DataReel Code Review Fixes

DataReel Code Review and Fixes, 10/14/2026

These fixes are included in DataReel 6.0 and later (current release 6.2).

The DataReel library in this repository was reviewed and fixed by Claude Code, Anthropic's AI coding assistant (https://claude.ai/code). Every change in the source is marked with a "10/14/2026" comment. Function names and parameters did not change, but gxsXMLNode_t gained a member (see Fixes From the Documentation Review), so programs that use the XML parser must be recompiled against the new headers.

How the Code Was Reviewed
Memory Fixes
Undefined Behavior Fixes
Logic and Bounds Fixes
Deprecated API Updates
Compiler Warning Fixes
SSL Updates
Example Program Fixes
Documentation Updates
Fixes From the Documentation Review
Behavior Changes
Known Items Left as Is

How the Code Was Reviewed

Every source file was compiled with GCC 13 using -Wall and -Wextra, with and without the OpenSSL extensions.
The database, general, and thread example programs (39 programs) were built with AddressSanitizer and UndefinedBehaviorSanitizer (-fsanitize=address,undefined) and run until no reports remained.
Programs built on the library were checked with valgrind.
The SSL server example was tested with a TLS 1.2 DHE-RSA handshake using "openssl s_client" against OpenSSL 3.0.

Results after the fixes:

No sanitizer reports from any of the 39 example programs.
No valgrind errors.
One warning with -Wall (see Known Items Left As Is).

Memory Fixes

Memory allocated with new[] was freed with a scalar delete, which is undefined behavior and is reported by valgrind as a mismatched free. All of these now use delete[]:

src/ustring.cpp    UString buffers (allocate() and delete_sptr() now
                   use unsigned char arrays), UString/UStringw
                   constructors and the four temporary
                   conversion buffers
src/strutil.cpp    temporary ASCII and Unicode buffers
src/gxdbase.cpp    gxDatabase::Alloc() block buffer
src/gxdfptr.cpp    file name and copy buffer in dio_close() and
                   dio_seek()
src/gxrdbhdr.cpp   table field array
src/gxrdbms.cpp    secondary key field arrays
src/gxdstats.cpp   file signature buffer
src/ehandler.cpp   error string buffer
src/gxssl.cpp      random number tables
include/membuf.h   MemoryBuffer destructor

gxSocket::GetIPAddress(), GetDomainName(), GetBoundIPAddress() and GetRemoteHostName() allocated a new buffer when passed a null pointer. The caller never received the buffer, so it leaked. These functions now return -1 for a null buffer. GetRemoteHostName() also null terminates the name after strncpy().

Undefined Behavior Fixes

gxINT16, gxINT32 and gxINT64 PackBits() shifted sign extended bytes and could overflow the signed type. The bytes are now combined with unsigned arithmetic. The results are unchanged.
UStringB::Find() and IFind() for char and wchar_t patterns trusted the length passed by the caller and could read past the end of a short pattern. The length is now limited to the pattern string, matching the UStringB overloads.
gxConfig::ChangeConfigLine() read LineBuffer[strlen(LineBuffer)-1] on blank lines, one byte before the buffer. A line that filled the 1024 byte buffer was also left without a null terminator. Both are fixed.
thrapiw.cpp: the thread exit code is passed to pthread_exit() through intptr_t instead of a direct int to pointer cast.
gxssl.cpp: "x = x=X509_new()" in MakeCertReq() had an undefined order of evaluation.

Logic and Bounds Fixes

gxdfptr.cpp dio_seek(): the write access test used a logical && instead of a bitwise &, so it was true for any open file.
pod.cpp: OpenIndex(), CloseIndex() and both Index() functions now reject an index number equal to the number of indexes (was off by one) and check that the index exists. OpenIndex() frees the B-tree on both error paths.
gxrdbms.cpp: the index number used for a search is checked against the number of B-trees.
gxsxml.cpp: the line chunk offset test compared against length()-1, which wrapped to a huge unsigned value for an empty chunk.
gxrdbhdr.cpp: field names are copied with room for the null terminator.
ustring.cpp: 64-bit number formatting uses snprintf() with precision limits instead of sprintf().
devcache.h and gxdbase.cpp: two statements on one line after an if were split so each has its own if.

