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 prepare_pager_args(struct child_process *pager_process, const char *pager)
  57 {
  58         argv_array_push(&pager_process->args, pager);
  59         pager_process->use_shell = 1;
  60         if (!getenv("LESS"))
  61                 argv_array_push(&pager_process->env_array, "LESS=FRX");
  62         if (!getenv("LV"))
  63                 argv_array_push(&pager_process->env_array, "LV=-c");
  64 }
  65
  66 void setup_pager(void)
  67 {
  68         const char *pager = git_pager(isatty(1));
  69
  70         if (!pager)
  71                 return;
  72
  73         /*
  74          * force computing the width of the terminal before we redirect
  75          * the standard output to the pager.
  76          */
  77         (void) term_columns();
  78
  79         setenv("GIT_PAGER_IN_USE", "true", 1);
  80
  81         /* spawn the pager */
  82         prepare_pager_args(&pager_process, pager);
  83         pager_process.in = -1;
  84         argv_array_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
  85         if (start_command(&pager_process))
  86                 return;
  87
  88         /* original process continues, but writes to the pipe */
  89         dup2(pager_process.in, 1);
  90         if (isatty(2))
  91                 dup2(pager_process.in, 2);
  92         close(pager_process.in);
  93
  94         /* this makes sure that the parent terminates after the pager */
  95         sigchain_push_common(wait_for_pager_signal);
  96         atexit(wait_for_pager);
  97 }
  98
  99 int pager_in_use(void)
 100 {
 101         const char *env;
 102         env = getenv("GIT_PAGER_IN_USE");
 103         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 104 }
 105
 106 /*
 107  * Return cached value (if set) or $COLUMNS environment variable (if
 108  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 109  * and default to 80 if all else fails.
 110  */
 111 int term_columns(void)
 112 {
 113         static int term_columns_at_startup;
 114
 115         char *col_string;
 116         int n_cols;
 117
 118         if (term_columns_at_startup)
 119                 return term_columns_at_startup;
 120
 121         term_columns_at_startup = 80;
 122
 123         col_string = getenv("COLUMNS");
 124         if (col_string && (n_cols = atoi(col_string)) > 0)
 125                 term_columns_at_startup = n_cols;
 126 #ifdef TIOCGWINSZ
 127         else {
 128                 struct winsize ws;
 129                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 130                         term_columns_at_startup = ws.ws_col;
 131         }
 132 #endif
 133
 134         return term_columns_at_startup;
 135 }
 136
 137 /*
 138  * How many columns do we need to show this number in decimal?
 139  */
 140 int decimal_width(uintmax_t number)
 141 {
 142         int width;
 143
 144         for (width = 1; number >= 10; width++)
 145                 number /= 10;
 146         return width;
 147 }
 148
 149 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 150 int check_pager_config(const char *cmd)
 151 {
 152         int want = -1;
 153         struct strbuf key = STRBUF_INIT;
 154         const char *value = NULL;
 155         strbuf_addf(&key, "pager.%s", cmd);
 156         if (!git_config_get_value(key.buf, &value)) {
 157                 int b = git_config_maybe_bool(key.buf, value);
 158                 if (b >= 0)
 159                         want = b;
 160                 else {
 161                         want = 1;
 162                         pager_program = xstrdup(value);
 163                 }
 164         }
 165         strbuf_release(&key);
 166         return want;
 167 }