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

fusl/src/passwd/getgr_r.c

+#include "pwf.h"
+#include <pthread.h>
+
+#define FIX(x) (gr->gr_##x = gr->gr_##x-line+buf)
+
+static int getgr_r(const char *name, gid_t gid, struct group *gr, char *buf, size_t size, struct group **res)
+{
+        char *line = 0;
+        size_t len = 0;
+        char **mem = 0;
+        size_t nmem = 0;
+        int rv = 0;
+        size_t i;
+        int cs;
+
+        pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+
+        rv = __getgr_a(name, gid, gr, &line, &len, &mem, &nmem, res);
+        if (*res && size < len + (nmem+1)*sizeof(char *) + 32) {
+                *res = 0;
+                rv = ERANGE;
+        }
+        if (*res) {
+                buf += (16-(uintptr_t)buf)%16;
+                gr->gr_mem = (void *)buf;
+                buf += (nmem+1)*sizeof(char *);
+                memcpy(buf, line, len);
+                FIX(name);
+                FIX(passwd);
+                for (i=0; mem[i]; i++)
+                        gr->gr_mem[i] = mem[i]-line+buf;
+                gr->gr_mem[i] = 0;
+        }
+        free(mem);
+        free(line);
+        pthread_setcancelstate(cs, 0);
+        return rv;
+}
+
+int getgrnam_r(const char *name, struct group *gr, char *buf, size_t size, struct group **res)
+{
+        return getgr_r(name, 0, gr, buf, size, res);
+}
+
+int getgrgid_r(gid_t gid, struct group *gr, char *buf, size_t size, struct group **res)
+{
+        return getgr_r(0, gid, gr, buf, size, res);
+}