annotate examples/dsl/redirect.cpp @ 6:607e3be6bad8

Adjust to the moving target called the C++ standard. Apparently nowadays it's not allowed to define an explicit copy constructor but not an assignment operator. Consequently, defining the explicit copy constructor in terms of the implicit/automatic assignment operator for general convenience no longer works. Add assignment operators. Caution: not tested with the IBM compiler, but there's no particular reason it shouldn't work.
author David A. Holland
date Mon, 30 May 2022 23:46:22 -0400
parents 13d2b8934445
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1 /*****
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2
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3 AnaGram Programming Examples
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4
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5 A Dos Script Language
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6 Redirection Class Module
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7
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8 Copyright 1993 Parsifal Software. All Rights Reserved.
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9
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10 This software is provided 'as-is', without any express or implied
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11 warranty. In no event will the authors be held liable for any damages
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12 arising from the use of this software.
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13
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14 Permission is granted to anyone to use this software for any purpose,
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15 including commercial applications, and to alter it and redistribute it
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16 freely, subject to the following restrictions:
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17
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18 1. The origin of this software must not be misrepresented; you must not
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19 claim that you wrote the original software. If you use this software
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20 in a product, an acknowledgment in the product documentation would be
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21 appreciated but is not required.
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22 2. Altered source versions must be plainly marked as such, and must not be
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23 misrepresented as being the original software.
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24 3. This notice may not be removed or altered from any source distribution.
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25
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26 *****/
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27
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28 #include "redirect.h"
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29 #include "assert.h"
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30 #include "util.h"
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31
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32 // Constructors
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33
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34 redirect::redirect(int h) {
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35 int temp;
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36 handle = h;
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37 #if defined(__MSDOS__) || defined(__WINDOWS__)
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38 tmpnam(name);
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39 temp = open(name, O_CREAT | O_RDWR | O_TEXT, S_IREAD | S_IWRITE);
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40 #else
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41 /* tmpnam() is unsafe, and causes a warning from many Unix linkers */
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42 strcpy(name, ".dsl.XXXXXX");
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43 temp = mkstemp(name);
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44 #endif
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45 assert(temp >= 0);
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46 old_handle = dup(handle);
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47 dup2(temp, handle);
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48 close(temp);
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49 copy_flag = 0; // live
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50 }
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51
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52 redirect::redirect(int h, char *file_name, int append_flag) {
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53 int temp;
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54 int flag;
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55 handle = h;
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56 temp = open(file_name, O_CREAT | O_RDWR | O_TEXT, S_IREAD | S_IWRITE);
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57 if (append_flag) lseek(temp, 0L, SEEK_END);
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58 name[0] = 0;
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59 assert(temp >= 0);
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60 old_handle = dup(handle);
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61 flag = dup2(temp, handle);
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62 assert(flag == 0);
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63 close(temp);
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64 copy_flag = 0; // live
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65 }
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66
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67 void redirect::operator = (const redirect &r) {
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68 handle = r.handle;
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69 old_handle = r.old_handle;
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70 strcpy(name, r.name);
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71 copy_flag = r.copy_flag;
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72 }
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73
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74 redirect::redirect(const redirect &r) {
0
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75 *this = r;
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76 copy_flag++; // memorex
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77 }
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78
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79
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80 // Destructor
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81
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82 redirect::~redirect() {
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83 if (copy_flag) return;
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84 dup2(old_handle, handle);
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85 close(old_handle);
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86 if (name[0]) unlink(name);
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87 }
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88
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89
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90 // Save temporary file
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91
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92 char *save_file(redirect &s) {
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93 assert(s.copy_flag == 0);
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94 char *result = memdup(s.name, 1+strlen(s.name));
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95 s.name[0] = 0;
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96 return result;
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97 }
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98
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99
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100 // Extract content of file
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101
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102 char *content(redirect &s) {
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103 long length = filelength(s.handle);
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104 long where = tell(s.handle); // Current file position
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105 unsigned n;
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106 char *result;
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107
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108 assert(length < 65520L);
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109 n = (unsigned) (length + 1);
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110 result = new char[n];
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111 assert(result != NULL);
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112 lseek(s.handle,0,0);
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113 n = read(s.handle, result, (unsigned) length);
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114 lseek(s.handle,where,0); // Restore file
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115 result[n] = 0; // Terminate string
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116 return result;
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117 }
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118
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119