[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 adds an errno message with the given type
	 *
	 * \param type of the error message
	 * \param Function which failed
	 * \param Description of the error
	 */
	bool InsertErrno(MsgType const &type, const char* Function,
			 const char* Description,...) __like_printf(4) __cold;

	/** \brief adds an errno message with the given type
	 *
	 * args needs to be initialized with va_start and terminated
	 * with va_end by the caller. msgSize is also an out-parameter
	 * in case the msgSize was not enough to store the complete message.
	 *
	 * \param type of the error message
	 * \param Function which failed
	 * \param Description is the format string for args
	 * \param args list from a printf-like function
	 * \param errsv is the errno the error is for
	 * \param msgSize is the size of the char[] used to store message
	 * \return true if the message was added, false if not - the caller
	 * should call this method again in that case
	 */
	bool InsertErrno(MsgType type, const char* Function,
			 const char* Description, va_list &args,
			 int const errsv, size_t &msgSize);

	/** \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 adds an error message with the given type
	 *
	 * \param type of the error message
	 * \param Description of the error
	 */
	bool Insert(MsgType const &type, const char* Description,...) __like_printf(3) __cold;

	/** \brief adds an error message with the given type
	 *
	 * args needs to be initialized with va_start and terminated
	 * with va_end by the caller. msgSize is also an out-parameter
	 * in case the msgSize was not enough to store the complete message.
	 *
	 * \param type of the error message
	 * \param Description is the format string for args
	 * \param args list from a printf-like function
	 * \param msgSize is the size of the char[] used to store message
	 * \return true if the message was added, false if not - the caller
	 * should call this method again in that case
	 */
	bool Insert(MsgType type, const char* Description,
			 va_list &args, size_t &msgSize) __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;
									/*}}}*/
};
									/*}}}*/

