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         /*
  13          * Work around bug in "less" by not starting it until we
  14          * have real input
  15          */
  16         fd_set in;
  17
  18         FD_ZERO(&in);
  19         FD_SET(0, &in);
  20         select(1, &in, NULL, &in, NULL);
  21
  22         execlp(pager, pager, NULL);
  23         execl("/bin/sh", "sh", "-c", pager, NULL);
  24 }
  25 #else
  26 static pid_t pager_pid;
  27 static void collect_pager(void)
  28 {
  29         fflush(stdout);
  30         close(1);       /* signals EOF to pager */
  31         cwait(NULL, pager_pid, 0);
  32 }
  33 #endif
  34
  35 void setup_pager(void)
  36 {
  37 #ifndef __MINGW32__
  38         pid_t pid;
  39 #else
  40         const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  41 #endif
  42         int fd[2];
  43         const char *pager = getenv("GIT_PAGER");
  44
  45         if (!isatty(1))
  46                 return;
  47         if (!pager)
  48                 pager = getenv("PAGER");
  49         if (!pager)
  50                 pager = "less";
  51         else if (!*pager || !strcmp(pager, "cat"))
  52                 return;
  53
  54         pager_in_use = 1; /* means we are emitting to terminal */
  55
  56         if (pipe(fd) < 0)
  57                 return;
  58 #ifndef __MINGW32__
  59         pid = fork();
  60         if (pid < 0) {
  61                 close(fd[0]);
  62                 close(fd[1]);
  63                 return;
  64         }
  65
  66         /* return in the child */
  67         if (!pid) {
  68                 dup2(fd[1], 1);
  69                 close(fd[0]);
  70                 close(fd[1]);
  71                 return;
  72         }
  73
  74         /* The original process turns into the PAGER */
  75         dup2(fd[0], 0);
  76         close(fd[0]);
  77         close(fd[1]);
  78
  79         setenv("LESS", "FRSX", 0);
  80         run_pager(pager);
  81         die("unable to execute pager '%s'", pager);
  82         exit(255);
  83 #else
  84         /* spawn the pager */
  85         pager_argv[2] = pager;
  86         pager_pid = spawnvpe_pipe(pager_argv[0], pager_argv, environ, fd, NULL);
  87         if (pager_pid < 0)
  88                 return;
  89
  90         /* original process continues, but writes to the pipe */
  91         dup2(fd[1], 1);
  92         close(fd[1]);
  93
  94         /* this makes sure that the parent terminates after the pager */
  95         atexit(collect_pager);
  96 #endif
  97 }