pager.c

   1 #define USE_THE_REPOSITORY_VARIABLE
   2
   3 #include "git-compat-util.h"
   4 #include "config.h"
   5 #include "editor.h"
   6 #include "pager.h"
   7 #include "run-command.h"
   8 #include "sigchain.h"
   9 #include "alias.h"
  10
  11 int pager_use_color = 1;
  12
  13 #ifndef DEFAULT_PAGER
  14 #define DEFAULT_PAGER "less"
  15 #endif
  16
  17 static struct child_process pager_process;
  18 static char *pager_program;
  19 static int old_fd1 = -1, old_fd2 = -1;
  20
  21 /* Is the value coming back from term_columns() just a guess? */
  22 static int term_columns_guessed;
  23
  24
  25 static void close_pager_fds(void)
  26 {
  27         /* signal EOF to pager */
  28         close(1);
  29         if (old_fd2 != -1)
  30                 close(2);
  31 }
  32
  33 static void finish_pager(void)
  34 {
  35         fflush(stdout);
  36         fflush(stderr);
  37         close_pager_fds();
  38         finish_command(&pager_process);
  39 }
  40
  41 static void wait_for_pager_atexit(void)
  42 {
  43         if (old_fd1 == -1)
  44                 return;
  45
  46         finish_pager();
  47 }
  48
  49 void wait_for_pager(void)
  50 {
  51         if (old_fd1 == -1)
  52                 return;
  53
  54         finish_pager();
  55         sigchain_pop_common();
  56         unsetenv("GIT_PAGER_IN_USE");
  57         dup2(old_fd1, 1);
  58         close(old_fd1);
  59         old_fd1 = -1;
  60         if (old_fd2 != -1) {
  61                 dup2(old_fd2, 2);
  62                 close(old_fd2);
  63                 old_fd2 = -1;
  64         }
  65 }
  66
  67 static void wait_for_pager_signal(int signo)
  68 {
  69         if (old_fd1 == -1)
  70                 return;
  71
  72         close_pager_fds();
  73         finish_command_in_signal(&pager_process);
  74         sigchain_pop(signo);
  75         raise(signo);
  76 }
  77
  78 static int core_pager_config(const char *var, const char *value,
  79                              const struct config_context *ctx UNUSED,
  80                              void *data UNUSED)
  81 {
  82         if (!strcmp(var, "core.pager"))
  83                 return git_config_string(&pager_program, var, value);
  84         return 0;
  85 }
  86
  87 const char *git_pager(int stdout_is_tty)
  88 {
  89         const char *pager;
  90
  91         if (!stdout_is_tty)
  92                 return NULL;
  93
  94         pager = getenv("GIT_PAGER");
  95         if (!pager) {
  96                 if (!pager_program)
  97                         read_early_config(the_repository,
  98                                           core_pager_config, NULL);
  99                 pager = pager_program;
 100         }
 101         if (!pager)
 102                 pager = getenv("PAGER");
 103         if (!pager)
 104                 pager = DEFAULT_PAGER;
 105         if (!*pager || !strcmp(pager, "cat"))
 106                 pager = NULL;
 107
 108         return pager;
 109 }
 110
 111 static void setup_pager_env(struct strvec *env)
 112 {
 113         const char **argv;
 114         int i;
 115         char *pager_env = xstrdup(PAGER_ENV);
 116         int n = split_cmdline(pager_env, &argv);
 117
 118         if (n < 0)
 119                 die("malformed build-time PAGER_ENV: %s",
 120                         split_cmdline_strerror(n));
 121
 122         for (i = 0; i < n; i++) {
 123                 char *cp = strchr(argv[i], '=');
 124
 125                 if (!cp)
 126                         die("malformed build-time PAGER_ENV");
 127
 128                 *cp = '\0';
 129                 if (!getenv(argv[i])) {
 130                         *cp = '=';
 131                         strvec_push(env, argv[i]);
 132                 }
 133         }
 134         free(pager_env);
 135         free(argv);
 136 }
 137
 138 void prepare_pager_args(struct child_process *pager_process, const char *pager)
 139 {
 140         strvec_push(&pager_process->args, pager);
 141         pager_process->use_shell = 1;
 142         setup_pager_env(&pager_process->env);
 143         pager_process->trace2_child_class = "pager";
 144 }
 145
 146 void setup_pager(void)
 147 {
 148         static int once = 0;
 149         const char *pager = git_pager(isatty(1));
 150
 151         if (!pager)
 152                 return;
 153
 154         /*
 155          * After we redirect standard output, we won't be able to use an ioctl
 156          * to get the terminal size. Let's grab it now, and then set $COLUMNS
 157          * to communicate it to any sub-processes.
