pager.c

   1 #include "cache.h"
   2 #include "spawn-pipe.h"
   3
   4 /*
   5  * This is split up from the rest of git so that we might do
   6  * something different on Windows, for example.
   7  */
   8
   9 #ifndef __MINGW32__
  10 static void run_pager(const char *pager)
  11 {
  12         execlp(pager, pager, NULL);
  13         execl("/bin/sh", "sh", "-c", pager, NULL);
  14 }
  15 #else
  16 static pid_t pager_pid;
  17 static void collect_pager(void)
  18 {
  19         close(1);       /* signals EOF to pager */
  20         cwait(NULL, pager_pid, 0);
  21 }
  22 #endif
  23
  24 void setup_pager(void)
  25 {
  26 #ifndef __MINGW32__
  27         pid_t pid;
  28 #else
  29         const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  30 #endif
  31         int fd[2];
  32         const char *pager = getenv("GIT_PAGER");
  33
  34         if (!isatty(1))
  35                 return;
  36         if (!pager)
  37                 pager = getenv("PAGER");
  38         if (!pager)
  39                 pager = "less";
  40         else if (!*pager || !strcmp(pager, "cat"))
  41                 return;
  42
  43         pager_in_use = 1; /* means we are emitting to terminal */
  44
  45         if (pipe(fd) < 0)
  46                 return;
  47 #ifndef __MINGW32__
  48         pid = fork();
  49         if (pid < 0) {
  50                 close(fd[0]);
  51                 close(fd[1]);
  52                 return;
  53         }
  54
  55         /* return in the child */
  56         if (!pid) {
  57                 dup2(fd[1], 1);
  58                 close(fd[0]);
  59                 close(fd[1]);
  60                 return;
  61         }
  62
  63         /* The original process turns into the PAGER */
  64         dup2(fd[0], 0);
  65         close(fd[0]);
  66         close(fd[1]);
  67
  68         setenv("LESS", "FRSX", 0);
  69         run_pager(pager);
  70         die("unable to execute pager '%s'", pager);
  71         exit(255);
  72 #else
  73         /* spawn the pager */
  74         pager_argv[2] = pager;
  75         pager_pid = spawnvpe_pipe(pager_argv[0], pager_argv, environ, fd, NULL);
  76         if (pager_pid < 0)
  77                 return;
  78
  79         /* original process continues, but writes to the pipe */
  80         dup2(fd[1], 1);
  81         close(fd[1]);
  82
  83         /* this makes sure that the parent terminates after the pager */
  84         atexit(collect_pager);
  85 #endif
  86 }