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>

1 files changed, 49 insertions, 0 deletions

diff --git a/scripts/undefsym.py b/scripts/undefsym.py
new file mode 100644
index 0000000000..69a895cd26
--- /dev/null
+++ b/scripts/undefsym.py
@@ -0,0 +1,49 @@
+#!/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)