pager.c

   1 #include "cache.h"
   2 #include "run-command.h"
   3 #include "sigchain.h"
   4
   5 #ifndef DEFAULT_PAGER
   6 #define DEFAULT_PAGER "less"
   7 #endif
   8
   9 /*
  10  * This is split up from the rest of git so that we can do
  11  * something different on Windows.
  12  */
  13
  14 static struct child_process pager_process = CHILD_PROCESS_INIT;
  15
  16 static void wait_for_pager(int in_signal)
  17 {
  18         if (!in_signal) {
  19                 fflush(stdout);
  20                 fflush(stderr);
  21         }
  22         /* signal EOF to pager */
  23         close(1);
  24         close(2);
  25         if (in_signal)
  26                 finish_command_in_signal(&pager_process);
  27         else
  28                 finish_command(&pager_process);
  29 }
  30
  31 static void wait_for_pager_atexit(void)
  32 {
  33         wait_for_pager(0);
  34 }
  35
  36 static void wait_for_pager_signal(int signo)
  37 {
  38         wait_for_pager(1);
  39         sigchain_pop(signo);
  40         raise(signo);
  41 }
  42
  43 const char *git_pager(int stdout_is_tty)
  44 {
  45         const char *pager;
  46
  47         if (!stdout_is_tty)
  48                 return NULL;
  49
  50         pager = getenv("GIT_PAGER");
  51         if (!pager) {
  52                 if (!pager_program)
  53                         git_config(git_default_config, NULL);
  54                 pager = pager_program;
  55         }
  56         if (!pager)
  57                 pager = getenv("PAGER");
  58         if (!pager)
  59                 pager = DEFAULT_PAGER;
  60         if (!*pager || !strcmp(pager, "cat"))
  61                 pager = NULL;
  62
  63         return pager;
  64 }
  65
  66 static void setup_pager_env(struct argv_array *env)
  67 {
  68         const char **argv;
  69         int i;
  70         char *pager_env = xstrdup(PAGER_ENV);
  71         int n = split_cmdline(pager_env, &argv);
  72
  73         if (n < 0)
  74                 die("malformed build-time PAGER_ENV: %s",
  75                         split_cmdline_strerror(n));
  76
  77         for (i = 0; i < n; i++) {
  78                 char *cp = strchr(argv[i], '=');
  79
  80                 if (!cp)
  81                         die("malformed build-time PAGER_ENV");
  82
  83                 *cp = '\0';
  84                 if (!getenv(argv[i])) {
  85                         *cp = '=';
  86                         argv_array_push(env, argv[i]);
  87                 }
  88         }
  89         free(pager_env);
  90         free(argv);
  91 }
  92
  93 void prepare_pager_args(struct child_process *pager_process, const char *pager)
  94 {
  95         argv_array_push(&pager_process->args, pager);
  96         pager_process->use_shell = 1;
  97         setup_pager_env(&pager_process->env_array);
  98 }
  99
 100 void setup_pager(void)
 101 {
 102         const char *pager = git_pager(isatty(1));
 103
 104         if (!pager)
 105                 return;
 106
 107         /*
 108          * force computing the width of the terminal before we redirect
 109          * the standard output to the pager.
 110          */
 111         (void) term_columns();
 112
 113         setenv("GIT_PAGER_IN_USE", "true", 1);
 114
 115         /* spawn the pager */
 116         prepare_pager_args(&pager_process, pager);
 117         pager_process.in = -1;
 118         argv_array_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
 119         if (start_command(&pager_process))
 120                 return;
 121
 122         /* original process continues, but writes to the pipe */
 123         dup2(pager_process.in, 1);
 124         if (isatty(2))
 125                 dup2(pager_process.in, 2);
 126         close(pager_process.in);
 127
 128         /* this makes sure that the parent terminates after the pager */
 129         sigchain_push_common(wait_for_pager_signal);
 130         atexit(wait_for_pager_atexit);
 131 }
 132
 133 int pager_in_use(void)
 134 {
 135         const char *env;
 136         env = getenv("GIT_PAGER_IN_USE");
 137         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 138 }
 139
 140 /*
 141  * Return cached value (if set) or $COLUMNS environment variable (if
 142  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 143  * and default to 80 if all else fails.
 144  */
 145 int term_columns(void)
 146 {
 147         static int term_columns_at_startup;
 148
 149         char *col_string;
 150         int n_cols;
 151
 152         if (term_columns_at_startup)
 153                 return term_columns_at_startup;
 154
 155         term_columns_at_startup = 80;
 156
 157         col_string = getenv("COLUMNS");
 158         if (col_string && (n_cols = atoi(col_string)) > 0)
 159                 term_columns_at_startup = n_cols;
 160 #ifdef TIOCGWINSZ
 161         else {
 162                 struct winsize ws;
 163                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 164                         term_columns_at_startup = ws.ws_col;
 165         }
 166 #endif
 167
 168         return term_columns_at_startup;
 169 }
 170
 171 /*
 172  * How many columns do we need to show this number in decimal?
 173  */
 174 int decimal_width(uintmax_t number)
 175 {
 176         int width;
 177
 178         for (width = 1; number >= 10; width++)
 179                 number /= 10;
 180         return width;
 181 }
 182
 183 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 184 int check_pager_config(const char *cmd)
 185 {
 186         int want = -1;
 187         struct strbuf key = STRBUF_INIT;
 188         const char *value = NULL;
 189         strbuf_addf(&key, "pager.%s", cmd);
 190         if (git_config_key_is_valid(key.buf) &&
 191             !git_config_get_value(key.buf, &value)) {
 192                 int b = git_config_maybe_bool(key.buf, value);
 193                 if (b >= 0)
 194                         want = b;
 195                 else {
 196                         want = 1;
 197                         pager_program = xstrdup(value);
 198                 }
 199         }
 200         strbuf_release(&key);
 201         return want;
 202 }