src/woeusb: workaround_win7_uefi: Properly detect existing EFI direct…

…ory, fixes #91

This fixes the case where the source image already have EFI directory.
The primary issue is that according to UEFI spec the efi directory path isn't case-sensitive, we have to detect them regardless of the case and use it as the bootmgfw.efi extract destination.
Also this implements check to skip workaround if any existing efi bootloader is found.

Related-GitHub-Issue: windows 7 iso failed · Issue #91 · slacka/WoeUSB <https://github.com/slacka/WoeUSB/issues/91>
Reported-by: kabnaj <https://github.com/kabnaj>
Original-patch-by: kabnaj <https://github.com/kabnaj>
Signed-off-by: 林博仁 <[email protected]>

src/woeusb

@@ -890,15 +890,88 @@ workaround_support_windows_7_uefi_boot(){
 		echo_with_color yellow "Warning: '7z' utility not found, workaround is not applied." >&2
 		return 0
 	fi
+
+	# Detect **case-insensitive** existing efi directories according to UEFI spec
+	local\
+		test_efi_directory\
+		efi_directory
+	test_efi_directory="$(
+		find\
+			"${target_fs_mountpoint}"\
+			-ipath "${target_fs_mountpoint}/efi"
+	)"
+	if [ -z "${test_efi_directory}" ]; then
+		efi_directory="${target_fs_mountpoint}/efi"
+		if [ "${verbose}" = "1" ]; then
+			printf\
+				"%s: DEBUG: Can't find efi directory, use %s.\n"\
+				"${FUNCNAME[0]}"\
+				"${efi_directory}"
+		fi
+	else # efi directory(case don't care) exists
+		efi_directory="${test_efi_directory}"
+		if [ "${verbose}" = "1" ]; then
+			printf\
+				"%s: DEBUG: %s detected.\n"\
+				"${FUNCNAME[0]}"\
+				"${efi_directory}"
+		fi
+	fi
+	unset test_efi_directory
+
+	local\
+		test_efi_boot_directory\
+		efi_boot_directory
+	test_efi_boot_directory="$(
+		find\
+			"${target_fs_mountpoint}"\
+			-ipath "${efi_directory}/boot"
+	)"
+	if [ -z "${test_efi_boot_directory}" ]; then
+		efi_boot_directory="${efi_directory}/boot"
+		if [ "${verbose}" = "1" ]; then
+			printf\
+				"%s: DEBUG: Can't find efi/boot directory, use %s.\n"\
+				"${FUNCNAME[0]}"\
+				"${efi_boot_directory}"
+		fi
+	else # boot directory(case don't care) exists
+		efi_boot_directory="${test_efi_boot_directory}"
+		if [ "${verbose}" = "1" ]; then
+			printf\
+				"%s: DEBUG: %s detected.\n"\
+				"${FUNCNAME[0]}"\
+				"${efi_boot_directory}"
+		fi
+	fi
+	unset\
+		efi_directory\
+		test_efi_boot_directory
+
+	# If there's already an EFI bootloader existed, skip the workaround
+	local test_efi_bootloader
+	test_efi_bootloader="$(
+		find\
+			"${target_fs_mountpoint}"\
+			-ipath "${target_fs_mountpoint}/efi/boot/boot*.efi"
+	)"
+	if [ -n "${test_efi_bootloader}" ]; then
+		printf\
+			"INFO: Detected existing EFI bootloader, workaround skipped.\n"
+		return 0
+	fi
+
 	mkdir\
 		--parents\
-		"${target_fs_mountpoint}/EFI/Boot"
+		"${efi_boot_directory}"
+
+	# Skip workaround if EFI bootloader already exist in efi_boot_directory
 	7z\
 		e\
 		-so\
 		"${source_fs_mountpoint}/sources/install.wim"\
 		"Windows/Boot/EFI/bootmgfw.efi"\
-		> "${target_fs_mountpoint}/EFI/Boot/bootx64.efi"
+		> "${efi_boot_directory}/bootx64.efi"
 }; declare -fr workaround_support_windows_7_uefi_boot
 
 install_bootloader_grub(){