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我一直在尝试在 Ruby 中读写进程内存，希望将一些旧的 C++ 程序迁移到更动态的语言中。但是，我搬过来并不容易。我已经阅读了一些内容，但在我的具体问题上找不到太多。我可能在下面有一些非常基本的错误，因为我不太确定指针管理在 Ruby-ffi 中是如何工作的。

无论如何，我目前已经ffi安装了 gem，并一直在使用它来获取功能。这就是我所拥有的：

module Memory
  PROC_READ = 0x10
  PROC_WRITE = 0x20
  PROC_RW = PROC_READ | PROC_WRITE

  extend FFI::Library

  ffi_lib 'kernel32'

  # HANDLE WINAPI OpenProcess(DWORD, BOOL, DWORD)
  attach_function :open, :OpenProcess, [:uint, :bool, :uint], :pointer

  # BOOL WINAPI CloseHandle(HANDLE)
  attach_function :close, :CloseHandle, [:pointer], :bool

  # BOOL WINAPI ReadProcessMemory(HANDLE, LPCVOID, out LPVOID, SIZE_T, out SIZE_T)
  attach_function :read, :ReadProcessMemory, [:pointer, :pointer, :pointer, :int, :int], :bool

  # BOOL WINAPI WriteProcessMemory(HANDLE, LPCVOID, LPVOID, SIZE_T, out SIZE_T)
  attach_function :write, :WriteProcessMemory, [:pointer, :pointer, :pointer, :int, :int], :bool

  # DWORD WINAPI GetLastError(void)
  attach_function :error, :GetLastError, [], :uint
end

似乎当我调用 Memory.open 时，我得到了正确的句柄。我不太确定，但这是存储结果的变量的输出，以防万一我错了。

#<FFI::Pointer address=0x00000000000150>

这是我目前拥有的完整代码：

# 1048 is a fixed pid currently
handle = Memory::open(Memory::PROC_RW, false, 1048)
puts "GetLastError: #{Memory::error()}"

# Address to read from
loc = 0x057C75F8

out = 0
read = 0

# Supposed to be the address of out to store the value read
val = FFI::MemoryPointer.new :uint, out

# Supposed to be a pointer to loc which holds the address to read from
addr = FFI::MemoryPointer.new :pointer, loc

res = Memory::read(handle, addr, val, 4, read)

puts "GetLastError: #{Memory::error()}"
puts "ReadProcessMemory: #{res}"
puts read
puts out

Memory::close(handle)

这将打印出以下内容：

GetLastError: 0
GetLastError: 0
ReadProcessMemory: false
0
0

我知道我必须对指针变量做一些根本错误的事情。如果我更改addr为 anFFI::Pointer类型:uint和值，loc则 ReadProcessMemory 返回true，但outandread变量不会改变。

我希望这已经足够清楚了。我可以尝试澄清是否缺少某些东西。

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1 回答 1

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在阅读了 Github 上该项目的示例页面后，我终于能够弄清楚我的指针问题：

https://github.com/ffi/ffi/wiki/Examples

特别是在“带有 MemoryPointer 的输出参数”部分下。阅读后，我能够将代码更改为以下内容：

require 'ffi'

module Memory
  PROC_READ = 0x10
  PROC_WRITE = 0x20
  PROC_RW = PROC_READ | PROC_WRITE

  extend FFI::Library

  ffi_lib 'kernel32'
  ffi_convention :stdcall

  attach_function :open, :OpenProcess, [:uint, :bool, :uint], :pointer
  attach_function :close, :CloseHandle, [:pointer], :bool
  attach_function :read, :ReadProcessMemory, [:pointer, :pointer, :pointer, :size_t, :pointer], :bool
  attach_function :write, :WriteProcessMemory, [:pointer, :pointer, :pointer, :size_t, :pointer], :bool
  attach_function :error, :GetLastError, [], :uint
end

# 1048 is a fixed pid currently
handle = Memory::open(Memory::PROC_RW, false, 1048)
puts "GetLastError: #{Memory::error()}"

# Output parameters for ReadProcessMemory
out = FFI::MemoryPointer.new :pointer
read = FFI::MemoryPointer.new :pointer

# Pointer holding the location to read from
addr = FFI::Pointer.new :pointer, 0x057C75F8

res = Memory::read(handle, addr, out, 4, read)

# get_pointer(0) grabs the pointer to the value
# address holds the value we actually want (at least in this case)
read = read.get_pointer(0).address
out = out.get_pointer(0).address

puts "GetLastError: #{Memory::error()}"
puts "ReadProcessMemory: #{res}"
puts "Bytes Read: #{read}"
puts "Value Read: #{out}"
Memory::close(handle)

在我的具体情况下，上述代码正确输出以下内容：

GetLastError: 0
GetLastError: 0
ReadProcessMemory: true
Bytes Read: 4
Value Read: 10

我希望这对将来的某人有所帮助。

于 2013-11-26T13:42:22.310 回答