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 /*
  10  * This is split up from the rest of git so that we can do
  11  * something different on Windows.
  12  */
  13
  14 static const char *pager_argv[] = { NULL, NULL };
  15 static struct child_process pager_process = CHILD_PROCESS_INIT;
  16
  17 static void wait_for_pager(int in_signal)
  18 {
  19         if (!in_signal) {
  20                 fflush(stdout);
  21                 fflush(stderr);
  22         }
  23         /* signal EOF to pager */
  24         close(1);
  25         close(2);
  26         if (in_signal)
  27                 finish_command_in_signal(&pager_process);
  28         else
  29                 finish_command(&pager_process);
  30 }
  31
  32 static void wait_for_pager_atexit(void)
  33 {
  34         wait_for_pager(0);
  35 }
  36
  37 static void wait_for_pager_signal(int signo)
  38 {
  39         wait_for_pager(1);
  40         sigchain_pop(signo);
  41         raise(signo);
  42 }
  43
  44 const char *git_pager(int stdout_is_tty)
  45 {
  46         const char *pager;
  47
  48         if (!stdout_is_tty)
  49                 return NULL;
  50
  51         pager = getenv("GIT_PAGER");
  52         if (!pager) {
  53                 if (!pager_program)
  54                         git_config(git_default_config, NULL);
  55                 pager = pager_program;
  56         }
  57         if (!pager)
  58                 pager = getenv("PAGER");
  59         if (!pager)
  60                 pager = DEFAULT_PAGER;
  61         if (!*pager || !strcmp(pager, "cat"))
  62                 pager = NULL;
  63
  64         return pager;
  65 }
  66
  67 void setup_pager(void)
  68 {
  69         const char *pager = git_pager(isatty(1));
  70         int ret;
  71
  72         if (!pager)
  73                 return;
  74
  75         /*
  76          * force computing the width of the terminal before we redirect
  77          * the standard output to the pager.
  78          */
  79         (void) term_columns();
  80
  81         setenv("GIT_PAGER_IN_USE", "true", 1);
  82
  83         /* spawn the pager */
  84         pager_argv[0] = pager;
  85         pager_process.argv = pager_argv;
  86         if (!getenv("LESS"))
  87                 argv_array_push(&pager_process.env_array, "LESS=FRX");
  88         if (!getenv("LV"))
  89                 argv_array_push(&pager_process.env_array, "LV=-c");
  90         argv_array_push(&pager_process.env_array, "GIT_PAGER_IN_USE");
  91         pager_process.in = -1;
  92         pager_process.silent_exec_failure = 1;
  93         ret = start_command(&pager_process);
  94         if (ret < 0 && errno == ENOENT) {
  95                 pager_process.use_shell = 1;
  96                 pager_process.in = -1;
  97                 pager_process.silent_exec_failure = 0;
  98                 ret = start_command(&pager_process);
  99         }
 100         if (ret)
 101                 return;         /* no pager */
 102
 103         /* original process continues, but writes to the pipe */
 104         dup2(pager_process.in, 1);
 105         if (isatty(2))
 106                 dup2(pager_process.in, 2);
 107         close(pager_process.in);
 108
 109         /* this makes sure that the parent terminates after the pager */
 110         sigchain_push_common(wait_for_pager_signal);
 111         atexit(wait_for_pager_atexit);
 112 }
 113
 114 int pager_in_use(void)
 115 {
 116         const char *env;
 117         env = getenv("GIT_PAGER_IN_USE");
 118         return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 119 }
 120
 121 /*
 122  * Return cached value (if set) or $COLUMNS environment variable (if
 123  * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),
 124  * and default to 80 if all else fails.
 125  */
 126 int term_columns(void)
 127 {
 128         static int term_columns_at_startup;
 129
 130         char *col_string;
 131         int n_cols;
 132
 133         if (term_columns_at_startup)
 134                 return term_columns_at_startup;
 135
 136         term_columns_at_startup = 80;
 137
 138         col_string = getenv("COLUMNS");
 139         if (col_string && (n_cols = atoi(col_string)) > 0)
 140                 term_columns_at_startup = n_cols;
 141 #ifdef TIOCGWINSZ
 142         else {
 143                 struct winsize ws;
 144                 if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col)
 145                         term_columns_at_startup = ws.ws_col;
 146         }
 147 #endif
 148
 149         return term_columns_at_startup;
 150 }
 151
 152 /*
 153  * How many columns do we need to show this number in decimal?
 154  */
 155 int decimal_width(uintmax_t number)
 156 {
 157         int width;
 158
 159         for (width = 1; number >= 10; width++)
 160                 number /= 10;
 161         return width;
 162 }
 163
 164 /* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */
 165 int check_pager_config(const char *cmd)
 166 {
 167         int want = -1;
 168         struct strbuf key = STRBUF_INIT;
 169         const char *value = NULL;
 170         strbuf_addf(&key, "pager.%s", cmd);
 171         if (git_config_key_is_valid(key.buf) &&
 172             !git_config_get_value(key.buf, &value)) {
 173                 int b = git_config_maybe_bool(key.buf, value);
 174                 if (b >= 0)
 175                         want = b;
 176                 else {
 177                         want = 1;
 178                         pager_program = xstrdup(value);
 179                 }
 180         }
 181         strbuf_release(&key);
 182         return want;
 183 }