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