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

fusl/src/stat/statvfs.c

+#include <sys/statvfs.h>
+#include <sys/statfs.h>
+#include "syscall.h"
+#include "libc.h"
+
+int __statfs(const char *path, struct statfs *buf)
+{
+        *buf = (struct statfs){0};
+#ifdef SYS_statfs64
+        return syscall(SYS_statfs64, path, sizeof *buf, buf);
+#else
+        return syscall(SYS_statfs, path, buf);
+#endif
+}
+
+int __fstatfs(int fd, struct statfs *buf)
+{
+        *buf = (struct statfs){0};
+#ifdef SYS_fstatfs64
+        return syscall(SYS_fstatfs64, fd, sizeof *buf, buf);
+#else
+        return syscall(SYS_fstatfs, fd, buf);
+#endif
+}
+
+weak_alias(__statfs, statfs);
+weak_alias(__fstatfs, fstatfs);
+
+static void fixup(struct statvfs *out, const struct statfs *in)
+{
+        *out = (struct statvfs){0};
+        out->f_bsize = in->f_bsize;
+        out->f_frsize = in->f_frsize ? in->f_frsize : in->f_bsize;
+        out->f_blocks = in->f_blocks;
+        out->f_bfree = in->f_bfree;
+        out->f_bavail = in->f_bavail;
+        out->f_files = in->f_files;
+        out->f_ffree = in->f_ffree;
+        out->f_favail = in->f_ffree;
+        out->f_fsid = in->f_fsid.__val[0];
+        out->f_flag = in->f_flags;
+        out->f_namemax = in->f_namelen;
+}
+
+int statvfs(const char *restrict path, struct statvfs *restrict buf)
+{
+        struct statfs kbuf;
+        if (__statfs(path, &kbuf)<0) return -1;
+        fixup(buf, &kbuf);
+        return 0;
+}
+
+int fstatvfs(int fd, struct statvfs *buf)
+{
+        struct statfs kbuf;
+        if (__fstatfs(fd, &kbuf)<0) return -1;
+        fixup(buf, &kbuf);
+        return 0;
+}
+
+LFS64(statvfs);
+LFS64(statfs);
+LFS64(fstatvfs);
+LFS64(fstatfs);