Add a "fork" of musl as //fusl.

fusl/include/fcntl.h

+#ifndef _FCNTL_H
+#define _FCNTL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <features.h>
+
+#define __NEED_off_t
+#define __NEED_pid_t
+#define __NEED_mode_t
+
+#ifdef _GNU_SOURCE
+#define __NEED_size_t
+#define __NEED_ssize_t
+#define __NEED_struct_iovec
+#endif
+
+#include <bits/alltypes.h>
+
+#include <bits/fcntl.h>
+
+struct flock
+{
+        short l_type;
+        short l_whence;
+        off_t l_start;
+        off_t l_len;
+        pid_t l_pid;
+};
+
+int creat(const char *, mode_t);
+int fcntl(int, int, ...);
+int open(const char *, int, ...);
+int openat(int, const char *, int, ...);
+int posix_fadvise(int, off_t, off_t, int);
+int posix_fallocate(int, off_t, off_t);
+
+#define O_SEARCH  O_PATH
+#define O_EXEC    O_PATH
+
+#define O_ACCMODE (03|O_SEARCH)
+#define O_RDONLY  00
+#define O_WRONLY  01
+#define O_RDWR    02
+
+#define F_OFD_GETLK 36
+#define F_OFD_SETLK 37
+#define F_OFD_SETLKW 38
+
+#define F_DUPFD_CLOEXEC 1030
+
+#define F_RDLCK 0
+#define F_WRLCK 1
+#define F_UNLCK 2
+
+#define FD_CLOEXEC 1
+
+#define AT_FDCWD (-100)
+#define AT_SYMLINK_NOFOLLOW 0x100
+#define AT_REMOVEDIR 0x200
+#define AT_SYMLINK_FOLLOW 0x400
+#define AT_EACCESS 0x200
+
+#define POSIX_FADV_NORMAL     0
+#define POSIX_FADV_RANDOM     1
+#define POSIX_FADV_SEQUENTIAL 2
+#define POSIX_FADV_WILLNEED   3
+#define POSIX_FADV_DONTNEED   4
+#define POSIX_FADV_NOREUSE    5
+
+#undef SEEK_SET
+#undef SEEK_CUR
+#undef SEEK_END
+#define SEEK_SET 0
+#define SEEK_CUR 1
+#define SEEK_END 2
+
+#ifndef S_IRUSR
+#define S_ISUID 04000
+#define S_ISGID 02000
+#define S_ISVTX 01000
+#define S_IRUSR 0400
+#define S_IWUSR 0200
+#define S_IXUSR 0100
+#define S_IRWXU 0700
+#define S_IRGRP 0040
+#define S_IWGRP 0020
+#define S_IXGRP 0010
+#define S_IRWXG 0070
+#define S_IROTH 0004
+#define S_IWOTH 0002
+#define S_IXOTH 0001
+#define S_IRWXO 0007
+#endif
+
+#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
+#define AT_NO_AUTOMOUNT 0x800
+#define AT_EMPTY_PATH 0x1000
+
+#define FAPPEND O_APPEND
+#define FFSYNC O_FSYNC
+#define FASYNC O_ASYNC
+#define FNONBLOCK O_NONBLOCK
+#define FNDELAY O_NDELAY
+
+#define F_OK 0
+#define R_OK 4
+#define W_OK 2
+#define X_OK 1
+#define F_ULOCK 0
+#define F_LOCK  1
+#define F_TLOCK 2
+#define F_TEST  3
+
+#define F_SETLEASE      1024
+#define F_GETLEASE      1025
+#define F_NOTIFY        1026
+#define F_CANCELLK      1029
+#define F_SETPIPE_SZ    1031
+#define F_GETPIPE_SZ    1032
+#define F_ADD_SEALS     1033
+#define F_GET_SEALS     1034
+
+#define F_SEAL_SEAL     0x0001
+#define F_SEAL_SHRINK   0x0002
+#define F_SEAL_GROW     0x0004
+#define F_SEAL_WRITE    0x0008
+
+#define DN_ACCESS       0x00000001
+#define DN_MODIFY       0x00000002
+#define DN_CREATE       0x00000004
+#define DN_DELETE       0x00000008
+#define DN_RENAME       0x00000010
+#define DN_ATTRIB       0x00000020
+#define DN_MULTISHOT    0x80000000
+
+int lockf(int, int, off_t);
+#endif
+
+#if defined(_GNU_SOURCE)
+#define F_OWNER_TID 0
+#define F_OWNER_PID 1
+#define F_OWNER_PGRP 2
+#define F_OWNER_GID 2
+struct f_owner_ex {
+        int type;
+        pid_t pid;
+};
+#define FALLOC_FL_KEEP_SIZE 1
+#define FALLOC_FL_PUNCH_HOLE 2
+#define SYNC_FILE_RANGE_WAIT_BEFORE 1
+#define SYNC_FILE_RANGE_WRITE 2
+#define SYNC_FILE_RANGE_WAIT_AFTER 4
+#define SPLICE_F_MOVE 1
+#define SPLICE_F_NONBLOCK 2
+#define SPLICE_F_MORE 4
+#define SPLICE_F_GIFT 8
+int fallocate(int, int, off_t, off_t);
+#define fallocate64 fallocate
+ssize_t readahead(int, off_t, size_t);
+int sync_file_range(int, off_t, off_t, unsigned);
+ssize_t vmsplice(int, const struct iovec *, size_t, unsigned);
+ssize_t splice(int, off_t *, int, off_t *, size_t, unsigned);
+ssize_t tee(int, int, size_t, unsigned);
+#define loff_t off_t
+#endif
+
+#if defined(_LARGEFILE64_SOURCE) || defined(_GNU_SOURCE)
+#define F_GETLK64 F_GETLK
+#define F_SETLK64 F_SETLK
+#define F_SETLKW64 F_SETLKW
+#define flock64 flock
+#define open64 open
+#define openat64 openat
+#define creat64 creat
+#define lockf64 lockf
+#define posix_fadvise64 posix_fadvise
+#define posix_fallocate64 posix_fallocate
+#define off64_t off_t
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif