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Diffstat (limited to 'apt-pkg/contrib/error.h')
| -rw-r--r-- | apt-pkg/contrib/error.h | 345 |
1 files changed, 345 insertions, 0 deletions
diff --git a/apt-pkg/contrib/error.h b/apt-pkg/contrib/error.h new file mode 100644 index 0000000..24eead8 --- /dev/null +++ b/apt-pkg/contrib/error.h @@ -0,0 +1,345 @@ +// -*- mode: cpp; mode: fold -*- +// Description /*{{{*/ +/* ###################################################################### + + Global Error 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> +#include <stddef.h> + +class APT_PUBLIC 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 addition 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? + * + * Can be used to check if the current stack level doesn't include + * anything equal or more severe than a given threshold, defaulting + * to warning level for historic reasons. + * + * \param threshold minimum level considered + * + * \return \b true if 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, even undisplayed ones. + * + * \param[out] out output stream to write the messages in + * \param threshold minimum level considered + * \param mergeStack if true recursively dumps the entire stack + */ + 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) {}; + + APT_HIDDEN friend std::ostream &operator<<(std::ostream &out, Item i); + }; + + APT_HIDDEN friend std::ostream &operator<<(std::ostream &out, Item i); + + std::list<Item> Messages; + bool PendingFlag; + + struct MsgStack { + std::list<Item> 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. +APT_PUBLIC GlobalError *_GetErrorObj(); +static struct { + inline GlobalError* operator ->() { return _GetErrorObj(); } +} _error APT_UNUSED; + +#endif |