[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 <stddef.h>
#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,...) APT_PRINTF(3) APT_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,...) APT_PRINTF(3) APT_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,...) APT_PRINTF(3) APT_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,...) APT_PRINTF(3) APT_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,...) APT_PRINTF(3) APT_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,...) APT_PRINTF(4) APT_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) APT_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,...) APT_PRINTF(2) APT_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,...) APT_PRINTF(2) APT_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,...) APT_PRINTF(2) APT_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,...) APT_PRINTF(2) APT_COLD;

	/** \brief add a debug message to the list
	 *
	 *  \param Description Format string for the message
	 *
	 *  \return \b false
	 */
	bool Debug(const char *Description,...) APT_PRINTF(2) APT_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,...) APT_PRINTF(3) APT_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) APT_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 APT_PURE {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 happened set the parameter
	 *  flag to \b false.
	 *
	 *  \param threshold minimim level considered
	 *
	 *  \return \b true if an the list is empty, \b false otherwise
	 */
	bool empty(MsgType const &threshold = WARNING) const APT_PURE;

	/** \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 APT_PURE {
		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
453b82a3	49	#include <stddef.h>
98ee7cd3 DK	50	#include <stdarg.h>
	51
	52	class GlobalError /{{{/
578bfd0a	53	{
98ee7cd3 DK	54	public: /{{{/
	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
98ee7cd3 DK	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
98ee7cd3 DK	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
98ee7cd3 DK	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
98ee7cd3 DK	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;
98ee7cd3 DK	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
cd7bbc47 DK	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
c7873955 DK	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
98ee7cd3 DK	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
	151	* to stderr in addiction to adding it to the list as the error
	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;
98ee7cd3 DK	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;
98ee7cd3 DK	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;
98ee7cd3 DK	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;
98ee7cd3 DK	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
cd7bbc47 DK	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
c7873955 DK	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
98ee7cd3 DK	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;};
98ee7cd3 DK	229
	230	/** \brief is the list empty?
	231	*
	232	* The default checks if the list is empty or contains only notices,
1e3f4083	233	* if you want to check if also no notices happened set the parameter
98ee7cd3 DK	234	* flag to \b false.
98ee7cd3 DK	235	*
255c9e4b	236	* \param threshold minimim level considered
98ee7cd3 DK	237	*
	238	* \return \b true if an the list is empty, \b false otherwise
	239	*/
a02db58f	240	bool empty(MsgType const &threshold = WARNING) const APT_PURE;
98ee7cd3 DK	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	*
	255	* Note that all messages are discarded, also the notices
	256	* displayed or not.
	257	*
	258	* \param[out] out output stream to write the messages in
12be8a62 MV	259	* \param threshold minimim level considered
12be8a62 MV	260	* \param mergeStack
98ee7cd3	261	*/
12be8a62	262	void DumpErrors(std::ostream &out, MsgType const &threshold = WARNING,
c4ba7c44	263	bool const &mergeStack = true);
98ee7cd3 DK	264
	265	/** \brief dumps the list of messages to std::cerr
	266	*
	267	* Note that all messages are discarded, also the notices
	268	* displayed or not.
	269	*
12be8a62	270	* \param threshold minimum level printed
98ee7cd3	271	*/
ca0d389c	272	void inline DumpErrors(MsgType const &threshold) {
12be8a62	273	DumpErrors(std::cerr, threshold);
98ee7cd3 DK	274	}
98ee7cd3 DK	275
ca0d389c MV	276	// mvo: we do this instead of using a default parameter in the
	277	// previous declaration to avoid a (subtle) API break for
	278	// e.g. sigc++ and mem_fun0
	279	/** \brief dumps the messages of type WARNING or higher to std::cerr
	280	*
	281	* Note that all messages are discarded, displayed or not.
	282	*
	283	*/
	284	void inline DumpErrors() {
	285	DumpErrors(WARNING);
	286	}
	287
c4ba7c44 DK	288	/** \brief put the current Messages into the stack
	289	*
	290	* All "old" messages will be pushed into a stack to
	291	* them later back, but for now the Message query will be
	292	* empty and performs as no messages were present before.
	293	*
	294	* The stack can be as deep as you want - all stack operations
	295	* will only operate on the last element in the stack.
	296	*/
	297	void PushToStack();
	298
	299	/** \brief throw away all current messages */
	300	void RevertToStack();
	301
	302	/** \brief merge current and stack together */
	303	void MergeWithStack();
	304
	305	/** \brief return the deep of the stack */
a02db58f	306	size_t StackCount() const APT_PURE {
c4ba7c44 DK	307	return Stacks.size();
	308	}
	309
98ee7cd3 DK	310	GlobalError();
	311	/}}}/
	312	private: /{{{/
	313	struct Item {
	314	std::string Text;
	315	MsgType Type;
	316
	317	Item(char const *Text, MsgType const &Type) :
	318	Text(Text), Type(Type) {};
	319
	320	friend std::ostream& operator<< (std::ostream &out, Item i) {
	321	switch(i.Type) {
	322	case FATAL:
	323	case ERROR: out << "E"; break;
	324	case WARNING: out << "W"; break;
	325	case NOTICE: out << "N"; break;
	326	case DEBUG: out << "D"; break;
	327	}
	328	return out << ": " << i.Text;
	329	}
	330	};
	331
	332	std::list<Item> Messages;
	333	bool PendingFlag;
	334
c4ba7c44 DK	335	struct MsgStack {
	336	std::list<Item> const Messages;
	337	bool const PendingFlag;
	338
	339	MsgStack(std::list<Item> const &Messages, bool const &Pending) :
	340	Messages(Messages), PendingFlag(Pending) {};
	341	};
	342
	343	std::list<MsgStack> Stacks;
98ee7cd3	344	/}}}/
578bfd0a	345	};
98ee7cd3	346	/}}}/
578bfd0a	347
6f27a7fc AL	348	// The 'extra-ansi' syntax is used to help with collisions.
	349	GlobalError *_GetErrorObj();
	350	#define _error _GetErrorObj()
578bfd0a AL	351
578bfd0a AL	352	#endif