Deprecated API Updates

futils.cpp: futils_readdir() uses readdir() on Linux instead of the deprecated readdir_r().
thelpers.cpp: robust mutexes use pthread_mutexattr_setrobust() and pthread_mutex_consistent() instead of the deprecated _np versions.
gxconfig.cpp, systime.cpp: string literals are held in const char pointers.
gxsutils.cpp: the "register" keyword was removed (removed in C++17).

Compiler Warning Fixes

memmove() and memset() calls on the byte array types in btnode.cpp, gxrdbhdr.cpp and strutil.cpp cast to void pointers (34 calls).
Copy constructors explicitly initialize their base class: UString, UStringw, gxDeviceBucket, gxConfig, gxsHTML and gxsXML.
gxshtml.cpp: an unused variable was removed.

SSL Updates

gxSSL (src/gxssl.cpp, include/gxssl.h) builds and runs with OpenSSL 3 and keeps the code paths for OpenSSL 1.1 and older.

MakeDHParms()

The default Diffie-Hellman group is now the RFC 7919 ffdhe2048 group (2048-bit prime, generator 2). OpenSSL 3 rejects the old 1024-bit default prime ("dh key too small"), and 1024-bit groups are too weak to use (Logjam).
With OpenSSL 3 the parameters are built with OSSL_PARAM_BLD and EVP_PKEY_fromdata() and written with PEM_write_bio_Parameters().
The prime and generator are checked and freed on every path.

LoadDHParms()

With OpenSSL 3 the parameters are read with PEM_read_bio_Parameters() and set with SSL_CTX_set0_tmp_dh_pkey().
Errors are now reported. The old test for SSL_CTX_set_tmp_dh() used "< 0", which missed its failure value of 0.
Checks for a null SSL context. The BIO is freed on every path.

MakeRSAPrivateKey()

With OpenSSL 3 the key is generated with EVP_PKEY_CTX_new_from_name("RSA"). The KeyGenCallbackFunc callback is still called during key generation.
The random number generator is seeded first, the key is generated before the key file is opened, and everything is freed on every path.
The default key_len is still 512 bits. Pass 2048 or more for any real use.

MakeRSAEphKey()

Does nothing with OpenSSL 1.1.0 and later, where SSL_CTX_set_tmp_rsa() no longer exists.

MakeCertReq()

Fixed the X509_new() sequence point bug.

Release()

New function that clears the context, SSL and BIO pointers without freeing them. The misspelled Relase() is kept for existing code and calls Release(). Relase() used "socket_bio = file_bio = memory_bio", which copied the memory BIO pointer into the other two instead of clearing all three.

Documentation

New gxSSL class page: docs/classes/socket/gxssl.htm, listed under Socket Classes in the class library index. See Documentation Updates for the other new pages.

ssl_server example

New dhparms.pem with 2048-bit parameters.
New matching server_private_key.pem (RSA 2048) and server_cert.pem. The certificate is self signed and expires 10/14/2027.

Example Program Fixes

examples_general/string_class: buffers from ASCII2Unicode() and the other conversion functions are freed with delete[].
examples_general/doubly_linked_list: the new[] strings are freed with delete[] instead of gxList::DestroyList(), and a string that could not be added to the list is freed.
examples_socket/http_server, multi_threaded_server (client and server) and ssl_server: the console command loop stops at end of input and limits the input length. It used to loop forever when stdin was closed.

Documentation Updates

New reference pages for classes and programs that had none:

All of them are listed in the Library, Examples and Utilities menus. The pages were written from the headers and source code, and they note behavior callers should know about.

classes/general/gxlistb.htm    gxListB non-template linked list
classes/thread/thrpool.htm     thrPool thread pool
classes/thread/thelpers.htm    thread mutex, condition and semaphore
                               helper functions
classes/socket/gxsxml.htm      gxsXML XML parser
classes/socket/gxsrss.htm      gxRSSfeed RSS feed writer
classes/database/gxrdbms.htm   gxRDBMS relational database layer
classes/database/btcache.htm   B-tree cache
classes/database/dbfcache.htm  database file cache
classes/database/dbugmgr.htm   database debug manager and statistics
utils/ix_debug.htm             index file debug utility
examples/programs.htm          guide to the example programs in the
                               examples_* folders

gxthread.htm now documents DestroyThreadPool() under its current name (it listed the misspelled DestoryThreadPool(), deprecated in 2003).

