[apt.git] / apt-pkg / contrib / error.h

// -*- mode: cpp; mode: fold -*-
// Description								/*{{{*/
// $Id: error.h,v 1.8 2001/05/07 05:06:52 jgg Exp $
/* ######################################################################
   
   Global Erorr Class - Global error mechanism

   This class has a single global instance. When a function needs to 
   generate an error condition, such as a read error, it calls a member
   in this class to add the error to a stack of errors. 
   
   By using a stack the problem with a scheme like errno is removed and
   it allows a very detailed account of what went wrong to be transmitted
   to the UI for display. (Errno has problems because each function sets
   errno to 0 if it didn't have an error thus eraseing erno in the process
   of cleanup)
   
   Several predefined error generators are provided to handle common 
   things like errno. The general idea is that all methods return a bool.
   If the bool is true then things are OK, if it is false then things 
   should start being undone and the stack should unwind under program
   control.
   
   A Warning should not force the return of false. Things did not fail, but
   they might have had unexpected problems. Errors are stored in a FIFO
   so Pop will return the first item..
   
   I have some thoughts about extending this into a more general UI<-> 
   Engine interface, ie allowing the Engine to say 'The disk is full' in 
   a dialog that says 'Panic' and 'Retry'.. The error generator functions
   like errno, Warning and Error return false always so this is normal:
     if (open(..))
        return _error->Errno(..);
   
   This source is placed in the Public Domain, do with it what you will
   It was originally written by Jason Gunthorpe.
   
   ##################################################################### */
									/*}}}*/
#ifndef PKGLIB_ERROR_H
#define PKGLIB_ERROR_H

#include <apt-pkg/macros.h>

#include <iostream>
#include <list>
#include <string>

#include <stdarg.h>

class GlobalError							/*{{{*/
{
public:									/*{{{*/
	/** \brief a message can have one of following severity */
	enum MsgType {
		/** \brief Message will be printed instantly as it is likely that
			this error will lead to a complete crash */
		FATAL = 40,
		/** \brief An error does hinder the correct execution and should be corrected */
		ERROR = 30,
		/** \brief indicates problem that can lead to errors later on */
		WARNING = 20,
		/** \brief deprecation warnings, old fallback behavior, … */
		NOTICE = 10,
		/** \brief for developers only in areas it is hard to print something directly */
		DEBUG = 0
	};

	/** \brief add a fatal error message with errno to the list
	 *
	 *  \param Function name of the function generating the error
	 *  \param Description format string for the error message
	 *
	 *  \return \b false
	 */
	bool FatalE(const char *Function,const char *Description,...) __like_printf(3) __cold;

	/** \brief add an Error message with errno to the list
	 *
	 *  \param Function name of the function generating the error
	 *  \param Description format string for the error message
	 *
	 *  \return \b false
	 */
	bool Errno(const char *Function,const char *Description,...) __like_printf(3) __cold;

	/** \brief add a warning message with errno to the list
	 *
	 *  A warning should be considered less severe than an error and
	 *  may be ignored by the client.
	 *
	 *  \param Function Name of the function generates the warning.
	 *  \param Description Format string for the warning message.
	 *
	 *  \return \b false
	 */
	bool WarningE(const char *Function,const char *Description,...) __like_printf(3) __cold;

	/** \brief add a notice message with errno to the list
	 *
	 *  \param Function name of the function generating the error
	 *  \param Description format string for the error message
	 *
	 *  \return \b false
	 */
	bool NoticeE(const char *Function,const char *Description,...) __like_printf(3) __cold;

	/** \brief add a debug message with errno to the list
	 *
	 *  \param Function name of the function generating the error
	 *  \param Description format string for the error message
	 *
	 *  \return \b false
	 */
	bool DebugE(const char *Function,const char *Description,...) __like_printf(3) __cold;

	/** \brief add an fatal error message to the list
	 *
	 *  Most of the stuff we consider as "error" is also "fatal" for
	 *  the user as the application will not have the expected result,
	 *  but a fatal message here means that it gets printed directly
	 *  to stderr in addiction to adding it to the list as the error
	 *  leads sometimes to crashes and a maybe duplicated message
	 *  is better than "Segfault" as the only displayed text
	 *
	 *  \param Description Format string for the fatal error message.
	 *
	 *  \return \b false
	 */
	bool Fatal(const char *Description,...) __like_printf(2) __cold;

	/** \brief add an Error message to the list
	 *
	 *  \param Description Format string for the error message.
	 *
	 *  \return \b false
	 */
	bool Error(const char *Description,...) __like_printf(2) __cold;

	/** \brief add a warning message to the list
	 *
	 *  A warning should be considered less severe than an error and
	 *  may be ignored by the client.
	 *
	 *  \param Description Format string for the message
	 *
	 *  \return \b false
	 */
	bool Warning(const char *Description,...) __like_printf(2) __cold;

