1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Mini more implementation for busybox
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4 | *
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5 | * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
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6 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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7 | *
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8 | * Latest version blended together by Erik Andersen <andersen@codepoet.org>,
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9 | * based on the original more implementation by Bruce, and code from the
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10 | * Debian boot-floppies team.
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11 | *
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12 | * Termios corrects by Vladimir Oleynik <dzo@simtreas.ru>
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13 | *
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14 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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15 | */
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16 |
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17 | //usage:#define more_trivial_usage
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18 | //usage: "[FILE]..."
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19 | //usage:#define more_full_usage "\n\n"
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20 | //usage: "View FILE (or stdin) one screenful at a time"
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21 | //usage:
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22 | //usage:#define more_example_usage
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23 | //usage: "$ dmesg | more\n"
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24 |
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25 | #include "libbb.h"
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26 |
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27 | /* Support for FEATURE_USE_TERMIOS */
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28 |
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29 | struct globals {
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30 | int cin_fileno;
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31 | struct termios initial_settings;
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32 | struct termios new_settings;
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33 | } FIX_ALIASING;
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34 | #define G (*(struct globals*)bb_common_bufsiz1)
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35 | #define INIT_G() ((void)0)
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36 | #define initial_settings (G.initial_settings)
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37 | #define new_settings (G.new_settings )
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38 | #define cin_fileno (G.cin_fileno )
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39 |
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40 | #define setTermSettings(fd, argp) \
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41 | do { \
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42 | if (ENABLE_FEATURE_USE_TERMIOS) \
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43 | tcsetattr(fd, TCSANOW, argp); \
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44 | } while (0)
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45 | #define getTermSettings(fd, argp) tcgetattr(fd, argp)
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46 |
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47 | static void gotsig(int sig UNUSED_PARAM)
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48 | {
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49 | /* bb_putchar_stderr doesn't use stdio buffering,
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50 | * therefore it is safe in signal handler */
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51 | bb_putchar_stderr('\n');
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52 | setTermSettings(cin_fileno, &initial_settings);
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53 | _exit(EXIT_FAILURE);
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54 | }
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55 |
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56 | #define CONVERTED_TAB_SIZE 8
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57 |
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58 | int more_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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59 | int more_main(int argc UNUSED_PARAM, char **argv)
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60 | {
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61 | int c = c; /* for compiler */
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62 | int lines;
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63 | int input = 0;
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64 | int spaces = 0;
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65 | int please_display_more_prompt;
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66 | struct stat st;
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67 | FILE *file;
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68 | FILE *cin;
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69 | int len;
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70 | unsigned terminal_width;
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71 | unsigned terminal_height;
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72 |
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73 | INIT_G();
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74 |
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75 | argv++;
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76 | /* Another popular pager, most, detects when stdout
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77 | * is not a tty and turns into cat. This makes sense. */
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78 | if (!isatty(STDOUT_FILENO))
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79 | return bb_cat(argv);
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80 | cin = fopen_for_read(CURRENT_TTY);
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81 | if (!cin)
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82 | return bb_cat(argv);
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83 |
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84 | if (ENABLE_FEATURE_USE_TERMIOS) {
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85 | cin_fileno = fileno(cin);
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86 | getTermSettings(cin_fileno, &initial_settings);
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87 | new_settings = initial_settings;
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88 | new_settings.c_lflag &= ~(ICANON | ECHO);
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89 | new_settings.c_cc[VMIN] = 1;
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90 | new_settings.c_cc[VTIME] = 0;
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91 | setTermSettings(cin_fileno, &new_settings);
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92 | bb_signals(0
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93 | + (1 << SIGINT)
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94 | + (1 << SIGQUIT)
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95 | + (1 << SIGTERM)
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96 | , gotsig);
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97 | }
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98 |
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99 | do {
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100 | file = stdin;
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101 | if (*argv) {
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102 | file = fopen_or_warn(*argv, "r");
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103 | if (!file)
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104 | continue;
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105 | }
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106 | st.st_size = 0;
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107 | fstat(fileno(file), &st);
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108 |
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109 | please_display_more_prompt = 0;
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110 | /* never returns w, h <= 1 */
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111 | get_terminal_width_height(fileno(cin), &terminal_width, &terminal_height);
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112 | terminal_height -= 1;
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113 |
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114 | len = 0;
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115 | lines = 0;
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116 | while (spaces || (c = getc(file)) != EOF) {
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117 | int wrap;
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118 | if (spaces)
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119 | spaces--;
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120 | loop_top:
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121 | if (input != 'r' && please_display_more_prompt) {
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122 | len = printf("--More-- ");
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123 | if (st.st_size != 0) {
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124 | uoff_t d = (uoff_t)st.st_size / 100;
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125 | if (d == 0)
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126 | d = 1;
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127 | len += printf("(%u%% of %"OFF_FMT"u bytes)",
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128 | (int) ((uoff_t)ftello(file) / d),
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129 | st.st_size);
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130 | }
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131 | fflush_all();
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132 |
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133 | /*
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134 | * We've just displayed the "--More--" prompt, so now we need
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135 | * to get input from the user.
