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70 lines
3.5 KiB
70 lines
3.5 KiB
14 years ago
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/** \page usage Usage
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*
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* This page provides general information on QuaZIP usage. See classes
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* QuaZip and QuaZipFile for the detailed documentation on what can
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* QuaZIP do and what can not. Also, reading comments in the zip.h and
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* unzip.h files (taken from the original ZIP/UNZIP package) is always a
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* good idea too. After all, QuaZIP is just a wrapper with a few
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* convenience extensions and reimplementations.
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*
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* QuaZip is a class representing ZIP archive, QuaZipFile represents a
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* file inside archive and subclasses QIODevice as well.
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*
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* \section terminology Terminology
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*
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* "QuaZIP" means whole this library, while "QuaZip" (not case
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* difference) is just one class in it.
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*
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* "ZIP/UNZIP API" means the original API of the Gilles Vollant's
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* ZIP/UNZIP package. I did not alter it in any way to make it easier to
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* port to the future ZIP/UNZIP versions.
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*
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* "ZIP", "ZIP archive" or "ZIP file" means any ZIP archive. Typically
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* this is a plain file with ".zip" (or ".ZIP") file name suffix.
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*
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* "A file inside archive", "a file inside ZIP" or something like that
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* means file either being read or written from/to some ZIP archive.
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*
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* \section error-handling Error handling
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*
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* Almost any call to ZIP/UNZIP API return some error code. Most of the
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* original API's error checking could be done in this wrapper as well,
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* but it would cause unnecessary code bloating without any benefit. So,
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* QuaZIP only checks for situations that ZIP/UNZIP API can not check
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* for. For example, ZIP/UNZIP API has no "ZIP open mode" concept
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* because read and write modes are completely separated. On the other
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* hand, to avoid creating classes like "QuaZipReader", "QuaZipWriter"
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* or something like that, QuaZIP introduces "ZIP open mode" concept
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* instead, thus making it possible to use one class (QuaZip) for both
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* reading and writing. But this leads to additional open mode checks
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* which are not done in ZIP/UNZIP package.
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*
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* Therefore, error checking is two-level (QuaZIP's level and ZIP/UNZIP
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* API level), which sometimes can be confusing, so here are some
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* advices on how the error checking should be properly done:
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*
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* - Both QuaZip and QuaZipFile have getZipError() function, which return
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* error code of the last ZIP/UNZIP API call. Most function calls
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* reset error code to UNZ_OK on success and set error code on
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* failure. Some functions do not reset error code. Most of them are
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* \c const and do not access ZIP archive in any way. Some, on the
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* other hand, \em do access ZIP archive, but do not reset or set
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* error code. For example, QuaZipFile::pos() function. Such functions
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* are explicitly marked in the documentation.
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* - Most functions have its own way to report errors, by returning a
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* null string, negative value or \c false. If such a function returns
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* error value, call getZipError() to get more information about
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* error. See "zip.h" and "unzip.h" of the ZIP/UNZIP package for error
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* codes.
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* - If the function returns error-stating value (like \c false), but
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* getZipError() returns UNZ_OK, it means that you did something
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* obviously wrong. For example, tried to write in the archive open
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* for reading or not open at all. You better just do not do that!
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* Most functions also issue a warning using qWarning() function in
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* such cases. See documentation for a specific function for details
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* on when it should not be called.
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*
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* I know that this is somewhat messy, but I could not find a better way
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* to do all the error handling.
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**/
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