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 static struct child_process pager_process = CHILD_PROCESS_INIT;
  10 static const char *pager_program;
  11
  12 static void wait_for_pager(int in_signal)
  13 {
  14         if (!in_signal) {
  15                 fflush(stdout);
  16                 fflush(stderr);
  17         }
  18         /* signal EOF to pager */
  19         close(1);
  20         close(2);
  21         if (in_signal)
  22                 finish_command_in_signal(&pager_process);
  23         else
  24                 finish_command(&pager_process);
  25 }
  26
  27 static void wait_for_pager_atexit(void)
  28 {
  29         wait_for_pager(0);
  30 }
  31
  32 static void wait_for_pager_signal(int signo)
  33 {
  34         wait_for_pager(1);
  35         sigchain_pop(signo);
  36         raise(signo);
  37 }
  38
  39 static int core_pager_config(const char *var, const char *value, void *data)
  40 {
  41         if (!strcmp(var, "core.pager"))
  42                 return git_config_string(&pager_program, var, value);
  43         return 0;
  44 }
  45
  46 const char *git_pager(int stdout_is_tty)
  47 {
  48         const char *pager;
  49
  50         if (!stdout_is_tty)
  51                 return NULL;
  52
  53         pager = getenv("GIT_PAGER");
  54         if (!pager) {
  55                 if (!pager_program)
  56                         read_early_config(core_pager_config, NULL);
  57                 pager = pager_program;
  58         }
  59         if (!pager)
  60                 pager = getenv("PAGER");
  61         if (!pager)
  62                 pager = DEFAULT_PAGER;
  63         if (!*pager || !strcmp(pager, "cat"))
  64                 pager = NULL;
  65
  66         return pager;
  67 }
  68
  69 static void setup_pager_env(struct argv_array *env)
  70 {
  71         const char **argv;
  72         int i;
  73         char *pager_env = xstrdup(PAGER_ENV);
  74         int n = split_cmdline(pager_env, &argv);
  75
  76         if (n < 0)
  77                 die("malformed build-time PAGER_ENV: %s",
  78                         split_cmdline_strerror(n));
  79
  80         for (i = 0; i < n; i++) {
  81                 char *cp = strchr(argv[i], '=');
  82
  83                 if (!cp)
  84                         die("malformed build-time PAGER_ENV");
  85
  86                 *cp = '\0';
  87                 if (!getenv(argv[i])) {
  88                         *cp = '=';
  89                         argv_array_push(env, argv[i]);
  90                 }
  91         }
  92         free(pager_env);
  93         free(argv);
  94 }
  95
  96 void prepare_pager_args(struct child_process *pager_process, const char *pager)
  97 {
  98         argv_array_push(&pager_process->args, pager);
  99         pager_process->use_shell = 1;
 100         setup_pager_env(&pager_process->env_array);
 101 }
 102
 103 void setup_pager(void)
 104 {
 105         const char *pager = git_pager(isatty(1));
 106
 107         if (!pager)
 108                 return;
 109
 110         /*
 111          * force computing the width of the terminal before we redirect
 112          * the standard output to the pager.
 113          */
 114         (void) term_columns();
 115
 116         setenv("GIT_PAGER_IN_USE", "true", 1);
 117
 118         /* spawn the pager */
 119         prepare_pager_args(&pager_process, pager);
 120         pager_process.in = -1;
 121         argv_array_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
 122         if (start_command(&pager_process))
 123                 return;
 124
 125         /* original process continues, but writes to the pipe */
 126         dup2(pager_process.in, 1);
 127         if (isatty(2))
 128                 dup2(pager_process.in, 2);
 129         close(pager_process.in);
 130
 131         /* this makes sure that the parent terminates after the pager */
 132         sigchain_push_common(wait_for_pager_signal);
 133         atexit(wait_for_pager_atexit);
 134 }
 135
 136 int pager_in_use(void)
 137 {
 138         return git_env_bool("GIT_PAGER_IN_USE", 0);
 139 }
 140
 141 /*
 142  * Return cached value (if set) or $COLUMNS environment variable (if
 143  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 144  * and default to 80 if all else fails.
 145  */
 146 int term_columns(void)
 147 {
 148         static int term_columns_at_startup;
 149
 150         char *col_string;
 151         int n_cols;
 152
 153         if (term_columns_at_startup)
 154                 return term_columns_at_startup;
 155
 156         term_columns_at_startup = 80;
 157
 158         col_string = getenv("COLUMNS");
 159         if (col_string && (n_cols = atoi(col_string)) > 0)
 160                 term_columns_at_startup = n_cols;
 161 #ifdef TIOCGWINSZ
 162         else {
 163                 struct winsize ws;
 164                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 165                         term_columns_at_startup = ws.ws_col;
 166         }
 167 #endif
 168
 169         return term_columns_at_startup;
 170 }
 171
 172 /*
 173  * How many columns do we need to show this number in decimal?
 174  */
 175 int decimal_width(uintmax_t number)
 176 {
 177         int width;
 178
 179         for (width = 1; number >= 10; width++)
 180                 number /= 10;
 181         return width;
 182 }
 183
 184 struct pager_command_config_data {
 185         const char *cmd;
 186         int want;
 187         char *value;
 188 };
 189
 190 static int pager_command_config(const char *var, const char *value, void *vdata)
 191 {
 192         struct pager_command_config_data *data = vdata;
 193         const char *cmd;
 194
 195         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 196                 int b = git_config_maybe_bool(var, value);
 197                 if (b >= 0)
 198                         data->want = b;
 199                 else {
 200                         data->want = 1;
 201                         data->value = xstrdup(value);
 202                 }
 203         }
 204
 205         return 0;
 206 }
 207
 208 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 209 int check_pager_config(const char *cmd)
 210 {
 211         struct pager_command_config_data data;
 212
 213         data.cmd = cmd;
 214         data.want = -1;
 215         data.value = NULL;
 216
 217         read_early_config(pager_command_config, &data);
 218
 219         if (data.value)
 220                 pager_program = data.value;
 221         return data.want;
 222 }