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1// -*- mode: cpp; mode: fold -*-
2// Description /*{{{*/
233b185f 3// $Id: error.h,v 1.8 2001/05/07 05:06:52 jgg Exp $
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4/* ######################################################################
5
6 Global Erorr Class - Global error mechanism
7
8 This class has a single global instance. When a function needs to
9 generate an error condition, such as a read error, it calls a member
10 in this class to add the error to a stack of errors.
11
12 By using a stack the problem with a scheme like errno is removed and
13 it allows a very detailed account of what went wrong to be transmitted
14 to the UI for display. (Errno has problems because each function sets
15 errno to 0 if it didn't have an error thus eraseing erno in the process
16 of cleanup)
17
18 Several predefined error generators are provided to handle common
19 things like errno. The general idea is that all methods return a bool.
20 If the bool is true then things are OK, if it is false then things
21 should start being undone and the stack should unwind under program
22 control.
23
24 A Warning should not force the return of false. Things did not fail, but
25 they might have had unexpected problems. Errors are stored in a FIFO
26 so Pop will return the first item..
27
28 I have some thoughts about extending this into a more general UI<->
29 Engine interface, ie allowing the Engine to say 'The disk is full' in
30 a dialog that says 'Panic' and 'Retry'.. The error generator functions
31 like errno, Warning and Error return false always so this is normal:
32 if (open(..))
33 return _error->Errno(..);
34
35 This source is placed in the Public Domain, do with it what you will
36 It was originally written by Jason Gunthorpe.
37
38 ##################################################################### */
39 /*}}}*/
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40#ifndef PKGLIB_ERROR_H
41#define PKGLIB_ERROR_H
42
2893f7b5 43#include <apt-pkg/macros.h>
13500573 44
578bfd0a 45#include <string>
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46
47class GlobalError
48{
49 struct Item
50 {
2893f7b5 51 std::string Text;
578bfd0a 52 bool Error;
6c139d6e 53 Item *Next;
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54 };
55
6c139d6e 56 Item *List;
578bfd0a 57 bool PendingFlag;
6c139d6e 58 void Insert(Item *I);
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59
60 public:
61
62 // Call to generate an error from a library call.
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63 bool Errno(const char *Function,const char *Description,...) __like_printf(3) __cold;
64 bool WarningE(const char *Function,const char *Description,...) __like_printf(3) __cold;
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65
66 /* A warning should be considered less severe than an error, and may be
67 ignored by the client. */
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68 bool Error(const char *Description,...) __like_printf(2) __cold;
69 bool Warning(const char *Description,...) __like_printf(2) __cold;
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70
71 // Simple accessors
72 inline bool PendingError() {return PendingFlag;};
6c139d6e 73 inline bool empty() {return List == 0;};
2893f7b5 74 bool PopMessage(std::string &Text);
6c139d6e 75 void Discard();
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76
77 // Usefull routine to dump to cerr
78 void DumpErrors();
79
80 GlobalError();
81};
82
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83// The 'extra-ansi' syntax is used to help with collisions.
84GlobalError *_GetErrorObj();
85#define _error _GetErrorObj()
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86
87#endif