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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
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45#include <iostream>
46#include <list>
578bfd0a 47#include <string>
578bfd0a 48
453b82a3 49#include <stddef.h>
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50#include <stdarg.h>
51
52class GlobalError /*{{{*/
578bfd0a 53{
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54public: /*{{{*/
55 /** \brief a message can have one of following severity */
56 enum MsgType {
57 /** \brief Message will be printed instantly as it is likely that
58 this error will lead to a complete crash */
59 FATAL = 40,
60 /** \brief An error does hinder the correct execution and should be corrected */
61 ERROR = 30,
62 /** \brief indicates problem that can lead to errors later on */
63 WARNING = 20,
64 /** \brief deprecation warnings, old fallback behavior, … */
65 NOTICE = 10,
66 /** \brief for developers only in areas it is hard to print something directly */
67 DEBUG = 0
68 };
578bfd0a 69
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70 /** \brief add a fatal error message with errno to the list
71 *
72 * \param Function name of the function generating the error
73 * \param Description format string for the error message
74 *
75 * \return \b false
76 */
453b82a3 77 bool FatalE(const char *Function,const char *Description,...) APT_PRINTF(3) APT_COLD;
578bfd0a 78
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79 /** \brief add an Error message with errno to the list
80 *
81 * \param Function name of the function generating the error
82 * \param Description format string for the error message
83 *
84 * \return \b false
85 */
453b82a3 86 bool Errno(const char *Function,const char *Description,...) APT_PRINTF(3) APT_COLD;
578bfd0a 87
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88 /** \brief add a warning message with errno to the list
89 *
90 * A warning should be considered less severe than an error and
91 * may be ignored by the client.
92 *
93 * \param Function Name of the function generates the warning.
94 * \param Description Format string for the warning message.
95 *
96 * \return \b false
97 */
453b82a3 98 bool WarningE(const char *Function,const char *Description,...) APT_PRINTF(3) APT_COLD;
578bfd0a 99
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100 /** \brief add a notice message with errno to the list
101 *
102 * \param Function name of the function generating the error
103 * \param Description format string for the error message
104 *
105 * \return \b false
106 */
453b82a3 107 bool NoticeE(const char *Function,const char *Description,...) APT_PRINTF(3) APT_COLD;
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108
109 /** \brief add a debug message with errno to the list
110 *
111 * \param Function name of the function generating the error
112 * \param Description format string for the error message
113 *
114 * \return \b false
115 */
453b82a3 116 bool DebugE(const char *Function,const char *Description,...) APT_PRINTF(3) APT_COLD;
98ee7cd3 117
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118 /** \brief adds an errno message with the given type
119 *
120 * \param type of the error message
121 * \param Function which failed
122 * \param Description of the error
123 */
124 bool InsertErrno(MsgType const &type, const char* Function,
453b82a3 125 const char* Description,...) APT_PRINTF(4) APT_COLD;
cd7bbc47 126
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127 /** \brief adds an errno message with the given type
128 *
129 * args needs to be initialized with va_start and terminated
130 * with va_end by the caller. msgSize is also an out-parameter
131 * in case the msgSize was not enough to store the complete message.
132 *
133 * \param type of the error message
134 * \param Function which failed
135 * \param Description is the format string for args
136 * \param args list from a printf-like function
137 * \param errsv is the errno the error is for
138 * \param msgSize is the size of the char[] used to store message
139 * \return true if the message was added, false if not - the caller
140 * should call this method again in that case
141 */
142 bool InsertErrno(MsgType type, const char* Function,
143 const char* Description, va_list &args,
a02db58f 144 int const errsv, size_t &msgSize) APT_COLD;
c7873955 145
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146 /** \brief add an fatal error message to the list
147 *
148 * Most of the stuff we consider as "error" is also "fatal" for
149 * the user as the application will not have the expected result,
150 * but a fatal message here means that it gets printed directly
646ebd92 151 * to stderr in addition to adding it to the list as the error
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152 * leads sometimes to crashes and a maybe duplicated message
153 * is better than "Segfault" as the only displayed text
154 *
155 * \param Description Format string for the fatal error message.
156 *
157 * \return \b false
158 */
453b82a3 159 bool Fatal(const char *Description,...) APT_PRINTF(2) APT_COLD;
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160
161 /** \brief add an Error message to the list
162 *
163 * \param Description Format string for the error message.
164 *
165 * \return \b false
166 */
453b82a3 167 bool Error(const char *Description,...) APT_PRINTF(2) APT_COLD;
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168
169 /** \brief add a warning message to the list
170 *
171 * A warning should be considered less severe than an error and
172 * may be ignored by the client.
173 *
174 * \param Description Format string for the message
175 *
176 * \return \b false
177 */
453b82a3 178 bool Warning(const char *Description,...) APT_PRINTF(2) APT_COLD;
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179
180 /** \brief add a notice message to the list
181 *
182 * A notice should be considered less severe than an error or a
183 * warning and can be ignored by the client without further problems
184 * for some times, but he should consider fixing the problem.
185 * This error type can be used for e.g. deprecation warnings of options.
186 *
187 * \param Description Format string for the message
188 *
189 * \return \b false
190 */
453b82a3 191 bool Notice(const char *Description,...) APT_PRINTF(2) APT_COLD;
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192
193 /** \brief add a debug message to the list
194 *
195 * \param Description Format string for the message
196 *
197 * \return \b false
198 */
453b82a3 199 bool Debug(const char *Description,...) APT_PRINTF(2) APT_COLD;
98ee7cd3 200
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201 /** \brief adds an error message with the given type
202 *
203 * \param type of the error message
204 * \param Description of the error
205 */
453b82a3 206 bool Insert(MsgType const &type, const char* Description,...) APT_PRINTF(3) APT_COLD;
cd7bbc47 207
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208 /** \brief adds an error message with the given type
209 *
210 * args needs to be initialized with va_start and terminated
211 * with va_end by the caller. msgSize is also an out-parameter
212 * in case the msgSize was not enough to store the complete message.
