ReadProperties() incorrectly strips trailing null byte from binary records, causing crash on Altium .SchLib import

Description

When adding a symbol library from Altium, an error occurs in some files and the program crashes.

Attiny-test.SchLib

Steps to reproduce

Importing an Altium .SchLib file fails silently when any PinFrac compressed record happens to end with a 0x00 byte.

kicad-cli sym upgrade file.SchLib -o output.kicad_sym --force prints Unable to convert library (exit code 2).

The root cause is in ALTIUM_BINARY_PARSER::ReadProperties() (common/io/altium/altium_binary_parser.cpp):

// Line 375:


bool hasNullByte = m_pos[length - 1] == '\0';

// Line 385: null byte is stripped BEFORE the isBinary check


std::string str = std::string( m_pos, length - ( hasNullByte ? 1 : 0 ) );
m_pos += length;

if( isBinary )
{
    return handleBinaryData( str );  // str is 1 byte too short!
}

The null-byte stripping logic is designed for text records (|KEY=VALUE|...\0), where \0 is a string terminator. For binary records (flagged by MSB of the length field), the data contains raw compressed bytes. When the zlib payload happens to end with 0x00, it is misidentified as a null terminator and truncated. This causes ALTIUM_COMPRESSED_READER::ReadCompressedString() → ReadFullPascalString() to throw std::out_of_range("ALTIUM_BINARY_READER: out of range").

Proposed fix

One-line change:

--- a/common/io/altium/altium_binary_parser.cpp
+++ b/common/io/altium/altium_binary_parser.cpp
@@ -382,7 +382,7 @@ std::map<wxString, wxString> ALTIUM_BINARY_PARSER::ReadProperties(
 
     // we use std::string because std::string can handle NULL-bytes
     // wxString would end the string at the first NULL-byte
-    std::string str = std::string( m_pos, length - ( hasNullByte ? 1 : 0 ) );
+    std::string str = std::string( m_pos, length - ( ( hasNullByte && !isBinary ) ? 1 : 0 ) );
     m_pos += length;
 
     if( isBinary )

===== STEPS TO REPRODUCE =====

  1. Download the attached Attiny-test.SchLib file (6 KB, single ATtiny13 component created in Altium Designer).
  2. Run: kicad-cli sym upgrade Attiny-test.SchLib -o /tmp/out.kicad_sym --force
  3. Observe: Unable to convert library (exit code 2).

Alternatively: open Symbol Editor → File → Import Non-KiCad Symbol Library → select the file → same failure.

Why this file triggers the bug: The ATtiny13 component has 8 PinFrac compressed records. Record #8 (closed) (pin index 7) has a zlib payload that ends with 0x00. ReadProperties() strips this byte, making ReadFullPascalString() throw out_of_range because the zlib length field says 17 bytes but only 16 remain.

KiCad Version 

Application: KiCad Schematic Editor x86_64 on x86_64

Version: 9.0.7-9.0.7~ubuntu24.04.1, release build

Libraries:
	wxWidgets 3.2.4
	FreeType 2.13.2
	HarfBuzz 8.3.0
	FontConfig 2.15.0
	libcurl/8.5.0 OpenSSL/3.0.13 zlib/1.3 brotli/1.1.0 zstd/1.5.5 libidn2/2.3.7 libpsl/0.21.2 (+libidn2/2.3.7) libssh/0.10.6/openssl/zlib nghttp2/1.59.0 librtmp/2.3 OpenLDAP/2.6.7

Platform: Linux Mint 22.2, 64 bit, Little endian, wxGTK, X11, cinnamon, x11
OpenGL: AMD, AMD Radeon 780M Graphics (radeonsi, phoenix, LLVM 20.1.2, DRM 3.61, 6.14.0-35-generic), 4.6 (Compatibility Profile) Mesa 25.2.8-0ubuntu0.24.04.1

Build Info:
	Date: Jan  1 2026 22:15:57
	wxWidgets: 3.2.4 (wchar_t,wx containers) GTK+ 3.24
	Boost: 1.83.0
	OCC: 7.6.3
	Curl: 8.5.0
	ngspice: 42
	Compiler: GCC 13.3.0 with C++ ABI 1018
	KICAD_IPC_API=ON

Locale: 
	Lang: ru_RU
	Enc: UTF-8
	Num: 1 234,5
	Encoded кΩ丈: D0BACEA9E4B888 (sys), D0BACEA9E4B888 (utf8)