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folkertdev merged 1 commit into from
Apr 7, 2026
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add a test file for a directory with a name not ending with a / character #28

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158 changes: 158 additions & 0 deletions testdata/readme.directory_no_slash
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# Directory names

Most (not all) ZIP implementations rely on names of directories being stored
with a `/` at the end of the entry name, even though the official ZIP
specification does not mention that a `/` is mandatory for a directory. At some
point this just became a convention. For example, the .NET API seems to rely on
it:

<https://github.com/PowerShell/Microsoft.PowerShell.Archive/blob/b783599348e726069f17b90bd490f4f856f661f6/src/ZipArchive.cs#L43>
<https://github.com/dotnet/runtime/blob/96a0fb1cd6210fc4842f32f549870a1d82e95c6f/src/libraries/System.IO.Compression.ZipFile/src/System/IO/Compression/ZipFile.Create.cs#L394>

as does `unzip` (comment from `zip30.tar.gz`, file `unix/unix.c`, line 163):

```
/* Add trailing / to the directory name */
```

Python's `zipfile` module also requires it. `p7zip` on the other hand does not.

There actually are some ZIP files that contain files where directory names do
not end in `/` and where most implementations fail: instead of creating a
directory a zero byte file with the same name as the directory is written.
Despite bug reports having been filed this is still a problem. A bug report
describing this problem can be found at:

<http://web.archive.org/web/20190814185417/https://bugzilla.redhat.com/show_bug.cgi?id=907442>

Trying to unpack the file mentioned in this bug report leads to the following
error with `unzip`:

```
$ unzip 1_06_03P.zip
Archive: 1_06_03P.zip
extracting: online_upgrade_img
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/bp28v_md5.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/bp28_md5.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/emergency_recovery.sh.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/J120.bp28.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/machine_type.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/md5.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/ouimg.bin.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/ouimg.ver.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/OU_Burner.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/Software_Version.
checkdir error: online_upgrade_img exists but is not directory
unable to process online_upgrade_img/V10X.bp28v.
```

`p7zip` will correctly unpack the archive:

```
$ 7z x 1_06_03P.zip

7-Zip [64] 16.02 : Copyright (c) 1999-2016 Igor Pavlov : 2016-05-21
p7zip Version 16.02 (locale=en_US.UTF-8,Utf16=on,HugeFiles=on,64 bits,8 CPUs Intel(R) Core(TM) i7-6770HQ CPU @ 2.60GHz (506E3),ASM,AES-NI)

Scanning the drive for archives:
1 file, 180253537 bytes (172 MiB)

Extracting archive: 1_06_03P.zip
--
Path = 1_06_03P.zip
Type = zip
Physical Size = 180253537

Everything is Ok

Folders: 1
Files: 12
Size: 190915623
Compressed: 180253537
```

A workaround for programs depending on Python's `zipfile` module (which cannot
correctly unpack these files) some workarounds are needed by first looking at
the "external file attributes" field from the central directory (section
4.3.12) and checking if the low order byte corresponds to the MS-DOS directory
attribute byte (section 4.4.15) while also checking that the size recorded for
the file is 0 and that Python's `zipfile` module does not recognize the file as
a directory. If this is the case, then the directory is not unpacked with
Python's `zipfile` module, and a directory with the name of the entry can be
created instead.

This might not be entirely fool proof, but it seems to be such a very rare edge
case that so far only very few examples have been found in the wild.

