(gcrypt.info) Error Handling

 
 Error Handling
 ==============
 
 Many functions in Libgcrypt can return an error if they fail.  For this
 reason, the application should always catch the error condition and
 take appropriate measures, for example by releasing the resources and
 passing the error up to the caller, or by displaying a descriptive
 message to the user and cancelling the operation.
 
    Some error values do not indicate a system error or an error in the
 operation, but the result of an operation that failed properly.  For
 example, if you try to decrypt a tempered message, the decryption will
 fail.  Another error value actually means that the end of a data buffer
 or list has been reached.  The following descriptions explain for many
 error codes what they mean usually.  Some error values have specific
 meanings if returned by a certain functions.  Such cases are described
 in the documentation of those functions.
 
    Libgcrypt uses the `libgpg-error' library.  This allows to share the
 error codes with other components of the GnuPG system, and thus pass
 error values transparently from the crypto engine, or some helper
 application of the crypto engine, to the user.  This way no information
 is lost.  As a consequence, Libgcrypt does not use its own identifiers
 for error codes, but uses those provided by `libgpg-error'.  They
 usually start with `GPG_ERR_'.
 
    However, Libgcrypt does provide aliases for the functions defined in
 libgpg-error, which might be preferred for name space consistency.
 
    Most functions in Libgcrypt return an error code in the case of
 failure.  For this reason, the application should always catch the
 error condition and take appropriate measures, for example by releasing
 the resources and passing the error up to the caller, or by displaying
 a descriptive message to the user and canceling the operation.
 
    Some error values do not indicate a system error or an error in the
 operation, but the result of an operation that failed properly.
 
    GnuPG components, including libgcrypt, use an extra library named
 libgpg-error to provide a common error handling scheme.  For more
 information on libgpg-error, see the according manual.
(gcrypt.info) Error Handling

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