meson: Convert undefsym.sh to undefsym.py

Shell scripts are not easily invoked from the build process
on MSYS, so convert undefsym.sh to a python script.

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Message-Id: <20200902170054.810-3-luoyonggang@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

meson.build

@@ -932,7 +932,7 @@ foreach d, list : modules
 endforeach
 
 nm = find_program('nm')
-undefsym = find_program('scripts/undefsym.sh')
+undefsym = find_program('scripts/undefsym.py')
 block_syms = custom_target('block.syms', output: 'block.syms',
                              input: [libqemuutil, block_mods],
                              capture: true,

scripts/undefsym.py

+#!/usr/bin/env python3
+
+# Before a shared module's DSO is produced, a static library is built for it
+# and passed to this script.  The script generates -Wl,-u options to force
+# the inclusion of symbol from libqemuutil.a if the shared modules need them,
+# This is necessary because the modules may use functions not needed by the
+# executable itself, which would cause the function to not be linked in.
+# Then the DSO loading would fail because of the missing symbol.
+
+
+import sys
+import subprocess
+
+def filter_lines_set(stdout, from_staticlib):
+    linesSet = set()
+    for line in stdout.splitlines():
+        tokens = line.split(b' ')
+        if len(tokens) >= 1:
+            if len(tokens) > 1:
+                if from_staticlib and tokens[1] == b'U':
+                    continue
+                if not from_staticlib and tokens[1] != b'U':
+                    continue
+            new_line = b'-Wl,-u,' + tokens[0]
+            if not new_line in linesSet:
+                linesSet.add(new_line)
+    return linesSet
+
+def main(args):
+    if len(args) <= 3:
+        sys.exit(0)
+
+    nm = args[1]
+    staticlib = args[2]
+    pc = subprocess.run([nm, "-P", "-g", staticlib], stdout=subprocess.PIPE)
+    if pc.returncode != 0:
+        sys.exit(1)
+    staticlib_syms = filter_lines_set(pc.stdout, True)
+
+    shared_modules = args[3:]
+    pc = subprocess.run([nm, "-P", "-g"] + shared_modules, stdout=subprocess.PIPE)
+    if pc.returncode != 0:
+        sys.exit(1)
+    modules_undef_syms = filter_lines_set(pc.stdout, False)
+    lines = sorted(staticlib_syms.intersection(modules_undef_syms))
+    sys.stdout.buffer.write(b'\n'.join(lines))
+
+if __name__ == "__main__":
+    main(sys.argv)

scripts/undefsym.sh

-#! /usr/bin/env bash
-
-# Before a shared module's DSO is produced, a static library is built for it
-# and passed to this script.  The script generates -Wl,-u options to force
-# the inclusion of symbol from libqemuutil.a if the shared modules need them,
-# This is necessary because the modules may use functions not needed by the
-# executable itself, which would cause the function to not be linked in.
-# Then the DSO loading would fail because of the missing symbol.
-
-if test $# -le 2; then
-  exit 0
-fi
-
-NM=$1
-staticlib=$2
-shift 2
-# Find symbols defined in static libraries and undefined in shared modules
-comm -12 \
-  <( $NM -P -g $staticlib | awk '$2!="U"{print "-Wl,-u," $1}' | sort -u) \
-  <( $NM -P -g "$@" | awk '$2=="U"{print "-Wl,-u," $1}' | sort -u)