	/** \brief add a notice message to the list
	 *
	 *  A notice should be considered less severe than an error or a
	 *  warning and can be ignored by the client without further problems
	 *  for some times, but he should consider fixing the problem.
	 *  This error type can be used for e.g. deprecation warnings of options.
	 *
	 *  \param Description Format string for the message
	 *
	 *  \return \b false
	 */
	bool Notice(const char *Description,...) __like_printf(2) __cold;

	/** \brief add a debug message to the list
	 *
	 *  \param Description Format string for the message
	 *
	 *  \return \b false
	 */
	bool Debug(const char *Description,...) __like_printf(2) __cold;

	/** \brief is an error in the list?
	 *
	 *  \return \b true if an error is included in the list, \b false otherwise
	 */
	inline bool PendingError() const {return PendingFlag;};

	/** \brief is the list empty?
	 *
	 *  The default checks if the list is empty or contains only notices,
	 *  if you want to check if also no notices happend set the parameter
	 *  flag to \b false.
	 *
	 *  \param WithoutNotice does notices count, default is \b true, so no
	 *
	 *  \return \b true if an the list is empty, \b false otherwise
	 */
	bool empty(MsgType const &trashhold = WARNING) const;

	/** \brief returns and removes the first (or last) message in the list
	 *
	 *  \param[out] Text message of the first/last item
	 *
	 *  \return \b true if the message was an error, \b false otherwise
	 */
	bool PopMessage(std::string &Text);

	/** \brief clears the list of messages */
	void Discard();

	/** \brief outputs the list of messages to the given stream
	 *
	 *  Note that all messages are discarded, also the notices
	 *  displayed or not.
	 *
	 *  \param[out] out output stream to write the messages in
	 *  \param threshold minimim level considered
         *  \param mergeStack 
	 */
	void DumpErrors(std::ostream &out, MsgType const &threshold = WARNING,
			bool const &mergeStack = true);

	/** \brief dumps the list of messages to std::cerr
	 *
	 *  Note that all messages are discarded, also the notices
	 *  displayed or not.
	 *
	 *  \param threshold minimum level printed
	 */
	void inline DumpErrors(MsgType const &threshold) {
		DumpErrors(std::cerr, threshold);
	}

        // mvo: we do this instead of using a default parameter in the
        //      previous declaration to avoid a (subtle) API break for
        //      e.g. sigc++ and mem_fun0
	/** \brief dumps the messages of type WARNING or higher to std::cerr
	 *
	 *  Note that all messages are discarded, displayed or not.
	 *
	 */
	void inline DumpErrors() {
                DumpErrors(WARNING);
	}

	/** \brief put the current Messages into the stack
	 *
	 *  All "old" messages will be pushed into a stack to
	 *  them later back, but for now the Message query will be
	 *  empty and performs as no messages were present before.
	 *
	 * The stack can be as deep as you want - all stack operations
	 * will only operate on the last element in the stack.
	 */
	void PushToStack();

	/** \brief throw away all current messages */
	void RevertToStack();

	/** \brief merge current and stack together */
	void MergeWithStack();

	/** \brief return the deep of the stack */
	size_t StackCount() const {
		return Stacks.size();
	}

	GlobalError();
									/*}}}*/
private:								/*{{{*/
	struct Item {
		std::string Text;
		MsgType Type;

		Item(char const *Text, MsgType const &Type) :
			Text(Text), Type(Type) {};

		friend std::ostream& operator<< (std::ostream &out, Item i) {
			switch(i.Type) {
			case FATAL:
			case ERROR: out << "E"; break;
			case WARNING: out << "W"; break;
			case NOTICE: out << "N"; break;
			case DEBUG: out << "D"; break;
			}
			return out << ": " << i.Text;
		}
	};

	std::list<Item> Messages;
	bool PendingFlag;

	struct MsgStack {
		std::list<Item> const Messages;
		bool const PendingFlag;

		MsgStack(std::list<Item> const &Messages, bool const &Pending) :
			 Messages(Messages), PendingFlag(Pending) {};
	};

	std::list<MsgStack> Stacks;

	bool InsertErrno(MsgType type, const char* Function,
			 const char* Description, va_list &args);
	bool Insert(MsgType type, const char* Description,
			 va_list &args);
									/*}}}*/
};
									/*}}}*/

// The 'extra-ansi' syntax is used to help with collisions. 
GlobalError *_GetErrorObj();
#define _error _GetErrorObj()

