File: echoff.c
   1 /*
   2 The MIT License (MIT)
   3 
   4 Copyright © 2020-2025 pacman64
   5 
   6 Permission is hereby granted, free of charge, to any person obtaining a copy of
   7 this software and associated documentation files (the “Software”), to deal
   8 in the Software without restriction, including without limitation the rights to
   9 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
  10 of the Software, and to permit persons to whom the Software is furnished to do
  11 so, subject to the following conditions:
  12 
  13 The above copyright notice and this permission notice shall be included in all
  14 copies or substantial portions of the Software.
  15 
  16 THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19 AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20 LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22 SOFTWARE.
  23 */
  24 
  25 /*
  26 You can build this command-line app by running
  27 
  28 cc -Wall -s -O3 -flto -o ./echoff ./echoff.c -lncursesw
  29 */
  30 
  31 #include <locale.h>
  32 #include <ncurses.h>
  33 #include <sys/stat.h>
  34 #include <unistd.h>
  35 
  36 #ifdef RED_ERRORS
  37 #define ERROR_STYLE "\x1b[38;2;204;0;0m"
  38 #ifdef __APPLE__
  39 #define ERROR_STYLE "\x1b[31m"
  40 #endif
  41 #define RESET_STYLE "\x1b[0m"
  42 #else
  43 #define ERROR_STYLE
  44 #define RESET_STYLE
  45 #endif
  46 
  47 #define ERROR_LINE(MSG) (ERROR_STYLE MSG RESET_STYLE "\n")
  48 
  49 /*
  50 const char* info = ""
  51 "alterecho [words...]\n"
  52 "\n"
  53 "Join all words given as arguments using single spaces, showing the result\n"
  54 "in an alternate screen. Press any key to quit.\n"
  55 "";
  56 */
  57 
  58 int main(int argc, char** argv) {
  59     // if stdout is being piped, just act like the `echo` command
  60     struct stat out_info;
  61     if (fstat(STDOUT_FILENO, &out_info) == 0 && S_ISFIFO(out_info.st_mode)) {
  62         for (size_t i = 1; i < argc; i++) {
  63             if (i > 1) {
  64                 fputc(' ', stdout);
  65             }
  66             fprintf(stdout, "%s", argv[i]);
  67         }
  68         if (argc > 1) {
  69             fputc('\n', stdout);
  70         }
  71         return 0;
  72     }
  73 
  74     FILE* in = fopen("/dev/tty", "rb");
  75     if (in == NULL) {
  76         fprintf(stderr, ERROR_LINE("can't open tty for input"));
  77         return 1;
  78     }
  79 
  80     FILE* out = fopen("/dev/tty", "wb");
  81     if (out == NULL) {
  82         fclose(in);
  83         fprintf(stderr, ERROR_LINE("can't open tty for output"));
  84         return 1;
  85     }
  86 
  87     // use UTF-8
  88     setlocale(LC_ALL, "");
  89 
  90     // initscr takes over stdin and stdout, which interferes with being
  91     // used/run via xargs
  92     newterm("xterm", out, in);
  93 
  94     noecho(); // don't show keys pressed
  95     keypad(stdscr, TRUE); // handle all keys correctly
  96     set_escdelay(10); // don't wait long after the escape key is pressed
  97     curs_set(0); // hide the cursor
  98     refresh(); // switch to alternate screen immediately
  99 
 100     for (size_t i = 1; i < argc; i++) {
 101         if (i > 1) {
 102             printw(" ");
 103         }
 104         printw("%s", argv[i]);
 105     }
 106     if (argc > 1) {
 107         printw("\n");
 108     }
 109 
 110     refresh(); // ensure contents show up
 111     getch(); // wait for any keypress, even the escape key
 112     endwin(); // restore normal screen and settings
 113 
 114     fclose(out);
 115     fclose(in);
 116     return 0;
 117 }