pager.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "sigchain.h"
   4
   5 #ifndef DEFAULT_PAGER
   6 #define DEFAULT_PAGER "less"
   7 #endif
   8
   9 /*
  10  * This is split up from the rest of git so that we can do
  11  * something different on Windows.
  12  */
  13
  14 #ifndef WIN32
  15 static void pager_preexec(void)
  16 {
  17         /*
  18          * Work around bug in "less" by not starting it until we
  19          * have real input
  20          */
  21         fd_set in;
  22
  23         FD_ZERO(&in);
  24         FD_SET(0, &in);
  25         select(1, &in, NULL, &in, NULL);
  26 }
  27 #endif
  28
  29 static const char *pager_argv[] = { NULL, NULL };
  30 static struct child_process pager_process;
  31
  32 static void wait_for_pager(void)
  33 {
  34         fflush(stdout);
  35         fflush(stderr);
  36         /* signal EOF to pager */
  37         close(1);
  38         close(2);
  39         finish_command(&pager_process);
  40 }
  41
  42 static void wait_for_pager_signal(int signo)
  43 {
  44         wait_for_pager();
  45         sigchain_pop(signo);
  46         raise(signo);
  47 }
  48
  49 const char *git_pager(int stdout_is_tty)
  50 {
  51         const char *pager;
  52
  53         if (!stdout_is_tty)
  54                 return NULL;
  55
  56         pager = getenv("GIT_PAGER");
  57         if (!pager) {
  58                 if (!pager_program)
  59                         git_config(git_default_config, NULL);
  60                 pager = pager_program;
  61         }
  62         if (!pager)
  63                 pager = getenv("PAGER");
  64         if (!pager)
  65                 pager = DEFAULT_PAGER;
  66         else if (!*pager || !strcmp(pager, "cat"))
  67                 pager = NULL;
  68
  69         return pager;
  70 }
  71
  72 void setup_pager(void)
  73 {
  74         const char *pager = git_pager(isatty(1));
  75
  76         if (!pager)
  77                 return;
  78
  79         /*
  80          * force computing the width of the terminal before we redirect
  81          * the standard output to the pager.
  82          */
  83         (void) term_columns();
  84
  85         setenv("GIT_PAGER_IN_USE", "true", 1);
  86
  87         /* spawn the pager */
  88         pager_argv[0] = pager;
  89         pager_process.use_shell = 1;
  90         pager_process.argv = pager_argv;
  91         pager_process.in = -1;
  92         if (!getenv("LESS")) {
  93                 static const char *env[] = { "LESS=FRSX", NULL };
  94                 pager_process.env = env;
  95         }
  96 #ifndef WIN32
  97         pager_process.preexec_cb = pager_preexec;
  98 #endif
  99         if (start_command(&pager_process))
 100                 return;
 101
 102         /* original process continues, but writes to the pipe */
 103         dup2(pager_process.in, 1);
 104         if (isatty(2))
 105                 dup2(pager_process.in, 2);
 106         close(pager_process.in);
 107
 108         /* this makes sure that the parent terminates after the pager */
 109         sigchain_push_common(wait_for_pager_signal);
 110         atexit(wait_for_pager);
 111 }
 112
 113 int pager_in_use(void)
 114 {
 115         const char *env;
 116         env = getenv("GIT_PAGER_IN_USE");
 117         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 118 }
 119
 120 /*
 121  * Return cached value (if set) or $COLUMNS environment variable (if
 122  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 123  * and default to 80 if all else fails.
 124  */
 125 int term_columns(void)
 126 {
 127         static int term_columns_at_startup;
 128
 129         char *col_string;
 130         int n_cols;
 131
 132         if (term_columns_at_startup)
 133                 return term_columns_at_startup;
 134
 135         term_columns_at_startup = 80;
 136
 137         col_string = getenv("COLUMNS");
 138         if (col_string && (n_cols = atoi(col_string)) > 0)
 139                 term_columns_at_startup = n_cols;
 140 #ifdef TIOCGWINSZ
 141         else {
 142                 struct winsize ws;
 143                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 144                         term_columns_at_startup = ws.ws_col;
 145         }
 146 #endif
 147
 148         return term_columns_at_startup;
 149 }