// 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
cd7bbc47 DK	117	/** \brief adds an errno message with the given type
	118	*
	119	* \param type of the error message
	120	* \param Function which failed
	121	* \param Description of the error
	122	*/
	123	bool InsertErrno(MsgType const &type, const char* Function,
	124	const char* Description,...) __like_printf(4) __cold;
	125
c7873955 DK	126	/** \brief adds an errno message with the given type
	127	*
	128	* args needs to be initialized with va_start and terminated
	129	* with va_end by the caller. msgSize is also an out-parameter
	130	* in case the msgSize was not enough to store the complete message.
	131	*
	132	* \param type of the error message
	133	* \param Function which failed
	134	* \param Description is the format string for args
	135	* \param args list from a printf-like function
	136	* \param errsv is the errno the error is for
	137	* \param msgSize is the size of the char[] used to store message
	138	* \return true if the message was added, false if not - the caller
	139	* should call this method again in that case
	140	*/
	141	bool InsertErrno(MsgType type, const char* Function,
	142	const char* Description, va_list &args,
	143	int const errsv, size_t &msgSize);
	144
98ee7cd3 DK	145	/** \brief add an fatal error message to the list
	146	*
	147	* Most of the stuff we consider as "error" is also "fatal" for
	148	* the user as the application will not have the expected result,
	149	* but a fatal message here means that it gets printed directly
	150	* to stderr in addiction to adding it to the list as the error
	151	* leads sometimes to crashes and a maybe duplicated message
	152	* is better than "Segfault" as the only displayed text
	153	*
	154	* \param Description Format string for the fatal error message.
	155	*
	156	* \return \b false
	157	*/
	158	bool Fatal(const char *Description,...) __like_printf(2) __cold;
	159
	160	/** \brief add an Error message to the list
	161	*
	162	* \param Description Format string for the error message.
	163	*
	164	* \return \b false
	165	*/
	166	bool Error(const char *Description,...) __like_printf(2) __cold;
	167
	168	/** \brief add a warning message to the list
	169	*
	170	* A warning should be considered less severe than an error and
	171	* may be ignored by the client.
	172	*
	173	* \param Description Format string for the message
	174	*
	175	* \return \b false
	176	*/
	177	bool Warning(const char *Description,...) __like_printf(2) __cold;
	178
	179	/** \brief add a notice message to the list
	180	*
	181	* A notice should be considered less severe than an error or a
	182	* warning and can be ignored by the client without further problems
	183	* for some times, but he should consider fixing the problem.
	184	* This error type can be used for e.g. deprecation warnings of options.
	185	*
	186	* \param Description Format string for the message
	187	*
	188	* \return \b false
	189	*/
	190	bool Notice(const char *Description,...) __like_printf(2) __cold;
	191
	192	/** \brief add a debug message to the list
	193	*
	194	* \param Description Format string for the message
	195	*
	196	* \return \b false
	197	*/
	198	bool Debug(const char *Description,...) __like_printf(2) __cold;
	199
cd7bbc47 DK	200	/** \brief adds an error message with the given type
	201	*
	202	* \param type of the error message
	203	* \param Description of the error
	204	*/
	205	bool Insert(MsgType const &type, const char* Description,...) __like_printf(3) __cold;
	206
c7873955 DK	207	/** \brief adds an error message with the given type
	208	*
	209	* args needs to be initialized with va_start and terminated
	210	* with va_end by the caller. msgSize is also an out-parameter
	211	* in case the msgSize was not enough to store the complete message.
	212	*
	213	* \param type of the error message
	214	* \param Description is the format string for args
	215	* \param args list from a printf-like function
	216	* \param msgSize is the size of the char[] used to store message
	217	* \return true if the message was added, false if not - the caller
	218	* should call this method again in that case
	219	*/
	220	bool Insert(MsgType type, const char* Description,
	221	va_list &args, size_t &msgSize) __cold;
	222
98ee7cd3 DK	223	/** \brief is an error in the list?
	224	*
	225	* \return \b true if an error is included in the list, \b false otherwise
	226	*/
	227	inline bool PendingError() const {return PendingFlag;};
	228
	229	/** \brief is the list empty?
	230	*
	231	* The default checks if the list is empty or contains only notices,
	232	* if you want to check if also no notices happend set the parameter
	233	* flag to \b false.
	234	*
	235	* \param WithoutNotice does notices count, default is \b true, so no
	236	*
	237	* \return \b true if an the list is empty, \b false otherwise
	238	*/
	239	bool empty(MsgType const &trashhold = WARNING) const;
	240
	241	/** \brief returns and removes the first (or last) message in the list
	242	*
	243	* \param[out] Text message of the first/last item
	244	*
	245	* \return \b true if the message was an error, \b false otherwise
	246	*/
	247	bool PopMessage(std::string &Text);
	248
	249	/** \brief clears the list of messages */
	250	void Discard();
	251
	252	/** \brief outputs the list of messages to the given stream
	253	*
	254	* Note that all messages are discarded, also the notices
	255	* displayed or not.
	256	*
	257	* \param[out] out output stream to write the messages in
12be8a62 MV	258	* \param threshold minimim level considered
12be8a62 MV	259	* \param mergeStack
98ee7cd3	260	*/
12be8a62	261	void DumpErrors(std::ostream &out, MsgType const &threshold = WARNING,
c4ba7c44	262	bool const &mergeStack = true);
98ee7cd3 DK	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);
98ee7cd3 DK	273	}
98ee7cd3 DK	274
ca0d389c MV	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
c4ba7c44 DK	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 */
	305	size_t StackCount() const {
	306	return Stacks.size();
	307	}
	308
98ee7cd3 DK	309	GlobalError();
	310	/}}}/
	311	private: /{{{/
	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
	319	friend std::ostream& operator<< (std::ostream &out, Item i) {
	320	switch(i.Type) {
	321	case FATAL:
	322	case ERROR: out << "E"; break;
	323	case WARNING: out << "W"; break;
	324	case NOTICE: out << "N"; break;
	325	case DEBUG: out << "D"; break;
	326	}
	327	return out << ": " << i.Text;
	328	}
	329	};
	330
	331	std::list<Item> Messages;
	332	bool PendingFlag;
	333
c4ba7c44 DK	334	struct MsgStack {
	335	std::list<Item> const Messages;
	336	bool const PendingFlag;
	337
	338	MsgStack(std::list<Item> const &Messages, bool const &Pending) :
	339	Messages(Messages), PendingFlag(Pending) {};
	340	};
	341
	342	std::list<MsgStack> Stacks;
98ee7cd3	343	/}}}/
578bfd0a	344	};
98ee7cd3	345	/}}}/
578bfd0a	346
6f27a7fc AL	347	// The 'extra-ansi' syntax is used to help with collisions.
	348	GlobalError *_GetErrorObj();
	349	#define _error _GetErrorObj()
578bfd0a AL	350
578bfd0a AL	351	#endif