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 "busybox.h"
  18
  19
  20 #if ENABLE_FEATURE_USE_TERMIOS
  21 static int cin_fileno;
  22 #include <termios.h>
  23 #define setTermSettings(fd, argp) tcsetattr(fd, TCSANOW, argp)
  24 #define getTermSettings(fd, argp) tcgetattr(fd, argp);
  25
  26 static struct termios initial_settings, new_settings;
  27
  28 static void set_tty_to_initial_mode(void)
  29 {
  30         setTermSettings(cin_fileno, &initial_settings);
  31 }
  32
  33 static void gotsig(int sig)
  34 {
  35         putchar('\n');
  36         exit(EXIT_FAILURE);
  37 }
  38 #endif /* FEATURE_USE_TERMIOS */
  39
  40
  41 int more_main(int argc, char **argv);
  42 int more_main(int argc, char **argv)
  43 {
  44         int c, lines, input = 0;
  45         int please_display_more_prompt = 0;
  46         struct stat st;
  47         FILE *file;
  48         FILE *cin;
  49         int len, page_height;
  50         int terminal_width;
  51         int terminal_height;
  52
  53         argv++;
  54         /* Another popular pager, most, detects when stdout
  55          * is not a tty and turns into cat. This makes sense. */
  56         if (!isatty(STDOUT_FILENO))
  57                 return bb_cat(argv);
  58         cin = fopen(CURRENT_TTY, "r");
  59         if (!cin)
  60                 return bb_cat(argv);
  61
  62 #if ENABLE_FEATURE_USE_TERMIOS
  63         cin_fileno = fileno(cin);
  64         getTermSettings(cin_fileno, &initial_settings);
  65         new_settings = initial_settings;
  66         new_settings.c_lflag &= ~ICANON;
  67         new_settings.c_lflag &= ~ECHO;
  68         new_settings.c_cc[VMIN] = 1;
  69         new_settings.c_cc[VTIME] = 0;
  70         setTermSettings(cin_fileno, &new_settings);
  71         atexit(set_tty_to_initial_mode);
  72         signal(SIGINT, gotsig);
  73         signal(SIGQUIT, gotsig);
  74         signal(SIGTERM, gotsig);
  75 #endif
  76         please_display_more_prompt = 2;
  77
  78         do {
  79                 file = stdin;
  80                 if (*argv) {
  81                         file = fopen_or_warn(*argv, "r");
  82                         if (!file)
  83                                 continue;
  84                 }
  85                 st.st_size = 0;
  86                 fstat(fileno(file), &st);
  87
  88                 please_display_more_prompt &= ~1;
  89                 /* never returns w, h <= 1 */
  90                 get_terminal_width_height(fileno(cin), &terminal_width, &terminal_height);
  91                 terminal_width -= 1;
  92                 terminal_height -= 1;
  93
  94                 len = 0;
  95                 lines = 0;
  96                 page_height = terminal_height;
  97                 while ((c = getc(file)) != EOF) {
  98
  99                         if ((please_display_more_prompt & 3) == 3) {
 100                                 len = printf("--More-- ");
 101                                 if (/*file != stdin &&*/ st.st_size > 0) {
 102                                         len += printf("(%d%% of %"OFF_FMT"d bytes)",
 103                                                 (int) (ftello(file)*100 / st.st_size),
 104                                                 st.st_size);
 105                                 }
 106                                 fflush(stdout);
 107
 108                                 /*
 109                                  * We've just displayed the "--More--" prompt, so now we need
 110                                  * to get input from the user.
 111                                  */
 112                                 input = getc(cin);
 113 #if !ENABLE_FEATURE_USE_TERMIOS
 114                                 printf("\033[A"); /* up cursor */
 115 #endif
 116                                 /* Erase the "More" message */
 117                                 printf("\r%*s\r", len, "");
 118                                 len = 0;
 119                                 lines = 0;
 120                                 /* Bottom line on page will become top line
 121                                  * after one page forward. Thus -1: */
 122                                 page_height = terminal_height - 1;
 123                                 please_display_more_prompt &= ~1;
 124
 125                                 if (input == 'q')
 126                                         goto end;
 127                         }
 128
 129                         /*
 130                          * There are two input streams to worry about here:
 131                          *
 132                          * c     : the character we are reading from the file being "mored"
 133                          * input : a character received from the keyboard
 134                          *
 135                          * If we hit a newline in the _file_ stream, we want to test and
 136                          * see if any characters have been hit in the _input_ stream. This
 137                          * allows the user to quit while in the middle of a file.
 138                          */
 139                         if (c == '\n') {
 140                                 /* increment by just one line if we are at
 141                                  * the end of this line */
 142                                 if (input == '\n')
 143                                         please_display_more_prompt |= 1;
 144                                 /* Adjust the terminal height for any overlap, so that
 145                                  * no lines get lost off the top. */
 146                                 if (len >= terminal_width) {
 147                                         int quot, rem;
 148                                         quot = len / terminal_width;
 149                                         rem  = len - (quot * terminal_width);
 150                                         page_height -= (quot - 1);
 151                                         if (rem)
 152                                                 page_height--;
 153                                 }
 154                                 if (++lines >= page_height) {
 155                                         please_display_more_prompt |= 1;
 156                                 }
 157                                 len = 0;
 158                         }
 159                         /*
 160                          * If we just read a newline from the file being 'mored' and any
 161                          * key other than a return is hit, scroll by one page
 162                          */
 163                         putc(c, stdout);
 164                         /* My small mind cannot fathom tabs, backspaces,
 165                          * and UTF-8 */
 166                         len++;
 167                 }
 168                 fclose(file);
 169                 fflush(stdout);
 170         } while (*argv && *++argv);
 171  end:
 172         return 0;
 173 }