git/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 = pager_program;
  49         if (!pager)
  50                 pager = getenv("PAGER");
  51         if (!pager)
  52                 pager = "less";
  53         else if (!*pager || !strcmp(pager, "cat"))
  54                 return;
  55
  56         pager_in_use = 1; /* means we are emitting to terminal */
  57
  58         if (pipe(fd) < 0)
  59                 return;
  60 #ifndef __MINGW32__
  61         pid = fork();
  62         if (pid < 0) {
  63                 close(fd[0]);
  64                 close(fd[1]);
  65                 return;
  66         }
  67
  68         /* return in the child */
  69         if (!pid) {
  70                 dup2(fd[1], 1);
  71                 close(fd[0]);
  72                 close(fd[1]);
  73                 return;
  74         }
  75
  76         /* The original process turns into the PAGER */
  77         dup2(fd[0], 0);
  78         close(fd[0]);
  79         close(fd[1]);
  80
  81         setenv("LESS", "FRSX", 0);
  82         run_pager(pager);
  83         die("unable to execute pager '%s'", pager);
  84         exit(255);
  85 #else
  86         /* spawn the pager */
  87         pager_argv[2] = pager;
  88         pager_pid = spawnvpe_pipe(pager_argv[0], pager_argv, environ, fd, NULL);
  89         if (pager_pid < 0)
  90                 return;
  91
  92         /* original process continues, but writes to the pipe */
  93         dup2(fd[1], 1);
  94         close(fd[1]);
  95
  96         /* this makes sure that the parent terminates after the pager */
  97         atexit(collect_pager);
  98 #endif
  99 }