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         close(1);       /* signals EOF to pager */
  30         cwait(NULL, pager_pid, 0);
  31 }
  32 #endif
  33
  34 void setup_pager(void)
  35 {
  36 #ifndef __MINGW32__
  37         pid_t pid;
  38 #else
  39         const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  40 #endif
  41         int fd[2];
  42         const char *pager = getenv("GIT_PAGER");
  43
  44         if (!isatty(1))
  45                 return;
  46         if (!pager)
  47                 pager = getenv("PAGER");
  48         if (!pager)
  49                 pager = "less";
  50         else if (!*pager || !strcmp(pager, "cat"))
  51                 return;
  52
  53         pager_in_use = 1; /* means we are emitting to terminal */
  54
  55         if (pipe(fd) < 0)
  56                 return;
  57 #ifndef __MINGW32__
  58         pid = fork();
  59         if (pid < 0) {
  60                 close(fd[0]);
  61                 close(fd[1]);
  62                 return;
  63         }
  64
  65         /* return in the child */
  66         if (!pid) {
  67                 dup2(fd[1], 1);
  68                 close(fd[0]);
  69                 close(fd[1]);
  70                 return;
  71         }
  72
  73         /* The original process turns into the PAGER */
  74         dup2(fd[0], 0);
  75         close(fd[0]);
  76         close(fd[1]);
  77
  78         setenv("LESS", "FRSX", 0);
  79         run_pager(pager);
  80         die("unable to execute pager '%s'", pager);
  81         exit(255);
  82 #else
  83         /* spawn the pager */
  84         pager_argv[2] = pager;
  85         pager_pid = spawnvpe_pipe(pager_argv[0], pager_argv, environ, fd, NULL);
  86         if (pager_pid < 0)
  87                 return;
  88
  89         /* original process continues, but writes to the pipe */
  90         dup2(fd[1], 1);
  91         close(fd[1]);
  92
  93         /* this makes sure that the parent terminates after the pager */
  94         atexit(collect_pager);
  95 #endif
  96 }