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linkage_checker: check variable references with dlopen

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The linkage check currently does nothing to check the validity of
variable-referenced libraries (prefixed with an `@`).

We could rectify that by mimicking the dynamic linker in looking up the
variable-referenced library, but this could get quite complicated.
Instead, let's let the linker do the hard work by checking if we can
`dlopen` libraries and bundles that contain variable linkage. The
`dlopen` will fail if the linker cannot resolve the variable reference.

There are at least two disadvantages to this approach relative to the
alternative suggested above:
1. This doesn't work for binary executables.
2. This doesn't identify which variable references are broken.

It's still better than not checking them at all, which is what we do
currently, and saves us from having to carry around code that parses and
verifies variable references directly.
This commit is contained in:
Carlo Cabrera 2021-11-15 02:24:16 +08:00
parent 1f0ab4a1ee
commit 0191a275cc
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GPG Key ID: C74D447FC549A1D0
1 changed files with 14 additions and 1 deletions
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15
Library/Homebrew/linkage_checker.rb
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@ -32,6 +32,7 @@ class LinkageChecker
@unnecessary_deps = []
@unwanted_system_dylibs = []
@version_conflict_deps = []
@broken_variable_dylibs = []
check_dylibs(rebuild_cache: rebuild_cache)
end
@ -46,6 +47,7 @@ class LinkageChecker
display_items "Undeclared dependencies with linkage", @undeclared_deps
display_items "Dependencies with no linkage", @unnecessary_deps
display_items "Unwanted system libraries", @unwanted_system_dylibs
display_items "Libraries with broken variable references", @broken_variable_dylibs
end
def display_reverse_output
@ -68,11 +70,12 @@ class LinkageChecker
display_items "Broken dependencies", @broken_deps, puts_output: puts_output
display_items "Unwanted system libraries", @unwanted_system_dylibs, puts_output: puts_output
display_items "Conflicting libraries", @version_conflict_deps, puts_output: puts_output
display_items "Libraries with broken variable references", @broken_variable_dylibs, puts_output: puts_output
end
sig { returns(T::Boolean) }
def broken_library_linkage?
issues = [@broken_deps, @unwanted_system_dylibs, @version_conflict_deps]
issues = [@broken_deps, @unwanted_system_dylibs, @version_conflict_deps, @broken_variable_dylibs]
[issues, unexpected_broken_dylibs, unexpected_present_dylibs].flatten.any?(&:present?)
end
@ -148,6 +151,7 @@ class LinkageChecker
end
checked_dylibs = Set.new
dlopened_if_needed_files = Set.new
keg_files_dylibs.each do |file, dylibs|
dylibs.each do |dylib|
@ -159,6 +163,15 @@ class LinkageChecker
if dylib.start_with? "@"
@variable_dylibs << dylib
if dlopened_if_needed_files.add?(file)
file = Pathname.new(file)
next if file.binary_executable?
next if dylib_found_via_dlopen(file.dylib_id)
@broken_variable_dylibs << file.dylib_id
end
next
end