Initial commit

Makefile

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+all: serial2mac
+
+clean: ; rm -fv serial2mac

PKGBUILD

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+# Maintainer: Baltazár Radics <baltazar.radics@gmail.com>
+pkgname=serial2mac
+pkgver=1.0
+pkgrel=1
+pkgdesc='Sets mac address based on cpu serial number'
+arch=(armv7h)
+url=
+license=(MIT)
+depends=(glibc)
+source=(Makefile $pkgname.c $pkgname.rules)
+noextract=()
+sha256sums=('b65d82482f4e2a5af2da3cece9a034e9a19c07a92149c774c2da75d07340f086'
+            '73acb463a7e9b8bf432b92d184194bcb086dcabbbf85dc9614c8dcf61a2a55b3'
+            '8332f739d99ec9e262be1a24ae1a3d708ef9214b9c29334cea36d1202d96d758')
+
+build() {
+	make
+}
+
+package() {
+	install -Dm755 $pkgname       "$pkgdir/usr/bin/$pkgname"
+	install -Dm644 $pkgname.rules "$pkgdir/usr/lib/udev/rules.d/75-$pkgname.rules"
+}

serial2mac.c

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+#include <net/if.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+
+unsigned char get_byte(FILE *fp) {
+	unsigned char ret = 0;
+	for (int i = 0; i < 2; ++i) {
+		int c = getc(fp);
+		if (c == EOF)
+			perror("getc"), exit(1);
+		c = c > '9' ? c - 'a' + 0xa : c - '0' + 0x0;
+		if (c > 0xf)
+			fputs("unexpected char in serial number\n", stderr), exit(1);
+		ret <<= 4;
+		ret |= c;
+	}
+	return ret;
+}
+
+int main(int argc, char *argv[]) {
+	if (argc != 2)
+		fputs("Expected a single argument.\n", stderr), exit(1);
+
+	struct ifreq dev;
+	strcpy(dev.ifr_name, argv[1]);
+
+	int sock = socket(AF_INET, SOCK_DGRAM, 0);
+	if (sock < 0)
+		perror("socket"), exit(1);
+
+	if (ioctl(sock, SIOCGIFHWADDR, &dev) < 0)
+		perror("get hwaddr ioctl"), exit(1);
+
+	FILE *fp = fopen("/sys/firmware/devicetree/base/serial-number", "r");
+	if (!fp)
+		perror("serial-number fopen"), exit(1);
+
+	dev.ifr_hwaddr.sa_data[0] = get_byte(fp);
+	if (fseek(fp, 4, SEEK_CUR))
+		perror("fseek"), exit(1);
+	for (uint i = 1; i < 6; ++i)
+		dev.ifr_hwaddr.sa_data[i] = get_byte(fp);
+
+	if (ioctl(sock, SIOCSIFHWADDR, &dev) < 0)
+		perror("set hwaddr ioctl"), exit(1);
+}

serial2mac.rules

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+ACTION=="add", SUBSYSTEM=="net", ATTR{type}=="1", RUN+="/usr/bin/serial2mac $name"