pager.c

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