read_R2004_section_info out of range

[rikan1]

Hello , i encountered a issue when converting a large (12MB) dwg file to json .

'Warning: checksum: 0x935dbb45 (calculated) CRC mismatch 0xaafa14-0xab29e5\n' + '\n' + 'ERROR: Skip section AcDb:Preview with max decompression size 0x7d20 > 0x1800\n' + 'ERROR: Skip section with size 89 > 1 * 0\n' + 'ERROR: read_R2004_section_info out of range\n' + 'Warning: Failed to find section_info[9] with type 1\n' + 'ERROR: Failed to read compressed Header section\n' + 'Warning: Failed to find section_info[9] with type 3\n' + 'ERROR: Failed to read compressed Classes section\n' + 'Warning: Failed to find section_info[9] with type 4\n' + 'ERROR: Failed to read compressed Handles section\n' + 'Warning: Failed to find section_info[9] with type 2\n' + 'ERROR: Failed to read uncompressed AuxHeader section\n' + 'ERROR: Invalid section AcDb:Preview count or max decompression size. Sections: 1, Max size: 0\n' + 'ERROR: Failed to read uncompressed Preview section\n' + 'ERROR: Template section not found\n' + '\n' + 'ERROR: Invalid num_segidx\n' + 'ERROR: Failed to decode file: /Users/somyaranjankar/Desktop/code/bbs-dwg-api/src/temp/1731333834741.dwg 0x940\n' + '\n' + 'ERROR 0x940\n'

dwgread 0.13.3.7338 is used for conversion.

• [x] read_R2004_section_info out of range
• [ ] ATTDEF with MTEXT
• [ ] Invalid FIELD.childval x 256
• [ ] ERROR: Invalid DICTIONARY.numitems 71471
• [x] object_ref realloc bug
• [ ] ERROR: Skip section AcDb:Preview with max decompression size 0x7d20 > 0x1800 looks wrong also

[michal-josef-spacek]

@rikan1 Hi, we need more information.

1. You could send us the AC string from the beginning of the file.
2. dwgread -v3 __DWG_FILE__ could help more.

[santanup]

@rikan1 Hi, we need more information.

1. You could send us the AC string from the beginning of the file.
2. dwgread -v3 __DWG_FILE__ could help more.

@michal-josef-spacek

we are getting this after adding "-v3"

'Reading DWG file /src/temp/1732731851358.dwg\n' + "This file's version code is: AC1027 (r2013)\n" + 'is_maint: 0x8 [RC 0]\n' + 'zero_one_or_three: 0x3 [RC 0]\n' + 'thumbnail_address: 576 [RL 0]\n' + 'dwg_version: 0x21 [RC 0]\n' + 'maint_version: 0x4 [RC 0]\n' + 'codepage: 30 [RS 0]\n' + 'ANSI_1252\n' + 'unknown_0: 0x0 [RC 0]\n' + 'app_dwg_version: 0x0 [RC 0]\n' + 'app_maint_version: 0x0 [RC 0]\n' + 'security_type: 0 [RL 0]\n' + 'rl_1c_address: 0 [RL 0]\n' +

[michal-josef-spacek]

ok, we know that is AC1027

[santanup]

ok, we know that is AC1027

How to fix it? @michal-josef-spacek

[michal-josef-spacek]

@santanup I don't know what your problem is.

1. The first message is: Hello , i encountered a issue when converting a large (12MB) dwg file to json . What is the result?

[michal-josef-spacek]

2. The Warning: checksum: 0x935dbb45 (calculated) CRC mismatch 0xaafa14-0xab29e5 is warning probably from system section. My example on some dwg file is

=== Read System Section (Section Page Map) @4e20 ===

section_type: 0x41630e3b [RLx 0]
decomp_data_size: 112 [RL 0]
comp_data_size: 103 [RL 0]
compression_type: 2 [RL 0]
checksum1 => 0x2099039f with seed and crc 0
checksum: 0xa8cb0e58 [RLx 0]
Warning: checksum: 0x6af11031 (calculated) CRC mismatch 0x4e34-0x4e9b

I don't know how much this is important. Probably not much in your case.

[michal-josef-spacek]

3. Issue with preview section:

ERROR: Skip section AcDb:Preview with max decompression size 0x7d20 > 0x1800

I have similar issue in my file:

section_info[5] fields:
size:            15754
num_sections:    1
max_decomp_size: 16384 / 0x4000
unknown:         1
compressed:      1 (1=no, 2=yes)
type:            10
encrypted:       0 (0=no, 1=yes, 2=unknown)
name:            AcDb:Preview
fixedtype:       10

ERROR: Skip section AcDb:Preview with max decompression size 0x4000 > 0x1800
Page count 1 in area 5
     section[5].info[0]: AcDb:Preview type 0 => type 10
Page:    2     size: 16384 address: 0x0 info: 0x220

I don't know how much this is important. Probably not much in your case.

