Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 48 insertions, 0 deletions

diff --git a/scripts/undefsym.py b/scripts/undefsym.py
new file mode 100644
index 000000000..4b6a72d95
--- /dev/null
+++ b/scripts/undefsym.py
@@ -0,0 +1,48 @@
+#!/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) >= 2:
+            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)