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

fusl/src/stdio/fread.c

+#include "stdio_impl.h"
+#include <string.h>
+
+#define MIN(a,b) ((a)<(b) ? (a) : (b))
+
+size_t fread(void *restrict destv, size_t size, size_t nmemb, FILE *restrict f)
+{
+        unsigned char *dest = destv;
+        size_t len = size*nmemb, l = len, k;
+
+        FLOCK(f);
+
+        f->mode |= f->mode-1;
+
+        if (f->rend - f->rpos > 0) {
+                /* First exhaust the buffer. */
+                k = MIN(f->rend - f->rpos, l);
+                memcpy(dest, f->rpos, k);
+                f->rpos += k;
+                dest += k;
+                l -= k;
+        }
+        
+        /* Read the remainder directly */
+        for (; l; l-=k, dest+=k) {
+                k = __toread(f) ? 0 : f->read(f, dest, l);
+                if (k+1<=1) {
+                        FUNLOCK(f);
+                        return (len-l)/size;
+                }
+        }
+
+        FUNLOCK(f);
+        return nmemb;
+}
+
+weak_alias(fread, fread_unlocked);