pager.c

   1 #include "git-compat-util.h"
   2 #include "config.h"
   3 #include "editor.h"
   4 #include "pager.h"
   5 #include "run-command.h"
   6 #include "sigchain.h"
   7 #include "alias.h"
   8
   9 int pager_use_color = 1;
  10
  11 #ifndef DEFAULT_PAGER
  12 #define DEFAULT_PAGER "less"
  13 #endif
  14
  15 static struct child_process pager_process;
  16 static char *pager_program;
  17 static int old_fd1 = -1, old_fd2 = -1;
  18
  19 /* Is the value coming back from term_columns() just a guess? */
  20 static int term_columns_guessed;
  21
  22
  23 static void close_pager_fds(void)
  24 {
  25         /* signal EOF to pager */
  26         close(1);
  27         if (old_fd2 != -1)
  28                 close(2);
  29 }
  30
  31 static void finish_pager(void)
  32 {
  33         fflush(stdout);
  34         fflush(stderr);
  35         close_pager_fds();
  36         finish_command(&pager_process);
  37 }
  38
  39 static void wait_for_pager_atexit(void)
  40 {
  41         if (old_fd1 == -1)
  42                 return;
  43
  44         finish_pager();
  45 }
  46
  47 void wait_for_pager(void)
  48 {
  49         if (old_fd1 == -1)
  50                 return;
  51
  52         finish_pager();
  53         sigchain_pop_common();
  54         unsetenv("GIT_PAGER_IN_USE");
  55         dup2(old_fd1, 1);
  56         close(old_fd1);
  57         old_fd1 = -1;
  58         if (old_fd2 != -1) {
  59                 dup2(old_fd2, 2);
  60                 close(old_fd2);
  61                 old_fd2 = -1;
  62         }
  63 }
  64
  65 static void wait_for_pager_signal(int signo)
  66 {
  67         if (old_fd1 == -1)
  68                 return;
  69
  70         close_pager_fds();
  71         finish_command_in_signal(&pager_process);
  72         sigchain_pop(signo);
  73         raise(signo);
  74 }
  75
  76 static int core_pager_config(const char *var, const char *value,
  77                              const struct config_context *ctx UNUSED,
  78                              void *data UNUSED)
  79 {
  80         if (!strcmp(var, "core.pager"))
  81                 return git_config_string(&pager_program, var, value);
  82         return 0;
  83 }
  84
  85 const char *git_pager(int stdout_is_tty)
  86 {
  87         const char *pager;
  88
  89         if (!stdout_is_tty)
  90                 return NULL;
  91
  92         pager = getenv("GIT_PAGER");
  93         if (!pager) {
  94                 if (!pager_program)
  95                         read_early_config(core_pager_config, NULL);
  96                 pager = pager_program;
  97         }
  98         if (!pager)
  99                 pager = getenv("PAGER");
 100         if (!pager)
 101                 pager = DEFAULT_PAGER;
 102         if (!*pager || !strcmp(pager, "cat"))
 103                 pager = NULL;
 104
 105         return pager;
 106 }
 107
 108 static void setup_pager_env(struct strvec *env)
 109 {
 110         const char **argv;
 111         int i;
 112         char *pager_env = xstrdup(PAGER_ENV);
 113         int n = split_cmdline(pager_env, &argv);
 114
 115         if (n < 0)
 116                 die("malformed build-time PAGER_ENV: %s",
 117                         split_cmdline_strerror(n));
 118
 119         for (i = 0; i < n; i++) {
 120                 char *cp = strchr(argv[i], '=');
 121
 122                 if (!cp)
 123                         die("malformed build-time PAGER_ENV");
 124
 125                 *cp = '\0';
 126                 if (!getenv(argv[i])) {
 127                         *cp = '=';
 128                         strvec_push(env, argv[i]);
 129                 }
 130         }
 131         free(pager_env);
 132         free(argv);
 133 }
 134
 135 void prepare_pager_args(struct child_process *pager_process, const char *pager)
 136 {
 137         strvec_push(&pager_process->args, pager);
 138         pager_process->use_shell = 1;
 139         setup_pager_env(&pager_process->env);
 140         pager_process->trace2_child_class = "pager";
 141 }
 142
 143 void setup_pager(void)
 144 {
 145         static int once = 0;
 146         const char *pager = git_pager(isatty(1));
 147
 148         if (!pager)
 149                 return;
 150
 151         /*
 152          * After we redirect standard output, we won't be able to use an ioctl
 153          * to get the terminal size. Let's grab it now, and then set $COLUMNS
 154          * to communicate it to any sub-processes.
