Add nologin decompiler regression fixture

[zardus]

THIS MESSAGE WAS GENERATED BY AN AUTOMATED PROCESS

Problem

The variadic-callsite regression needs the real main function from the x86-64 nologin program to verify recovery of arguments passed to syslog. The binaries baseline has no suitable fixture.

Root cause

The reproducer lived only in public DecBench. A consumer test cannot fetch that dataset or build a substitute at run time, and a fabricated byte string would not exercise the compiler-produced callsite.

Fix

Add tests/x86_64/decompiler/nologin, stripped with GNU Binutils, plus a README that pins the DecBench and upstream source revisions, both hashes, the transformation, and BSD 2-Clause terms.

Testing

GNU Binutils 2.46 strip --strip-all reproduces the committed fixture byte-for-byte, and the focused consumer regression passes on it. The validation record contains the full consumer and workspace results plus content-identical rebase evidence.

Validation: #195 (comment)

session: sharpen

[zardus]

THIS MESSAGE WAS GENERATED BY AN AUTOMATED PROCESS

Validation record for head c5cc24bb824bdf5f04a9e1dff0309b5d891040a8 against baseline a87538bc248531d2a1d22434143e8b9752459bac.

• Exact PR shape: the own-merge-base/head scan verifies the added compiler-produced fixture and its load-bearing format/address shape: Stripped ELF64 x86-64 executable; recovered main is at 0x401229 and contains the public syslog call path.
• Provenance/reproduction: GNU Binutils 2.46 strip --strip-all of DecBench O0 shadow nologin was rerun twice in separate fresh directories; both outputs byte-compare with each other and with the committed bytes.
• Input/native identity: committed SHA-256 e368a4f622a05943dcc1cdb1fb0d7a22e79b894794489b17b547e68230eaa38d; rustylib mapped from the isolated consumer worktrees on both arms, SHA-256 6cc4d9f576ebff26e0d99d3d2a03dd2f351ff4f8db0a3b59904f73df34301c85.
• Real consumer: Decompiler: Recover syslog variadic arguments angr#6945 at baseline 829ea98f577ac04d9cd3927ddc868713a5b0a1ab and head 7ae7bf06e228c5e925a1e3bba861a407b02a677f loaded the committed fixture and produced the complete output linked in this PR's output record.
• Repeat/order control: A/B/B/A, ASLR disabled and PYTHONHASHSEED=0; same-arm output is byte-identical and the cross-arm delta is nonempty.
• Local scope: this recapture validates fixture bytes, fixture shape, and the actual consumer path only. It does not claim a fresh full-workspace gate.
• Hosted status: fresh hosted dependency validation for this exact binaries head has not been observed in this recapture; it remains pending and no hosted success is claimed here.

[zardus]

THIS MESSAGE WAS GENERATED BY AN AUTOMATED PROCESS

Exact fixture-shape and consumer-output record for #195.

• Fixture comparison: own merge base a87538bc248531d2a1d22434143e8b9752459bac versus exact head c5cc24bb824bdf5f04a9e1dff0309b5d891040a8. The target path/shape is absent on the merge base and present on the head. Stripped ELF64 x86-64 executable; recovered main is at 0x401229 and contains the public syslog call path.
• Fixture identity: SHA-256 e368a4f622a05943dcc1cdb1fb0d7a22e79b894794489b17b547e68230eaa38d; source provenance: DecBench revision e5eb576d66ee36793b800a4dd45e291e0add4472, O0/shadow/nologin (source object SHA-256 e5f129967f4cc6980359cee7bf892f104edd183848507f8b30c5d808f7999b40). The complete readelf/objdump scan is retained with the exact script. The recorded recipe (GNU Binutils 2.46 strip --strip-all of DecBench O0 shadow nologin) was rerun twice in fresh directories; both runs are byte-identical to the committed fixture.
• Actual consumer: Decompiler: Recover syslog variadic arguments angr#6945, exact baseline 829ea98f577ac04d9cd3927ddc868713a5b0a1ab versus exact head 7ae7bf06e228c5e925a1e3bba861a407b02a677f; target main; configuration full / SAILR.
• Native identity: rustylib mapped from the isolated consumer worktrees on both arms, SHA-256 6cc4d9f576ebff26e0d99d3d2a03dd2f351ff4f8db0a3b59904f73df34301c85.
• Determinism: fresh A/B/B/A order, ASLR disabled and PYTHONHASHSEED=0; each same-arm pair is byte-identical and every base/head comparison below is nonempty. Absolute checkout prefixes in tracebacks are normalized to <workspace> for publication; raw output is retained unchanged.

Before — main

Exact consumer baseline

extern char g_40202d;

unsigned int main(void)
{
    char *v6;  // rax
    char *v0;  // [bp-0x38]
    unsigned int v1;  // [bp-0x24]
    char *v2;  // [bp-0x20], Other Possible Types: unsigned long long
    char *v3;  // [bp-0x18], Other Possible Types: unsigned long long
    char *v4;  // [bp-0x10]

    v3 = ttyname(0);
    if (!v3)
        v3 = "UNKNOWN";
    v2 = getlogin();
    if (!v2)
        v2 = "UNKNOWN";
    v4 = getenv("SSH_ORIGINAL_COMMAND");
    v1 = getuid();
    openlog("nologin", 2, 32);
    if (v4)
        v6 = v4;
    else
        v6 = &g_40202d;
    v0 = v6;
    syslog(2, "Attempted login by %s (UID: %d) on %s%s%s");
    closelog();
    printf("%s", "This account is currently not available.\n");
    return 1;
}

After — main

Exact consumer head

extern char g_40202d;

unsigned int main(void)
{
    char *v5;  // rax
    unsigned int v0;  // [bp-0x24]
    char *v1;  // [bp-0x20]
    char *v2;  // [bp-0x18]
    char *v3;  // [bp-0x10]

    v2 = ttyname(0);
    if (!v2)
        v2 = "UNKNOWN";
    v1 = getlogin();
    if (!v1)
        v1 = "UNKNOWN";
    v3 = getenv("SSH_ORIGINAL_COMMAND");
    v0 = getuid();
    openlog("nologin", 2, 32);
    if (v3)
        v5 = v3;
    else
        v5 = &g_40202d;
    syslog(2, "Attempted login by %s (UID: %d) on %s%s%s", v1, v0, v2, (!v3 ? &g_40202d : " SSH_ORIGINAL_COMMAND="), v5);
    closelog();
    printf("%s", "This account is currently not available.\n");
    return 1;
}