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#
# Listing C's global variables in .so or .o, or .bundle on Mac OS using "objdump -t" (elf64-x86-64)
# to check ractor-safety.
#
# Usage: ruby search-cgvars.rb foo.so bar.o .ext/x86_64-darwin18/psych.bundle
#
MAC_OS = RbConfig::CONFIG['host_os'].match? /darwin|mac os/
def gvars file
# '0000000000031ac8 g O .bss 0000000000000008 rb_cSockIfaddr'
# On mac, with .bundle files:
# '0000000000004258 l O __DATA,__bss _passwd_blocking'
strs = `objdump -t #{file}`
found = {}
strs.each_line{|line|
if /[\da-f]{16} / =~ line
addr = line[0...16]
flags = line[17...24].tr(' ', '').split(//).sort.uniq
rest = line[25..]
if MAC_OS
seg, name = rest.split(/\s+/)
else
seg, size, name = rest.split(/\s+/)
end
if flags.include?('O')
# p [addr, flags, seg, size, name]
found[name] = [flags, seg, *size]
end
end
}
puts "## #{file}:"
found.sort_by{|name, (flags, *)|
[flags, name]
}.each{|name, rest|
flags, seg, size = *rest
next if (size.to_i == 0 && !MAC_OS) && seg != '*UND*'
case seg
when ".rodata", ".data.rel.ro", ".got.plt", ".eh_frame", ".fini_array"
next
when /,__const$/ # Mac OS
next
end
case name
when /^id_/, /^rbimpl_id/, /^sym_/, /^rb_[cme]/, /\Acompleted\.\d+\z/
next
when /^_id_/, /\.rbimpl_id(\.\d+)?$/ # Mac OS
next
end
puts " %40s %s" % [name, rest.inspect]
}
end
ARGV.each{|file|
gvars file
}
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