devtools: Improve *-check.py tool detection

This is important to make sure that we're not testing tools different
from the one we're building with.

Introduce determine_wellknown_cmd, which encapsulates how we
should handle well-known tools specification (IFS splitting, env
override, etc.).

4 files changed, 39 insertions, 14 deletions

diff --git a/contrib/devtools/symbol-check.py b/contrib/devtools/symbol-check.py
index 407c0a2d72..61f727fa63 100755
--- a/contrib/devtools/symbol-check.py
+++ b/contrib/devtools/symbol-check.py
@@ -12,12 +12,13 @@ Example usage:
 '''
 import subprocess
 import sys
-import os
 from typing import List, Optional
 
 import lief
 import pixie
 
+from utils import determine_wellknown_cmd
+
 # Debian 8 (Jessie) EOL: 2020. https://wiki.debian.org/DebianReleases#Production_Releases
 #
 # - g++ version 4.9.2 (https://packages.debian.org/search?suite=jessie&arch=any&searchon=names&keywords=g%2B%2B)
@@ -60,7 +61,6 @@ IGNORE_EXPORTS = {
 '_edata', '_end', '__end__', '_init', '__bss_start', '__bss_start__', '_bss_end__', '__bss_end__', '_fini', '_IO_stdin_used', 'stdin', 'stdout', 'stderr',
 'environ', '_environ', '__environ',
 }
-CPPFILT_CMD = os.getenv('CPPFILT', '/usr/bin/c++filt')
 
 # Allowed NEEDED libraries
 ELF_ALLOWED_LIBRARIES = {
@@ -140,7 +140,7 @@ class CPPFilt(object):
     Use a pipe to the 'c++filt' command.
     '''
     def __init__(self):
-        self.proc = subprocess.Popen(CPPFILT_CMD, stdin=subprocess.PIPE, stdout=subprocess.PIPE, universal_newlines=True)
+        self.proc = subprocess.Popen(determine_wellknown_cmd('CPPFILT', 'c++filt'), stdin=subprocess.PIPE, stdout=subprocess.PIPE, universal_newlines=True)
 
     def __call__(self, mangled):
         self.proc.stdin.write(mangled + '\n')
diff --git a/contrib/devtools/test-security-check.py b/contrib/devtools/test-security-check.py
index c079fe5b4d..73c8732bb6 100755
--- a/contrib/devtools/test-security-check.py
+++ b/contrib/devtools/test-security-check.py
@@ -9,6 +9,8 @@ import os
 import subprocess
 import unittest
 
+from utils import determine_wellknown_cmd
+
 def write_testcode(filename):
     with open(filename, 'w', encoding="utf8") as f:
         f.write('''
@@ -25,7 +27,7 @@ def clean_files(source, executable):
     os.remove(executable)
 
 def call_security_check(cc, source, executable, options):
-    subprocess.run([cc,source,'-o',executable] + options, check=True)
+    subprocess.run([*cc,source,'-o',executable] + options, check=True)
     p = subprocess.run(['./contrib/devtools/security-check.py',executable], stdout=subprocess.PIPE, universal_newlines=True)
     return (p.returncode, p.stdout.rstrip())
 
@@ -33,7 +35,7 @@ class TestSecurityChecks(unittest.TestCase):
     def test_ELF(self):
         source = 'test1.c'
         executable = 'test1'
-        cc = 'gcc'
+        cc = determine_wellknown_cmd('CC', 'gcc')
         write_testcode(source)
 
         self.assertEqual(call_security_check(cc, source, executable, ['-Wl,-zexecstack','-fno-stack-protector','-Wl,-znorelro','-no-pie','-fno-PIE', '-Wl,-z,separate-code']),
@@ -54,7 +56,7 @@ class TestSecurityChecks(unittest.TestCase):
     def test_PE(self):
         source = 'test1.c'
         executable = 'test1.exe'
-        cc = 'x86_64-w64-mingw32-gcc'
+        cc = determine_wellknown_cmd('CC', 'x86_64-w64-mingw32-gcc')
         write_testcode(source)
 