#endif
Commit	Line	Data
578bfd0a AL	1	// -- mode: cpp; mode: fold --
578bfd0a AL	2	// Description /{{{/
233b185f	3	// $Id: error.h,v 1.8 2001/05/07 05:06:52 jgg Exp $
578bfd0a AL	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	/}}}/
578bfd0a AL	40	#ifndef PKGLIB_ERROR_H
	41	#define PKGLIB_ERROR_H
	42
2893f7b5	43	#include <apt-pkg/macros.h>
13500573	44
98ee7cd3 DK	45	#include <iostream>
98ee7cd3 DK	46	#include <list>
578bfd0a	47	#include <string>
578bfd0a	48
98ee7cd3 DK	49	#include <stdarg.h>
	50
	51	class GlobalError /{{{/
578bfd0a	52	{
98ee7cd3 DK	53	public: /{{{/
	54	/** \brief a message can have one of following severity */
	55	enum MsgType {
	56	/** \brief Message will be printed instantly as it is likely that
	57	this error will lead to a complete crash */
	58	FATAL = 40,
	59	/** \brief An error does hinder the correct execution and should be corrected */
	60	ERROR = 30,
	61	/** \brief indicates problem that can lead to errors later on */
	62	WARNING = 20,
	63	/** \brief deprecation warnings, old fallback behavior, … */
	64	NOTICE = 10,
	65	/** \brief for developers only in areas it is hard to print something directly */
	66	DEBUG = 0
	67	};
578bfd0a	68
98ee7cd3 DK	69	/** \brief add a fatal error message with errno to the list
	70	*
	71	* \param Function name of the function generating the error
	72	* \param Description format string for the error message
	73	*
	74	* \return \b false
	75	*/
	76	bool FatalE(const char Function,const char Description,...) __like_printf(3) __cold;
578bfd0a	77
98ee7cd3 DK	78	/** \brief add an Error message with errno to the list
	79	*
	80	* \param Function name of the function generating the error
	81	* \param Description format string for the error message
	82	*
	83	* \return \b false
	84	*/
	85	bool Errno(const char Function,const char Description,...) __like_printf(3) __cold;
578bfd0a	86
98ee7cd3 DK	87	/** \brief add a warning message with errno to the list
	88	*
	89	* A warning should be considered less severe than an error and
	90	* may be ignored by the client.
	91	*
	92	* \param Function Name of the function generates the warning.
	93	* \param Description Format string for the warning message.
	94	*
	95	* \return \b false
	96	*/
	97	bool WarningE(const char Function,const char Description,...) __like_printf(3) __cold;
578bfd0a	98
98ee7cd3 DK	99	/** \brief add a notice message with errno to the list
	100	*
	101	* \param Function name of the function generating the error
	102	* \param Description format string for the error message
	103	*
	104	* \return \b false
	105	*/
	106	bool NoticeE(const char Function,const char Description,...) __like_printf(3) __cold;
	107
	108	/** \brief add a debug message with errno to the list
	109	*
	110	* \param Function name of the function generating the error
	111	* \param Description format string for the error message
	112	*
	113	* \return \b false
	114	*/
	115	bool DebugE(const char Function,const char Description,...) __like_printf(3) __cold;
	116
	117	/** \brief add an fatal error message to the list
	118	*
	119	* Most of the stuff we consider as "error" is also "fatal" for
	120	* the user as the application will not have the expected result,
	121	* but a fatal message here means that it gets printed directly
	122	* to stderr in addiction to adding it to the list as the error
	123	* leads sometimes to crashes and a maybe duplicated message
	124	* is better than "Segfault" as the only displayed text
	125	*
	126	* \param Description Format string for the fatal error message.
	127	*
	128	* \return \b false
	129	*/
	130	bool Fatal(const char *Description,...) __like_printf(2) __cold;
	131
	132	/** \brief add an Error message to the list
	133	*
	134	* \param Description Format string for the error message.
	135	*
	136	* \return \b false
	137	*/
	138	bool Error(const char *Description,...) __like_printf(2) __cold;
	139
	140	/** \brief add a warning message to the list
	141	*
	142	* A warning should be considered less severe than an error and
	143	* may be ignored by the client.
	144	*
	145	* \param Description Format string for the message
	146	*
	147	* \return \b false
	148	*/
	149	bool Warning(const char *Description,...) __like_printf(2) __cold;
	150
	151	/** \brief add a notice message to the list
	152	*
	153	* A notice should be considered less severe than an error or a
	154	* warning and can be ignored by the client without further problems
	155	* for some times, but he should consider fixing the problem.
	156	* This error type can be used for e.g. deprecation warnings of options.
	157	*
	158	* \param Description Format string for the message
