diff --git a/lib/getopt-core.h b/lib/getopt-core.h
new file mode 100644
index 0000000..c5dd493
--- /dev/null
+++ b/lib/getopt-core.h
@@ -0,0 +1,96 @@
+/* Declarations for getopt (basic, portable features only).
+   Copyright (C) 1989-2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library and is also part of gnulib.
+   Patches to this file should be submitted to both projects.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _GETOPT_CORE_H
+#define _GETOPT_CORE_H 1
+
+/* This header should not be used directly; include getopt.h or
+   unistd.h instead.  Unlike most bits headers, it does not have
+   a protective #error, because the guard macro for getopt.h in
+   gnulib is not fixed.  */
+
+__BEGIN_DECLS
+
+/* For communication from 'getopt' to the caller.
+   When 'getopt' finds an option that takes an argument,
+   the argument value is returned here.
+   Also, when 'ordering' is RETURN_IN_ORDER,
+   each non-option ARGV-element is returned here.  */
+
+extern char *optarg;
+
+/* Index in ARGV of the next element to be scanned.
+   This is used for communication to and from the caller
+   and for communication between successive calls to 'getopt'.
+
+   On entry to 'getopt', zero means this is the first call; initialize.
+
+   When 'getopt' returns -1, this is the index of the first of the
+   non-option elements that the caller should itself scan.
+
+   Otherwise, 'optind' communicates from one call to the next
+   how much of ARGV has been scanned so far.  */
+
+extern int optind;
+
+/* Callers store zero here to inhibit the error message 'getopt' prints
+   for unrecognized options.  */
+
+extern int opterr;
+
+/* Set to an option character which was unrecognized.  */
+
+extern int optopt;
+
+/* Get definitions and prototypes for functions to process the
+   arguments in ARGV (ARGC of them, minus the program name) for
+   options given in OPTS.
+
+   Return the option character from OPTS just read.  Return -1 when
+   there are no more options.  For unrecognized options, or options
+   missing arguments, 'optopt' is set to the option letter, and '?' is
+   returned.
+
+   The OPTS string is a list of characters which are recognized option
+   letters, optionally followed by colons, specifying that that letter
+   takes an argument, to be placed in 'optarg'.
+
+   If a letter in OPTS is followed by two colons, its argument is
+   optional.  This behavior is specific to the GNU 'getopt'.
+
+   The argument '--' causes premature termination of argument
+   scanning, explicitly telling 'getopt' that there are no more
+   options.
+
+   If OPTS begins with '-', then non-option arguments are treated as
+   arguments to the option '\1'.  This behavior is specific to the GNU
+   'getopt'.  If OPTS begins with '+', or POSIXLY_CORRECT is set in
+   the environment, then do not permute arguments.
+
+   For standards compliance, the 'argv' argument has the type
+   char *const *, but this is inaccurate; if argument permutation is
+   enabled, the argv array (not the strings it points to) must be
+   writable.  */
+
+extern int getopt (int ___argc, char *const *___argv, const char *__shortopts)
+       __THROW _GL_ARG_NONNULL ((2, 3));
+
+__END_DECLS
+
+#endif /* _GETOPT_CORE_H */
diff --git a/lib/getopt-ext.h b/lib/getopt-ext.h
new file mode 100644
index 0000000..d37c293
--- /dev/null
+++ b/lib/getopt-ext.h
@@ -0,0 +1,77 @@
+/* Declarations for getopt (GNU extensions).
+   Copyright (C) 1989-2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library and is also part of gnulib.
+   Patches to this file should be submitted to both projects.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _GETOPT_EXT_H
+#define _GETOPT_EXT_H 1
+
+/* This header should not be used directly; include getopt.h instead.
+   Unlike most bits headers, it does not have a protective #error,
+   because the guard macro for getopt.h in gnulib is not fixed.  */
+
+__BEGIN_DECLS
+
+/* Describe the long-named options requested by the application.
+   The LONG_OPTIONS argument to getopt_long or getopt_long_only is a vector
+   of 'struct option' terminated by an element containing a name which is
+   zero.
+
+   The field 'has_arg' is:
+   no_argument		(or 0) if the option does not take an argument,
+   required_argument	(or 1) if the option requires an argument,
+   optional_argument 	(or 2) if the option takes an optional argument.
+
+   If the field 'flag' is not NULL, it points to a variable that is set
+   to the value given in the field 'val' when the option is found, but
+   left unchanged if the option is not found.
+
+   To have a long-named option do something other than set an 'int' to
+   a compiled-in constant, such as set a value from 'optarg', set the
+   option's 'flag' field to zero and its 'val' field to a nonzero
+   value (the equivalent single-letter option character, if there is
+   one).  For long options that have a zero 'flag' field, 'getopt'
+   returns the contents of the 'val' field.  */
+
+struct option
+{
+  const char *name;
+  /* has_arg can't be an enum because some compilers complain about
+     type mismatches in all the code that assumes it is an int.  */
+  int has_arg;
+  int *flag;
+  int val;
+};
+
+/* Names for the values of the 'has_arg' field of 'struct option'.  */
+
+#define no_argument		0
+#define required_argument	1
+#define optional_argument	2
+
+extern int getopt_long (int ___argc, char *__getopt_argv_const *___argv,
+			const char *__shortopts,
+		        const struct option *__longopts, int *__longind)
+       __THROW _GL_ARG_NONNULL ((2, 3));
+extern int getopt_long_only (int ___argc, char *__getopt_argv_const *___argv,
+			     const char *__shortopts,
+		             const struct option *__longopts, int *__longind)
+       __THROW _GL_ARG_NONNULL ((2, 3));
+
+__END_DECLS
+
+#endif /* _GETOPT_EXT_H */
diff --git a/lib/getopt-pfx-core.h b/lib/getopt-pfx-core.h
new file mode 100644
index 0000000..095e393
--- /dev/null
+++ b/lib/getopt-pfx-core.h
@@ -0,0 +1,66 @@
+/* getopt (basic, portable features) gnulib wrapper header.
