pager.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "run-command.h"
   4 #include "sigchain.h"
   5
   6 #ifndef DEFAULT_PAGER
   7 #define DEFAULT_PAGER "less"
   8 #endif
   9
  10 static struct child_process pager_process = CHILD_PROCESS_INIT;
  11 static const char *pager_program;
  12
  13 static void wait_for_pager(int in_signal)
  14 {
  15         if (!in_signal) {
  16                 fflush(stdout);
  17                 fflush(stderr);
  18         }
  19         /* signal EOF to pager */
  20         close(1);
  21         close(2);
  22         if (in_signal)
  23                 finish_command_in_signal(&pager_process);
  24         else
  25                 finish_command(&pager_process);
  26 }
  27
  28 static void wait_for_pager_atexit(void)
  29 {
  30         wait_for_pager(0);
  31 }
  32
  33 static void wait_for_pager_signal(int signo)
  34 {
  35         wait_for_pager(1);
  36         sigchain_pop(signo);
  37         raise(signo);
  38 }
  39
  40 static int core_pager_config(const char *var, const char *value, void *data)
  41 {
  42         if (!strcmp(var, "core.pager"))
  43                 return git_config_string(&pager_program, var, value);
  44         return 0;
  45 }
  46
  47 const char *git_pager(int stdout_is_tty)
  48 {
  49         const char *pager;
  50
  51         if (!stdout_is_tty)
  52                 return NULL;
  53
  54         pager = getenv("GIT_PAGER");
  55         if (!pager) {
  56                 if (!pager_program)
  57                         read_early_config(core_pager_config, NULL);
  58                 pager = pager_program;
  59         }
  60         if (!pager)
  61                 pager = getenv("PAGER");
  62         if (!pager)
  63                 pager = DEFAULT_PAGER;
  64         if (!*pager || !strcmp(pager, "cat"))
  65                 pager = NULL;
  66
  67         return pager;
  68 }
  69
  70 static void setup_pager_env(struct argv_array *env)
  71 {
  72         const char **argv;
  73         int i;
  74         char *pager_env = xstrdup(PAGER_ENV);
  75         int n = split_cmdline(pager_env, &argv);
  76
  77         if (n < 0)
  78                 die("malformed build-time PAGER_ENV: %s",
  79                         split_cmdline_strerror(n));
  80
  81         for (i = 0; i < n; i++) {
  82                 char *cp = strchr(argv[i], '=');
  83
  84                 if (!cp)
  85                         die("malformed build-time PAGER_ENV");
  86
  87                 *cp = '\0';
  88                 if (!getenv(argv[i])) {
  89                         *cp = '=';
  90                         argv_array_push(env, argv[i]);
  91                 }
  92         }
  93         free(pager_env);
  94         free(argv);
  95 }
  96
  97 void prepare_pager_args(struct child_process *pager_process, const char *pager)
  98 {
  99         argv_array_push(&pager_process->args, pager);
 100         pager_process->use_shell = 1;
 101         setup_pager_env(&pager_process->env_array);
 102 }
 103
 104 void setup_pager(void)
 105 {
 106         const char *pager = git_pager(isatty(1));
 107
 108         if (!pager)
 109                 return;
 110
 111         /*
 112          * force computing the width of the terminal before we redirect
 113          * the standard output to the pager.
 114          */
 115         (void) term_columns();
 116
 117         setenv("GIT_PAGER_IN_USE", "true", 1);
 118
 119         /* spawn the pager */
 120         prepare_pager_args(&pager_process, pager);
 121         pager_process.in = -1;
 122         argv_array_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
 123         if (start_command(&pager_process))
 124                 return;
 125
 126         /* original process continues, but writes to the pipe */
 127         dup2(pager_process.in, 1);
 128         if (isatty(2))
 129                 dup2(pager_process.in, 2);
 130         close(pager_process.in);
 131
 132         /* this makes sure that the parent terminates after the pager */
 133         sigchain_push_common(wait_for_pager_signal);
 134         atexit(wait_for_pager_atexit);
 135 }
 136
 137 int pager_in_use(void)
 138 {
 139         return git_env_bool("GIT_PAGER_IN_USE", 0);
 140 }
 141
 142 /*
 143  * Return cached value (if set) or $COLUMNS environment variable (if
 144  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 145  * and default to 80 if all else fails.
 146  */
 147 int term_columns(void)
 148 {
 149         static int term_columns_at_startup;
 150
 151         char *col_string;
 152         int n_cols;
 153
 154         if (term_columns_at_startup)
 155                 return term_columns_at_startup;
 156
 157         term_columns_at_startup = 80;
 158
 159         col_string = getenv("COLUMNS");
 160         if (col_string && (n_cols = atoi(col_string)) > 0)
 161                 term_columns_at_startup = n_cols;
 162 #ifdef TIOCGWINSZ
 163         else {
 164                 struct winsize ws;
 165                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 166                         term_columns_at_startup = ws.ws_col;
 167         }
 168 #endif
 169
 170         return term_columns_at_startup;
 171 }
 172
 173 /*
 174  * How many columns do we need to show this number in decimal?
 175  */
 176 int decimal_width(uintmax_t number)
 177 {
 178         int width;
 179
 180         for (width = 1; number >= 10; width++)
 181                 number /= 10;
 182         return width;
 183 }
 184
 185 struct pager_command_config_data {
 186         const char *cmd;
 187         int want;
 188         char *value;
 189 };
 190
 191 static int pager_command_config(const char *var, const char *value, void *vdata)
 192 {
 193         struct pager_command_config_data *data = vdata;
 194         const char *cmd;
 195
 196         if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {
 197                 int b = git_config_maybe_bool(var, value);
 198                 if (b >= 0)
 199                         data->want = b;
 200                 else {
 201                         data->want = 1;
 202                         data->value = xstrdup(value);
 203                 }
 204         }
 205
 206         return 0;
 207 }
 208
 209 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 210 int check_pager_config(const char *cmd)
 211 {
 212         struct pager_command_config_data data;
 213
 214         data.cmd = cmd;
 215         data.want = -1;
 216         data.value = NULL;
 217
 218         read_early_config(pager_command_config, &data);
 219
 220         if (data.value)
 221                 pager_program = data.value;
 222         return data.want;
 223 }