util-linux/more.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini more implementation for busybox
   4  *
   5  * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
   6  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
   7  *
   8  * Latest version blended together by Erik Andersen <andersen@codepoet.org>,
   9  * based on the original more implementation by Bruce, and code from the
  10  * Debian boot-floppies team.
  11  *
  12  * Termios corrects by Vladimir Oleynik <dzo@simtreas.ru>
  13  *
  14  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  15  */
  16
  17 #include "libbb.h"
  18
  19 /* Support for FEATURE_USE_TERMIOS */
  20
  21 struct globals {
  22         int cin_fileno;
  23         struct termios initial_settings;
  24         struct termios new_settings;
  25 } FIX_ALIASING;
  26 #define G (*(struct globals*)bb_common_bufsiz1)
  27 #define INIT_G() ((void)0)
  28 #define initial_settings (G.initial_settings)
  29 #define new_settings     (G.new_settings    )
  30 #define cin_fileno       (G.cin_fileno      )
  31
  32 #define setTermSettings(fd, argp) do { \
  33                 if (ENABLE_FEATURE_USE_TERMIOS) tcsetattr(fd, TCSANOW, argp); \
  34         } while (0)
  35 #define getTermSettings(fd, argp) tcgetattr(fd, argp)
  36
  37 static void gotsig(int sig UNUSED_PARAM)
  38 {
  39         bb_putchar('\n');
  40         setTermSettings(cin_fileno, &initial_settings);
  41         exit(EXIT_FAILURE);
  42 }
  43
  44 #define CONVERTED_TAB_SIZE 8
  45
  46 int more_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  47 int more_main(int argc UNUSED_PARAM, char **argv)
  48 {
  49         int c = c; /* for compiler */
  50         int lines;
  51         int input = 0;
  52         int spaces = 0;
  53         int please_display_more_prompt;
  54         struct stat st;
  55         FILE *file;
  56         FILE *cin;
  57         int len;
  58         unsigned terminal_width;
  59         unsigned terminal_height;
  60
  61         INIT_G();
  62
  63         argv++;
  64         /* Another popular pager, most, detects when stdout
  65          * is not a tty and turns into cat. This makes sense. */
  66         if (!isatty(STDOUT_FILENO))
  67                 return bb_cat(argv);
  68         cin = fopen_for_read(CURRENT_TTY);
  69         if (!cin)
  70                 return bb_cat(argv);
  71
  72         if (ENABLE_FEATURE_USE_TERMIOS) {
  73                 cin_fileno = fileno(cin);
  74                 getTermSettings(cin_fileno, &initial_settings);
  75                 new_settings = initial_settings;
  76                 new_settings.c_lflag &= ~ICANON;
  77                 new_settings.c_lflag &= ~ECHO;
  78                 new_settings.c_cc[VMIN] = 1;
  79                 new_settings.c_cc[VTIME] = 0;
  80                 setTermSettings(cin_fileno, &new_settings);
  81                 bb_signals(0
  82                         + (1 << SIGINT)
  83                         + (1 << SIGQUIT)
  84                         + (1 << SIGTERM)
  85                         , gotsig);
  86         }
  87
  88         do {
  89                 file = stdin;
  90                 if (*argv) {
  91                         file = fopen_or_warn(*argv, "r");
  92                         if (!file)
  93                                 continue;
  94                 }
  95                 st.st_size = 0;
  96                 fstat(fileno(file), &st);
  97
  98                 please_display_more_prompt = 0;
  99                 /* never returns w, h <= 1 */
 100                 get_terminal_width_height(fileno(cin), &terminal_width, &terminal_height);
 101                 terminal_height -= 1;
 102
 103                 len = 0;
 104                 lines = 0;
 105                 while (spaces || (c = getc(file)) != EOF) {
 106                         int wrap;
 107                         if (spaces)
 108                                 spaces--;
 109  loop_top:
 110                         if (input != 'r' && please_display_more_prompt) {
 111                                 len = printf("--More-- ");
 112                                 if (st.st_size > 0) {
 113                                         len += printf("(%u%% of %"OFF_FMT"u bytes)",
 114                                                 (int) (ftello(file)*100 / st.st_size),
 115                                                 st.st_size);
 116                                 }
 117                                 fflush_all();
 118
 119                                 /*
 120                                  * We've just displayed the "--More--" prompt, so now we need
 121                                  * to get input from the user.
 122                                  */
 123                                 for (;;) {
 124                                         input = getc(cin);
 125                                         input = tolower(input);
 126                                         if (!ENABLE_FEATURE_USE_TERMIOS)
 127                                                 printf("\033[A"); /* cursor up */
 128                                         /* Erase the last message */
 129                                         printf("\r%*s\r", len, "");
 130
 131                                         /* Due to various multibyte escape
 132                                          * sequences, it's not ok to accept
 133                                          * any input as a command to scroll
 134                                          * the screen. We only allow known
 135                                          * commands, else we show help msg. */
 136                                         if (input == ' ' || input == '\n' || input == 'q' || input == 'r')
 137                                                 break;
 138                                         len = printf("(Enter:next line Space:next page Q:quit R:show the rest)");
 139                                 }
 140                                 len = 0;
 141                                 lines = 0;
 142                                 please_display_more_prompt = 0;
 143
 144                                 if (input == 'q')
 145                                         goto end;
 146
 147                                 /* The user may have resized the terminal.
 148                                  * Re-read the dimensions. */
 149                                 if (ENABLE_FEATURE_USE_TERMIOS) {
 150                                         get_terminal_width_height(cin_fileno, &terminal_width, &terminal_height);
 151                                         terminal_height -= 1;
 152                                 }
 153                         }
 154
 155                         /* Crudely convert tabs into spaces, which are
 156                          * a bajillion times easier to deal with. */
 157                         if (c == '\t') {
 158                                 spaces = CONVERTED_TAB_SIZE - 1;
 159                                 c = ' ';
 160                         }
 161
 162                         /*
 163                          * There are two input streams to worry about here:
 164                          *
 165                          * c    : the character we are reading from the file being "mored"
 166                          * input: a character received from the keyboard
 167                          *
 168                          * If we hit a newline in the _file_ stream, we want to test and
 169                          * see if any characters have been hit in the _input_ stream. This
 170                          * allows the user to quit while in the middle of a file.
 171                          */
 172                         wrap = (++len > terminal_width);
 173                         if (c == '\n' || wrap) {
 174                                 /* Then outputting this character
 175                                  * will move us to a new line. */
 176                                 if (++lines >= terminal_height || input == '\n')
 177                                         please_display_more_prompt = 1;
 178                                 len = 0;
 179                         }
 180                         if (c != '\n' && wrap) {
 181                                 /* Then outputting this will also put a character on
 182                                  * the beginning of that new line. Thus we first want to
 183                                  * display the prompt (if any), so we skip the putchar()
 184                                  * and go back to the top of the loop, without reading
 185                                  * a new character. */
 186                                 goto loop_top;
 187                         }
 188                         /* My small mind cannot fathom backspaces and UTF-8 */
 189                         putchar(c);
 190                 }
 191                 fclose(file);
 192                 fflush_all();
 193         } while (*argv && *++argv);
 194  end:
 195         setTermSettings(cin_fileno, &initial_settings);
 196         return 0;
 197 }