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