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136 | */
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137 | for (;;) {
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138 | input = getc(cin);
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139 | input = tolower(input);
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140 | if (!ENABLE_FEATURE_USE_TERMIOS)
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141 | printf("\033[A"); /* cursor up */
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142 | /* Erase the last message */
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143 | printf("\r%*s\r", len, "");
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144 |
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145 | /* Due to various multibyte escape
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146 | * sequences, it's not ok to accept
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147 | * any input as a command to scroll
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148 | * the screen. We only allow known
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149 | * commands, else we show help msg. */
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150 | if (input == ' ' || input == '\n' || input == 'q' || input == 'r')
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151 | break;
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152 | len = printf("(Enter:next line Space:next page Q:quit R:show the rest)");
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153 | }
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154 | len = 0;
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155 | lines = 0;
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156 | please_display_more_prompt = 0;
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157 |
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158 | if (input == 'q')
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159 | goto end;
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160 |
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161 | /* The user may have resized the terminal.
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162 | * Re-read the dimensions. */
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163 | if (ENABLE_FEATURE_USE_TERMIOS) {
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164 | get_terminal_width_height(cin_fileno, &terminal_width, &terminal_height);
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165 | terminal_height -= 1;
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166 | }
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167 | }
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168 |
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169 | /* Crudely convert tabs into spaces, which are
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170 | * a bajillion times easier to deal with. */
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171 | if (c == '\t') {
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172 | spaces = ((unsigned)~len) % CONVERTED_TAB_SIZE;
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173 | c = ' ';
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174 | }
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175 |
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176 | /*
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177 | * There are two input streams to worry about here:
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178 | *
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179 | * c : the character we are reading from the file being "mored"
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180 | * input: a character received from the keyboard
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181 | *
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182 | * If we hit a newline in the _file_ stream, we want to test and
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183 | * see if any characters have been hit in the _input_ stream. This
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184 | * allows the user to quit while in the middle of a file.
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185 | */
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186 | wrap = (++len > terminal_width);
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187 | if (c == '\n' || wrap) {
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188 | /* Then outputting this character
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189 | * will move us to a new line. */
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190 | if (++lines >= terminal_height || input == '\n')
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191 | please_display_more_prompt = 1;
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192 | len = 0;
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193 | }
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194 | if (c != '\n' && wrap) {
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195 | /* Then outputting this will also put a character on
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196 | * the beginning of that new line. Thus we first want to
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197 | * display the prompt (if any), so we skip the putchar()
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198 | * and go back to the top of the loop, without reading
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199 | * a new character. */
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200 | goto loop_top;
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201 | }
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202 | /* My small mind cannot fathom backspaces and UTF-8 */
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203 | putchar(c);
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204 | die_if_ferror_stdout(); /* if tty was destroyed (closed xterm, etc) */
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205 | }
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206 | fclose(file);
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207 | fflush_all();
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208 | } while (*argv && *++argv);
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209 | end:
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210 | setTermSettings(cin_fileno, &initial_settings);
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211 | return 0;
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212 | }
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