pager.c

   1 #include "cache.h"
   2 #include "spawn-pipe.h"
   3
   4 #include <sys/select.h>
   5
   6 /*
   7  * This is split up from the rest of git so that we might do
   8  * something different on Windows, for example.
   9  */
  10
  11 #ifndef __MINGW32__
  12 static void run_pager(const char *pager)
  13 {
  14         /*
  15          * Work around bug in "less" by not starting it until we
  16          * have real input
  17          */
  18         fd_set in;
  19
  20         FD_ZERO(&in);
  21         FD_SET(0, &in);
  22         select(1, &in, NULL, &in, NULL);
  23
  24         execlp(pager, pager, NULL);
  25         execl("/bin/sh", "sh", "-c", pager, NULL);
  26 }
  27 #else
  28 static pid_t pager_pid;
  29 static void collect_pager(void)
  30 {
  31         close(1);       /* signals EOF to pager */
  32         cwait(NULL, pager_pid, 0);
  33 }
  34 #endif
  35
  36 void setup_pager(void)
  37 {
  38 #ifndef __MINGW32__
  39         pid_t pid;
  40 #else
  41         const char *pager_argv[] = { "sh", "-c", NULL, NULL };
  42 #endif
  43         int fd[2];
  44         const char *pager = getenv("GIT_PAGER");
  45
  46         if (!isatty(1))
  47                 return;
  48         if (!pager)
  49                 pager = getenv("PAGER");
  50         if (!pager)
  51                 pager = "less";
  52         else if (!*pager || !strcmp(pager, "cat"))
  53                 return;
  54
  55         pager_in_use = 1; /* means we are emitting to terminal */
  56
  57         if (pipe(fd) < 0)
  58                 return;
  59 #ifndef __MINGW32__
  60         pid = fork();
  61         if (pid < 0) {
  62                 close(fd[0]);
  63                 close(fd[1]);
  64                 return;
  65         }
  66
  67         /* return in the child */
  68         if (!pid) {
  69                 dup2(fd[1], 1);
  70                 close(fd[0]);
  71                 close(fd[1]);
  72                 return;
  73         }
  74
  75         /* The original process turns into the PAGER */
  76         dup2(fd[0], 0);
  77         close(fd[0]);
  78         close(fd[1]);
  79
  80         setenv("LESS", "FRSX", 0);
  81         run_pager(pager);
  82         die("unable to execute pager '%s'", pager);
  83         exit(255);
  84 #else
  85         /* spawn the pager */
  86         pager_argv[2] = pager;
  87         pager_pid = spawnvpe_pipe(pager_argv[0], pager_argv, environ, fd, NULL);
  88         if (pager_pid < 0)
  89                 return;
  90
  91         /* original process continues, but writes to the pipe */
  92         dup2(fd[1], 1);
  93         close(fd[1]);
  94
  95         /* this makes sure that the parent terminates after the pager */
  96         atexit(collect_pager);
  97 #endif
  98 }