ply-Import fails if first byte of binary vertex coordinates is equal to 0x0a or 0x0d #116022

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Michael-Patra · 2023-12-11T10:02:13+01:00

Michael-Patra commented

2023-12-11 10:02:13 +01:00

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: Intel(R) Iris(R) Xe Graphics Intel 4.6.0 - Build 31.0.101.4575

Blender Version
Broken: version: 4.1.0 Alpha, branch: main, commit date: 2023-12-10 23:52, hash: fb5d03b5baae
Worked: (newest version of Blender that worked as expected)

Short description of error

The Blender ply-import will fail if the first byte of the vertex data is equal to 0x0a or 0x0d. The error message shown in the console is (a similar message is also shown in the main window for a short while).

PLY Importer: failed importing bad: Invalid face size, must be between 1 and 255

The error will appear whenever the binary data of the vertex point coordinates will start with a 0x0a or 0x0d. The header of a ply-file (as e.g., exported by blender) will end with the text "end_header", followed by a 0x0a byte for line-feed. After that follows the binary representation of the vertex coordinates.

The two attached ply-files differ only in the one byte directly following the line-feed after "end_header" - one will be imported correctly, the other will give an error message.

--- bad.hexdump 2023-12-11 09:51:21.655242354 +0100
+++ good.hexdump 2023-12-11 09:51:15.287243512 +0100
@@ -13,7 +13,7 @@
000000c0 31 0a 70 72 6f 70 65 72 74 79 20 6c 69 73 74 20 |1.property list |
000000d0 75 63 68 61 72 20 75 69 6e 74 20 76 65 72 74 65 |uchar uint verte|
000000e0 78 5f 69 6e 64 69 63 65 73 0a 65 6e 64 5f 68 65 |x_indices.end_he|
-000000f0 61 64 65 72 0a 0a 00 80 bf 00 00 80 bf 00 00 00 |ader............|
+000000f0 61 64 65 72 0a 0b 00 80 bf 00 00 80 bf 00 00 00 |ader............|
00000100 00 00 00 00 00 00 00 00 00 00 00 80 3f 00 00 80 |............?...|
00000110 bf 00 00 00 00 00 00 80 3f 00 00 00 00 00 00 80 |........?.......|
00000120 3f 00 00 80 3f 00 00 00 00 00 00 80 3f 00 00 80 |?...?.......?...|

My educated guess that the ply-importer will read an arbitrary number of 0x0a and 0x0d-bytes after "end_header" believing that they are line-feeds and carriage-returns and thus irrelevant. However, these bytes can belong to the point data, and the entire data is now read shifted by one position - resulting in garbage.

Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]

File - Import - Stanford PLY (.ply) - bad.ply ==> This will give an error message
File - Import - Stanford PLY (.ply) - good.ply ==> This will result in a square being imported

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: Intel(R) Iris(R) Xe Graphics Intel 4.6.0 - Build 31.0.101.4575 **Blender Version** Broken: version: 4.1.0 Alpha, branch: main, commit date: 2023-12-10 23:52, hash: `fb5d03b5baae` Worked: (newest version of Blender that worked as expected) **Short description of error** The Blender ply-import will fail if the first byte of the vertex data is equal to 0x0a or 0x0d. The error message shown in the console is (a similar message is also shown in the main window for a short while). PLY Importer: failed importing bad: Invalid face size, must be between 1 and 255 The error will appear whenever the binary data of the vertex point coordinates will start with a 0x0a or 0x0d. The header of a ply-file (as e.g., exported by blender) will end with the text "end_header", followed by a 0x0a byte for line-feed. After that follows the binary representation of the vertex coordinates. The two attached ply-files differ only in the one byte directly following the line-feed after "end_header" - one will be imported correctly, the other will give an error message. --- bad.hexdump 2023-12-11 09:51:21.655242354 +0100 +++ good.hexdump 2023-12-11 09:51:15.287243512 +0100 @@ -13,7 +13,7 @@ 000000c0 31 0a 70 72 6f 70 65 72 74 79 20 6c 69 73 74 20 |1.property list | 000000d0 75 63 68 61 72 20 75 69 6e 74 20 76 65 72 74 65 |uchar uint verte| 000000e0 78 5f 69 6e 64 69 63 65 73 0a 65 6e 64 5f 68 65 |x_indices.end_he| -000000f0 61 64 65 72 0a 0a 00 80 bf 00 00 80 bf 00 00 00 |ader............| +000000f0 61 64 65 72 0a 0b 00 80 bf 00 00 80 bf 00 00 00 |ader............| 00000100 00 00 00 00 00 00 00 00 00 00 00 80 3f 00 00 80 |............?...| 00000110 bf 00 00 00 00 00 00 80 3f 00 00 00 00 00 00 80 |........?.......| 00000120 3f 00 00 80 3f 00 00 00 00 00 00 80 3f 00 00 80 |?...?.......?...| My educated guess that the ply-importer will read an arbitrary number of 0x0a and 0x0d-bytes after "end_header" believing that they are line-feeds and carriage-returns and thus irrelevant. However, these bytes can belong to the point data, and the entire data is now read shifted by one position - resulting in garbage. **Exact steps for others to reproduce the error** [Please describe the exact steps needed to reproduce the issue] [Based on the default startup or an attached .blend file (as simple as possible)] File - Import - Stanford PLY (.ply) - bad.ply ==> This will give an error message File - Import - Stanford PLY (.ply) - good.ply ==> This will result in a square being imported

good.ply

342 B

bad.ply

342 B

Michael-Patra added the

labels 2023-12-11 10:02:14 +01:00