[buyemune-sys]

The problem

The getopt family went straight to musl, apart from the optind/optarg shuttle around it (lib/glibc_shim.cpp:1603). glibc's getopt behaves differently in ways programs notice:

• Permutation. glibc's getopt permutes argv just like getopt_long. Only a string starting with + or -, POSIXLY_CORRECT, or __posix_getopt keep it in order. musl's getopt never permutes, so prog file -v loses -v:

  $ ./getopt_permute file1 -a -b x file2      # glibc
  opt a / opt b x / operand file1 / operand file2
  $ solo ./getopt_permute file1 -a -b x file2
  operand file1 / operand -a / operand -b / operand x / operand file2
  

• argv corruption. In musl's getopt_long, when the short option's argument is missing at the end of argv after a permuted operand (prog file -n), getopt leaves optind = argc + 1. The permutation step (ext/musl/src/misc/getopt_long.c:47) then rotates argv's NULL terminator into the vector: argv[2] = NULL, argv[3] = "file". glibc stops at argc and keeps argv terminated.

• Diagnostics. glibc prints invalid option -- 'Z', option requires an argument -- 'n', unrecognized option '--bogus=1', option '--ver' is ambiguous; possibilities: '--verbose' '--version', option '--verbose' doesn't allow an argument. musl prints unrecognized option: Z, option requires an argument: n, and so on. Tarantool's own test suite matches glibc's wording (app-luatest/args_test.lua, app-luatest/gh_8613_centralized_config_options_test.lua).

• __posix_getopt. musl exports a __posix_getopt of its own, so the name resolved straight to musl. That bypassed the shuttle: in a COPY-relocated executable the guest's optind never advanced, and a parse loop spun on the same argument.

The fix

sh_getopt_run (lib/glibc_shim.cpp:1710) backs getopt, __posix_getopt, getopt_long and getopt_long_only. The order of work:

1. The bridge itself finds the next option element.
2. musl parses only that element, with its own messages off.
3. The bridge clamps optind at argc and rotates what musl consumed in front of the skipped operands, the order glibc's exchange leaves (sh_getopt_rotate, :1617).
4. It prints glibc's message (sh_getopt_complain, :1631).

The element is classified exactly as musl's parser classified it. __posix_getopt joins overrideNames.

Two glibc rules stay out of reach without replacing musl's parser:

• an abbreviation that matches several options with identical effect is not ambiguous to glibc;
• getopt_long_only skips an unknown -xyz as a whole.

Test

• The conformance battery (tst/glibc_shim_test.c, options()) checks:

  • permutation and argv layout;
  • + and __posix_getopt keeping order;
  • argv integrity and optind after a missing argument;
  • each diagnostic, with stderr captured.

  All of these values were first checked against real glibc.

• The guest executable calls __posix_getopt through its own copy of optind. Needle: guest getopt q optind=2.

On main: 13 battery checks fail, and the guest prints guest getopt q optind=1. With the fix: ./build test passes. rootfs_smoke is skipped here because user namespaces are unavailable.

This conflicts with #9 in lib/glibc_shim.cpp and tst/run_smoke.py, both near the getopt wrappers. The resolution keeps both sides. Once both are in, POSIXLY_CORRECT should be read through sh_getenv.