[ACA Sandboxes] azure-containerapps-sandbox: FileInfo drops isSymlink/symlinkTarget, mis-maps isDir, and types mode as str

[antsok]

Originally filed as Azure/azure-sdk-for-python#48523 and closed there with a pointer to this repository as the right home for azure-containerapps-sandbox issues. Refiled unchanged; nothing in it has been addressed.

• Package Name: azure-containerapps-sandbox
• Package Version: 0.1.0b4
• Operating System: Windows 11 (build 26220.8764)
• Python Version: 3.12

Describe the bug

FileInfo loses type information that the service actually returns. The data-plane GET .../files/stat response carries isSymlink and symlinkTarget, and FileInfo has no field for either — so a caller using the typed surface cannot tell a symlink from a regular file. isDir is also mis-mapped, and mode is annotated as str but arrives as an int.

Three defects, in one model:

Wire field	Value returned by the service	FileInfo
isSymlink	true for a symlink	absent — no field at all
symlinkTarget	e.g. /etc/hostname	absent — no field at all
isDir	true for a directory	is_directory is False
mode	420 / 511 / 493 (int)	typed str | None, populated with the int

This matters beyond tidiness because read_file follows symlinks. Reading a path that happens to be a symlink returns the target's contents, from anywhere in the guest filesystem. A caller that wants to refuse symlinked paths has the information available on the wire and no supported way to reach it — mode is permission bits only (0o644 / 0o777 / 0o755, no S_IFLNK), and is_directory cannot be trusted.

To Reproduce

1. Create a sandbox and seed a regular file, a symlink and a directory:

sc.write_file("/work/real.txt", "REAL-CONTENT", create_dirs=True)
sc.exec("ln -sf /etc/hostname /work/link-out.txt; mkdir -p /work/sub", working_directory="/work")

2. Stat each through the typed surface:

for p in ["/work/real.txt", "/work/link-out.txt", "/work/sub"]:
    f = sc.stat_file(p)
    print(p, f.size, f.is_directory, repr(f.mode))

/work/real.txt      12   False  420
/work/link-out.txt  13   False  511
/work/sub           4096 False  493

/work/sub is a directory and reports is_directory=False; the symlink is indistinguishable from the regular file; every mode is an int despite the str | None annotation.

3. Compare against the raw response for the same three paths:

{"name":"real.txt",     "size":12,   "mode":420, "isDir":false, "isSymlink":false, "modifiedTime":1786404028}
{"name":"link-out.txt", "size":13,   "mode":511, "isDir":false, "isSymlink":true, "symlinkTarget":"/etc/hostname", "modifiedTime":1786404028}
{"name":"sub",          "size":4096, "mode":493, "isDir":true,  "isSymlink":false, "modifiedTime":1786404028}

4. Confirm the follow behaviour:

sc.read_file("/work/link-out.txt")   # b'adc-sandbox\n' — the contents of /etc/hostname

list_files returns the same FileInfo shape and so loses the same fields.

Expected behavior

FileInfo exposes what the service sends:

• an is_symlink: bool and a symlink_target: str | None, so a caller can identify and refuse a symlink;
• is_directory reflecting the wire's isDir;
• mode typed as int | None, matching what is sent — or documented as permission bits only, since it carries no file-type bits and cannot be used for type discrimination.

Additional context

Environment: swedencentral, api-version as shipped in 0.1.0b4, sandbox created from the python-3.13 public disk-image preset. Reproduced against a live sandbox group, not a mock.

The workaround available today is to bypass FileInfo and read the raw stat payload, which means depending on wire shape the typed surface is supposed to insulate callers from.

[aca-github-agent]

Thanks for the detailed repro and wire-vs-typed comparison — this is very actionable. Assigning this issue to jkalis-MS.