pager.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "run-command.h"
   4 #include "sigchain.h"
   5 #include "alias.h"
   6
   7 #ifndef DEFAULT_PAGER
   8 #define DEFAULT_PAGER "less"
   9 #endif
  10
  11 static struct child_process pager_process;
  12 static const char *pager_program;
  13
  14 /* Is the value coming back from term_columns() just a guess? */
  15 static int term_columns_guessed;
  16
  17
  18 static void close_pager_fds(void)
  19 {
  20         /* signal EOF to pager */
  21         close(1);
  22         close(2);
  23 }
  24
  25 static void wait_for_pager_atexit(void)
  26 {
  27         fflush(stdout);
  28         fflush(stderr);
  29         close_pager_fds();
  30         finish_command(&pager_process);
  31 }
  32
  33 static void wait_for_pager_signal(int signo)
  34 {
  35         close_pager_fds();
  36         finish_command_in_signal(&pager_process);
  37         sigchain_pop(signo);
  38         raise(signo);
  39 }
  40
  41 static int core_pager_config(const char *var, const char *value,
  42                              void *data UNUSED)
  43 {
  44         if (!strcmp(var, "core.pager"))
  45                 return git_config_string(&pager_program, var, value);
  46         return 0;
  47 }
  48
  49 const char *git_pager(int stdout_is_tty)
  50 {
  51         const char *pager;
  52
  53         if (!stdout_is_tty)
  54                 return NULL;
  55
  56         pager = getenv("GIT_PAGER");
  57         if (!pager) {
  58                 if (!pager_program)
  59                         read_early_config(core_pager_config, NULL);
  60                 pager = pager_program;
  61         }
  62         if (!pager)
  63                 pager = getenv("PAGER");
  64         if (!pager)
  65                 pager = DEFAULT_PAGER;
  66         if (!*pager || !strcmp(pager, "cat"))
  67                 pager = NULL;
  68
  69         return pager;
  70 }
  71
  72 static void setup_pager_env(struct strvec *env)
  73 {
  74         const char **argv;
  75         int i;
  76         char *pager_env = xstrdup(PAGER_ENV);
  77         int n = split_cmdline(pager_env, &argv);
  78
  79         if (n < 0)
  80                 die("malformed build-time PAGER_ENV: %s",
  81                         split_cmdline_strerror(n));
  82
  83         for (i = 0; i < n; i++) {
  84                 char *cp = strchr(argv[i], '=');
  85
  86                 if (!cp)
  87                         die("malformed build-time PAGER_ENV");
  88
  89                 *cp = '\0';
  90                 if (!getenv(argv[i])) {
  91                         *cp = '=';
  92                         strvec_push(env, argv[i]);
  93                 }
  94         }
  95         free(pager_env);
  96         free(argv);
  97 }
  98
  99 void prepare_pager_args(struct child_process *pager_process, const char *pager)
 100 {
 101         strvec_push(&pager_process->args, pager);
 102         pager_process->use_shell = 1;
 103         setup_pager_env(&pager_process->env);
 104         pager_process->trace2_child_class = "pager";
 105 }
 106
 107 void setup_pager(void)
 108 {
 109         const char *pager = git_pager(isatty(1));
 110
 111         if (!pager)
 112                 return;
 113
 114         /*
 115          * After we redirect standard output, we won't be able to use an ioctl
 116          * to get the terminal size. Let's grab it now, and then set $COLUMNS
 117          * to communicate it to any sub-processes.
 118          */
 119         {
 120                 char buf[64];
 121                 xsnprintf(buf, sizeof(buf), "%d", term_columns());
 122                 if (!term_columns_guessed)
 123                         setenv("COLUMNS", buf, 0);
 124         }
 125
 126         setenv("GIT_PAGER_IN_USE", "true", 1);
 127
 128         child_process_init(&pager_process);
 129
 130         /* spawn the pager */
 131         prepare_pager_args(&pager_process, pager);
 132         pager_process.in = -1;
 133         strvec_push(&pager_process.env, "GIT_PAGER_IN_USE");
 134         if (start_command(&pager_process))
 135                 return;
 136
 137         /* original process continues, but writes to the pipe */
 138         dup2(pager_process.in, 1);
 139         if (isatty(2))
 140                 dup2(pager_process.in, 2);
 141         close(pager_process.in);
 142
 143         /* this makes sure that the parent terminates after the pager */
 144         sigchain_push_common(wait_for_pager_signal);
 145         atexit(wait_for_pager_atexit);
 146 }
 147
 148 int pager_in_use(void)
 149 {
 150         return git_env_bool("GIT_PAGER_IN_USE", 0);
 151 }
 152
 153 /*
 154  * Return cached value (if set) or $COLUMNS environment variable (if
 155  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 156  * and default to 80 if all else fails.
 157  */
 158 int term_columns(void)
 159 {
 160         static int term_columns_at_startup;
 161
 162         char *col_string;
 163         int n_cols;
 164
 165         if (term_columns_at_startup)
 166                 return term_columns_at_startup;
 167
 168         term_columns_at_startup = 80;
 169         term_columns_guessed = 1;
 170
 171         col_string = getenv("COLUMNS");
 172         if (col_string && (n_cols = atoi(col_string)) > 0) {
 173                 term_columns_at_startup = n_cols;
 174                 term_columns_guessed = 0;
 175         }
 176 #ifdef TIOCGWINSZ
 177         else {
 178                 struct winsize ws;
 179                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {
 180                         term_columns_at_startup = ws.ws_col;
 181                         term_columns_guessed = 0;
 182                 }
 183         }
 184 #endif
 185
 186         return term_columns_at_startup;
 187 }
 188
 189 /*
 190  * Clear the entire line, leave cursor in first column.
 191  */
 192 void term_clear_line(void)
 193 {
 194         if (is_terminal_dumb())
 195                 /*
 196                  * Fall back to print a terminal width worth of space
 197                  * characters (hoping that the terminal is still as wide
 198                  * as it was upon the first call to term_columns()).
 199                  */
 200                 fprintf(stderr, "\r%*s\r", term_columns(), "");
 201         else
 202                 /*
 203                  * On non-dumb terminals use an escape sequence to clear
 204                  * the whole line, no matter how wide the terminal.
 205                  */
 206                 fputs("\r\033[K", stderr);
 207 }
 208
 209 /*
 210  * How many columns do we need to show this number in decimal?
 211  */
 212 int decimal_width(uintmax_t number)
 213 {
 214         int width;
 215
 216         for (width = 1; number >= 10; width++)
 217                 number /= 10;
 218         return width;
 219 }
 220
 221 struct pager_command_config_data {
 222         const char *cmd;
 223         int want;
 224         char *value;
 225 };
 226
 227 static int pager_command_config(const char *var, const char *value, void *vdata)
 228 {
 229         struct pager_command_config_data *data = vdata;
 230         const char *cmd;
 231
 232         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 233                 int b = git_parse_maybe_bool(value);
 234                 if (b >= 0)
 235                         data->want = b;
 236                 else {
 237                         data->want = 1;
 238                         data->value = xstrdup(value);
 239                 }
 240         }
 241
 242         return 0;
 243 }
 244
 245 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 246 int check_pager_config(const char *cmd)
 247 {
 248         struct pager_command_config_data data;
 249
 250         data.cmd = cmd;
 251         data.want = -1;
 252         data.value = NULL;
 253
 254         read_early_config(pager_command_config, &data);
 255
 256         if (data.value)
 257                 pager_program = data.value;
 258         return data.want;
 259 }