ZIP Compatibility Fix Copy link

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Description

Category: Testing and Tuning
Plugin: Blitz Report Development (fix-zip-compatibility)
Works with: Claude Code

Re-compress a ZIP file for Oracle compatibility.

When to use it

Use when Oracle unzip (UTL_COMPRESS/XXEN_REPORT) fails on a ZIP created by Windows 11 or other tools that use data descriptors, ZIP64, or non-standard extra fields.

Install

Claude Code

Add the Enginatics marketplace in Claude Code.
```
/plugin marketplace add enginatics/ai-skills
```

Install the plugin.

/plugin install blitz-report-ai-skills@enginatics

Run the environment setup once; it describes your EBS development instance (never production).
```
/blitz-report-ai-skills:blitz-environment-setup
```
Run the skill, or just describe the task and Claude picks it up.
```
/blitz-report-ai-skills:fix-zip-compatibility
```
Keep it current: enable auto-update for the enginatics marketplace, or update manually.
```
/plugin marketplace update enginatics
```

Requirements: Blitz Report installed on your Oracle EBS development instance, and database access from Claude Code to that instance (Oracle SQLcl MCP server, SQLcl or SQL*Plus). Never point the skills at production.

Re-compresses a ZIP file to ensure compatibility with Oracle's unzipping routines (UTL_COMPRESS, XXEN_REPORT, etc.). Windows 11 and some Linux tools create ZIPs with features that Oracle cannot parse.

When to Use

Oracle reports "invalid zip" or fails to extract a ZIP file
ZIP was created on Windows 11 (built-in "Compress to ZIP") or Linux
Upload processing fails during ZIP extraction on the EBS server

Known Incompatibilities

Feature	Problem
Data descriptor (bit 3)	Compressed/uncompressed sizes are 0 in the local file header; actual sizes trail the file data. Oracle expects sizes in the header.
ZIP64 extensions	Extended headers for files >4GB. Oracle's routines may not parse ZIP64 end-of-central-directory records.
Unix extra fields (`0x7875` UID/GID, `0x5455` timestamps)	Non-standard extra field tags that Oracle may choke on.
UTF-8 flag (bit 11)	Filenames encoded as UTF-8 instead of CP437. May cause name mismatch.

Fix Procedure

Run this Python script to re-create the ZIP with maximum Oracle compatibility:

import zipfile, os, sys
src = sys.argv[1]  # input zip path
dst = sys.argv[2] if len(sys.argv) > 2 else src.replace('.zip', '_fixed.zip')
with zipfile.ZipFile(src, 'r') as zin:
    with zipfile.ZipFile(dst, 'w', compression=zipfile.ZIP_DEFLATED, allowZip64=False) as zout:
        for info in zin.infolist():
            data = zin.read(info.filename)
            # Create clean ZipInfo — no extra fields, no data descriptor
            new_info = zipfile.ZipInfo(info.filename, date_time=info.date_time)
            new_info.compress_type = zipfile.ZIP_DEFLATED
            zout.writestr(new_info, data)
print(f'Fixed: {dst}')

What the fix does

Clears data descriptor flag (bit 3) — sizes written directly in local file header
Removes Unix extra fields — no 0x7875 or 0x5455 tags
Disables ZIP64 — standard 32-bit headers only
Standard Deflate compression — method 8, version 2.0

Verification

After fixing, verify the output:

import zipfile, struct
with open('fixed.zip', 'rb') as f:
    f.read(4)  # skip signature
    header = f.read(26)
    ver, flags, method = struct.unpack('<HHH', header[:6])
    print(f'Flags: {flags:#06x}, Data descriptor: {bool(flags & 8)}, Method: {method}')
    # Expect: Flags: 0x0000, Data descriptor: False, Method: 8

Diagnostic: Check a ZIP Before Fixing

import zipfile
zf = zipfile.ZipFile('suspect.zip', 'r')
for info in zf.infolist():
    method = {0: 'Stored', 8: 'Deflated', 9: 'Deflate64', 12: 'BZIP2', 14: 'LZMA'}.get(
        info.compress_type, f'Unknown({info.compress_type})')
    print(f'{info.filename}: method={method}, version={info.create_version}')
zf.close()

XXEN_REPORT ZIP Parsing Context

The Blitz Report ZIP parsing logic reads local file headers sequentially, expecting:

Sizes present in the local file header (not in a trailing data descriptor)
Standard Deflate (method 8) or Stored (method 0)
No ZIP64 extended information extra fields