213 *
214 * \param type of the error message
215 * \param Description is the format string for args
216 * \param args list from a printf-like function
217 * \param msgSize is the size of the char[] used to store message
218 * \return true if the message was added, false if not - the caller
219 * should call this method again in that case
220 */
221 bool Insert(MsgType type, const char* Description,
453b82a3 222 va_list &args, size_t &msgSize) APT_COLD;
c7873955 223
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224 /** \brief is an error in the list?
225 *
226 * \return \b true if an error is included in the list, \b false otherwise
227 */
a02db58f 228 inline bool PendingError() const APT_PURE {return PendingFlag;};
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229
230 /** \brief is the list empty?
231 *
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232 * Can be used to check if the current stack level doesn't include
233 * anything equal or more severe than a given threshold, defaulting
234 * to warning level for historic reasons.
98ee7cd3 235 *
646ebd92 236 * \param threshold minimum level considered
98ee7cd3 237 *
646ebd92 238 * \return \b true if the list is empty, \b false otherwise
98ee7cd3 239 */
a02db58f 240 bool empty(MsgType const &threshold = WARNING) const APT_PURE;
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241
242 /** \brief returns and removes the first (or last) message in the list
243 *
244 * \param[out] Text message of the first/last item
245 *
246 * \return \b true if the message was an error, \b false otherwise
247 */
248 bool PopMessage(std::string &Text);
249
250 /** \brief clears the list of messages */
251 void Discard();
252
253 /** \brief outputs the list of messages to the given stream
254 *
646ebd92 255 * Note that all messages are discarded, even undisplayed ones.
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256 *
257 * \param[out] out output stream to write the messages in
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258 * \param threshold minimum level considered
259 * \param mergeStack if true recursively dumps the entire stack
98ee7cd3 260 */
12be8a62 261 void DumpErrors(std::ostream &out, MsgType const &threshold = WARNING,
c4ba7c44 262 bool const &mergeStack = true);
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263
264 /** \brief dumps the list of messages to std::cerr
265 *
266 * Note that all messages are discarded, also the notices
267 * displayed or not.
268 *
12be8a62 269 * \param threshold minimum level printed
98ee7cd3 270 */
ca0d389c 271 void inline DumpErrors(MsgType const &threshold) {
12be8a62 272 DumpErrors(std::cerr, threshold);
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273 }
274
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275 // mvo: we do this instead of using a default parameter in the
276 // previous declaration to avoid a (subtle) API break for
277 // e.g. sigc++ and mem_fun0
278 /** \brief dumps the messages of type WARNING or higher to std::cerr
279 *
280 * Note that all messages are discarded, displayed or not.
281 *
282 */
283 void inline DumpErrors() {
284 DumpErrors(WARNING);
285 }
286
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287 /** \brief put the current Messages into the stack
288 *
289 * All "old" messages will be pushed into a stack to
290 * them later back, but for now the Message query will be
291 * empty and performs as no messages were present before.
292 *
293 * The stack can be as deep as you want - all stack operations
294 * will only operate on the last element in the stack.
295 */
296 void PushToStack();
297
298 /** \brief throw away all current messages */
299 void RevertToStack();
300
301 /** \brief merge current and stack together */
302 void MergeWithStack();
303
304 /** \brief return the deep of the stack */
a02db58f 305 size_t StackCount() const APT_PURE {
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306 return Stacks.size();
307 }
308
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309 GlobalError();
310 /*}}}*/
311private: /*{{{*/
312 struct Item {
313 std::string Text;
314 MsgType Type;
315
316 Item(char const *Text, MsgType const &Type) :
317 Text(Text), Type(Type) {};
318
82153438 319 APT_HIDDEN friend std::ostream& operator<< (std::ostream &out, Item i) {
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320 switch(i.Type) {
321 case FATAL:
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322 case ERROR: out << 'E'; break;
323 case WARNING: out << 'W'; break;
324 case NOTICE: out << 'N'; break;
325 case DEBUG: out << 'D'; break;
98ee7cd3 326 }
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327 out << ": ";
328 std::string::size_type line_start = 0;
329 std::string::size_type line_end;
330 while ((line_end = i.Text.find_first_of("\n\r", line_start)) != std::string::npos) {
331 if (line_start != 0)
332 out << std::endl << " ";
333 out << i.Text.substr(line_start, line_end - line_start);
334 line_start = i.Text.find_first_not_of("\n\r", line_end + 1);
335 if (line_start == std::string::npos)
336 break;
337 }
338 if (line_start == 0)
339 out << i.Text;
340 else if (line_start != std::string::npos)
341 out << std::endl << " " << i.Text.substr(line_start);
342 return out;
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343 }
344 };
345
346 std::list<Item> Messages;
347 bool PendingFlag;
348
c4ba7c44 349 struct MsgStack {
95278287 350 std::list<Item> Messages;
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351 bool const PendingFlag;
352
353 MsgStack(std::list<Item> const &Messages, bool const &Pending) :
354 Messages(Messages), PendingFlag(Pending) {};
355 };
356
357 std::list<MsgStack> Stacks;
98ee7cd3 358 /*}}}*/
578bfd0a 359};
98ee7cd3 360 /*}}}*/
578bfd0a 361
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362// The 'extra-ansi' syntax is used to help with collisions.
363GlobalError *_GetErrorObj();
364#define _error _GetErrorObj()
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365
366#endif