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