systemd/src/basic/missing_syscalls.py

#!/usr/bin/env python3
import sys
import os
import functools

# We only generate numbers for a dozen or so syscalls
SYSCALLS = [
    'bpf',
    'close_range',
    'copy_file_range',
    'getrandom',
    'memfd_create',
    'name_to_handle_at',
    'pidfd_open',
    'pidfd_send_signal',
    'pkey_mprotect',
    'renameat2',
    'setns',
    'statx']

def dictify(f):
    def wrap(*args, **kwargs):
        return dict(f(*args, **kwargs))
    return functools.update_wrapper(wrap, f)

@dictify
def parse_syscall_table(filename):
    print(f'Reading {filename}…')
    for line in open(filename):
        items = line.split()
        if len(items) >= 2:
            yield items[0], int(items[1])

def parse_syscall_tables(filenames):
    return {filename.split('-')[-1]: parse_syscall_table(filename)
            for filename in filenames}

DEF_TEMPLATE = '''\
#ifndef __IGNORE_{syscall}
#  if defined(__aarch64__)
#    define systemd_NR_{syscall} {nr_arm64}
#  elif defined(__alpha__)
#    define systemd_NR_{syscall} {nr_alpha}
#  elif defined(__arc__) || defined(__tilegx__)
#    define systemd_NR_{syscall} {nr_arc}
#  elif defined(__arm__)
#    define systemd_NR_{syscall} {nr_arm}
#  elif defined(__i386__)
#    define systemd_NR_{syscall} {nr_i386}
#  elif defined(__ia64__)
#    define systemd_NR_{syscall} {nr_ia64}
#  elif defined(__m68k__)
#    define systemd_NR_{syscall} {nr_m68k}
#  elif defined(_MIPS_SIM)
#    if _MIPS_SIM == _MIPS_SIM_ABI32
#      define systemd_NR_{syscall} {nr_mipso32}
#    elif _MIPS_SIM == _MIPS_SIM_NABI32
#      define systemd_NR_{syscall} {nr_mips64n32}
#    elif _MIPS_SIM == _MIPS_SIM_ABI64
#      define systemd_NR_{syscall} {nr_mips64}
#    else
#      error "Unknown MIPS ABI"
#    endif
#  elif defined(__powerpc__)
#    define systemd_NR_{syscall} {nr_powerpc}
#  elif defined(__s390__)
#    define systemd_NR_{syscall} {nr_s390}
#  elif defined(__sparc__)
#    define systemd_NR_{syscall} {nr_sparc}
#  elif defined(__x86_64__)
#    if defined(__ILP32__)
#      define systemd_NR_{syscall} ({nr_x86_64} | /* __X32_SYSCALL_BIT */ 0x40000000)
#    else
#      define systemd_NR_{syscall} {nr_x86_64}
#    endif
#  else
#    warning "{syscall}() syscall number is unknown for your architecture"
#  endif

/* may be (invalid) negative number due to libseccomp, see PR 13319 */
#  if defined __NR_{syscall} && __NR_{syscall} >= 0
#    if defined systemd_NR_{syscall}
assert_cc(__NR_{syscall} == systemd_NR_{syscall});
#    endif
#  else
#    if defined __NR_{syscall}
#      undef __NR_{syscall}
#    endif
#    if defined systemd_NR_{syscall} && systemd_NR_{syscall} >= 0
#      define __NR_{syscall} systemd_NR_{syscall}
#    endif
#  endif
#endif
'''

def print_syscall_def(syscall, tables, out):
    mappings = {f'nr_{arch}':t.get(syscall, -1)
                for arch, t in tables.items()}
    print(DEF_TEMPLATE.format(syscall=syscall, **mappings),
          file=out)

def print_syscall_defs(syscalls, tables, out):
    print('/* This file is generated. Do not edit! */\n', file=out)
    for syscall in syscalls:
        print_syscall_def(syscall, tables, out)

if __name__ == '__main__':
    output_file = sys.argv[1]
    arch_files = sys.argv[2:]
    out = open(output_file, 'wt')

    tables = parse_syscall_tables(arch_files)
    print_syscall_defs(SYSCALLS, tables, out)

    print(f'Wrote {output_file}')