[michal-josef-spacek]

4. Issue:

ERROR: Skip section with size 89 > 1 * 0

and probably all other. Probably related to something bad with reading of sections. My exmaple of this kind of error:

ERROR: Skip section AcDb:AcDsPrototype_1b with size 2637952 > 25 * 29696
Page count 0 in area 2

section_info[3] fields:
size:            42537356099614
num_sections:    0
max_decomp_size: 0 / 0x0
unknown:         6
compressed:      10948 (1=no, 2=yes)
type:            29696
encrypted:       0 (0=no, 1=yes, 2=unknown)
name:            .
fixedtype:       0

ERROR: Skip section . with size 42537356099614 > 0 * 0
Page count 0 in area 3

section_info[4] fields:
size:            45260365365259
num_sections:    178176
max_decomp_size: 0 / 0x0
unknown:         12
compressed:      8760 (1=no, 2=yes)
type:            207872
encrypted:       0 (0=no, 1=yes, 2=unknown)
name:
fixedtype:       0

ERROR: read_R2004_section_info out of range
Warning: Failed to find section_info[4] with type 1
ERROR: Failed to read compressed Header section
Found no section_info[4] with type 9
ERROR: Failed to read uncompressed SummaryInfo section
Warning: Failed to find section_info[4] with type 3
ERROR: Failed to read compressed Classes section
Warning: Failed to find section_info[4] with type 7
ERROR: Failed to read compressed AcDbObjects section
Warning: Failed to find section_info[4] with type 2
ERROR: Failed to read uncompressed AuxHeader section
Found no section_info[4] with type 10
ERROR: Failed to read uncompressed Preview section
Found no section_info[4] with type 11
ERROR: Failed to read uncompressed AppInfo section
Found no section_info[4] with type 12
AppInfoHistory section not found

I don't know how much this is important. Probably not much in your case

[michal-josef-spacek]

What is the result? So, some section errors, and some cannot block functionality. Something is probably very bad. Without an example DWG file we cannot fix it.

[santanup]

What is the result? So, some section errors, and some cannot block functionality. Something is probably very bad. Without an example DWG file we cannot fix it.

@michal-josef-spacek These are the files -

• https://d2k638bldkf5wf.cloudfront.net/importDwg/1732784727769.dwg
• https://d2k638bldkf5wf.cloudfront.net/importDwg/1732784624493.dwg

[michal-josef-spacek]

@santanup Thank you. Analysis:

a) 1732784727769.dwg Version: AC1027 Created by: Teigha (be careful, Teigha has issues itself) I see errors in PROXY_OBJECTs, DICTIONARY

b) 1732784624493.dwg Version: AC1032 Created by: AutoCAD I see many errors in many entities, In AC1032 we need to fix many things.

I could export both to JSON by: dwgread -O JSON __INPUT_DWG__ | tee __OUTPUT_JSON__

What is the root cause, which you are trying to resolve?

[michal-josef-spacek]

@santanup Could you export some of this files to DXF by AutoCAD?

[santanup]

Okay we will try, thanks

[rikan1]

@michal-josef-spacek Can you please check this file . https://d2k638bldkf5wf.cloudfront.net/importDwg/1731333834741.dwg

dwgread -O JSON INPUT_DWG. This command is failing

[michal-josef-spacek]

@rikan1 Ok, this is the real issue with no possibility of reading this file.

[rikan1]

@michal-josef-spacek How to fix this , do you have any suggestions ?

[michal-josef-spacek]

@rikan1 Check section parsing. This is not easy to do for me.

[rurban]

With the latest large file 1732784727769.dwg I see this internal problem:

entities[13065]: (3.4.1A1D7E78) abs:438140536 [H* 0] REALLOC dwg->object_ref vector to 32768 entities[13066]: (3.4.1A1D7E79) abs:438140537 [H* 0]Warning: Object handle not found 606492518/0x24265766

after realloc the refs, the handles cannot be found anymore. ...

[rurban]

The first warning checksum: 0x935dbb45 (calculated) CRC mismatch 0xaafa14-0xab29e5 is in a lot of DWG's. looks the 2nd crc algo is still wrong, but this only affects writing 2004 formats, which we cannot do yet.

ignore it.

[rurban]

The section info bugs are now fixed with #439 (the new decompressor) The remaining ATTDEF with MTEXT and FIELD bugs are known limitations and will be fixed later. Also the object_ref realloc bug. ERROR: Skip section AcDb:Preview with max decompression size 0x7d20 > 0x1800 looks wrong also

[rurban]

2. The Warning: checksum: 0x935dbb45 (calculated) CRC mismatch 0xaafa14-0xab29e5 is warning probably from system section. My example on some dwg file is

=== Read System Section (Section Page Map) @4e20 ===

section_type: 0x41630e3b [RLx 0]
decomp_data_size: 112 [RL 0]
comp_data_size: 103 [RL 0]
compression_type: 2 [RL 0]
checksum1 => 0x2099039f with seed and crc 0
checksum: 0xa8cb0e58 [RLx 0]
Warning: checksum: 0x6af11031 (calculated) CRC mismatch 0x4e34-0x4e9b

I don't know how much this is important. Probably not much in your case.

This was fixed with GH #1044