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                 if (!pager_program)
  49                         git_config(git_default_config);
  50                 pager = pager_program;
  51         }
  52         if (!pager)
  53                 pager = getenv("PAGER");
  54         if (!pager)
  55                 pager = "less";
  56         else if (!*pager || !strcmp(pager, "cat"))
  57                 return;
  58
  59         pager_in_use = 1; /* means we are emitting to terminal */
  60
  61         if (pipe(fd) < 0)
  62                 return;
  63 #ifndef __MINGW32__
  64         pid = fork();
  65         if (pid < 0) {
  66                 close(fd[0]);
  67                 close(fd[1]);
  68                 return;
  69         }
  70
  71         /* return in the child */
  72         if (!pid) {
  73                 dup2(fd[1], 1);
  74                 close(fd[0]);
  75                 close(fd[1]);
  76                 return;
  77         }
  78
  79         /* The original process turns into the PAGER */
  80         dup2(fd[0], 0);
  81         close(fd[0]);
  82         close(fd[1]);
  83
  84         setenv("LESS", "FRSX", 0);
  85         run_pager(pager);
  86         die("unable to execute pager '%s'", pager);
  87         exit(255);
  88 #else
  89         /* spawn the pager */
  90         pager_argv[2] = pager;
  91         pager_pid = spawnvpe_pipe(pager_argv[0], pager_argv, (const char**) environ, fd, NULL);
  92         if (pager_pid < 0)
  93                 return;
  94
  95         /* original process continues, but writes to the pipe */
  96         dup2(fd[1], 1);
  97         close(fd[1]);
  98
  99         /* this makes sure that the parent terminates after the pager */
 100         atexit(collect_pager);
 101 #endif
 102 }