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 || pager_in_use())
  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")) {
  84                 static const char *env[] = { "LESS=FRSX", NULL };
  85                 pager_process.env = env;
  86         }
  87         if (start_command(&pager_process))
  88                 return;
  89
  90         /* original process continues, but writes to the pipe */
  91         dup2(pager_process.in, 1);
  92         if (isatty(2))
  93                 dup2(pager_process.in, 2);
  94         close(pager_process.in);
  95
  96         /* this makes sure that the parent terminates after the pager */
  97         sigchain_push_common(wait_for_pager_signal);
  98         atexit(wait_for_pager);
  99 }
 100
 101 int pager_in_use(void)
 102 {
 103         const char *env;
 104         env = getenv("GIT_PAGER_IN_USE");
 105         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 106 }
 107
 108 /*
 109  * Return cached value (if set) or $COLUMNS environment variable (if
 110  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 111  * and default to 80 if all else fails.
 112  */
 113 int term_columns(void)
 114 {
 115         static int term_columns_at_startup;
 116
 117         char *col_string;
 118         int n_cols;
 119
 120         if (term_columns_at_startup)
 121                 return term_columns_at_startup;
 122
 123         term_columns_at_startup = 80;
 124
 125         col_string = getenv("COLUMNS");
 126         if (col_string && (n_cols = atoi(col_string)) > 0)
 127                 term_columns_at_startup = n_cols;
 128 #ifdef TIOCGWINSZ
 129         else {
 130                 struct winsize ws;
 131                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 132                         term_columns_at_startup = ws.ws_col;
 133         }
 134 #endif
 135
 136         return term_columns_at_startup;
 137 }
 138
 139 /*
 140  * How many columns do we need to show this number in decimal?
 141  */
 142 int decimal_width(uintmax_t number)
 143 {
 144         int width;
 145
 146         for (width = 1; number >= 10; width++)
 147                 number /= 10;
 148         return width;
 149 }
 150
 151 static int pager_command_config(const char *var, const char *value, void *data)
 152 {
 153         struct pager_config *c = data;
 154         if (!prefixcmp(var, "pager.") && !strcmp(var + 6, c->cmd)) {
 155                 int b = git_config_maybe_bool(var, value);
 156                 if (b >= 0)
 157                         c->want = b;
 158                 else {
 159                         c->want = 1;
 160                         c->value = xstrdup(value);
 161                 }
 162         }
 163         return 0;
 164 }
 165
 166 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 167 int check_pager_config(const char *cmd)
 168 {
 169         struct pager_config c;
 170         c.cmd = cmd;
 171         c.want = -1;
 172         c.value = NULL;
 173         git_config(pager_command_config, &c);
 174         if (c.value)
 175                 pager_program = c.value;
 176         return c.want;
 177 }