scripts: Add python script to read SPDK's GPT GUID from device

Signed-off-by: Michal Berger <michalx.berger@intel.com>
Change-Id: Ib24714363405f926ac8483244b24296fe35d5a86
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/9591
Reviewed-by: Konrad Sztyber <konrad.sztyber@gmail.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

scripts/spdk-gpt.py

@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+
+import argparse
+import os
+import stat
+import struct
+
+
+def block_exists(block):
+    return os.path.exists(block) and stat.S_ISBLK(os.stat(block).st_mode)
+
+
+def lbsize(block):
+    if not os.path.exists("/sys/block/%s/queue/logical_block_size"):
+        return 512
+
+    with open("/sys/block/%s/queue/logical_block_size" % block) as lbs:
+        return int(lbs.read())
+
+
+def readb(block, offset, length, format="Q"):
+    b = os.open(block, os.O_RDONLY)
+    os.lseek(b, offset, os.SEEK_SET)
+    data = os.read(b, length)
+    os.close(b)
+    return struct.unpack(format, data)[0]
+
+
+def is_spdk_gpt(block, entry):
+    block_path = "/dev/" + block
+
+    if not block_exists(block_path):
+        print("%s is not a block device" % block)
+        return False
+
+    disk_lbsize = lbsize(block)
+    gpt_sig = 0x5452415020494645  # EFI PART
+    spdk_guid = [0x7c5222bd, 0x8f5d, 0x4087, 0x9c00, 0xbf9843c7b58c]
+
+    if readb(block_path, disk_lbsize, 8) != gpt_sig:
+        print("No valid GPT data, bailing")
+        return False
+
+    part_entry_lba = disk_lbsize * readb(block_path, disk_lbsize + 72, 8)
+    part_entry_lba = part_entry_lba + (entry - 1) * 128
+
+    guid = [
+        readb(block_path, part_entry_lba, 4, "I"),
+        readb(block_path, part_entry_lba + 4, 2, "H"),
+        readb(block_path, part_entry_lba + 6, 2, "H"),
+        readb(block_path, part_entry_lba + 8, 2, ">H"),
+        readb(block_path, part_entry_lba + 10, 8, ">Q") >> 16
+    ]
+
+    return guid == spdk_guid
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description='Checks if SPDK GUID is present on given block device')
+    parser.add_argument('block', type=str, help='block device to check')
+    parser.add_argument('-e', '--entry', dest='entry', help='GPT partition entry',
+                        required=False, type=int, default=1)
+    args = parser.parse_args()
+    try:
+        if is_spdk_gpt(args.block.replace("/dev/", ""), args.entry):
+            exit(0)
+        exit(1)
+    except Exception as e:
+        print("Failed to read GPT data from %s (%s)" % (args.block, e))
+        exit(1)