37 lines
1.7 KiB
Ruby
Executable File
37 lines
1.7 KiB
Ruby
Executable File
#!/usr/bin/env ruby
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# typed: strict
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# frozen_string_literal: true
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pid = ARGV[0]&.to_i
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raise "Missing `pid` argument!" unless pid
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require "fiddle"
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# Canonically, this is a part of libproc.dylib. libproc is however just a symlink to libSystem
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# and some security tools seem to not support aliases from the dyld shared cache and incorrectly flag this.
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libproc = Fiddle.dlopen("/usr/lib/libSystem.B.dylib")
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libproc_proc_pidpath_function = Fiddle::Function.new(
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libproc["proc_pidpath"],
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[Fiddle::TYPE_INT, Fiddle::TYPE_VOIDP, Fiddle::TYPE_UINT32_T],
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Fiddle::TYPE_INT,
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)
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# We have to allocate a (char) buffer of exactly `PROC_PIDPATHINFO_MAXSIZE` to use `proc_pidpath`
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# From `include/sys/proc_info.h`, PROC_PIDPATHINFO_MAXSIZE = 4 * MAXPATHLEN
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# From `include/sys/param.h`, MAXPATHLEN = PATH_MAX
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# From `include/sys/syslimits.h`, PATH_MAX = 1024
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# https://github.com/apple-oss-distributions/xnu/blob/e3723e1f17661b24996789d8afc084c0c3303b26/libsyscall/wrappers/libproc/libproc.c#L268-L275
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buffer_size = 4 * 1024 # PROC_PIDPATHINFO_MAXSIZE = 4 * MAXPATHLEN
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buffer = "\0" * buffer_size
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pointer_to_buffer = Fiddle::Pointer.to_ptr(buffer)
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# `proc_pidpath` returns a positive value on success. See:
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# https://stackoverflow.com/a/8149198
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# https://github.com/chromium/chromium/blob/86df41504a235f9369f6f53887da12a718a19db4/base/process/process_handle_mac.cc#L37-L44
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# https://github.com/apple-oss-distributions/xnu/blob/e3723e1f17661b24996789d8afc084c0c3303b26/libsyscall/wrappers/libproc/libproc.c#L263-L283
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return_value = libproc_proc_pidpath_function.call(pid, pointer_to_buffer, buffer_size)
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raise "Call to `proc_pidpath` failed! `proc_pidpath` returned #{return_value}." unless return_value.positive?
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puts pointer_to_buffer.to_s.strip
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