+   Copyright (C) 1989-2023 Free Software Foundation, Inc.
+   This file is part of gnulib.
+   Unlike most of the getopt implementation, it is NOT shared
+   with the GNU C Library.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _GETOPT_PFX_CORE_H
+#define _GETOPT_PFX_CORE_H 1
+
+/* This header should not be used directly; include getopt.h or
+   unistd.h instead.  It does not have a protective #error, because
+   the guard macro for getopt.h in gnulib is not fixed.  */
+
+/* Standalone applications should #define __GETOPT_PREFIX to an
+   identifier that prefixes the external functions and variables
+   defined in getopt-core.h and getopt-ext.h.  Systematically
+   rename identifiers so that they do not collide with the system
+   functions and variables.  Renaming avoids problems with some
+   compilers and linkers.  */
+#ifdef __GETOPT_PREFIX
+# ifndef __GETOPT_ID
+#  define __GETOPT_CONCAT(x, y) x ## y
+#  define __GETOPT_XCONCAT(x, y) __GETOPT_CONCAT (x, y)
+#  define __GETOPT_ID(y) __GETOPT_XCONCAT (__GETOPT_PREFIX, y)
+# endif
+# undef getopt
+# undef optarg
+# undef opterr
+# undef optind
+# undef optopt
+# define getopt __GETOPT_ID (getopt)
+# define optarg __GETOPT_ID (optarg)
+# define opterr __GETOPT_ID (opterr)
+# define optind __GETOPT_ID (optind)
+# define optopt __GETOPT_ID (optopt)
+
+/* Work around a problem on macOS, which declares getopt with a
+   trailing __DARWIN_ALIAS(getopt) that would expand to something like
+   __asm("_" "rpl_getopt" "$UNIX2003") were it not for the following
+   hack to suppress the macOS declaration <https://bugs.gnu.org/40205>.  */
+# ifdef __APPLE__
+#  define _GETOPT
+# endif
+
+/* The system's getopt.h may have already included getopt-core.h to
+   declare the unprefixed identifiers.  Undef _GETOPT_CORE_H so that
+   getopt-core.h declares them with prefixes.  */
+# undef _GETOPT_CORE_H
+#endif
+
+#include <getopt-core.h>
+
+#endif /* _GETOPT_PFX_CORE_H */
diff --git a/lib/getopt-pfx-ext.h b/lib/getopt-pfx-ext.h
new file mode 100644
index 0000000..8578d72
--- /dev/null
+++ b/lib/getopt-pfx-ext.h
@@ -0,0 +1,70 @@
+/* getopt (GNU extensions) gnulib wrapper header.
+   Copyright (C) 1989-2023 Free Software Foundation, Inc.
+   This file is part of gnulib.
+   Unlike most of the getopt implementation, it is NOT shared
+   with the GNU C Library.
+
+   This file is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Lesser General Public License as
+   published by the Free Software Foundation; either version 2.1 of the
+   License, or (at your option) any later version.
+
+   This file is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
+
+#ifndef _GETOPT_PFX_EXT_H
+#define _GETOPT_PFX_EXT_H 1
+
+/* This header should not be used directly; include getopt.h instead.
+   It does not have a protective #error, because the guard macro for
+   getopt.h in gnulib is not fixed.  */
+
+/* Standalone applications should #define __GETOPT_PREFIX to an
+   identifier that prefixes the external functions and variables
+   defined in getopt-core.h and getopt-ext.h.  Systematically
+   rename identifiers so that they do not collide with the system
+   functions and variables.  Renaming avoids problems with some
+   compilers and linkers.  */
+#ifdef __GETOPT_PREFIX
+# ifndef __GETOPT_ID
+#  define __GETOPT_CONCAT(x, y) x ## y
+#  define __GETOPT_XCONCAT(x, y) __GETOPT_CONCAT (x, y)
+#  define __GETOPT_ID(y) __GETOPT_XCONCAT (__GETOPT_PREFIX, y)
+# endif
+# undef getopt_long
+# undef getopt_long_only
+# undef option
+# undef _getopt_internal
+# define getopt_long __GETOPT_ID (getopt_long)
+# define getopt_long_only __GETOPT_ID (getopt_long_only)
+# define option __GETOPT_ID (option)
+# define _getopt_internal __GETOPT_ID (getopt_internal)
+
+/* The system's getopt.h may have already included getopt-ext.h to
+   declare the unprefixed identifiers.  Undef _GETOPT_EXT_H so that
+   getopt-ext.h declares them with prefixes.  */
+# undef _GETOPT_EXT_H
+#endif
+
+/* Standalone applications get correct prototypes for getopt_long and
+   getopt_long_only; they declare "char **argv".  For backward
+   compatibility with old applications, if __GETOPT_PREFIX is not
+   defined, we supply GNU-libc-compatible, but incorrect, prototypes
+   using "char *const *argv".  (GNU libc is stuck with the incorrect
+   prototypes, as they are baked into older versions of LSB.)  */
+#ifndef __getopt_argv_const
+# if defined __GETOPT_PREFIX
+#  define __getopt_argv_const /* empty */
+# else
+#  define __getopt_argv_const const
+# endif
+#endif
+
+#include <getopt-ext.h>
+
+#endif /* _GETOPT_PFX_EXT_H */