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 struct pager_config {
  10         const char *cmd;
  11         int want;
  12         char *value;
  13 };
  14
  15 /*
  16  * This is split up from the rest of git so that we can do
  17  * something different on Windows.
  18  */
  19
  20 static const char *pager_argv[] = { NULL, NULL };
  21 static struct child_process pager_process;
  22
  23 static void wait_for_pager(void)
  24 {
  25         fflush(stdout);
  26         fflush(stderr);
  27         /* signal EOF to pager */
  28         close(1);
  29         close(2);
  30         finish_command(&pager_process);
  31 }
  32
  33 static void wait_for_pager_signal(int signo)
  34 {
  35         wait_for_pager();
  36         sigchain_pop(signo);
  37         raise(signo);
  38 }
  39
  40 const char *git_pager(int stdout_is_tty)
  41 {
  42         const char *pager;
  43
  44         if (!stdout_is_tty)
  45                 return NULL;
  46
  47         pager = getenv("GIT_PAGER");
  48         if (!pager) {
  49                 if (!pager_program)
  50                         git_config(git_default_config, NULL);
  51                 pager = pager_program;
  52         }
  53         if (!pager)
  54                 pager = getenv("PAGER");
  55         if (!pager)
  56                 pager = DEFAULT_PAGER;
  57         if (!*pager || !strcmp(pager, "cat"))
  58                 pager = NULL;
  59
  60         return pager;
  61 }
  62
  63 void setup_pager(void)
  64 {
  65         const char *pager = git_pager(isatty(1));
  66
  67         if (!pager)
  68                 return;
  69
  70         /*
  71          * force computing the width of the terminal before we redirect
  72          * the standard output to the pager.
  73          */
  74         (void) term_columns();
  75
  76         setenv("GIT_PAGER_IN_USE", "true", 1);
  77
  78         /* spawn the pager */
  79         pager_argv[0] = pager;
  80         pager_process.use_shell = 1;
  81         pager_process.argv = pager_argv;
  82         pager_process.in = -1;
  83         if (!getenv("LESS") || !getenv("LV")) {
  84                 static const char *env[3];
  85                 int i = 0;
  86
  87                 if (!getenv("LESS"))
  88                         env[i++] = "LESS=FRSX";
  89                 if (!getenv("LV"))
  90                         env[i++] = "LV=-c";
  91                 env[i] = NULL;
  92                 pager_process.env = env;
  93         }
  94         if (start_command(&pager_process))
  95                 return;
  96
  97         /* original process continues, but writes to the pipe */
  98         dup2(pager_process.in, 1);
  99         if (isatty(2))
 100                 dup2(pager_process.in, 2);
 101         close(pager_process.in);
 102
 103         /* this makes sure that the parent terminates after the pager */
 104         sigchain_push_common(wait_for_pager_signal);
 105         atexit(wait_for_pager);
 106 }
 107
 108 int pager_in_use(void)
 109 {
 110         const char *env;
 111         env = getenv("GIT_PAGER_IN_USE");
 112         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 113 }
 114
 115 /*
 116  * Return cached value (if set) or $COLUMNS environment variable (if
 117  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 118  * and default to 80 if all else fails.
 119  */
 120 int term_columns(void)
 121 {
 122         static int term_columns_at_startup;
 123
 124         char *col_string;
 125         int n_cols;
 126
 127         if (term_columns_at_startup)
 128                 return term_columns_at_startup;
 129
 130         term_columns_at_startup = 80;
 131
 132         col_string = getenv("COLUMNS");
 133         if (col_string && (n_cols = atoi(col_string)) > 0)
 134                 term_columns_at_startup = n_cols;
 135 #ifdef TIOCGWINSZ
 136         else {
 137                 struct winsize ws;
 138                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 139                         term_columns_at_startup = ws.ws_col;
 140         }
 141 #endif
 142
 143         return term_columns_at_startup;
 144 }
 145
 146 /*
 147  * How many columns do we need to show this number in decimal?
 148  */
 149 int decimal_width(int number)
 150 {
 151         int i, width;
 152
 153         for (width = 1, i = 10; i <= number; width++)
 154                 i *= 10;
 155         return width;
 156 }
 157
 158 static int pager_command_config(const char *var, const char *value, void *data)
 159 {
 160         struct pager_config *c = data;
 161         if (starts_with(var, "pager.") && !strcmp(var + 6, c->cmd)) {
 162                 int b = git_config_maybe_bool(var, value);
 163                 if (b >= 0)
 164                         c->want = b;
 165                 else {
 166                         c->want = 1;
 167                         c->value = xstrdup(value);
 168                 }
 169         }
 170         return 0;
 171 }
 172
 173 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 174 int check_pager_config(const char *cmd)
 175 {
 176         struct pager_config c;
 177         c.cmd = cmd;
 178         c.want = -1;
 179         c.value = NULL;
 180         git_config(pager_command_config, &c);
 181         if (c.value)
 182                 pager_program = c.value;
 183         return c.want;
 184 }