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

fusl/src/stdio/getdelim.c

+#include "stdio_impl.h"
+#include <string.h>
+#include <inttypes.h>
+#include <errno.h>
+
+#define MIN(a,b) ((a)<(b) ? (a) : (b))
+
+ssize_t getdelim(char **restrict s, size_t *restrict n, int delim, FILE *restrict f)
+{
+        char *tmp;
+        unsigned char *z;
+        size_t k;
+        size_t i=0;
+        int c;
+
+        FLOCK(f);
+
+        if (!n || !s) {
+                f->flags |= F_ERR;
+                FUNLOCK(f);
+                errno = EINVAL;
+                return -1;
+        }
+
+        if (!*s) *n=0;
+
+        for (;;) {
+                z = memchr(f->rpos, delim, f->rend - f->rpos);
+                k = z ? z - f->rpos + 1 : f->rend - f->rpos;
+                if (i+k+1 >= *n) {
+                        if (k >= SIZE_MAX/2-i) goto oom;
+                        size_t m = i+k+2;
+                        if (!z && m < SIZE_MAX/4) m += m/2;
+                        tmp = realloc(*s, m);
+                        if (!tmp) {
+                                m = i+k+2;
+                                tmp = realloc(*s, m);
+                                if (!tmp) goto oom;
+                        }
+                        *s = tmp;
+                        *n = m;
+                }
+                memcpy(*s+i, f->rpos, k);
+                f->rpos += k;
+                i += k;
+                if (z) break;
+                if ((c = getc_unlocked(f)) == EOF) {
+                        if (!i || !feof(f)) {
+                                FUNLOCK(f);
+                                return -1;
+                        }
+                        break;
+                }
+                if (((*s)[i++] = c) == delim) break;
+        }
+        (*s)[i] = 0;
+
+        FUNLOCK(f);
+
+        return i;
+oom:
+        f->flags |= F_ERR;
+        FUNLOCK(f);
+        errno = ENOMEM;
+        return -1;
+}
+
+weak_alias(getdelim, __getdelim);