[Bug]: --mount rejects a directive whose value contains "="

Start at Parser.mount in Sources/Services/ContainerAPIService/Client/Parser.swift around line 371, then reproduce the issue with the provided container run command. Verify that a mount source or destination containing an equals sign is accepted as one value and that the existing invalid-directive behavior remains intact.

I have done the following

• I have searched the existing issues
• If possible, I've reproduced the issue using the 'main' branch of this project

Steps to reproduce

Run a container with a mount whose source path contains an equals sign:

container run --rm --mount type=virtiofs,source=/tmp/a=b,destination=/mnt alpine true

The command fails with:

invalid directive format missing value source=/tmp/a=b in type=virtiofs,source=/tmp/a=b,destination=/mnt

Creating the directory first makes no difference, because the failure happens while parsing the flag.

Problem description

Parser.mount splits each comma-separated directive on = with maxSplits: 2:

https://github.com/apple/container/blob/main/Sources/Services/ContainerAPIService/Client/Parser.swift#L371

In Swift, maxSplits counts splits rather than resulting elements, so a value that itself contains = produces three components:

"source=/tmp/a=b".split(separator: "=", maxSplits: 2)
// ["source", "/tmp/a", "b"]

The code then requires exactly two components and throws otherwise:

if keyVal.count != 2 {
    throw ContainerizationError(.invalidArgument, message: "invalid directive format missing value \(part) in \(mount)")
}

A directive should split on the first = only, so that everything after it is the value. maxSplits: 1 produces ["source", "/tmp/a=b"].

Equals signs are legal in POSIX path names, so any bind mount whose source or destination contains one is currently unusable.

This is the same defect that #1978 and #1999 fix for Parser.labels. Neither touches Parser.mount, so mounts remain affected.

Environment

• OS: macOS 26.5.2 (25F84)
• Xcode: 26.6 (17F113)
• Container: main at 07ff3c0 (also present in 1.1.0)

Code of Conduct

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