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, 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         child_process_init(&pager_process);
 128
 129         /* spawn the pager */
 130         prepare_pager_args(&pager_process, pager);
 131         pager_process.in = -1;
 132         strvec_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
 133         if (start_command(&pager_process))
 134                 return;
 135
 136         /* original process continues, but writes to the pipe */
 137         dup2(pager_process.in, 1);
 138         if (isatty(2))
 139                 dup2(pager_process.in, 2);
 140         close(pager_process.in);
 141
 142         /* this makes sure that the parent terminates after the pager */
 143         sigchain_push_common(wait_for_pager_signal);
 144         atexit(wait_for_pager_atexit);
 145 }
 146
 147 int pager_in_use(void)
 148 {
 149         return git_env_bool("GIT_PAGER_IN_USE", 0);
 150 }
 151
 152 /*
 153  * Return cached value (if set) or $COLUMNS environment variable (if
 154  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 155  * and default to 80 if all else fails.
 156  */
 157 int term_columns(void)
 158 {
 159         static int term_columns_at_startup;
 160
 161         char *col_string;
 162         int n_cols;
 163
 164         if (term_columns_at_startup)
 165                 return term_columns_at_startup;
 166
 167         term_columns_at_startup = 80;
 168         term_columns_guessed = 1;
 169
 170         col_string = getenv("COLUMNS");
 171         if (col_string && (n_cols = atoi(col_string)) > 0) {
 172                 term_columns_at_startup = n_cols;
 173                 term_columns_guessed = 0;
 174         }
 175 #ifdef TIOCGWINSZ
 176         else {
 177                 struct winsize ws;
 178                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {
 179                         term_columns_at_startup = ws.ws_col;
 180                         term_columns_guessed = 0;
 181                 }
 182         }
 183 #endif
 184
 185         return term_columns_at_startup;
 186 }
 187
 188 /*
 189  * Clear the entire line, leave cursor in first column.
 190  */
 191 void term_clear_line(void)
 192 {
 193         if (is_terminal_dumb())
 194                 /*
 195                  * Fall back to print a terminal width worth of space
 196                  * characters (hoping that the terminal is still as wide
 197                  * as it was upon the first call to term_columns()).
 198                  */
 199                 fprintf(stderr, "\r%*s\r", term_columns(), "");
 200         else
 201                 /*
 202                  * On non-dumb terminals use an escape sequence to clear
 203                  * the whole line, no matter how wide the terminal.
 204                  */
 205                 fputs("\r\033[K", stderr);
 206 }
 207
 208 /*
 209  * How many columns do we need to show this number in decimal?
 210  */
 211 int decimal_width(uintmax_t number)
 212 {
 213         int width;
 214
 215         for (width = 1; number >= 10; width++)
 216                 number /= 10;
 217         return width;
 218 }
 219
 220 struct pager_command_config_data {
 221         const char *cmd;
 222         int want;
 223         char *value;
 224 };
 225
 226 static int pager_command_config(const char *var, const char *value, void *vdata)
 227 {
 228         struct pager_command_config_data *data = vdata;
 229         const char *cmd;
 230
 231         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 232                 int b = git_parse_maybe_bool(value);
 233                 if (b >= 0)
 234                         data->want = b;
 235                 else {
 236                         data->want = 1;
 237                         data->value = xstrdup(value);
 238                 }
 239         }
 240
 241         return 0;
 242 }
 243
 244 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 245 int check_pager_config(const char *cmd)
 246 {
 247         struct pager_command_config_data data;
 248
 249         data.cmd = cmd;
 250         data.want = -1;
 251         data.value = NULL;
 252
 253         read_early_config(pager_command_config, &data);
 254
 255         if (data.value)
 256                 pager_program = data.value;
 257         return data.want;
 258 }