Skip to content

Make separate "create" and "update" functions for LC_BUILD_VERSION #16

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Make separate "create" and "update" functions for LC_BUILD_VERSION #16

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
24 changes: 14 additions & 10 deletions Sources/Arm64ToSimLib/Transmogrifier.swift
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,7 @@ public enum Transmogrifier {
return datas.merge()
}

private static func updateVersionMin(_ data: Data, _ offset: UInt32, minos: UInt32, sdk: UInt32) -> Data {
private static func createLcBuildVersion(minos: UInt32, sdk: UInt32) -> Data {
var command = build_version_command(cmd: UInt32(LC_BUILD_VERSION),
cmdsize: UInt32(MemoryLayout<build_version_command>.stride),
platform: UInt32(PLATFORM_IOSSIMULATOR),
Expand All @@ -115,6 +115,15 @@ public enum Transmogrifier {
return Data(bytes: &command, count: MemoryLayout<build_version_command>.stride)
}

private static func updateLcBuildVersion(_ data: Data, minos: UInt32, sdk: UInt32) -> Data {
var command: build_version_command = data.asStruct()
command.platform = UInt32(PLATFORM_IOSSIMULATOR)
command.minos = minos << 16 | 0 << 8 | 0
command.sdk = sdk << 16 | 0 << 8 | 0

return Data(bytes: &command, count: data.count)
}

private static func updateDataInCode(_ data: Data, _ offset: UInt32) -> Data {
var command: linkedit_data_command = data.asStruct()
command.dataoff += offset
Expand Down Expand Up @@ -154,8 +163,6 @@ public enum Transmogrifier {
}

if contains_LC_VERSION_MIN_IPHONEOS {
// `offset` is kind of a magic number here, since we know that's the only meaningful change to binary size
// having a dynamic `offset` requires two passes over the load commands and is left as an exercise to the reader
return updatePreiOS12ObjectFile
} else {
return updatePostiOS12ObjectFile
Expand All @@ -167,7 +174,7 @@ public enum Transmogrifier {
let cmd = Int32(bitPattern: lc.loadCommand)
switch cmd {
case LC_BUILD_VERSION:
return updateVersionMin(lc, 0, minos: minos, sdk: sdk)
return updateLcBuildVersion(lc, minos: minos, sdk: sdk)
default:
return lc
}
Expand All @@ -182,28 +189,25 @@ public enum Transmogrifier {
case LC_SEGMENT_64:
return updateSegment64(lc, offset)
case LC_VERSION_MIN_IPHONEOS:
return updateVersionMin(lc, offset, minos: minos, sdk: sdk)
return createLcBuildVersion(minos: minos, sdk: sdk)
case LC_DATA_IN_CODE, LC_LINKER_OPTIMIZATION_HINT:
return updateDataInCode(lc, offset)
case LC_SYMTAB:
return updateSymTab(lc, offset)
case LC_BUILD_VERSION:
return updateVersionMin(lc, offset, minos: minos, sdk: sdk)
fatalError("pre-12 object file shold not contain LC_BUILD_VERSION!")
default:
return lc
}
}

static func updateDylibFile(lc: Data, minos: UInt32, sdk: UInt32) -> Data {
// `offset` is kind of a magic number here, since we know that's the only meaningful change to binary size
// having a dynamic `offset` requires two passes over the load commands and is left as an exercise to the reader
let offset = UInt32(abs(MemoryLayout<build_version_command>.stride - MemoryLayout<version_min_command>.stride))
let cmd = Int32(bitPattern: lc.loadCommand)
guard cmd != LC_BUILD_VERSION else {
fatalError("This arm64 binary already contains an LC_BUILD_VERSION load command!")
}
if cmd == LC_VERSION_MIN_IPHONEOS {
return updateVersionMin(lc, offset, minos: minos, sdk: sdk)
return createLcBuildVersion(minos: minos, sdk: sdk)
}
return lc
}
Expand Down