 155          */
 156         {
 157                 char buf[64];
 158                 xsnprintf(buf, sizeof(buf), "%d", term_columns());
 159                 if (!term_columns_guessed)
 160                         setenv("COLUMNS", buf, 0);
 161         }
 162
 163         setenv("GIT_PAGER_IN_USE", "true", 1);
 164
 165         child_process_init(&pager_process);
 166
 167         /* spawn the pager */
 168         prepare_pager_args(&pager_process, pager);
 169         pager_process.in = -1;
 170         strvec_push(&pager_process.env, "GIT_PAGER_IN_USE");
 171         if (start_command(&pager_process))
 172                 die("unable to execute pager '%s'", pager);
 173
 174         /* original process continues, but writes to the pipe */
 175         old_fd1 = dup(1);
 176         dup2(pager_process.in, 1);
 177         if (isatty(2)) {
 178                 old_fd2 = dup(2);
 179                 dup2(pager_process.in, 2);
 180         }
 181         close(pager_process.in);
 182
 183         sigchain_push_common(wait_for_pager_signal);
 184
 185         if (!once) {
 186                 once++;
 187                 atexit(wait_for_pager_atexit);
 188         }
 189 }
 190
 191 int pager_in_use(void)
 192 {
 193         return git_env_bool("GIT_PAGER_IN_USE", 0);
 194 }
 195
 196 /*
 197  * Return cached value (if set) or $COLUMNS environment variable (if
 198  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 199  * and default to 80 if all else fails.
 200  */
 201 int term_columns(void)
 202 {
 203         static int term_columns_at_startup;
 204
 205         char *col_string;
 206         int n_cols;
 207
 208         if (term_columns_at_startup)
 209                 return term_columns_at_startup;
 210
 211         term_columns_at_startup = 80;
 212         term_columns_guessed = 1;
 213
 214         col_string = getenv("COLUMNS");
 215         if (col_string && (n_cols = atoi(col_string)) > 0) {
 216                 term_columns_at_startup = n_cols;
 217                 term_columns_guessed = 0;
 218         }
 219 #ifdef TIOCGWINSZ
 220         else {
 221                 struct winsize ws;
 222                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {
 223                         term_columns_at_startup = ws.ws_col;
 224                         term_columns_guessed = 0;
 225                 }
 226         }
 227 #endif
 228
 229         return term_columns_at_startup;
 230 }
 231
 232 /*
 233  * Clear the entire line, leave cursor in first column.
 234  */
 235 void term_clear_line(void)
 236 {
 237         if (!isatty(2))
 238                 return;
 239         if (is_terminal_dumb())
 240                 /*
 241                  * Fall back to print a terminal width worth of space
 242                  * characters (hoping that the terminal is still as wide
 243                  * as it was upon the first call to term_columns()).
 244                  */
 245                 fprintf(stderr, "\r%*s\r", term_columns(), "");
 246         else
 247                 /*
 248                  * On non-dumb terminals use an escape sequence to clear
 249                  * the whole line, no matter how wide the terminal.
 250                  */
 251                 fputs("\r\033[K", stderr);
 252 }
 253
 254 /*
 255  * How many columns do we need to show this number in decimal?
 256  */
 257 int decimal_width(uintmax_t number)
 258 {
 259         int width;
 260
 261         for (width = 1; number >= 10; width++)
 262                 number /= 10;
 263         return width;
 264 }
 265
 266 struct pager_command_config_data {
 267         const char *cmd;
 268         int want;
 269         char *value;
 270 };
 271
 272 static int pager_command_config(const char *var, const char *value,
 273                                 const struct config_context *ctx UNUSED,
 274                                 void *vdata)
 275 {
 276         struct pager_command_config_data *data = vdata;
 277         const char *cmd;
 278
 279         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 280                 int b = git_parse_maybe_bool(value);
 281                 if (b >= 0)
 282                         data->want = b;
 283                 else {
 284                         data->want = 1;
 285                         data->value = xstrdup(value);
 286                 }
 287         }
 288
 289         return 0;
 290 }
 291
 292 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 293 int check_pager_config(const char *cmd)
 294 {
 295         struct pager_command_config_data data;
 296
 297         data.cmd = cmd;
 298         data.want = -1;
 299         data.value = NULL;
 300
 301         read_early_config(pager_command_config, &data);
 302
 303         if (data.value)
 304                 pager_program = data.value;
 305         return data.want;
 306 }