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 static void setup_pager_env(struct argv_array *env)
 101 {
 102         const char **argv;
 103         int i;
 104         char *pager_env = xstrdup(PAGER_ENV);
 105         int n = split_cmdline(pager_env, &argv);
 106
 107         if (n < 0)
 108                 die("malformed build-time PAGER_ENV: %s",
 109                         split_cmdline_strerror(n));
 110
 111         for (i = 0; i < n; i++) {
 112                 char *cp = strchr(argv[i], '=');
 113
 114                 if (!cp)
 115                         die("malformed build-time PAGER_ENV");
 116
 117                 *cp = '\0';
 118                 if (!getenv(argv[i])) {
 119                         *cp = '=';
 120                         argv_array_push(env, argv[i]);
 121                 }
 122         }
 123         free(pager_env);
 124         free(argv);
 125 }
 126
 127 void prepare_pager_args(struct child_process *pager_process, const char *pager)
 128 {
 129         argv_array_push(&pager_process->args, pager);
 130         pager_process->use_shell = 1;
 131         setup_pager_env(&pager_process->env_array);
 132 }
 133
 134 void setup_pager(void)
 135 {
 136         const char *pager = git_pager(isatty(1));
 137
 138         if (!pager)
 139                 return;
 140
 141         /*
 142          * force computing the width of the terminal before we redirect
 143          * the standard output to the pager.
 144          */
 145         (void) term_columns();
 146
 147         setenv("GIT_PAGER_IN_USE", "true", 1);
 148
 149         /* spawn the pager */
 150         prepare_pager_args(&pager_process, pager);
 151         pager_process.in = -1;
 152         argv_array_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
 153         if (start_command(&pager_process))
 154                 return;
 155
 156         /* original process continues, but writes to the pipe */
 157         dup2(pager_process.in, 1);
 158         if (isatty(2))
 159                 dup2(pager_process.in, 2);
 160         close(pager_process.in);
 161
 162         /* this makes sure that the parent terminates after the pager */
 163         sigchain_push_common(wait_for_pager_signal);
 164         atexit(wait_for_pager_atexit);
 165 }
 166
 167 int pager_in_use(void)
 168 {
 169         const char *env;
 170         env = getenv("GIT_PAGER_IN_USE");
 171         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 172 }
 173
 174 /*
 175  * Return cached value (if set) or $COLUMNS environment variable (if
 176  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 177  * and default to 80 if all else fails.
 178  */
 179 int term_columns(void)
 180 {
 181         static int term_columns_at_startup;
 182
 183         char *col_string;
 184         int n_cols;
 185
 186         if (term_columns_at_startup)
 187                 return term_columns_at_startup;
 188
 189         term_columns_at_startup = 80;
 190
 191         col_string = getenv("COLUMNS");
 192         if (col_string && (n_cols = atoi(col_string)) > 0)
 193                 term_columns_at_startup = n_cols;
 194 #ifdef TIOCGWINSZ
 195         else {
 196                 struct winsize ws;
 197                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 198                         term_columns_at_startup = ws.ws_col;
 199         }
 200 #endif
 201
 202         return term_columns_at_startup;
 203 }
 204
 205 /*
 206  * How many columns do we need to show this number in decimal?
 207  */
 208 int decimal_width(uintmax_t number)
 209 {
 210         int width;
 211
 212         for (width = 1; number >= 10; width++)
 213                 number /= 10;
 214         return width;
 215 }
 216
 217 struct pager_command_config_data {
 218         const char *cmd;
 219         int want;
 220         char *value;
 221 };
 222
 223 static int pager_command_config(const char *var, const char *value, void *vdata)
 224 {
 225         struct pager_command_config_data *data = vdata;
 226         const char *cmd;
 227
 228         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 229                 int b = git_config_maybe_bool(var, value);
 230                 if (b >= 0)
 231                         data->want = b;
 232                 else {
 233                         data->want = 1;
 234                         data->value = xstrdup(value);
 235                 }
 236         }
 237
 238         return 0;
 239 }
 240
 241 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 242 int check_pager_config(const char *cmd)
 243 {
 244         struct pager_command_config_data data;
 245
 246         data.cmd = cmd;
 247         data.want = -1;
 248         data.value = NULL;
 249
 250         read_early_config(pager_command_config, &data);
 251
 252         if (data.value)
 253                 pager_program = data.value;
 254         return data.want;
 255 }