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