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