         self.assertEqual(call_security_check(cc, source, executable, ['-Wl,--no-nxcompat','-Wl,--no-dynamicbase','-Wl,--no-high-entropy-va','-no-pie','-fno-PIE']),
@@ -73,7 +75,7 @@ class TestSecurityChecks(unittest.TestCase):
     def test_MACHO(self):
         source = 'test1.c'
         executable = 'test1'
-        cc = 'clang'
+        cc = determine_wellknown_cmd('CC', 'clang')
         write_testcode(source)
 
         self.assertEqual(call_security_check(cc, source, executable, ['-Wl,-no_pie','-Wl,-flat_namespace','-Wl,-allow_stack_execute','-fno-stack-protector']),
@@ -95,4 +97,3 @@ class TestSecurityChecks(unittest.TestCase):
 
 if __name__ == '__main__':
     unittest.main()
-
diff --git a/contrib/devtools/test-symbol-check.py b/contrib/devtools/test-symbol-check.py
index 6ce2fa3560..56ea02719d 100755
--- a/contrib/devtools/test-symbol-check.py
+++ b/contrib/devtools/test-symbol-check.py
@@ -7,10 +7,13 @@ Test script for symbol-check.py
 '''
 import os
 import subprocess
+from typing import List
 import unittest
 
-def call_symbol_check(cc, source, executable, options):
-    subprocess.run([cc,source,'-o',executable] + options, check=True)
+from utils import determine_wellknown_cmd
+
+def call_symbol_check(cc: List[str], source, executable, options):
+    subprocess.run([*cc,source,'-o',executable] + options, check=True)
     p = subprocess.run(['./contrib/devtools/symbol-check.py',executable], stdout=subprocess.PIPE, universal_newlines=True)
     os.remove(source)
     os.remove(executable)
@@ -20,7 +23,7 @@ class TestSymbolChecks(unittest.TestCase):
     def test_ELF(self):
         source = 'test1.c'
         executable = 'test1'
-        cc = 'gcc'
+        cc = determine_wellknown_cmd('CC', 'gcc')
 
         # renameat2 was introduced in GLIBC 2.28, so is newer than the upper limit
         # of glibc for all platforms
@@ -82,7 +85,7 @@ class TestSymbolChecks(unittest.TestCase):
     def test_MACHO(self):
         source = 'test1.c'
         executable = 'test1'
-        cc = 'clang'
+        cc = determine_wellknown_cmd('CC', 'clang')
 
         with open(source, 'w', encoding="utf8") as f:
             f.write('''
@@ -132,7 +135,7 @@ class TestSymbolChecks(unittest.TestCase):
     def test_PE(self):
         source = 'test1.c'
         executable = 'test1.exe'
-        cc = 'x86_64-w64-mingw32-gcc'
+        cc = determine_wellknown_cmd('CC', 'x86_64-w64-mingw32-gcc')
 
         with open(source, 'w', encoding="utf8") as f:
             f.write('''
@@ -182,4 +185,3 @@ class TestSymbolChecks(unittest.TestCase):
 
 if __name__ == '__main__':
     unittest.main()
-
diff --git a/contrib/devtools/utils.py b/contrib/devtools/utils.py
new file mode 100755
index 0000000000..68ad1c3aba
--- /dev/null
+++ b/contrib/devtools/utils.py
@@ -0,0 +1,22 @@
+#!/usr/bin/env python3
+# Copyright (c) 2021 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+'''
+Common utility functions
+'''
+import shutil
+import sys
+import os
+from typing import List
+
+
+def determine_wellknown_cmd(envvar, progname) -> List[str]:
+    maybe_env = os.getenv(envvar)
+    maybe_which = shutil.which(progname)
+    if maybe_env:
+        return maybe_env.split(' ')  # Well-known vars are often meant to be word-split
+    elif maybe_which:
+        return [ maybe_which ]
+    else:
+        sys.exit(f"{progname} not found")