The test file `test_dir_no_slash.zip` contains a single entry with a directory
named `test`. In the file the slash character was replaced by a NUL character.
`unzip` unpacks an empty file, while `p7zip` unpacks a directory. `zipinfo`
correctly identifies it as a directory in the field `MS-DOS file attributes`
as well as in the Unix file attributes (stored as an "extra" field).

```
$ zipinfo -v test_dir_no_slash.zip
Archive: test_dir_no_slash.zip
There is no zipfile comment.

End-of-central-directory record:
-------------------------------

Zip archive file size: 160 (00000000000000A0h)
Actual end-cent-dir record offset: 138 (000000000000008Ah)
Expected end-cent-dir record offset: 138 (000000000000008Ah)
(based on the length of the central directory and its expected offset)

This zipfile constitutes the sole disk of a single-part archive; its
central directory contains 1 entry.
The central directory is 75 (000000000000004Bh) bytes long,
and its (expected) offset in bytes from the beginning of the zipfile
is 63 (000000000000003Fh).


Central directory entry #1:
---------------------------

test

offset of local header from start of archive: 0
(0000000000000000h) bytes
file system or operating system of origin: Unix
version of encoding software: 3.0
minimum file system compatibility required: MS-DOS, OS/2 or NT FAT
minimum software version required to extract: 1.0
compression method: none (stored)
file security status: not encrypted
extended local header: no
file last modified on (DOS date/time): 2026 Feb 5 13:30:40
file last modified on (UT extra field modtime): 2026 Feb 5 13:30:40 local
file last modified on (UT extra field modtime): 2026 Feb 5 12:30:40 UTC
32-bit CRC value (hex): 00000000
compressed size: 0 bytes
uncompressed size: 0 bytes
length of filename: 5 characters
length of extra field: 24 bytes
length of file comment: 0 characters
disk number on which file begins: disk 1
apparent file type: binary
Unix file attributes (040755 octal): drwxr-xr-x
MS-DOS file attributes (10 hex): dir

The central-directory extra field contains:
- A subfield with ID 0x5455 (universal time) and 5 data bytes.
The local extra field has UTC/GMT modification/access times.
- A subfield with ID 0x7875 (Unix UID/GID (any size)) and 11 data bytes:
01 04 e8 03 00 00 04 e8 03 00 00.

There is no file comment.
```
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152 changes: 152 additions & 0 deletions ziplinter/src/snapshots/ziplinter__test__test_dir_no_slash.zip.snap
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---
source: ziplinter/src/lib.rs
expression: result
---
{
"comment": "",
"contents": [
{
"central": {
"comment": "",
"compressed_size": 0,
"crc32": 0,
"creator_version": {
"host_system": "Unix",
"version": 30
},
"disk_nbr_start": 0,
"external_attrs": 1106051088,
"extra": [
85,
84,
5,
0,
3,
112,
141,
132,
105,
117,
120,
11,
0,
1,
4,
232,
3,
0,
0,
4,
232,
3,
0,
0
],
"flags": 0,
"header_offset": 0,
"internal_attrs": 0,
"method": "Store",
"mode": 2147484141,
"modified": "2026-02-05T12:30:40Z",
"name": "test\u0000",
"reader_version": {
"host_system": "MsDos",
"version": 10
},
"uncompressed_size": 0
},
"local": {
"accessed": null,
"compressed_size": 0,
"crc32": 0,
"created": null,
"extra": [
85,
84,
9,
0,
3,
112,
141,
132,
105,
125,
141,
132,
105,
117,
120,
11,
0,
1,
4,
232,
3,
0,
0,
4,
232,
3,
0,
0
],
"flags": 0,
"gid": 1000,
"header_offset": 0,
"method": "Store",
"method_specific": "None",
"mode": 0,
"modified": "2026-02-05T12:30:40Z",
"name": "test\u0000",
"reader_version": {
"host_system": "MsDos",
"version": 10
},
"uid": 1000,
"uncompressed_size": 0
}
}
],
"encoding": "Utf8",
"eocd": {
"dir": {
"inner": {
"dir_disk_nbr": 0,
"dir_records_this_disk": 1,
"directory_offset": 63,
"directory_records": 1,
"directory_size": 75,
"disk_nbr": 0
},
"offset": 138
},
"dir64": null,
"global_offset": 0
},
"parsed_ranges": [
{
"contains": "end of central directory record",
"end": 160,
"start": 138
},
{
"contains": "central directory header",
"end": 138,
"filename": "test\u0000",
"start": 63
},
{
"contains": "local file header",
"end": 63,
"filename": "test\u0000",
"start": 0
},
{
"contains": "file data",
"end": 63,
"filename": "test\u0000",
"start": 63
}
],
"size": 160
}
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