	159	*
	160	* \return \b false
	161	*/
	162	bool Notice(const char *Description,...) __like_printf(2) __cold;
163
164	/** \brief add a debug message to the list
165	*
166	* \param Description Format string for the message
167	*
168	* \return \b false
169	*/
170	bool Debug(const char *Description,...) __like_printf(2) __cold;
171
172	/** \brief is an error in the list?
173	*
174	* \return \b true if an error is included in the list, \b false otherwise
175	*/
176	inline bool PendingError() const {return PendingFlag;};
177
178	/** \brief is the list empty?
179	*
180	* The default checks if the list is empty or contains only notices,
181	* if you want to check if also no notices happend set the parameter
182	* flag to \b false.
183	*
184	* \param WithoutNotice does notices count, default is \b true, so no
185	*
186	* \return \b true if an the list is empty, \b false otherwise
187	*/
188	bool empty(MsgType const &trashhold = WARNING) const;
189
190	/** \brief returns and removes the first (or last) message in the list
191	*
192	* \param[out] Text message of the first/last item
193	*
194	* \return \b true if the message was an error, \b false otherwise
195	*/
196	bool PopMessage(std::string &Text);
197
198	/** \brief clears the list of messages */
199	void Discard();
200
201	/** \brief outputs the list of messages to the given stream
202	*
203	* Note that all messages are discarded, also the notices
204	* displayed or not.
205	*
206	* \param[out] out output stream to write the messages in
12be8a62 MV	207	* \param threshold minimim level considered
12be8a62 MV	208	* \param mergeStack
98ee7cd3	209	*/
12be8a62	210	void DumpErrors(std::ostream &out, MsgType const &threshold = WARNING,
c4ba7c44	211	bool const &mergeStack = true);
98ee7cd3 DK	212
	213	/** \brief dumps the list of messages to std::cerr
	214	*
	215	* Note that all messages are discarded, also the notices
	216	* displayed or not.
	217	*
12be8a62	218	* \param threshold minimum level printed
98ee7cd3	219	*/
ca0d389c	220	void inline DumpErrors(MsgType const &threshold) {
12be8a62	221	DumpErrors(std::cerr, threshold);
98ee7cd3 DK	222	}
98ee7cd3 DK	223
ca0d389c MV	224	// mvo: we do this instead of using a default parameter in the
	225	// previous declaration to avoid a (subtle) API break for
	226	// e.g. sigc++ and mem_fun0
	227	/** \brief dumps the messages of type WARNING or higher to std::cerr
	228	*
	229	* Note that all messages are discarded, displayed or not.
	230	*
	231	*/
	232	void inline DumpErrors() {
	233	DumpErrors(WARNING);
	234	}
	235
c4ba7c44 DK	236	/** \brief put the current Messages into the stack
	237	*
	238	* All "old" messages will be pushed into a stack to
	239	* them later back, but for now the Message query will be
	240	* empty and performs as no messages were present before.
	241	*
	242	* The stack can be as deep as you want - all stack operations
	243	* will only operate on the last element in the stack.
	244	*/
	245	void PushToStack();
	246
	247	/** \brief throw away all current messages */
	248	void RevertToStack();
	249
	250	/** \brief merge current and stack together */
	251	void MergeWithStack();
	252
	253	/** \brief return the deep of the stack */
	254	size_t StackCount() const {
	255	return Stacks.size();
	256	}
	257
98ee7cd3 DK	258	GlobalError();
	259	/}}}/
	260	private: /{{{/
	261	struct Item {
	262	std::string Text;
	263	MsgType Type;
	264
	265	Item(char const *Text, MsgType const &Type) :
	266	Text(Text), Type(Type) {};
	267
	268	friend std::ostream& operator<< (std::ostream &out, Item i) {
	269	switch(i.Type) {
	270	case FATAL:
	271	case ERROR: out << "E"; break;
	272	case WARNING: out << "W"; break;
	273	case NOTICE: out << "N"; break;
	274	case DEBUG: out << "D"; break;
	275	}
	276	return out << ": " << i.Text;
	277	}
	278	};
	279
	280	std::list<Item> Messages;
	281	bool PendingFlag;
	282
c4ba7c44 DK	283	struct MsgStack {
	284	std::list<Item> const Messages;
	285	bool const PendingFlag;
	286
	287	MsgStack(std::list<Item> const &Messages, bool const &Pending) :
	288	Messages(Messages), PendingFlag(Pending) {};
	289	};
	290
	291	std::list<MsgStack> Stacks;
	292
98ee7cd3	293	bool InsertErrno(MsgType type, const char* Function,
3c0929ec	294	const char* Description, va_list &args);
98ee7cd3	295	bool Insert(MsgType type, const char* Description,
3c0929ec	296	va_list &args);
98ee7cd3	297	/}}}/
578bfd0a	298	};
98ee7cd3	299	/}}}/
578bfd0a	300
6f27a7fc AL	301	// The 'extra-ansi' syntax is used to help with collisions.
	302	GlobalError *_GetErrorObj();
	303	#define _error _GetErrorObj()
578bfd0a AL	304
578bfd0a AL	305	#endif