README.apichanges 2003-07-28
NOTE: THESE ARE API CHANGES DONE BEFORE THE FIRST STABLE RELEASE SO
THEY ARE NOT RELEVANT ANYMORE [stable is 1.2.4 right now]
We decided to change a couple of annoying things in Libgcrypt and to
cleanup the API. The new API better fits into a multi-threaded
environment and is more consistent. One import change is that all
functions return error codes from a set of error codes shared between
GnuPG, GPGME and Libgcrypt.
This file contains some hints on how to port your application from
libgcrypt <= 1.1.12 to the current API as of 1.1.42. We hope that
there won't be another need for such a major change.
* Types
All types definitions changed to a foo_t scheme; for some time we
will support the old names but you better start to rename them:
s/GCRY_MPI/gcry_mpi_t/
s/GcryMPI/gcry_mpi_t/
s/GCRY_SEXP/gcry_sexp_t/
s/GcrySexp/gcry_sexp_t/
s/GCRY_CIPHER_HD/gcry_cipher_hd_t/
s/GcryCipherHd/gcry_cipher_hd_t/
s/GCRY_MD_HD/gcry_md_hd_t/
s/GcryMDHd/gcry_md_hd_t/
* Initialization
For proper initialization of the library, you must call
gcry_check_version() before calling any other function except for
these gcry_control operations:
GCRYCTL_SUSPEND_SECMEM_WARN
GCRYCTL_DISABLE_INTERNAL_LOCKING
GCRYCTL_ANY_INITIALIZATION_P
GCRYCTL_INITIALIZATION_FINISHED_P
* Handles
gcry_cipher_open and gcry_md_open do now return an error code
instead of a NULL handle; the handle is now returned by
asigning it to the first argument. Example on how to change your
code:
Old:
hd = gcry_md_open (algo, flags);
if (!hd)
{
fprintf (stderr, "md_open failed: %s\n", gcry_errno (-1));
....
New:
rc = gcry_md_open (&hd, algo, flags);
if (rc)
{
fprintf (stderr, "md_open failed: %s\n", gcry_strerror (rc));
....
If you are not interested in the error code, you can do it in a
simplified way:
gcry_md_open (&hd, algo, flags);
if (!hd)
abort ();
i.e. the function makes sure that HD points to NULL in case of an error.
The required change for gcry_cipher_open is similar.
* Message Digests
The order of the arguments to gcry_md_copy has been changed in order
to be more consistent with other functions of this type. This means
that the new message digest handle will be a copy of the message
handle specified by the second argument and stored at the address
pointed to by the first argument.
* Error codes
gcry_errno () has been removed because it is hard to use in
multi-threaded environment. You need to save the error code
returned by the functions and use it either numerical or passing it
to gcry_strerror (since gcry_strerror is a wrapper function for
gpg_strerror, the latter function can also be used).
Instead of using the error codes GCRYERR_*, you have to use the
GPG_ERR_* names.
* S-expressions
gcry_sexp_canon_len used to return a `historical' error code in
`errcode', this is not the case anymore; the value returned in
`errcode' is now a standard Libgcrypt (i.e. gpg-error) error code.
* MPI
gcry_mpi_scan and gcry_mpi_print need the size of a provided buffer
as input and return the number of bytes actually scanned/printed to
the user. The old API used a single size_t Pointer for both tasks,
the new API distinguishes between the input and the output values.
* Public Key cryptography
gcry_pk_decrypt used to return a `simple S-expression part' that
contains a single MPI value. In case the `data' S-expression
contains a `flags' element, the result S-expression is filled with a
complete S-expression of the following format:
(value PLAINTEXT)
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