pager.c

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