fix(guix): add dedicated build step to compile and run loopback bind helper before python server

steps-guix/loopback-bind-127001/files/loopback-bind-127001.c

@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <net/if.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+
+int main(void) {
+    int fd;
+    struct ifreq ifr;
+    struct sockaddr_in addr;
+
+    fd = socket(AF_INET, SOCK_DGRAM, 0);
+    if (fd < 0) {
+        perror("socket");
+        return 1;
+    }
+
+    memset(&ifr, 0, sizeof(ifr));
+    memset(&addr, 0, sizeof(addr));
+
+    addr.sin_family = AF_INET;
+    if (inet_pton(AF_INET, "127.0.0.1", &addr.sin_addr) != 1) {
+        perror("inet_pton");
+        close(fd);
+        return 1;
+    }
+
+    strncpy(ifr.ifr_name, "lo", IFNAMSIZ - 1);
+    memcpy(&ifr.ifr_addr, &addr, sizeof(addr));
+    if (ioctl(fd, SIOCSIFADDR, &ifr) < 0) {
+        perror("ioctl(SIOCSIFADDR)");
+        close(fd);
+        return 1;
+    }
+
+    if (ioctl(fd, SIOCGIFFLAGS, &ifr) < 0) {
+        perror("ioctl(SIOCGIFFLAGS)");
+        close(fd);
+        return 1;
+    }
+
+    ifr.ifr_flags |= IFF_UP | IFF_RUNNING;
+    if (ioctl(fd, SIOCSIFFLAGS, &ifr) < 0) {
+        perror("ioctl(SIOCSIFFLAGS)");
+        close(fd);
+        return 1;
+    }
+
+    close(fd);
+    return 0;
+}

steps-guix/loopback-bind-127001/pass1.sh

@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+src_prepare() {
+    default
+}
+
+src_configure() {
+    :
+}
+
+src_compile() {
+    gcc -O2 -std=c99 -Wall -Wextra -Werror \
+        -o /tmp/loopback-bind-127001 \
+        loopback-bind-127001.c
+
+    /tmp/loopback-bind-127001
+}
+
+src_install() {
+    install -D -m 0644 /dev/null "${DESTDIR}/usr/share/loopback-bind-127001.done"
+}