tests/test-term-style-control-yes.c

   1 /* Interactive test program for the term-style-control module.
   2    Copyright (C) 2019-2024 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2019.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation, either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include "term-style-control.h"
  22
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26
  27 #include "full-write.h"
  28
  29 /* This program outputs an endless amount of lines, each consisting of a
  30    single 'y', in red color and underlined.
  31    It can be used to exercise race conditions caused by
  32      - simultaneous keyboard input on the terminal,
  33      - pressing Ctrl-C,
  34      - pressing Ctrl-Z and then "fg".  */
  35
  36 /* ECMA-48 / ISO 6429 escape sequences.  See
  37    https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters
  38  */
  39 static const char set_underline_on[] = "\033[4m";
  40 static const char set_underline_off[] = "\033[24m";
  41 static const char set_foreground_color_red[] = "\033[31m";
  42 static const char set_foreground_color_default[] = "\033[39m";
  43
  44 struct term_style_user_data
  45 {
  46   /* This field is marked volatile, because it is accessed from the
  47      async-safe function async_set_attributes_from_default.  */
  48   bool volatile red_and_underline;
  49
  50   struct term_style_control_data ctrl_data;
  51 };
  52
  53 static struct term_style_control_data *
  54 get_control_data (struct term_style_user_data *user_data)
  55 {
  56   return &user_data->ctrl_data;
  57 }
  58
  59 static void
  60 restore (_GL_UNUSED struct term_style_user_data *user_data)
  61 {
  62   fputs (set_underline_off, stdout);
  63   fputs (set_foreground_color_default, stdout);
  64   fflush (stdout);
  65 }
  66
  67 static _GL_ASYNC_SAFE void
  68 async_restore (_GL_UNUSED struct term_style_user_data *user_data)
  69 {
  70   /* No <stdio.h> calls here!  */
  71   full_write (STDOUT_FILENO, set_underline_off,
  72               strlen (set_underline_off));
  73   full_write (STDOUT_FILENO, set_foreground_color_default,
  74               strlen (set_foreground_color_default));
  75 }
  76
  77 static _GL_ASYNC_SAFE void
  78 async_set_attributes_from_default (struct term_style_user_data *user_data)
  79 {
  80   /* No <stdio.h> calls here!  */
  81   if (user_data->red_and_underline)
  82     {
  83       full_write (STDOUT_FILENO, set_underline_on,
  84                   strlen (set_underline_on));
  85       full_write (STDOUT_FILENO, set_foreground_color_red,
  86                   strlen (set_foreground_color_red));
  87     }
  88 }
  89
  90 static const struct term_style_controller controller =
  91 {
  92   get_control_data,
  93   restore,
  94   async_restore,
  95   async_set_attributes_from_default
  96 };
  97
  98 int
  99 main ()
 100 {
 101   struct term_style_user_data user_data;
 102
 103   /* Initialization.  */
 104   user_data.red_and_underline = false;
 105
 106   activate_term_style_controller (&controller, &user_data, STDOUT_FILENO,
 107                                   TTYCTL_AUTO);
 108
 109   for (;;)
 110     {
 111       /* Before any styling, enable the non-default mode.  */
 112       activate_term_non_default_mode (&controller, &user_data);
 113
 114       /* Set user_data.red_and_underline *before* emitting the appropriate
 115          escape sequences, otherwise async_set_attributes_from_default will not
 116          do its job correctly.  */
 117       user_data.red_and_underline = true;
 118       fputs (set_underline_on, stdout);
 119       fputs (set_foreground_color_red, stdout);
 120       fflush (stdout);
 121
 122       fputs ("y", stdout);
 123       fflush (stdout);
 124
 125       /* Revert to the default style before emitting a newline.  */
 126       user_data.red_and_underline = false;
 127       fputs (set_underline_off, stdout);
 128       fputs (set_foreground_color_default, stdout);
 129       fflush (stdout);
 130
 131       /* Optional.  */
 132       deactivate_term_non_default_mode (&controller, &user_data);
 133
 134       fputs ("\n", stdout);
 135       fflush (stdout);
 136     }
 137 }