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 tarball for details.
  15  */
  16
  17 #include "libbb.h"
  18 #if ENABLE_FEATURE_USE_TERMIOS
  19 #include <termios.h>
  20 #endif /* FEATURE_USE_TERMIOS */
  21
  22
  23 #if ENABLE_FEATURE_USE_TERMIOS
  24
  25 struct globals {
  26         int cin_fileno;
  27         struct termios initial_settings;
  28         struct termios new_settings;
  29 };
  30 #define G (*(struct globals*)bb_common_bufsiz1)
  31 //#define G (*ptr_to_globals)
  32 #define INIT_G() ((void)0)
  33 //#define INIT_G() PTR_TO_GLOBALS = xzalloc(sizeof(G))
  34 #define initial_settings (G.initial_settings)
  35 #define new_settings     (G.new_settings    )
  36 #define cin_fileno       (G.cin_fileno      )
  37
  38 #define setTermSettings(fd, argp) tcsetattr(fd, TCSANOW, argp)
  39 #define getTermSettings(fd, argp) tcgetattr(fd, argp)
  40
  41 static void gotsig(int sig)
  42 {
  43         putchar('\n');
  44         setTermSettings(cin_fileno, &initial_settings);
  45         exit(EXIT_FAILURE);
  46 }
  47
  48 #else /* !FEATURE_USE_TERMIOS */
  49 #define INIT_G() ((void)0)
  50 #define setTermSettings(fd, argp) ((void)0)
  51 #endif /* FEATURE_USE_TERMIOS */
  52
  53 #define CONVERTED_TAB_SIZE 8
  54
  55 int more_main(int argc, char **argv);
  56 int more_main(int argc, char **argv)
  57 {
  58         int c = c; /* for gcc */
  59         int lines;
  60         int input = 0;
  61         int spaces = 0;
  62         int please_display_more_prompt;
  63         struct stat st;
  64         FILE *file;
  65         FILE *cin;
  66         int len;
  67         int terminal_width;
  68         int terminal_height;
  69
  70         INIT_G();
  71
  72         argv++;
  73         /* Another popular pager, most, detects when stdout
  74          * is not a tty and turns into cat. This makes sense. */
  75         if (!isatty(STDOUT_FILENO))
  76                 return bb_cat(argv);
  77         cin = fopen(CURRENT_TTY, "r");
  78         if (!cin)
  79                 return bb_cat(argv);
  80
  81 #if ENABLE_FEATURE_USE_TERMIOS
  82         cin_fileno = fileno(cin);
  83         getTermSettings(cin_fileno, &initial_settings);
  84         new_settings = initial_settings;
  85         new_settings.c_lflag &= ~ICANON;
  86         new_settings.c_lflag &= ~ECHO;
  87         new_settings.c_cc[VMIN] = 1;
  88         new_settings.c_cc[VTIME] = 0;
  89         setTermSettings(cin_fileno, &new_settings);
  90         signal(SIGINT, gotsig);
  91         signal(SIGQUIT, gotsig);
  92         signal(SIGTERM, gotsig);
  93 #endif
  94
  95         do {
  96                 file = stdin;
  97                 if (*argv) {
  98                         file = fopen_or_warn(*argv, "r");
  99                         if (!file)
 100                                 continue;
 101                 }
 102                 st.st_size = 0;
 103                 fstat(fileno(file), &st);
 104
 105                 please_display_more_prompt = 0;
 106                 /* never returns w, h <= 1 */
 107                 get_terminal_width_height(fileno(cin), &terminal_width, &terminal_height);
 108                 terminal_height -= 1;
 109
 110                 len = 0;
 111                 lines = 0;
 112                 while (spaces || (c = getc(file)) != EOF) {
 113                         int wrap;
 114                         if (spaces)
 115                                 spaces--;
 116  loop_top:
 117                         if (input != 'r' && please_display_more_prompt) {
 118                                 len = printf("--More-- ");
 119                                 if (st.st_size > 0) {
 120                                         len += printf("(%d%% of %"OFF_FMT"d bytes)",
 121                                                 (int) (ftello(file)*100 / st.st_size),
 122                                                 st.st_size);
 123                                 }
 124                                 fflush(stdout);
 125
 126                                 /*
 127                                  * We've just displayed the "--More--" prompt, so now we need
 128                                  * to get input from the user.
 129                                  */
 130                                 for (;;) {
 131                                         input = getc(cin);
 132                                         input = tolower(input);
 133 #if !ENABLE_FEATURE_USE_TERMIOS
 134                                         printf("\033[A"); /* up cursor */
 135 #endif
 136                                         /* Erase the last message */
 137                                         printf("\r%*s\r", len, "");
 138
 139                                         /* Due to various multibyte escape
 140                                          * sequences, it's not ok to accept
 141                                          * any input as a command to scroll
 142                                          * the screen. We only allow known
 143                                          * commands, else we show help msg. */
 144                                         if (input == ' ' || input == '\n' || input == 'q' || input == 'r')
 145                                                 break;
 146                                         len = printf("(Enter:next line Space:next page Q:quit R:show the rest)");
 147                                 }
 148                                 len = 0;
 149                                 lines = 0;
 150                                 please_display_more_prompt = 0;
 151
 152                                 if (input == 'q')
 153                                         goto end;
 154
 155                                 /* The user may have resized the terminal.
 156                                  * Re-read the dimensions. */
 157                                 get_terminal_width_height(cin_fileno, &terminal_width, &terminal_height);
 158                                 terminal_height -= 1;
 159                         }
 160
 161                         /* Crudely convert tabs into spaces, which are
 162                          * a bajillion times easier to deal with. */
 163                         if (c == '\t') {
 164                                 spaces = CONVERTED_TAB_SIZE - 1;
 165                                 c = ' ';
 166                         }
 167
 168                         /*
 169                          * There are two input streams to worry about here:
 170                          *
 171                          * c    : the character we are reading from the file being "mored"
 172                          * input: a character received from the keyboard
 173                          *
 174                          * If we hit a newline in the _file_ stream, we want to test and
 175                          * see if any characters have been hit in the _input_ stream. This
 176                          * allows the user to quit while in the middle of a file.
 177                          */
 178                         wrap = (++len > terminal_width);
 179                         if (c == '\n' || wrap) {
 180                                 /* Then outputting this character
 181                                  * will move us to a new line. */
 182                                 if (++lines >= terminal_height || input == '\n')
 183                                         please_display_more_prompt = 1;
 184                                 len = 0;
 185                         }
 186                         if (c != '\n' && wrap) {
 187                                 /* Then outputting this will also put a character on
 188                                  * the beginning of that new line. Thus we first want to
 189                                  * display the prompt (if any), so we skip the putchar()
 190                                  * and go back to the top of the loop, without reading
 191                                  * a new character. */
 192                                 goto loop_top;
 193                         }
 194                         /* My small mind cannot fathom backspaces and UTF-8 */
 195                         putchar(c);
 196                 }
 197                 fclose(file);
 198                 fflush(stdout);
 199         } while (*argv && *++argv);
 200  end:
 201         setTermSettings(cin_fileno, &initial_settings);
 202         return 0;
 203 }