FreeTDS Development Group

[Aaron Ucko <ucko AT ncbi.nlm.nih.gov>]

Long story short, I am the primary maintainer of a convenience (aka
vendorized) copy of FreeTDS's client libraries that has accumulated some
local changes over the years.  I have now forward-ported these changes
to your master branch and would belatedly like to submit them for your
consideration, both because they may also be of interest to other users
and to make future releases easier to integrate.

Some of the developers who contributed to (the original versions of)
these changes have moved on to other jobs, but we were all working on
behalf of the US federal government, which cannot hold copyright, so
there shouldn't be any legal concerns; I'm just citing them in (so far
unpublished) Git metadata to give credit where credit's due.

I tested these changes via your test suite against both Microsoft SQL
Server and Sybase ASE, and observed no regressions, just one failure
that turned out to be preexisting (specifically, of the ODBC utf8_2 test
against Microsoft SQL Server).  We currently have Microsoft SQL Server
2014 and 2017 and Sybase ASE 15.5 and 16.0 on hand, and additionally
tested many of these changes against older server versions too.  That
said, in a few cases (some predating my involvement with this code), we
made deliberate changes to semantics.  In such cases, I've updated the
test suite accordingly.  However, if you don't agree with these changes,
I can of course instead arrange to make them conditional in some
fashion; please let me know whether I should do so for any or all of
these changes.

I have grouped these changes into 59 patches.  Please don't take this
count as criticism of your code, which works well for the most part;
we've just been sitting on our changes for entirely too long and
gradually accumulating more along the way.  Also, I suspect our needs
are somewhat atypical -- we use the CT-LIB interface, and do so via a
home-grown abstraction library rather than directly from application
code.

How would you like me to proceed?  Should I send the patches here, or
put them online through a GitHub fork?  In the latter case, should I
proceed to issue a formal pull request?

Here's a quick rundown:

* Fix miscellaneous configuration-specific issues, mostly on Windows.
* Enable automatic TDS protocol version detection.
* thread.h (tds_mutex_trylock): Disallow recursive locking on Windows.
* tds_iconv: Accommodate FreeBSD/Citrus iconv.
* net.c (tds_socket_write): Don't let fake short writes break headers.
* Fix unit tests that manipulate raw network connections.
* cancel.c: Skip return_data tests with Sybase 15+.
* numeric.c: Don't force TDS 5.0 (DBVERSION_100).
* threadsafe.c (tds_getservice): Set AI_CANONNAME where available.
* dblib.c: Honor dbsetversion; improve dbcolinfo and dbwritetext.
* odbc.c (SQLSetEnvAttr): Uncomment SQL_ATTR_OUTPUT_NTS-handling code.
* ct.c (ct_describe): Populate datafmt->format per Valgrind.
* connectparams.c (odbc_parse_connect_string): Handle client_charset.
* ct.c (ct_connect): Set client_charset in addition to server_charset.
* tds_process_tokens: For DONEPROC, always restore rows_affected.
* Implement blk_textxfer, over a resumable tds_bcp_send_record.
* query.c: Handle return codes of tds_put_data and tds_put_data_info.
* net.c: Improve handling of certain error conditions.
* ctlib: Handle CS_TIMEOUT and CS_LOGIN_TIMEOUT.
* ct.c (_ct_get_server_type): Handle CS_LONGCHAR_TYPE.
* blk.c (_blk_get_col_data): Use on-server size for destfmt.maxlength.
* ct.c (ct_cursor): Predict cursor type for CS_CURSOR_DECLARE.
* Fix server timeout handling and ctlib severity propagation.
* Don't log directly to stdout or stderr.
* blk.c: Handle CS_BLK_CANCEL in blk_done.
* cs_convert, dbconvert: Truncate data as needed; update unit tests.
* ct.c (ct_data_info): Encode/decode CS_IODESC datatype field.
* ctlib: Work with non-NULL empty strings if the server supports them.
* ctlib: Implement full Unicode support for TDS 7+ (MSSQL).
* Improve support for TDS 5 (Sybase), mainly around bulk transfers.
* Improve TDS 5 (Sybase) LONGBINARY and LONGCHAR handling.
* Address miscellaneous compiler warnings.
* Report system errors' descriptions to ctlib clients.
* mem.c (tds_deinit_bcpinfo): Free and reset current_row for xfers in.
* read.c (tds_get_n): Avoid potential hangs on short replies.
* tds_checks.c (tds_check_column_extra): Skip size check for BLOBs.
* Address Clang static analyzer errors, many long-standing.
* Improve CTLIB support for TDS 7.2+.
* cs.c (cs_convert): Fix *resultlen for conversions to SYBIMAGE.
* bulk.c (tds_bcp_send_record): Reject invalid NULL data.
* ctlib: Optimize blob conversion for bulk transfers in.
* Declare and implement blk_sethints(_ver95).
* data.c (tds_generic_row_len): Account for column_varint_size.
* ct.c (ct_get_data): Populate cmd->iodesc->name more efficiently.
* mem.c (tds_init_login): Enable use_utf16 by default.
* query.c (tds_fix_column_size): Allow full size for output columns.
* login.c (SET_FIELD_DSTR, for tds7_send_login): Cap lengths at 128.
* tds/u.t./common.c (try_tds_login): Pass base name to tds_set_app.
* Address more issues caught by LLVM/Clang scan-build.
* odbc.c (odbc_process_tokens): Pre-zero done_flags per Valgrind.
* threadsafe.c (tds_get_homedir/_WIN32): Initialize path.
* data.c (tds_set_param_type): Under TDS 7.1+, send SYBBIT as SYBINT1.
* ct.c (paraminfoalloc): Report long variable-width values.
* packet.c (tds_write_packet): fix a TDS_ADDITIONAL_SPACE corner case.
* tds5_process_dyn_result2: Don't trust Sybase to accept blob params.
* net.c (tds_close_socket): Don't try to close invalid sockets.
* stream.c (tds_datain_stream_read): Bail if tds_get_n returns NULL.
* login.c (tds_connect): Skip non-TCP tries to connect to a host:port.
* Address gaps in ctlib support for new MS date/time types.

-- 
Aaron Ucko <ucko at ncbi>, NCBI C++ Toolkit core development group