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(struct repository *r, 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(r,
  96                                           core_pager_config, NULL);
  97                 pager = pager_program;
  98         }
  99         if (!pager)
 100                 pager = getenv("PAGER");
 101         if (!pager)
 102                 pager = DEFAULT_PAGER;
 103         if (!*pager || !strcmp(pager, "cat"))
 104                 pager = NULL;
 105
 106         return pager;
 107 }
 108
 109 static void setup_pager_env(struct strvec *env)
 110 {
 111         const char **argv;
 112         int i;
 113         char *pager_env = xstrdup(PAGER_ENV);
 114         int n = split_cmdline(pager_env, &argv);
 115
 116         if (n < 0)
 117                 die("malformed build-time PAGER_ENV: %s",
 118                         split_cmdline_strerror(n));
 119
 120         for (i = 0; i < n; i++) {
 121                 char *cp = strchr(argv[i], '=');
 122
 123                 if (!cp)
 124                         die("malformed build-time PAGER_ENV");
 125
 126                 *cp = '\0';
 127                 if (!getenv(argv[i])) {
 128                         *cp = '=';
 129                         strvec_push(env, argv[i]);
 130                 }
 131         }
 132         free(pager_env);
 133         free(argv);
 134 }
 135
 136 void prepare_pager_args(struct child_process *pager_process, const char *pager)
 137 {
 138         strvec_push(&pager_process->args, pager);
 139         pager_process->use_shell = 1;
 140         setup_pager_env(&pager_process->env);
 141         pager_process->trace2_child_class = "pager";
 142 }
 143
 144 void setup_pager(struct repository *r)
 145 {
 146         static int once = 0;
 147         const char *pager = git_pager(r, isatty(1));
 148
 149         if (!pager)
 150                 return;
 151
 152         /*
 153          * After we redirect standard output, we won't be able to use an ioctl
 154          * to get the terminal size. Let's grab it now, and then set $COLUMNS
 155          * to communicate it to any sub-processes.
 156          */
 157         {
 158                 char buf[64];
 159                 xsnprintf(buf, sizeof(buf), "%d", term_columns());
 160                 if (!term_columns_guessed)
 161                         setenv("COLUMNS", buf, 0);
 162         }
 163
 164         setenv("GIT_PAGER_IN_USE", "true", 1);
 165
 166         child_process_init(&pager_process);
 167
 168         /* spawn the pager */
 169         prepare_pager_args(&pager_process, pager);
 170         pager_process.in = -1;
 171         strvec_push(&pager_process.env, "GIT_PAGER_IN_USE");
 172         if (start_command(&pager_process))
 173                 die("unable to execute pager '%s'", pager);
 174
 175         /* original process continues, but writes to the pipe */
 176         old_fd1 = dup(1);
 177         dup2(pager_process.in, 1);
 178         if (isatty(2)) {
 179                 old_fd2 = dup(2);
 180                 dup2(pager_process.in, 2);
 181         }
 182         close(pager_process.in);
 183
 184         sigchain_push_common(wait_for_pager_signal);
 185
 186         if (!once) {
 187                 once++;
 188                 atexit(wait_for_pager_atexit);
 189         }
 190 }
 191
 192 int pager_in_use(void)
 193 {
 194         return git_env_bool("GIT_PAGER_IN_USE", 0);
 195 }
 196
 197 /*
 198  * Return cached value (if set) or $COLUMNS environment variable (if
 199  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 200  * and default to 80 if all else fails.
 201  */
 202 int term_columns(void)
 203 {
 204         static int term_columns_at_startup;
 205
 206         char *col_string;
 207         int n_cols;
 208
 209         if (term_columns_at_startup)
 210                 return term_columns_at_startup;
 211
 212         term_columns_at_startup = 80;
 213         term_columns_guessed = 1;
 214
 215         col_string = getenv("COLUMNS");
 216         if (col_string && (n_cols = atoi(col_string)) > 0) {
 217                 term_columns_at_startup = n_cols;
 218                 term_columns_guessed = 0;
 219         }
 220 #ifdef TIOCGWINSZ
 221         else {
 222                 struct winsize ws;
 223                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {
 224                         term_columns_at_startup = ws.ws_col;
 225                         term_columns_guessed = 0;
 226                 }
 227         }
 228 #endif
 229
 230         return term_columns_at_startup;
 231 }
 232
 233 /*
 234  * Clear the entire line, leave cursor in first column.
 235  */
 236 void term_clear_line(void)
 237 {
 238         if (!isatty(2))
 239                 return;
 240         if (is_terminal_dumb())
 241                 /*
 242                  * Fall back to print a terminal width worth of space
 243                  * characters (hoping that the terminal is still as wide
 244                  * as it was upon the first call to term_columns()).
 245                  */
 246                 fprintf(stderr, "\r%*s\r", term_columns(), "");
 247         else
 248                 /*
 249                  * On non-dumb terminals use an escape sequence to clear
 250                  * the whole line, no matter how wide the terminal.
 251                  */
 252                 fputs("\r\033[K", stderr);
 253 }
 254
 255 /*
 256  * How many columns do we need to show this number in decimal?
 257  */
 258 int decimal_width(uintmax_t number)
 259 {
 260         int width;
 261
 262         for (width = 1; number >= 10; width++)
 263                 number /= 10;
 264         return width;
 265 }
 266
 267 struct pager_command_config_data {
 268         const char *cmd;
 269         int want;
 270         char *value;
 271 };
 272
 273 static int pager_command_config(const char *var, const char *value,
 274                                 const struct config_context *ctx UNUSED,
 275                                 void *vdata)
 276 {
 277         struct pager_command_config_data *data = vdata;
 278         const char *cmd;
 279
 280         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 281                 int b = git_parse_maybe_bool(value);
 282                 if (b >= 0)
 283                         data->want = b;
 284                 else {
 285                         data->want = 1;
 286                         data->value = xstrdup(value);
 287                 }
 288         }
 289
 290         return 0;
 291 }
 292
 293 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 294 int check_pager_config(struct repository *r, const char *cmd)
 295 {
 296         struct pager_command_config_data data;
 297
 298         data.cmd = cmd;
 299         data.want = -1;
 300         data.value = NULL;
 301
 302         read_early_config(r, pager_command_config, &data);
 303
 304         if (data.value)
 305                 pager_program = data.value;
 306         return data.want;
 307 }