[libc] Add dlinfo + RTLD_DI_* macros to dlfcn.h

[Caslyn]

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.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Caslyn Tonelli (Caslyn)

Changes

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

---

Full diff: https://github.com/llvm/llvm-project/pull/149938.diff

4 Files Affected:

• (modified) libc/include/dlfcn.yaml (+31)
• (modified) libc/src/dlfcn/CMakeLists.txt (+11)
• (added) libc/src/dlfcn/dlinfo.cpp (+22)
• (added) libc/src/dlfcn/dlinfo.h (+20)

diff --git a/libc/include/dlfcn.yaml b/libc/include/dlfcn.yaml
index 28be34dbd95bd..275279afb48d2 100644
--- a/libc/include/dlfcn.yaml
+++ b/libc/include/dlfcn.yaml
@@ -29,6 +29,29 @@ macros:
     standards:
       - gnu
     macro_value: "0x01000"
+enums:
+  - name: RTLD_DI_LMID
+    value: 1
+  - name: RTLD_DI_LINKMAP
+    value: 2
+  - name: RTLD_DI_CONFIGADDR,
+    value: 3
+  - name: RTLD_DI_SERINFO
+    value: 4
+  - name: RTLD_DI_SERINFOSIZE
+    value: 5
+  - name: RTLD_DI_ORIGIN
+    value: 6
+  - name: RTLD_DI_PROFILENAME
+    value: 7
+  - name: RTLD_DI_PROFILEOUT
+    value: 8
+  - name: RTLD_DI_TLSMODID
+    value: 9
+  - name: RTLD_DI_TLS_DATA
+    value: 10
+  - name: RTLD_DI_PHDR
+    value: 11
 functions:
   - name: dlclose
     standards:
@@ -55,3 +78,11 @@ functions:
     arguments:
       - type: void *__restrict
       - type: const char *__restrict
+  - name: dlinfo
+    standards:
+      - GNUExtensions
+    return_type: int
+    arguments:
+      - type: void *__restrict
+      - type: int
+      - type: void *__restrict
diff --git a/libc/src/dlfcn/CMakeLists.txt b/libc/src/dlfcn/CMakeLists.txt
index e3a51ba65764d..1ee05fc380c94 100644
--- a/libc/src/dlfcn/CMakeLists.txt
+++ b/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
+)
diff --git a/libc/src/dlfcn/dlinfo.cpp b/libc/src/dlfcn/dlinfo.cpp
new file mode 100644
index 0000000000000..7dae9592a9d90
--- /dev/null
+++ b/libc/src/dlfcn/dlinfo.cpp
@@ -0,0 +1,22 @@
+
+//===-- 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, int, void *restrict)) {
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/src/dlfcn/dlinfo.h b/libc/src/dlfcn/dlinfo.h
new file mode 100644
index 0000000000000..c2c34f02bd6f1
--- /dev/null
+++ b/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

[frobtech]

lgtm