mkbootimg: Add Loki support

* I want my target-files built images to be Loki'd if the device
  needs Loki.
* With this, devices that rely on Loki can ship Lineage Recovery
  officially.
* Import loki_tool from: https://github.com/Stricted/android_external_loki.

Change-Id: I45ef363e05566268c8f24f7e8939a2d785478fbe
diff --git a/loki_tool/loki_flash.c b/loki_tool/loki_flash.c
new file mode 100644
index 0000000..16bdd4d
--- /dev/null
+++ b/loki_tool/loki_flash.c
@@ -0,0 +1,145 @@
+/*
+ * loki_flash
+ *
+ * A sample utility to validate and flash .lok files
+ *
+ * by Dan Rosenberg (@djrbliss)
+ *
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "loki.h"
+
+int loki_flash(const char* partition_label, const char* loki_image)
+{
+	int ifd, aboot_fd, ofd, recovery, offs, match;
+	void *orig, *aboot, *patch;
+	struct stat st;
+	struct boot_img_hdr *hdr;
+	struct loki_hdr *loki_hdr;
+	char outfile[1024];
+
+	if (!strcmp(partition_label, "boot")) {
+		recovery = 0;
+	} else if (!strcmp(partition_label, "recovery")) {
+		recovery = 1;
+	} else {
+		printf("[+] First argument must be \"boot\" or \"recovery\".\n");
+		return 1;
+	}
+
+	/* Verify input file */
+	aboot_fd = open(ABOOT_PARTITION, O_RDONLY);
+	if (aboot_fd < 0) {
+		printf("[-] Failed to open aboot for reading.\n");
+		return 1;
+	}
+
+	ifd = open(loki_image, O_RDONLY);
+	if (ifd < 0) {
+		printf("[-] Failed to open %s for reading.\n", loki_image);
+		return 1;
+	}
+
+	/* Map the image to be flashed */
+	if (fstat(ifd, &st)) {
+		printf("[-] fstat() failed.\n");
+		return 1;
+	}
+
+	orig = mmap(0, (st.st_size + 0x2000 + 0xfff) & ~0xfff, PROT_READ, MAP_PRIVATE, ifd, 0);
+	if (orig == MAP_FAILED) {
+		printf("[-] Failed to mmap Loki image.\n");
+		return 1;
+	}
+
+	hdr = orig;
+	loki_hdr = orig + 0x400;
+
+	/* Verify this is a Loki image */
+	if (memcmp(loki_hdr->magic, "LOKI", 4)) {
+		printf("[-] Input file is not a Loki image.\n");
+		return 1;
+	}
+
+	/* Verify this is the right type of image */
+	if (loki_hdr->recovery != recovery) {
+		printf("[-] Loki image is not a %s image.\n", recovery ? "recovery" : "boot");
+		return 1;
+	}
+
+	/* Verify the to-be-patched address matches the known code pattern */
+	aboot = mmap(0, 0x40000, PROT_READ, MAP_PRIVATE, aboot_fd, 0);
+	if (aboot == MAP_FAILED) {
+		printf("[-] Failed to mmap aboot.\n");
+		return 1;
+	}
+
+	match = 0;
+
+	for (offs = 0; offs < 0x10; offs += 0x4) {
+
+		patch = NULL;
+
+		if (hdr->ramdisk_addr > ABOOT_BASE_LG)
+			patch = hdr->ramdisk_addr - ABOOT_BASE_LG + aboot + offs;
+		else if (hdr->ramdisk_addr > ABOOT_BASE_SAMSUNG)
+			patch = hdr->ramdisk_addr - ABOOT_BASE_SAMSUNG + aboot + offs;
+		else if (hdr->ramdisk_addr > ABOOT_BASE_VIPER)
+			patch = hdr->ramdisk_addr - ABOOT_BASE_VIPER + aboot + offs;
+		else if (hdr->ramdisk_addr > ABOOT_BASE_G2)
+			patch = hdr->ramdisk_addr - ABOOT_BASE_G2 + aboot + offs;
+
+		if (patch < aboot || patch > aboot + 0x40000 - 8) {
+			printf("[-] Invalid .lok file.\n");
+			return 1;
+		}
+
+		if (!memcmp(patch, PATTERN1, 8) ||
+			!memcmp(patch, PATTERN2, 8) ||
+			!memcmp(patch, PATTERN3, 8) ||
+			!memcmp(patch, PATTERN4, 8) ||
+			!memcmp(patch, PATTERN5, 8) ||
+			!memcmp(patch, PATTERN6, 8)) {
+
+			match = 1;
+			break;
+		}
+	}
+
+	if (!match) {
+		printf("[-] Loki aboot version does not match device.\n");
+		return 1;
+	}
+
+	printf("[+] Loki validation passed, flashing image.\n");
+
+	snprintf(outfile, sizeof(outfile),
+			 "%s",
+			 recovery ? RECOVERY_PARTITION : BOOT_PARTITION);
+
+	ofd = open(outfile, O_WRONLY);
+	if (ofd < 0) {
+		printf("[-] Failed to open output block device.\n");
+		return 1;
+	}
+
+	if (write(ofd, orig, st.st_size) != st.st_size) {
+		printf("[-] Failed to write to block device.\n");
+		return 1;
+	}
+
+	printf("[+] Loki flashing complete!\n");
+
+	close(ifd);
+	close(aboot_fd);
+	close(ofd);
+
+	return 0;
+}