 158          */
 159         {
 160                 char buf[64];
 161                 xsnprintf(buf, sizeof(buf), "%d", term_columns());
 162                 if (!term_columns_guessed)
 163                         setenv("COLUMNS", buf, 0);
 164         }
 165
 166         setenv("GIT_PAGER_IN_USE", "true", 1);
 167
 168         child_process_init(&pager_process);
 169
 170         /* spawn the pager */
 171         prepare_pager_args(&pager_process, pager);
 172         pager_process.in = -1;
 173         strvec_push(&pager_process.env, "GIT_PAGER_IN_USE");
 174         if (start_command(&pager_process))
 175                 die("unable to execute pager '%s'", pager);
 176
 177         /* original process continues, but writes to the pipe */
 178         old_fd1 = dup(1);
 179         dup2(pager_process.in, 1);
 180         if (isatty(2)) {
 181                 old_fd2 = dup(2);
 182                 dup2(pager_process.in, 2);
 183         }
 184         close(pager_process.in);
 185
 186         sigchain_push_common(wait_for_pager_signal);
 187
 188         if (!once) {
 189                 once++;
 190                 atexit(wait_for_pager_atexit);
 191         }
 192 }
 193
 194 int pager_in_use(void)
 195 {
 196         return git_env_bool("GIT_PAGER_IN_USE", 0);
 197 }
 198
 199 /*
 200  * Return cached value (if set) or $COLUMNS environment variable (if
 201  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 202  * and default to 80 if all else fails.
 203  */
 204 int term_columns(void)
 205 {
 206         static int term_columns_at_startup;
 207
 208         char *col_string;
 209         int n_cols;
 210
 211         if (term_columns_at_startup)
 212                 return term_columns_at_startup;
 213
 214         term_columns_at_startup = 80;
 215         term_columns_guessed = 1;
 216
 217         col_string = getenv("COLUMNS");
 218         if (col_string && (n_cols = atoi(col_string)) > 0) {
 219                 term_columns_at_startup = n_cols;
 220                 term_columns_guessed = 0;
 221         }
 222 #ifdef TIOCGWINSZ
 223         else {
 224                 struct winsize ws;
 225                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {
 226                         term_columns_at_startup = ws.ws_col;
 227                         term_columns_guessed = 0;
 228                 }
 229         }
 230 #endif
 231
 232         return term_columns_at_startup;
 233 }
 234
 235 /*
 236  * Clear the entire line, leave cursor in first column.
 237  */
 238 void term_clear_line(void)
 239 {
 240         if (!isatty(2))
 241                 return;
 242         if (is_terminal_dumb())
 243                 /*
 244                  * Fall back to print a terminal width worth of space
 245                  * characters (hoping that the terminal is still as wide
 246                  * as it was upon the first call to term_columns()).
 247                  */
 248                 fprintf(stderr, "\r%*s\r", term_columns(), "");
 249         else
 250                 /*
 251                  * On non-dumb terminals use an escape sequence to clear
 252                  * the whole line, no matter how wide the terminal.
 253                  */
 254                 fputs("\r\033[K", stderr);
 255 }
 256
 257 /*
 258  * How many columns do we need to show this number in decimal?
 259  */
 260 int decimal_width(uintmax_t number)
 261 {
 262         int width;
 263
 264         for (width = 1; number >= 10; width++)
 265                 number /= 10;
 266         return width;
 267 }
 268
 269 struct pager_command_config_data {
 270         const char *cmd;
 271         int want;
 272         char *value;
 273 };
 274
 275 static int pager_command_config(const char *var, const char *value,
 276                                 const struct config_context *ctx UNUSED,
 277                                 void *vdata)
 278 {
 279         struct pager_command_config_data *data = vdata;
 280         const char *cmd;
 281
 282         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 283                 int b = git_parse_maybe_bool(value);
 284                 if (b >= 0)
 285                         data->want = b;
 286                 else {
 287                         data->want = 1;
 288                         data->value = xstrdup(value);
 289                 }
 290         }
 291
 292         return 0;
 293 }
 294
 295 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 296 int check_pager_config(const char *cmd)
 297 {
 298         struct pager_command_config_data data;
 299
 300         data.cmd = cmd;
 301         data.want = -1;
 302         data.value = NULL;
 303
 304         read_early_config(the_repository, pager_command_config, &data);
 305
 306         if (data.value)
 307                 pager_program = data.value;
 308         return data.want;
 309 }