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 static void read_early_config(config_fn_t cb, void *data)
  47 {
  48         git_config_with_options(cb, data, NULL, 1);
  49
  50         /*
  51          * Note that this is a really dirty hack that does the wrong thing in
  52          * many cases. The crux of the problem is that we cannot run
  53          * setup_git_directory() early on in git's setup, so we have no idea if
  54          * we are in a repository or not, and therefore are not sure whether
  55          * and how to read repository-local config.
  56          *
  57          * So if we _aren't_ in a repository (or we are but we would reject its
  58          * core.repositoryformatversion), we'll read whatever is in .git/config
  59          * blindly. Similarly, if we _are_ in a repository, but not at the
  60          * root, we'll fail to find .git/config (because it's really
  61          * ../.git/config, etc). See t7006 for a complete set of failures.
  62          *
  63          * However, we have historically provided this hack because it does
  64          * work some of the time (namely when you are at the top-level of a
  65          * valid repository), and would rarely make things worse (i.e., you do
  66          * not generally have a .git/config file sitting around).
  67          */
  68         if (!startup_info->have_repository) {
  69                 struct git_config_source repo_config;
  70
  71                 memset(&repo_config, 0, sizeof(repo_config));
  72                 repo_config.file = ".git/config";
  73                 git_config_with_options(cb, data, &repo_config, 1);
  74         }
  75 }
  76
  77 const char *git_pager(int stdout_is_tty)
  78 {
  79         const char *pager;
  80
  81         if (!stdout_is_tty)
  82                 return NULL;
  83
  84         pager = getenv("GIT_PAGER");
  85         if (!pager) {
  86                 if (!pager_program)
  87                         read_early_config(core_pager_config, NULL);
  88                 pager = pager_program;
  89         }
  90         if (!pager)
  91                 pager = getenv("PAGER");
  92         if (!pager)
  93                 pager = DEFAULT_PAGER;
  94         if (!*pager || !strcmp(pager, "cat"))
  95                 pager = NULL;
  96
  97         return pager;
  98 }
  99
 100 void prepare_pager_args(struct child_process *pager_process, const char *pager)
 101 {
 102         argv_array_push(&pager_process->args, pager);
 103         pager_process->use_shell = 1;
 104         if (!getenv("LESS"))
 105                 argv_array_push(&pager_process->env_array, "LESS=FRX");
 106         if (!getenv("LV"))
 107                 argv_array_push(&pager_process->env_array, "LV=-c");
 108 }
 109
 110 void setup_pager(void)
 111 {
 112         const char *pager = git_pager(isatty(1));
 113
 114         if (!pager)
 115                 return;
 116
 117         /*
 118          * force computing the width of the terminal before we redirect
 119          * the standard output to the pager.
 120          */
 121         (void) term_columns();
 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         const char *env;
 146         env = getenv("GIT_PAGER_IN_USE");
 147         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 148 }
 149
 150 /*
 151  * Return cached value (if set) or $COLUMNS environment variable (if
 152  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 153  * and default to 80 if all else fails.
 154  */
 155 int term_columns(void)
 156 {
 157         static int term_columns_at_startup;
 158
 159         char *col_string;
 160         int n_cols;
 161
 162         if (term_columns_at_startup)
 163                 return term_columns_at_startup;
 164
 165         term_columns_at_startup = 80;
 166
 167         col_string = getenv("COLUMNS");
 168         if (col_string && (n_cols = atoi(col_string)) > 0)
 169                 term_columns_at_startup = n_cols;
 170 #ifdef TIOCGWINSZ
 171         else {
 172                 struct winsize ws;
 173                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 174                         term_columns_at_startup = ws.ws_col;
 175         }
 176 #endif
 177
 178         return term_columns_at_startup;
 179 }
 180
 181 /*
 182  * How many columns do we need to show this number in decimal?
 183  */
 184 int decimal_width(uintmax_t number)
 185 {
 186         int width;
 187
 188         for (width = 1; number >= 10; width++)
 189                 number /= 10;
 190         return width;
 191 }
 192
 193 struct pager_command_config_data {
 194         const char *cmd;
 195         int want;
 196         char *value;
 197 };
 198
 199 static int pager_command_config(const char *var, const char *value, void *vdata)
 200 {
 201         struct pager_command_config_data *data = vdata;
 202         const char *cmd;
 203
 204         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 205                 int b = git_config_maybe_bool(var, value);
 206                 if (b >= 0)
 207                         data->want = b;
 208                 else {
 209                         data->want = 1;
 210                         data->value = xstrdup(value);
 211                 }
 212         }
 213
 214         return 0;
 215 }
 216
 217 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 218 int check_pager_config(const char *cmd)
 219 {
 220         struct pager_command_config_data data;
 221
 222         data.cmd = cmd;
 223         data.want = -1;
 224         data.value = NULL;
 225
 226         read_early_config(pager_command_config, &data);
 227
 228         if (data.value)
 229                 pager_program = data.value;
 230         return data.want;
 231 }