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

fusl/src/network/if_nameindex.c

Index: fusl/src/network/if_nameindex.c
diff --git a/fusl/src/network/if_nameindex.c b/fusl/src/network/if_nameindex.c
new file mode 100644
index 0000000000000000000000000000000000000000..2deaef769600e5bb6b67d613eb3b3e1f65597383
--- /dev/null
+++ b/fusl/src/network/if_nameindex.c
@@ -0,0 +1,114 @@
+#define _GNU_SOURCE
+#include <net/if.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <pthread.h>
+#include "netlink.h"
+
+#define IFADDRS_HASH_SIZE 64
+
+struct ifnamemap {
+	unsigned int hash_next;
+	unsigned int index;
+	unsigned char namelen;
+	char name[IFNAMSIZ];
+};
+
+struct ifnameindexctx {
+	unsigned int num, allocated, str_bytes;
+	struct ifnamemap *list;
+	unsigned int hash[IFADDRS_HASH_SIZE];
+};
+
+static int netlink_msg_to_nameindex(void *pctx, struct nlmsghdr *h)
+{
+	struct ifnameindexctx *ctx = pctx;
+	struct ifnamemap *map;
+	struct rtattr *rta;
+	unsigned int i;
+	int index, type, namelen, bucket;
+
+	if (h->nlmsg_type == RTM_NEWLINK) {
+		struct ifinfomsg *ifi = NLMSG_DATA(h);
+		index = ifi->ifi_index;
+		type = IFLA_IFNAME;
+		rta = NLMSG_RTA(h, sizeof(*ifi));
+	} else {
+		struct ifaddrmsg *ifa = NLMSG_DATA(h);
+		index = ifa->ifa_index;
+		type = IFA_LABEL;
+		rta = NLMSG_RTA(h, sizeof(*ifa));
+	}
+	for (; NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
+		if (rta->rta_type != type) continue;
+
+		namelen = RTA_DATALEN(rta) - 1;
+		if (namelen > IFNAMSIZ) return 0;
+
+		/* suppress duplicates */
+		bucket = index % IFADDRS_HASH_SIZE;
+		i = ctx->hash[bucket];
+		while (i) {
+			map = &ctx->list[i-1];
+			if (map->index == index &&
+			    map->namelen == namelen &&
+			    memcmp(map->name, RTA_DATA(rta), namelen) == 0)
+				return 0;
+			i = map->hash_next;
+		}
+
+		if (ctx->num >= ctx->allocated) {
+			size_t a = ctx->allocated ? ctx->allocated * 2 + 1 : 8;
+			if (a > SIZE_MAX/sizeof *map) return -1;
+			map = realloc(ctx->list, a * sizeof *map);
+			if (!map) return -1;
+			ctx->list = map;
+			ctx->allocated = a;
+		}
+		map = &ctx->list[ctx->num];
+		map->index = index;
+		map->namelen = namelen;
+		memcpy(map->name, RTA_DATA(rta), namelen);
+		ctx->str_bytes += namelen + 1;
+		ctx->num++;
+		map->hash_next = ctx->hash[bucket];
+		ctx->hash[bucket] = ctx->num;
+		return 0;
+	}
+	return 0;
+}
+
+struct if_nameindex *if_nameindex()
+{
+	struct ifnameindexctx _ctx, *ctx = &_ctx;
+	struct if_nameindex *ifs = 0, *d;
+	struct ifnamemap *s;
+	char *p;
+	int i;
+	int cs;
+
+	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
+	memset(ctx, 0, sizeof(*ctx));
+	if (__rtnetlink_enumerate(AF_UNSPEC, AF_INET, netlink_msg_to_nameindex, ctx) < 0) goto err;
+
+	ifs = malloc(sizeof(struct if_nameindex[ctx->num+1]) + ctx->str_bytes);
+	if (!ifs) goto err;
+
+	p = (char*)(ifs + ctx->num + 1);
+	for (i = ctx->num, d = ifs, s = ctx->list; i; i--, s++, d++) {
+		d->if_index = s->index;
+		d->if_name = p;
+		memcpy(p, s->name, s->namelen);
+		p += s->namelen;
+		*p++ = 0;
+	}
+	d->if_index = 0;
+	d->if_name = 0;
+err:
+	pthread_setcancelstate(cs, 0);
+	free(ctx->list);
+	errno = ENOBUFS;
+	return ifs;
+}