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Support dt needed in linker #50

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Merged
katsyoshi merged 2 commits into from
Apr 18, 2026
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Support dt needed in linker #50

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296ae41
add start-based tests for glibc linking
katsyoshi Apr 18, 2026
0b9f417
add glibc linker test for start and shared objects
katsyoshi Apr 18, 2026
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81 changes: 81 additions & 0 deletions test/caotral/linker/needed_test.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -38,4 +38,85 @@ def test_needed_in_executable
pid, exit_code = check_process($?.to_i)
assert_equal(0, exit_code)
end

def test_needed_in_shared_object
@output = "libneeded.so"
compile_path = Pathname.new("sample/C/needed.c").to_s
IO.popen(["gcc", "-fPIC", "-c", "-o", @input, "%s" % compile_path]).close

Caotral::Linker.link!(inputs: [@input], output: @output, linker: "self", needed: ["libc.so.6"], executable: false, shared: true)

elf = Caotral::Binary::ELF::Reader.read!(input: @output, debug: false)
dynstr = elf.find_by_name(".dynstr")
dynsym = elf.find_by_name(".dynsym")
needed = elf.find_by_name(".dynamic").body.select(&:needed?)

assert_equal(1, needed.size)
assert_equal(dynstr.body.lookup(needed.first.un), "libc.so.6")
assert_include(dynsym.body.map(&:name_string), "puts")
end

def test_start_in_dynamic_section
@input = "start.o"
@output = "start"
compile_path = Pathname.new("sample/C/start.c").to_s
IO.popen(["gcc", "-fPIC", "-c", "-o", @input, "%s" % compile_path]).close

Caotral::Linker.link!(inputs: [@input], output: @output, linker: "self", pie: true, needed: ["libc.so.6"], executable: false)

elf = Caotral::Binary::ELF::Reader.read!(input: @output, debug: false)
dynstr = elf.find_by_name(".dynstr")
dynsym = elf.find_by_name(".dynsym")
needed = elf.find_by_name(".dynamic").body.select(&:needed?)
got_plt = elf.find_by_name(".dynamic").body.select(&:plt_got?)
jmp_rel = elf.find_by_name(".dynamic").body.select(&:jmp_rel?)
dynsym_names = dynsym.body.map(&:name_string)
assert_equal(1, needed.size)
assert_equal(dynstr.body.lookup(needed.first.un), "libc.so.6")
assert_include(dynsym_names, "_exit")
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@chatgpt-codex-connector chatgpt-codex-connector bot Apr 18, 2026

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P1 Badge Drop _exit assertion from dynsym checks

These new assertions make the test suite fail against the current linker implementation because _exit is an undefined import in start.o, and the builder only exports defined symbols to .dynsym (next if sym.shndx == 0 in Caotral::Linker::Builder). As written, test_start_in_dynamic_section (and the same check later in test_start_in_shared_object) will fail even when DT_NEEDED handling is correct, turning this feature test into a persistent false negative.

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assert_include(dynsym_names, "_start")
assert_equal(1, got_plt.size)
assert_equal(1, jmp_rel.size)
end

def test_start_in_executable
@input = "start.o"
@output = "start"

compile_path = Pathname.new("sample/C/start.c").to_s
IO.popen(["gcc", "-fPIC", "-c", "-o", @input, "%s" % compile_path]).close

Caotral::Linker.link!(inputs: [@input], output: @output, linker: "self", pie: true, needed: ["libc.so.6"], executable: true)

io = IO.popen(["./#{@output}"])
stdout = io.read
io.close
pid, exit_code = check_process($?.to_i)
assert_equal("hello, world!!!\n", stdout)
assert_equal(0, exit_code)
end

def test_start_in_shared_object
@input = "start.o"
@output = "libstart.so"

compile_path = Pathname.new("sample/C/start.c").to_s
IO.popen(["gcc", "-fPIC", "-c", "-o", @input, "%s" % compile_path]).close

Caotral::Linker.link!(inputs: [@input], output: @output, linker: "self", needed: ["libc.so.6"], executable: false, shared: true)

elf = Caotral::Binary::ELF::Reader.read!(input: @output, debug: false)
dynstr = elf.find_by_name(".dynstr")
dynsym = elf.find_by_name(".dynsym")
needed = elf.find_by_name(".dynamic").body.select(&:needed?)
got_plt = elf.find_by_name(".dynamic").body.select(&:plt_got?)
jmp_rel = elf.find_by_name(".dynamic").body.select(&:jmp_rel?)
dynsym_names = dynsym.body.map(&:name_string)
assert_equal(1, needed.size)
assert_equal(dynstr.body.lookup(needed.first.un), "libc.so.6")
assert_include(dynsym_names, "_exit")
assert_include(dynsym_names, "_start")
assert_equal(1, got_plt.size)
assert_equal(1, jmp_rel.size)
end
end
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