1 /** \page usage Usage

     2  * 

     3  * This page provides general information on QuaZIP usage. See classes

     4  * QuaZip and QuaZipFile for the detailed documentation on what can

     5  * QuaZIP do and what can not. Also, reading comments in the zip.h and

     6  * unzip.h files (taken from the original ZIP/UNZIP package) is always a

     7  * good idea too. After all, QuaZIP is just a wrapper with a few

     8  * convenience extensions and reimplementations.

     9  *

    10  * QuaZip is a class representing ZIP archive, QuaZipFile represents a

    11  * file inside archive and subclasses QIODevice as well.

    12  *

    13  * \section terminology Terminology

    14  *

    15  * "QuaZIP" means whole this library, while "QuaZip" (not case

    16  * difference) is just one class in it.

    17  *

    18  * "ZIP/UNZIP API" means the original API of the Gilles Vollant's

    19  * ZIP/UNZIP package. I did not alter it in any way to make it easier to

    20  * port to the future ZIP/UNZIP versions.

    21  *

    22  * "ZIP", "ZIP archive" or "ZIP file" means any ZIP archive. Typically

    23  * this is a plain file with ".zip" (or ".ZIP") file name suffix.

    24  *

    25  * "A file inside archive", "a file inside ZIP" or something like that

    26  * means file either being read or written from/to some ZIP archive.

    27  *

    28  * \section error-handling Error handling

    29  *

    30  * Almost any call to ZIP/UNZIP API return some error code. Most of the

    31  * original API's error checking could be done in this wrapper as well,

    32  * but it would cause unnecessary code bloating without any benefit. So,

    33  * QuaZIP only checks for situations that ZIP/UNZIP API can not check

    34  * for. For example, ZIP/UNZIP API has no "ZIP open mode" concept

    35  * because read and write modes are completely separated. On the other

    36  * hand, to avoid creating classes like "QuaZipReader", "QuaZipWriter"

    37  * or something like that, QuaZIP introduces "ZIP open mode" concept

    38  * instead, thus making it possible to use one class (QuaZip) for both

    39  * reading and writing. But this leads to additional open mode checks

    40  * which are not done in ZIP/UNZIP package.

    41  *

    42  * Therefore, error checking is two-level (QuaZIP's level and ZIP/UNZIP

    43  * API level), which sometimes can be confusing, so here are some

    44  * advices on how the error checking should be properly done:

    45  *

    46  * - Both QuaZip and QuaZipFile have getZipError() function, which return

    47  *   error code of the last ZIP/UNZIP API call. Most function calls

    48  *   reset error code to UNZ_OK on success and set error code on

    49  *   failure. Some functions do not reset error code. Most of them are

    50  *   \c const and do not access ZIP archive in any way. Some, on the

    51  *   other hand, \em do access ZIP archive, but do not reset or set

    52  *   error code. For example, QuaZipFile::pos() function. Such functions

    53  *   are explicitly marked in the documentation.

    54  * - Most functions have its own way to report errors, by returning a

    55  *   null string, negative value or \c false. If such a function returns

    56  *   error value, call getZipError() to get more information about

    57  *   error. See "zip.h" and "unzip.h" of the ZIP/UNZIP package for error

    58  *   codes.

    59  * - If the function returns error-stating value (like \c false), but

    60  *   getZipError() returns UNZ_OK, it means that you did something

    61  *   obviously wrong. For example, tried to write in the archive open

    62  *   for reading or not open at all. You better just do not do that!

    63  *   Most functions also issue a warning using qWarning() function in

    64  *   such cases. See documentation for a specific function for details

    65  *   on when it should not be called.

    66  *

    67  * I know that this is somewhat messy, but I could not find a better way

    68  * to do all the error handling.

    69  **/