Module: OS::Linux::Elf Private

Defined in:
os/linux/elf.rb

Overview

This module is part of a private API. This module may only be used in the Homebrew/brew repository. Third parties should avoid using this module if possible, as it may be removed or changed without warning.

Helper functions for working with ELF objects.

Class Method Summary collapse

Class Method Details

.expand_elf_dst(str, ref, repl) ⇒ String

This method is part of a private API. This method may only be used in the Homebrew/brew repository. Third parties should avoid using this method if possible, as it may be removed or changed without warning.

Parameters:

Returns:



249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
 
# File 'os/linux/elf.rb', line 249

def self.expand_elf_dst(str, ref, repl)
  # ELF gABI rules for DSTs:
  #   - Longest possible sequence using the rules (greedy).
  #   - Must start with a $ (enforced by caller).
  #   - Must follow $ with one underscore or ASCII [A-Za-z] (caller
  #     follows these rules for REF) or '{' (start curly quoted name).
  #   - Must follow first two characters with zero or more [A-Za-z0-9_]
  #     (enforced by caller) or '}' (end curly quoted name).
  # (from https://github.com/bminor/glibc/blob/41903cb6f460d62ba6dd2f4883116e2a624ee6f8/elf/dl-load.c#L182-L228)

  # In addition to capturing a token, also attempt to capture opening/closing braces and check that they are not
  # mismatched before expanding.
  str.gsub(/\$({?)([a-zA-Z_][a-zA-Z0-9_]*)(}?)/) do |orig_str|
    has_opening_brace = ::Regexp.last_match(1).present?
    matched_text = ::Regexp.last_match(2)
    has_closing_brace = ::Regexp.last_match(3).present?
    if (matched_text == ref) && (has_opening_brace == has_closing_brace)
      repl
    else
      orig_str
    end
  end
end