run_pager(pager);
  89         die("unable to execute pager '%s'", pager);
  90         exit(255);
  91 #else
  92         /* spawn the pager */
  93         pager_argv[2] = pager;
  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         close(pager_process.in);
 100
 101         /* this makes sure that the parent terminates after the pager */
 102         atexit(collect_pager);
 103 #endif
 104 }