chore(magicgen): migrate script to Python

The old script was in Go, and naively split the lines by whitespace to
identify the magic names and values. The new Python script uses a proper
regex rule to parse the input and generate the output.

Signed-off-by: Prajwal S N <prajwalnadig21@gmail.com>

.gitignore

@@ -15,3 +15,4 @@ scripts/magic-gen/expected.go
 scripts/magic-gen/output.go
 crit/bin
 crit/test-imgs/
+__pycache__

scripts/magic-gen/Makefile

@@ -1,17 +1,17 @@
-GO ?= go
+PY ?= python3
 
 MAGIC_DEST ?= ../../magic/magic.go
 
-magic-gen: clean magic.h
-	$(GO) run magicgen.go magic.h $(MAGIC_DEST)
+magic-gen: clean magic.h magicgen.py
+	@$(PY) magicgen.py magic.h $(MAGIC_DEST)
 
 magic.h:
 	curl -s https://raw.githubusercontent.com/checkpoint-restore/criu/criu-dev/criu/include/magic.h -o magic.h
 
-test:
-	@echo "Running unit test"
-	$(GO) test -v
-	@echo "Running E2E test"
+test: test_magicgen.py magicgen-test.sh
+	@echo "Running unit tests..."
+	@$(PY) test_magicgen.py
+	@echo "Running E2E tests..."
 	@./magicgen-test.sh
 	@rm -f input.h output.go expected.go
 

scripts/magic-gen/magicgen-test.sh

@@ -29,18 +29,14 @@ func LoadMagic() MagicMap {
 }
 EOF
 
-if [ -n "$GOCOVERDIR" ]; then
-	export LOCALFLAGS="-cover"
-fi
-
-go run $LOCALFLAGS magicgen.go input.h output.go
+python3 magicgen.py input.h output.go
 cmp output.go expected.go
 if [[ $? -eq 0 ]]
 then
-	echo "PASS"
+	echo "---PASS---"
 	exit 0
 else
-	echo "FAIL"
+	echo "---FAIL---"
 	diff output.go expected.go
 	exit 1
 fi

scripts/magic-gen/magicgen.py

@@ -0,0 +1,86 @@
+import sys
+import re
+import argparse
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="A script to generate Go bindings for the CRIU magic values provided by magic.h"
+    )
+    parser.add_argument("src", help="Input path (magic.h)", type=str)
+    parser.add_argument("dest", help="Output path (magic.go)", type=str)
+
+    args = parser.parse_args()
+
+    try:
+        with open(args.src, "r") as src:
+            magics = read_magics(src)
+    except IOError:
+        sys.exit("Failed to open magic.h")
+
+    try:
+        with open(args.dest, "w") as dest:
+            write_magics(dest, magics)
+    except IOError:
+        sys.exit("Failed to open magic.py")
+
+
+def read_magics(src):
+    magics = {}
+    # The magic.h header file contains lines like below:
+    # #define MAGIC_NAME MAGIC_VALUE
+    # where the magic value can be a hexadecimal or regular
+    # integer value. The regex below matches lines in the
+    # header and extracts the name and value as regex groups.
+    pattern = re.compile(r"#define\s+(\S+)\s+(0x[0-9A-Fa-f]+|\d+)")
+
+    for line in src:
+        match = pattern.match(line)
+        if match:
+            name = match.group(1)
+            value_str = match.group(2)
+            # If the magic is defined as another magic, skip it
+            if value_str in magics:
+                continue
+            try:
+                value = int(value_str, 16)
+                magics[name] = value
+            except ValueError:
+                print(f"Failed to parse magic {name}")
+                continue
+
+    return magics
+
+
+def write_magics(dest, magics):
+    dest.write(
+        """// Code generated by magicgen. DO NOT EDIT.
+
+package magic
+
+type MagicMap struct {
+\tByName  map[string]uint64
+\tByValue map[uint64]string
+}
+
+func LoadMagic() MagicMap {
+\tmagicMap := MagicMap{
+\t\tByName:  make(map[string]uint64),
+\t\tByValue: make(map[uint64]string),
+\t}"""
+    )
+
+    for name in sorted(magics.keys()):
+        value = magics[name]
+        # Ignore RAW_IMAGE_MAGIC and V1 magic
+        if value == 0 or value == 1:
+            continue
+        name = name.replace("_MAGIC", "")
+        dest.write(f'\n\tmagicMap.ByName["{name}"] = {value}')
+        dest.write(f'\n\tmagicMap.ByValue[{value}] = "{name}"')
+
+    dest.write("\n\treturn magicMap\n}\n")
+
+
+if __name__ == "__main__":
+    main()