Modern page style:

Every page uses one stylesheet (docs/css/datareel.css) and a small script (docs/js/datareel.js): a site header, readable type, function entries shown as cards, code blocks and source listings with highlighted comments, light and dark themes, and layouts that work on phones.
The Library, Examples and Utilities pages replace the old frames with a searchable sidebar and a content pane. Each page can be linked directly, for example classes/classes.htm#/socket/gxssl.htm.
docs/bin/modernize_docs.py converted the pages and keeps all of their text. New pages can be written in the old inc2help layout and converted by running the script again (--force rebuilds the menus after a link is added to a p_lchild.htm page).

Fixes From the Documentation Review

Writing the new reference pages meant reading each class line by line, which turned up the bugs below. Each fix was proven with a sanitizer test program that fails on the old code, and the pages describe the corrected behavior.

Relational database (gxrdbms.cpp, gxrdbms.h, gxrdbhdr.cpp)

gxrdDatabaseRecord::Compare() on all fields always returned -1.
Heap overflows in record Copy()/CreateRecord(), DefineKeys() and LoadDiskRecord(); exclude-field and table-header Copy() bugs.
Find() and RebuildIndex chose the B-tree from the column number; the short Search()/SortOrderList() overloads used the wrong index.
ChangeRecordField(), VerifyDataFile() and Find() mixed error codes with results; ChangeOrAdd() added the "from" record; changes now re-index every changed key.
DefineKeys() did not reset its counts between calls; Close() left IsOpen() true; RebuildDataFile() ignored copy_static_data.
Records whose keys share a CRC-32 value are no longer confused.

Threads and lists (thelpers.cpp/.h, thrpool.cpp, gxthread.cpp, gxlistb.cpp)

Mutex and condition init never marked themselves initialized, so destroy did nothing; errors were never cleared after a success.
Shared conditions and semaphores were disabled on Linux.
Lock/TryLock tested an enum value instead of ENOTRECOVERABLE.
POSIX timed waits computed the wrong deadline, so the gxThread sleep functions returned at once.
Semaphore Wait kept its mutex locked on failure; Increment did not wake waiters; value fields were uninitialized.
WIN32 TryLock and condition wait/signal error paths (written to the Win32 API rules; not compiled on Windows for this review).
HIGH priority threads lost their order in the pool; RebuildThreadPool() dropped running threads; list node links were left set after DetachNode() and inserts into an empty list.

XML parser and RSS feed writer (gxsxml.cpp/.h, gxsrss.cpp)

Debug trace output was printed on every load.
Elements after a nested element were dropped, and nesting deeper than one level was flattened on write. gxsXMLNode_t has a new depth member and gxsXML a new protected explode_sub_elements() function.
WriteXMLFile() reported success when the file could not be created; LoadXMLFile() appended to the previous tree; DecodeString() decoded "&" first; DTD, CDATA and comment nodes had the wrong type; GetXMLAttribute() matched partial names; CDATA text and empty tags changed on every write.
RSS: <cloud> was closed with <channel> (invalid XML); RSS 1.0 used hard-coded sample addresses; Clear() left the channel; fields were not XML encoded; rating, skipHours and skipDays were never written.

Caches and debug tools (btcache.cpp, dbfcache.cpp/.h, dbugmgr.cpp, gxdstats.cpp, utils/ix_debug)

B-tree cache: reused buckets kept stale keys; failed loads left buckets assigned; a cache with no file reused dirty buckets; small node orders got undersized buckets; null pointer dereferences.
Database cache: stale data in reused segments; failed reads left segments assigned or dirty; LRU order; copy address.
Debug manager: heap start checks tested the wrong pointer; Rebuild() left the static signature changed, always returned 1, looped or over-allocated on bad block lengths and wrote static data at the wrong offset; BlindOpen() buffer overflow.
Statistics output left cout formatting changed.
ix_debug shows every B-tree header and exits non-zero on errors.

