feat: Detect remote conflicts when uploading data sets or USS files

[traeok]

What It Does

• Adds conflict detection in zowex to prevent overwriting changes made on the remote system.
  • When the developer/user passes an E-tag as part of their write request, it will compare the current e-tag to the one that's given. If the tags do not match, this indicates a change was made on the mainframe and the write request fails as a result (e-tag mismatch)
  • If the user does not pass an e-tag, this assumes a destructive operation, and the write request always overwrites the contents of the Data Set or USS file.

The following methods are used to build e-tags:

• USS files: <mtime in hex>-<byte size in hex>
  • Example: 4d101bfc-7 for a file with 7 bytes
• Data Set: SIMD-optimized Adler-32 algorithm
  • Adler-32 is a faster alternative to CRC32. This implementation takes advantage of SIMD support in newer hardware so that the checksum is calculated in chunks of 16 bytes rather than each byte at a time.

How to Test

• USS file:
  1. Open up a USS file through your SSH profile in Zowe Explorer
  2. From a terminal in the same window, open an SSH connection to the same server and make a change to the same USS file
  3. Make a change to the file in the Zowe Explorer editor and save
  4. Notice the conflict dialog appears and you are prompted to compare changes or overwrite
  • Clicking "Compare" shows the server data beside your requested changes
  • Clicking "Overwrite" replaces the data on the server with your changes
• Data Set:
  • This is more complicated to reproduce because once alt-tabbing back into ZE, the change detection pulls the new data for the data set before a conflict can occur. However, if you change the data set from a 3270 emulator without changing window focus in VS Code, OR if another person introduces the conflict, you can follow step iii and onward for "USS file".

Review Checklist
I certify that I have:

• tested my changes
• added/updated automated tests
• updated the changelog
• followed the contribution guidelines

[sonarqubecloud]

Quality Gate failed

Failed conditions
5 Security Hotspots
4.1% Duplication on New Code (required ≤ 3%)

See analysis details on SonarQube Cloud