[libc] Add dlinfo + RTLD_DI_* macros to dlfcn.h (#149938)

An initial commit for #149911, this adds a stub implementation for
dlinfo and the enums list of `RTLD_DI_*` values.

While the dlinfo implementation relies on dynamic linker support, this
patch will add its prototype in the generated dlfcn.h header so that it
can be used by downstream platforms that have their own dlinfo
implementation.

Author: Caslyn

libc/include/dlfcn.yaml

@@ -37,6 +37,55 @@ macros:
     standards:
       - gnu
     macro_value: "((void *) 0)"
+enums:
+  - name: RTLD_DI_LMID
+    standards:
+      - gnu
+    value: 1
+  - name: RTLD_DI_LINKMAP
+    standards:
+      - gnu
+    value: 2
+  - name: RTLD_DI_CONFIGADDR,
+    standards:
+      - gnu
+    value: 3
+  - name: RTLD_DI_SERINFO
+    standards:
+      - gnu
+    value: 4
+  - name: RTLD_DI_SERINFOSIZE
+    standards:
+      - gnu
+    value: 5
+  - name: RTLD_DI_ORIGIN
+    standards:
+      - gnu
+    value: 6
+  - name: RTLD_DI_PROFILENAME
+    standards:
+      - gnu
+    value: 7
+  - name: RTLD_DI_PROFILEOUT
+    standards:
+      - gnu
+    value: 8
+  - name: RTLD_DI_TLS_MODID
+    standards:
+      - gnu
+    value: 9
+  - name: RTLD_DI_TLS_DATA
+    standards:
+      - gnu
+    value: 10
+  - name: RTLD_DI_PHDR
+    standards:
+      - gnu
+    value: 11
+  - name: RTLD_DI_MAX
+    standards:
+      - gnu
+    value: 11
 functions:
   - name: dlclose
     standards:
@@ -63,3 +112,11 @@ functions:
     arguments:
       - type: void *__restrict
       - type: const char *__restrict
+  - name: dlinfo
+    standards:
+      - gnu
+    return_type: int
+    arguments:
+      - type: void *__restrict
+      - type: int
+      - type: void *__restrict

libc/src/dlfcn/CMakeLists.txt

@@ -38,3 +38,14 @@ add_entrypoint_object(
     libc.include.dlfcn
     libc.src.errno.errno
 )
+
+add_entrypoint_object(
+  dlinfo
+  SRCS
+    dlinfo.cpp
+  HDRS
+    dlinfo.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)

libc/src/dlfcn/dlinfo.cpp

@@ -0,0 +1,23 @@
+
+//===-- Implementation of dlinfo ------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "dlinfo.h"
+
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// TODO: https://github.com/llvm/llvm-project/issues/149911
+LLVM_LIBC_FUNCTION(int, dlinfo,
+                   (void *restrict handle, int request, void *restrict info)) {
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/dlfcn/dlinfo.h

@@ -0,0 +1,20 @@
+//===-- Implementation header of dlinfo -------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_DLFCN_DLINFO_H
+#define LLVM_LIBC_SRC_DLFCN_DLINFO_H
+
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int dlinfo(void *restrict, int, void *restrict);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLINFO_H