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 static const char *pager_argv[] = { NULL, NULL };
  15 static struct child_process pager_process;
  16
  17 static void wait_for_pager(void)
  18 {
  19         fflush(stdout);
  20         fflush(stderr);
  21         /* signal EOF to pager */
  22         close(1);
  23         close(2);
  24         finish_command(&pager_process);
  25 }
  26
  27 static void wait_for_pager_signal(int signo)
  28 {
  29         wait_for_pager();
  30         sigchain_pop(signo);
  31         raise(signo);
  32 }
  33
  34 const char *git_pager(int stdout_is_tty)
  35 {
  36         const char *pager;
  37
  38         if (!stdout_is_tty)
  39                 return NULL;
  40
  41         pager = getenv("GIT_PAGER");
  42         if (!pager) {
  43                 if (!pager_program)
  44                         git_config(git_default_config, NULL);
  45                 pager = pager_program;
  46         }
  47         if (!pager)
  48                 pager = getenv("PAGER");
  49         if (!pager)
  50                 pager = DEFAULT_PAGER;
  51         else if (!*pager || !strcmp(pager, "cat"))
  52                 pager = NULL;
  53
  54         return pager;
  55 }
  56
  57 void setup_pager(void)
  58 {
  59         const char *pager = git_pager(isatty(1));
  60
  61         if (!pager || pager_in_use())
  62                 return;
  63
  64         /*
  65          * force computing the width of the terminal before we redirect
  66          * the standard output to the pager.
  67          */
  68         (void) term_columns();
  69
  70         setenv("GIT_PAGER_IN_USE", "true", 1);
  71
  72         /* spawn the pager */
  73         pager_argv[0] = pager;
  74         pager_process.use_shell = 1;
  75         pager_process.argv = pager_argv;
  76         pager_process.in = -1;
  77         if (!getenv("LESS")) {
  78                 static const char *env[] = { "LESS=FRSX", NULL };
  79                 pager_process.env = env;
  80         }
  81         if (start_command(&pager_process))
  82                 return;
  83
  84         /* original process continues, but writes to the pipe */
  85         dup2(pager_process.in, 1);
  86         if (isatty(2))
  87                 dup2(pager_process.in, 2);
  88         close(pager_process.in);
  89
  90         /* this makes sure that the parent terminates after the pager */
  91         sigchain_push_common(wait_for_pager_signal);
  92         atexit(wait_for_pager);
  93 }
  94
  95 int pager_in_use(void)
  96 {
  97         const char *env;
  98         env = getenv("GIT_PAGER_IN_USE");
  99         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 100 }
 101
 102 /*
 103  * Return cached value (if set) or $COLUMNS environment variable (if
 104  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 105  * and default to 80 if all else fails.
 106  */
 107 int term_columns(void)
 108 {
 109         static int term_columns_at_startup;
 110
 111         char *col_string;
 112         int n_cols;
 113
 114         if (term_columns_at_startup)
 115                 return term_columns_at_startup;
 116
 117         term_columns_at_startup = 80;
 118
 119         col_string = getenv("COLUMNS");
 120         if (col_string && (n_cols = atoi(col_string)) > 0)
 121                 term_columns_at_startup = n_cols;
 122 #ifdef TIOCGWINSZ
 123         else {
 124                 struct winsize ws;
 125                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 126                         term_columns_at_startup = ws.ws_col;
 127         }
 128 #endif
 129
 130         return term_columns_at_startup;
 131 }
 132
 133 /*
 134  * How many columns do we need to show this number in decimal?
 135  */
 136 int decimal_width(int number)
 137 {
 138         int i, width;
 139
 140         for (width = 1, i = 10; i <= number; width++)
 141                 i *= 10;
 142         return width;
 143 }