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