snagflash: Fastboot cmd file now supports "paths-relative-to" env variable

docs/snagflash.md

@@ -108,6 +108,7 @@ flash <image_path> <image_offset> [<partition_name>]
 
 	Optional environment variables:
 		- fb-size
+		- paths-relative-to
 
 	If a file named "<image_path>.bmap" exists, snagflash will automatically
 	parse it and flash only the block ranges described.
@@ -127,8 +128,11 @@ fb-addr: address in memory of the Fastboot buffer
 eraseblk-size: size in bytes of an erase block on the target Flash device
 
 fb-size: size in bytes of the Fastboot buffer, this can only be used to reduce
-         the U-Boot Fastboot buffer size, not increase it.
+  the U-Boot Fastboot buffer size, not increase it.
 
+paths-relative-to: controls how relative image paths in flash commands are resolved
+	CWD       (default) paths are relative to the current working directory
+	THIS_FILE paths are relative to the directory containing the cmdfile
 ```
 
 ## UMS mode

src/snagflash/fastboot.py

@@ -145,7 +145,7 @@ def fastboot(args):
 		with open(args.interactive_cmdfile, "r") as file:
 			cmds = file.read(-1).splitlines()
 
-		session.run(cmds)
+		session.run(cmds, args.interactive_cmdfile)
 
 	if args.interactive:
 		if args.protocol == "fastboot":

src/snagflash/fastboot_uboot.py

@@ -48,6 +48,7 @@ class SnagflashFastbootUboot:
 
 	Optional environment variables:
 		- fb-size
+		- paths-relative-to
 
 	If a file named "<image_path>.bmap" exists, snagflash will automatically
 	parse it and flash only the block ranges described.
@@ -67,7 +68,11 @@ class SnagflashFastbootUboot:
 eraseblk-size: size in bytes of an erase block on the target Flash device
 
 fb-size: size in bytes of the Fastboot buffer, this can only be used to reduce
-         the U-Boot Fastboot buffer size, not increase it.
+	the U-Boot Fastboot buffer size, not increase it.
+
+paths-relative-to: controls how relative image paths in flash commands are resolved
+	CWD       (default) paths are relative to the current working directory
+	THIS_FILE paths are relative to the directory containing the cmdfile
 """
 
 	op_pattern = r"[\w\-]+"
@@ -77,6 +82,7 @@ def __init__(self, fast):
 		self.fast = fast
 		self.env = {}
 		self.checked = False
+		self.cmdfile = None
 
 	def err(self, msg: str):
 		print(f"CLI Error: {msg}")
@@ -206,6 +212,24 @@ def preflash_checks(self):
 
 		self.checked = True
 
+	def resolve_path(self, path: str) -> str:
+		if os.path.isabs(path):
+			return path
+		paths_relative_to = self.env.get("paths-relative-to", "CWD")
+		if paths_relative_to == "CWD":
+			pass  # path is relative to CWD by default
+		elif paths_relative_to == "THIS_FILE":
+			if self.cmdfile is None:
+				raise SnagflashCmdError(
+					"paths-relative-to is THIS_FILE but no cmdfile is set"
+				)
+			path = os.path.join(os.path.dirname(self.cmdfile), path)
+		else:
+			raise SnagflashCmdError(
+				f"unsupported paths-relative-to value: '{paths_relative_to}'"
+			)
+		return path
+
 	def cmd_flash(self, args: str):
 		self.preflash_checks()
 
@@ -215,6 +239,8 @@ def cmd_flash(self, args: str):
 		path = path.strip('"').strip('"')
 		rest = rest.strip(" ")
 
+		path = self.resolve_path(path)
+
 		if " " in rest:
 			offset, sep, part = rest.partition(" ")
 			part = part.strip(" ")
@@ -420,7 +446,8 @@ def flash_mmc(
 			MMC_LBA_SIZE,
 		)
 
-	def run(self, cmds: list):
+	def run(self, cmds: list, cmdfile: str = None):
+		self.cmdfile = os.path.abspath(cmdfile) if cmdfile is not None else None
 		for cmd in cmds:
 			cmd = cmd.strip()
 

tests/fastboot_uboot.py

@@ -1,9 +1,14 @@
+import os
 import unittest
 import unittest.mock
 import tempfile
 import random
 
-from snagflash.fastboot_uboot import SnagflashFastbootUboot, MMC_LBA_SIZE
+from snagflash.fastboot_uboot import (
+	SnagflashFastbootUboot,
+	SnagflashCmdError,
+	MMC_LBA_SIZE,
+)
 
 MAX_IMAGE_LEN = 100000000
 MAX_FLASH_OFFSET = 4096
@@ -79,3 +84,42 @@ def test_flash_range(self):
 				)
 
 				offset += rd_size
+
+
+class TestResolvePath(unittest.TestCase):
+	def setUp(self):
+		self.fb = SnagflashFastbootUboot(unittest.mock.MagicMock())
+
+	def test_default_is_cwd(self):
+		# paths-relative-to unset -> path returned unchanged (relative to CWD)
+		self.assertEqual(self.fb.resolve_path("img/boot.bin"), "img/boot.bin")
+
+	def test_explicit_cwd(self):
+		self.fb.env["paths-relative-to"] = "CWD"
+		self.assertEqual(self.fb.resolve_path("img/boot.bin"), "img/boot.bin")
+
+	def test_absolute_path_is_untouched(self):
+		self.fb.env["paths-relative-to"] = "THIS_FILE"
+		self.fb.cmdfile = "/some/dir/flash.cmds"
+		self.assertEqual(self.fb.resolve_path("/abs/boot.bin"), "/abs/boot.bin")
+
+	def test_this_file_joins_cmdfile_dir(self):
+		self.fb.env["paths-relative-to"] = "THIS_FILE"
+		self.fb.cmdfile = "/some/dir/flash.cmds"
+		self.assertEqual(
+			self.fb.resolve_path("img/boot.bin"),
+			os.path.join("/some/dir", "img/boot.bin"),
+		)
+
+	def test_this_file_without_cmdfile_raises(self):
+		self.fb.env["paths-relative-to"] = "THIS_FILE"
+		self.fb.cmdfile = None
+		with self.assertRaises(SnagflashCmdError):
+			self.fb.resolve_path("img/boot.bin")
+
+	def test_unsupported_value_raises(self):
+		self.fb.env["paths-relative-to"] = (
+			"this_file"  # case-sensitive: lowercase invalid
+		)
+		with self.assertRaises(SnagflashCmdError):
+			self.fb.resolve_path("img/boot.bin")