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 = CHILD_PROCESS_INIT;
  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         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)
  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") || !getenv("LV")) {
  78                 static const char *env[3];
  79                 int i = 0;
  80
  81                 if (!getenv("LESS"))
  82                         env[i++] = "LESS=FRX";
  83                 if (!getenv("LV"))
  84                         env[i++] = "LV=-c";
  85                 env[i] = NULL;
  86                 pager_process.env = env;
  87         }
  88         if (start_command(&pager_process))
  89                 return;
  90
  91         /* original process continues, but writes to the pipe */
  92         dup2(pager_process.in, 1);
  93         if (isatty(2))
  94                 dup2(pager_process.in, 2);
  95         close(pager_process.in);
  96
  97         /* this makes sure that the parent terminates after the pager */
  98         sigchain_push_common(wait_for_pager_signal);
  99         atexit(wait_for_pager);
 100 }
 101
 102 int pager_in_use(void)
 103 {
 104         const char *env;
 105         env = getenv("GIT_PAGER_IN_USE");
 106         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 107 }
 108
 109 /*
 110  * Return cached value (if set) or $COLUMNS environment variable (if
 111  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 112  * and default to 80 if all else fails.
 113  */
 114 int term_columns(void)
 115 {
 116         static int term_columns_at_startup;
 117
 118         char *col_string;
 119         int n_cols;
 120
 121         if (term_columns_at_startup)
 122                 return term_columns_at_startup;
 123
 124         term_columns_at_startup = 80;
 125
 126         col_string = getenv("COLUMNS");
 127         if (col_string && (n_cols = atoi(col_string)) > 0)
 128                 term_columns_at_startup = n_cols;
 129 #ifdef TIOCGWINSZ
 130         else {
 131                 struct winsize ws;
 132                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 133                         term_columns_at_startup = ws.ws_col;
 134         }
 135 #endif
 136
 137         return term_columns_at_startup;
 138 }
 139
 140 /*
 141  * How many columns do we need to show this number in decimal?
 142  */
 143 int decimal_width(int number)
 144 {
 145         int i, width;
 146
 147         for (width = 1, i = 10; i <= number; width++)
 148                 i *= 10;
 149         return width;
 150 }
 151
 152 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 153 int check_pager_config(const char *cmd)
 154 {
 155         int want = -1;
 156         struct strbuf key = STRBUF_INIT;
 157         const char *value = NULL;
 158         strbuf_addf(&key, "pager.%s", cmd);
 159         if (!git_config_get_value(key.buf, &value)) {
 160                 int b = git_config_maybe_bool(key.buf, value);
 161                 if (b >= 0)
 162                         want = b;
 163                 else {
 164                         want = 1;
 165                         pager_program = xstrdup(value);
 166                 }
 167         }
 168         strbuf_release(&key);
 169         return want;
 170 }