Database engine (gxbtree.cpp, gxdbase.cpp)

gxBtree::Find() read the key before a node's key buffer when the search key sorted before every key in the node (heap overflow in the btree_cached example).
gxDatabase::Create() and Open() copied the file name into a fixed 1024 byte buffer without a length check.
gxDatabase::Read() treated a read that returned no bytes (past the end of the file) as success.
TestBlockHeader() accepted a header when only one of the two reserved status bytes was set; the library never sets them.

Utilities

hexdump: the -x, -X, -D and -B number conversions printed wrong results ("0x1255 = 1255" for -xFF) because "hex" and "dec" named DataReel's DiskFileB stream functions, which printed as 1, and the numbers were read with sscanf() formats for the wrong size. A check of each word in hex text files tested the array address. Removed the C++17 "register" keyword and unused variables (hexdump, ffind).

Example programs

examples_general/xml_parser prints the tree with WriteTree(), so it shows the nesting the fixed parser loads.

Behavior Changes

Programs that use these functions may see different results:

The MakeDHParms() default group is 2048-bit ffdhe2048.
LoadDHParms() returns an error when the parameters cannot be set.
gxSocket::GetIPAddress(), GetDomainName(), GetBoundIPAddress() and GetRemoteHostName() return -1 when passed a null buffer.
MakeRSAEphKey() does nothing with OpenSSL 1.1.0 and later.
gxSSL::Relase() clears the memory BIO pointer as well.
UStringB::Find() and IFind() limit the pattern length to the length of the pattern string.
gxRDBMS: Compare() on all fields returns 0/+1/-1; ChangeOrAdd() adds the "to" record; Close() deletes the POD object (IsOpen() is 0 until reopened); DefineKeys() resets its settings on each call; Find() on a field without a B-tree searches the data file. Run RebuildIndex on ALLOWDUP index files built by older versions.
Threads: destroy functions release the native objects; POSIX timed waits and the gxThread sleep functions wait the full time; WIN32 timed waits return 1 on timeout; error fields reflect the last call.
gxsXML: LoadXMLFile() replaces the loaded tree; DTD, CDATA and comment nodes have their own node types; <a></a> loads with empty data and is written as <a />; WriteXMLFile() returns 0 on failure.
gxRSSfeed: all text fields are XML encoded (do not pass pre-encoded text); Clear() empties the channel; versions 0.9x write <rss>.
Caches: reused buckets and segments start empty; a cache with no file returns null instead of reusing a dirty bucket.
gxDatabaseDebugManager::Rebuild() returns 0 when it finds errors; ix_debug exits with 1 on errors.
gxDatabase::Read() of bytes past the end of the file returns gxDBASE_FILE_READ_ERROR; Create() and Open() reject names of 1024 characters or more.

Known Items Left as Is

10/24/2026: All of the items below are fixed in DataReel 6.0. See the DataReel 6.0 Release Notes.

gxList::DestroyList() frees each item with a scalar delete. It is only for items allocated with a single object new. Items allocated with new[] must be removed and freed with delete[] by the caller. This is noted in include/gxlist.h.
The -Woverloaded-virtual warning for gxListB::Add(). Bringing the base class overload into scope would change which function Add("text") calls.
-Wextra unused-parameter and ignored-qualifiers warnings. These are part of the public interfaces and do not affect behavior.
Items that need a new interface or would change existing files are described on the class pages: thrPool::ClearPool() deletes threads without stopping them; gxDBCacheNode::Bind() loads one byte; gxDatabaseCache::ReleaseSegments() keeps its array; gxRDBMS keys for BLOB fields in all-field keys and ALLOWDUP lookups by key; gxsXML text mixed with child elements; the RSS cloud attribute form.
glibc 2.39: pthread_mutex_trylock() on a robust mutex that is not recoverable leaves it in a state that crashes a later unlock. This is a glibc problem and is described on the thread helper page.