Help with Linux only functions

probe_src/libprobe/Makefile

@@ -1,4 +1,4 @@
-UNAME_S := $(shell uname -s)
+ UNAME_S := $(shell uname -s)
 
 SOURCE_VERSION ?= $(shell git rev-parse --short HEAD)
 CFLAGS_COMMON ?= -DSOURCE_VERSION=\"$(SOURCE_VERSION)\" -Wall -Wextra -pthread -fPIC $(NIX_CFLAGS_COMPILE)
@@ -37,7 +37,7 @@ build/lib%-dbg.$(LIB_EXTENSION): $(SOURCE_FILES) $(GENERATED_FILES)
 	gcc $(CFLAGS_COMMON) $(DBGCFLAGS) $(SHARED_LIB_FLAGS) $(EXTRA_LIBS) -o $@ src/lib.c
 
 $(GENERATED_FILES): $(wildcard generator/*)
-	./generator/gen_libc_hooks.py
+	./generator/gen_libc_hooks.py $(UNAME_S)
 
 install:
 	$(INSTALL_CMD)

probe_src/libprobe/generator/gen_libc_hooks.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 from __future__ import annotations
+import sys
 import dataclasses
 import pycparser  # type: ignore
 import pycparser.c_generator  # type: ignore
@@ -160,6 +161,24 @@ def ptr_type(type: Node) -> pycparser.c_ast.PtrDecl:
 )
 
 
+def find_decl(
+        block: typing.Sequence[Node],
+        name: str,
+        comment: typing.Any,
+) -> Decl | None:
+    relevant_stmts = [
+        stmt
+        for stmt in block
+        if isinstance(stmt, Decl) and stmt.name == name
+    ]
+    if not relevant_stmts:
+        return None
+    elif len(relevant_stmts) > 1:
+        raise ValueError(f"Multiple definitions of {name}" + " ({})".format(comment) if comment else "")
+    else:
+        return relevant_stmts[0]
+
+
 @dataclasses.dataclass(frozen=True)
 class ParsedFunc:
     name: str
@@ -248,6 +267,26 @@ def definition(self) -> pycparser.c_ast.FuncDef:
         if isinstance(node, Decl) and isinstance(node.type, pycparser.c_ast.TypeDecl) and node.type.type.names == ["fn"]
     },
 }
+if len(sys.argv) != 2:
+    raise RuntimeError("Need to pass exactly 1 arg")
+match sys.argv[1]:
+    case "Darwin":
+        compiling_for_linux = False
+    case "Linux":
+        compiling_for_linux = True
+    case _:
+        raise RuntimeError("First argument should be uname -s")
+platform_funcs = {}
+for func_name, func in funcs.items():
+    linux_only_field = find_decl(func.stmts, "linux_only", func.name)
+    linux_only_field_init = None if linux_only_field is None else linux_only_field.init
+    linux_only = linux_only_field_init is not None and linux_only_field_init.name == "true" # type: ignore
+    if linux_only and compiling_for_linux:
+        platform_funcs[func_name] = func
+    elif linux_only and not compiling_for_linux:
+        pass
+    else:
+        platform_funcs[func_name] = func
 # funcs = {
 #     key: val
 #     for key, val in list(funcs.items())
@@ -267,7 +306,7 @@ def definition(self) -> pycparser.c_ast.FuncDef:
         init=None,
         bitsize=None,
     )
-    for func_name, func in funcs.items()
+    for func_name, func in platform_funcs.items()
 ]
 init_function_pointers = ParsedFunc(
     name="init_function_pointers",
@@ -288,7 +327,7 @@ def definition(self) -> pycparser.c_ast.FuncDef:
                 ),
             ),
         )
-        for func_name, func in funcs.items()
+        for func_name, func in platform_funcs.items()
     ],
 ).definition()
 
@@ -302,24 +341,6 @@ def raise_thunk(exception: Exception) -> typing.Callable[..., typing.NoReturn]:
     return lambda *args, **kwarsg: raise_(exception)
 
 
-def find_decl(
-        block: typing.Sequence[Node],
-        name: str,
-        comment: typing.Any,
-) -> Decl | None:
-    relevant_stmts = [
-        stmt
-        for stmt in block
-        if isinstance(stmt, Decl) and stmt.name == name
-    ]
-    if not relevant_stmts:
-        return None
-    elif len(relevant_stmts) > 1:
-        raise ValueError(f"Multiple definitions of {name}" + " ({})".format(comment) if comment else "")
-    else:
-        return relevant_stmts[0]
-
-
 def wrapper_func_body(func: ParsedFunc) -> typing.Sequence[Node]:
     pre_call_stmts = [
         pycparser.c_ast.FuncCall(
@@ -419,7 +440,7 @@ def wrapper_func_body(func: ParsedFunc) -> typing.Sequence[Node]:
         func,
         stmts=wrapper_func_body(func),
     ).definition()
-    for _, func in funcs.items()
+    for _, func in platform_funcs.items()
 ]
 pathlib.Path("generated/libc_hooks.h").write_text(
     GccCGenerator().visit(

probe_src/libprobe/generator/libc_hooks_source.c

@@ -304,6 +304,7 @@ int close (int filedes) {
     });
 }
 int close_range (unsigned int lowfd, unsigned int maxfd, int flags) {
+    bool linux_only = true;
     void* pre_call = ({
         if (flags != 0) {
             NOT_IMPLEMENTED("I don't know how to handle close_rnage flags yet");