qemu/scripts/undefsym.py
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   1#!/usr/bin/env python3
   2
   3# Before a shared module's DSO is produced, a static library is built for it
   4# and passed to this script.  The script generates -Wl,-u options to force
   5# the inclusion of symbol from libqemuutil.a if the shared modules need them,
   6# This is necessary because the modules may use functions not needed by the
   7# executable itself, which would cause the function to not be linked in.
   8# Then the DSO loading would fail because of the missing symbol.
   9
  10
  11import sys
  12import subprocess
  13
  14def filter_lines_set(stdout, from_staticlib):
  15    linesSet = set()
  16    for line in stdout.splitlines():
  17        tokens = line.split(b' ')
  18        if len(tokens) >= 2:
  19            if from_staticlib and tokens[1] == b'U':
  20                continue
  21            if not from_staticlib and tokens[1] != b'U':
  22                continue
  23            new_line = b'-Wl,-u,' + tokens[0]
  24            if not new_line in linesSet:
  25                linesSet.add(new_line)
  26    return linesSet
  27
  28def main(args):
  29    if len(args) <= 3:
  30        sys.exit(0)
  31
  32    nm = args[1]
  33    staticlib = args[2]
  34    pc = subprocess.run([nm, "-P", "-g", staticlib], stdout=subprocess.PIPE)
  35    if pc.returncode != 0:
  36        sys.exit(1)
  37    staticlib_syms = filter_lines_set(pc.stdout, True)
  38
  39    shared_modules = args[3:]
  40    pc = subprocess.run([nm, "-P", "-g"] + shared_modules, stdout=subprocess.PIPE)
  41    if pc.returncode != 0:
  42        sys.exit(1)
  43    modules_undef_syms = filter_lines_set(pc.stdout, False)
  44    lines = sorted(staticlib_syms.intersection(modules_undef_syms))
  45    sys.stdout.buffer.write(b'\n'.join(lines))
  46
  47if __name__ == "__main__":
  48    main(sys.argv)
  49