SOCK_SEQPACKET UNIX Socket Fallback and Direct Shebang Execution

[doanbaotrung]

SOCK_SEQPACKET UNIX Socket Fallback

Updated sys_socket and sys_socketpair
to automatically downgrade AF_UNIX
sockets of type SOCK_SEQPACKET to
SOCK_STREAM on macOS hosts.
Initialized the socket options
cache using the original
LINUX_SOCK_SEQPACKET type,
ensuring getsockopt queries for
SO_TYPE correctly report
SOCK_SEQPACKET to the guest.

Direct Shebang Execution

Implemented a recursive shebang parsing loop
in the standalone loader's entry point.
It reads shebang interpreter lines
(including optional arguments like #!/bin/sh -x),
updates elf_path to point to the interpreter,
prepends them to guest_argv, and resolves the
host path recursively up to a depth of 5 levels.

---

Summary by cubic

Adds macOS-safe AF_UNIX SOCK_SEQPACKET by creating SOCK_STREAM sockets on the host while still reporting SOCK_SEQPACKET to the guest. Also adds direct shebang execution with recursive interpreter resolution (max 5) and a daily upstream sync workflow.

• New Features
  • AF_UNIX SOCK_SEQPACKET fallback on macOS: downgrade to SOCK_STREAM in sys_socket and sys_socketpair, but initialize the socket option cache with the original type so getsockopt(SO_TYPE) returns SOCK_SEQPACKET (compatible with the Rosetta shim path).
  • Standalone loader: parse shebang (#!, supports one optional arg), prepend interpreter to argv, update elf_path, resolve recursively up to 5 levels, clean up temp files between steps, and fail cleanly on overflow.
  • CI: add a workflow to sync the fork with upstream daily.

^{Written for commit c8288ed. Summary will update on new commits.}

[doanbaotrung]

Fix #104

[cubic-dev-ai]

3 issues found and verified against the latest diff

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/main.c">

<violation number="1" location="src/main.c:565">
P2: Shebang recursion limit is off by one: exactly max depth always fails. Allow max depth and fail only when an additional shebang is encountered.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P2: Shebang recursion limit is off by one: exactly max depth always fails. Allow max depth and fail only when an additional shebang is encountered.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At src/main.c, line 565:

<comment>Shebang recursion limit is off by one: exactly max depth always fails. Allow max depth and fail only when an additional shebang is encountered.</comment>

<file context>
@@ -440,16 +440,134 @@ int main(int argc, char **argv)
+        }
+    }
+
+    if (shebang_depth >= max_shebang_depth) {
+        log_error("too many levels of shebang recursion (max %d) resolving %s",
+                  max_shebang_depth, argv[arg_start]);
</file context>