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

fusl/src/stdio/fgets.c

+#include "stdio_impl.h"
+#include <string.h>
+
+#define MIN(a,b) ((a)<(b) ? (a) : (b))
+
+char *fgets(char *restrict s, int n, FILE *restrict f)
+{
+        char *p = s;
+        unsigned char *z;
+        size_t k;
+        int c;
+
+        FLOCK(f);
+
+        if (n--<=1) {
+                f->mode |= f->mode-1;
+                FUNLOCK(f);
+                if (n) return 0;
+                *s = 0;
+                return s;
+        }
+
+        while (n) {
+                z = memchr(f->rpos, '\n', f->rend - f->rpos);
+                k = z ? z - f->rpos + 1 : f->rend - f->rpos;
+                k = MIN(k, n);
+                memcpy(p, f->rpos, k);
+                f->rpos += k;
+                p += k;
+                n -= k;
+                if (z || !n) break;
+                if ((c = getc_unlocked(f)) < 0) {
+                        if (p==s || !feof(f)) s = 0;
+                        break;
+                }
+                n--;
+                if ((*p++ = c) == '\n') break;
+        }
+        if (s) *p = 0;
+
+        FUNLOCK(f);
+
+        return s;
+}
+
+weak_alias(fgets, fgets_unlocked);