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

fusl/src/passwd/getgrouplist.c

Index: fusl/src/passwd/getgrouplist.c
diff --git a/fusl/src/passwd/getgrouplist.c b/fusl/src/passwd/getgrouplist.c
new file mode 100644
index 0000000000000000000000000000000000000000..43e518245f8e6bfdafdbdb2ff5aec92a247798e4
--- /dev/null
+++ b/fusl/src/passwd/getgrouplist.c
@@ -0,0 +1,80 @@
+#define _GNU_SOURCE
+#include "pwf.h"
+#include <grp.h>
+#include <string.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <byteswap.h>
+#include <errno.h>
+#include "nscd.h"
+
+int getgrouplist(const char *user, gid_t gid, gid_t *groups, int *ngroups)
+{
+	int rv, nlim, ret = -1;
+	ssize_t i, n = 1;
+	struct group gr;
+	struct group *res;
+	FILE *f;
+	int swap = 0;
+	int32_t resp[INITGR_LEN];
+	uint32_t *nscdbuf = 0;
+	char *buf = 0;
+	char **mem = 0;
+	size_t nmem = 0;
+	size_t size;
+	nlim = *ngroups;
+	if (nlim >= 1) *groups++ = gid;
+
+	f = __nscd_query(GETINITGR, user, resp, sizeof resp, &swap);
+	if (!f) goto cleanup;
+	if (resp[INITGRFOUND]) {
+		nscdbuf = calloc(resp[INITGRNGRPS], sizeof(uint32_t));
+		if (!nscdbuf) goto cleanup;
+		if (!fread(nscdbuf, sizeof(*nscdbuf)*resp[INITGRNGRPS], 1, f)) {
+			if (!ferror(f)) errno = EIO;
+			goto cleanup;
+		}
+		if (swap) {
+			for (i = 0; i < resp[INITGRNGRPS]; i++)
+				nscdbuf[i] = bswap_32(nscdbuf[i]);
+		}
+	}
+	fclose(f);
+
+	f = fopen("/etc/group", "rbe");
+	if (!f && errno != ENOENT && errno != ENOTDIR)
+		goto cleanup;
+
+	if (f) {
+		while (!(rv = __getgrent_a(f, &gr, &buf, &size, &mem, &nmem, &res)) && res) {
+			if (nscdbuf)
+				for (i=0; i < resp[INITGRNGRPS]; i++) {
+					if (nscdbuf[i] == gr.gr_gid) nscdbuf[i] = gid;
+				}
+			for (i=0; gr.gr_mem[i] && strcmp(user, gr.gr_mem[i]); i++);
+			if (!gr.gr_mem[i]) continue;
+			if (++n <= nlim) *groups++ = gr.gr_gid;
+		}
+		if (rv) {
+			errno = rv;
+			goto cleanup;
+		}
+	}
+	if (nscdbuf) {
+		for(i=0; i < resp[INITGRNGRPS]; i++) {
+			if (nscdbuf[i] != gid)
+				if(++n <= nlim) *groups++ = nscdbuf[i];
+		}
+	}
+
+	ret = n > nlim ? -1 : n;
+	*ngroups = n;
+
+cleanup:
+	if (f) fclose(f);
+	free(nscdbuf);
+	free(buf);
+	free(mem);
+	return ret;
+}