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

   1 /* Simple 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 the line:     Hello Dr. Linus Pauling!
  30    with underlining here:                   _________________
  31    and a cyan background color here:            _____
  32  */
  33
  34 /* ECMA-48 / ISO 6429 escape sequences.  See
  35    https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters
  36  */
  37 static const char set_underline_on[] = "\033[4m";
  38 static const char set_underline_off[] = "\033[24m";
  39 static const char set_background_color_cyan[] = "\033[46m";
  40 static const char set_background_color_default[] = "\033[49m";
  41
  42 struct term_style_user_data
  43 {
  44   /* These fields are marked volatile, because they are accessed from the
  45      async-safe function async_set_attributes_from_default.  */
  46   bool volatile underline;
  47   bool volatile background_color_cyan;
  48
  49   struct term_style_control_data ctrl_data;
  50 };
  51
  52 static struct term_style_control_data *
  53 get_control_data (struct term_style_user_data *user_data)
  54 {
  55   return &user_data->ctrl_data;
  56 }
  57
  58 static void
  59 restore (_GL_UNUSED struct term_style_user_data *user_data)
  60 {
  61   fputs (set_underline_off, stdout);
  62   fputs (set_background_color_default, stdout);
  63   fflush (stdout);
  64 }
  65
  66 static _GL_ASYNC_SAFE void
  67 async_restore (_GL_UNUSED struct term_style_user_data *user_data)
  68 {
  69   /* No <stdio.h> calls here!  */
  70   full_write (STDOUT_FILENO, set_underline_off,
  71               strlen (set_underline_off));
  72   full_write (STDOUT_FILENO, set_background_color_default,
  73               strlen (set_background_color_default));
  74 }
  75
  76 static _GL_ASYNC_SAFE void
  77 async_set_attributes_from_default (struct term_style_user_data *user_data)
  78 {
  79   /* No <stdio.h> calls here!  */
  80   if (user_data->underline)
  81     full_write (STDOUT_FILENO, set_underline_on,
  82                 strlen (set_underline_on));
  83   if (user_data->background_color_cyan)
  84     full_write (STDOUT_FILENO, set_background_color_cyan,
  85                 strlen (set_background_color_cyan));
  86 }
  87
  88 static const struct term_style_controller controller =
  89 {
  90   get_control_data,
  91   restore,
  92   async_restore,
  93   async_set_attributes_from_default
  94 };
  95
  96 int
  97 main ()
  98 {
  99   struct term_style_user_data user_data;
 100
 101   /* Initialization.  */
 102   user_data.underline = false;
 103   user_data.background_color_cyan = false;
 104
 105   activate_term_style_controller (&controller, &user_data, STDOUT_FILENO,
 106                                   TTYCTL_AUTO);
 107
 108   /* As long as no styling is needed, we can stay in the default mode.  */
 109   fputs ("Hello ", stdout);
 110   fflush (stdout);
 111
 112   /* Before any styling, enable the non-default mode.  */
 113   activate_term_non_default_mode (&controller, &user_data);
 114
 115   /* Set user_data.underline *before* emitting the appropriate
 116      escape sequences, otherwise async_set_attributes_from_default will not
 117      do its job correctly.  */
 118   user_data.underline = true;
 119   fputs (set_underline_on, stdout);
 120   fflush (stdout);
 121
 122   fputs ("Dr. ", stdout);
 123   fflush (stdout);
 124
 125   /* Set user_data.background_color_cyan *before* emitting the appropriate
 126      escape sequences, otherwise async_set_attributes_from_default will not
 127      do its job correctly.  */
 128   user_data.background_color_cyan = true;
 129   fputs (set_background_color_cyan, stdout);
 130   fflush (stdout);
 131
 132   fputs ("Linus", stdout);
 133   fflush (stdout);
 134
 135   user_data.background_color_cyan = false;
 136   fputs (set_background_color_default, stdout);
 137   fflush (stdout);
 138
 139   fputs (" Pauling", stdout);
 140   fflush (stdout);
 141
 142   user_data.underline = false;
 143   fputs (set_underline_off, stdout);
 144   fflush (stdout);
 145
 146   /* Needed as a prerequisite of the deactivate_term_style_controller call
 147      below.  */
 148   deactivate_term_non_default_mode (&controller, &user_data);
 149
 150   fputs ("!\n", stdout);
 151
 152   /* If the user_data was allocated in heap memory, with indefinite extent,
 153      this call would be optional.  But since we have allocated it on the
 154      stack, we must deactivate it before it goes out of scope.  Otherwise
 155      we get undefined behaviour in an atexit() handler.  */
 156   deactivate_term_style_controller (&controller, &user_data);
 157
 158   return 0;
 159 }