[libc-commits] [libc] [libc] Add `link.h` and `elf.h` (PR #97504)

Izaak Schroeder via libc-commits libc-commits at lists.llvm.org
Wed Jul 3 20:32:59 PDT 2024


https://github.com/izaakschroeder updated https://github.com/llvm/llvm-project/pull/97504

>From eb521738bd7ce3ff9df1838a704e4a3e984255bb Mon Sep 17 00:00:00 2001
From: Izaak Schroeder <izaak.schroeder at gmail.com>
Date: Mon, 1 Jul 2024 16:23:01 -0700
Subject: [PATCH 1/2] [libc] Add `dlfcn.h` placeholder

---
 libc/config/linux/aarch64/entrypoints.txt    |  6 +++
 libc/config/linux/aarch64/headers.txt        |  1 +
 libc/config/linux/x86_64/entrypoints.txt     |  6 +++
 libc/config/linux/x86_64/headers.txt         |  1 +
 libc/include/CMakeLists.txt                  |  9 ++++
 libc/include/dlfcn.h.def                     | 17 ++++++++
 libc/include/llvm-libc-macros/CMakeLists.txt |  6 +++
 libc/include/llvm-libc-macros/dlfcn-macros.h | 23 +++++++++++
 libc/spec/posix.td                           | 35 ++++++++++++++++
 libc/src/CMakeLists.txt                      |  1 +
 libc/src/dlfcn/CMakeLists.txt                | 43 ++++++++++++++++++++
 libc/src/dlfcn/dlclose.cpp                   | 17 ++++++++
 libc/src/dlfcn/dlclose.h                     | 18 ++++++++
 libc/src/dlfcn/dlerror.cpp                   | 19 +++++++++
 libc/src/dlfcn/dlerror.h                     | 18 ++++++++
 libc/src/dlfcn/dlopen.cpp                    | 17 ++++++++
 libc/src/dlfcn/dlopen.h                      | 18 ++++++++
 libc/src/dlfcn/dlsym.cpp                     | 17 ++++++++
 libc/src/dlfcn/dlsym.h                       | 18 ++++++++
 19 files changed, 290 insertions(+)
 create mode 100644 libc/include/dlfcn.h.def
 create mode 100644 libc/include/llvm-libc-macros/dlfcn-macros.h
 create mode 100644 libc/src/dlfcn/CMakeLists.txt
 create mode 100644 libc/src/dlfcn/dlclose.cpp
 create mode 100644 libc/src/dlfcn/dlclose.h
 create mode 100644 libc/src/dlfcn/dlerror.cpp
 create mode 100644 libc/src/dlfcn/dlerror.h
 create mode 100644 libc/src/dlfcn/dlopen.cpp
 create mode 100644 libc/src/dlfcn/dlopen.h
 create mode 100644 libc/src/dlfcn/dlsym.cpp
 create mode 100644 libc/src/dlfcn/dlsym.h

diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 940df63e3912b7..70c588622ec6b2 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -17,6 +17,12 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.tolower
     libc.src.ctype.toupper
 
+    # dlfcn.h entrypoints
+    libc.src.dlfcn.dlopen
+    libc.src.dlfcn.dlsym
+    libc.src.dlfcn.dlclose
+    libc.src.dlfcn.dlerror
+
     # errno.h entrypoints
     libc.src.errno.errno
 
diff --git a/libc/config/linux/aarch64/headers.txt b/libc/config/linux/aarch64/headers.txt
index 7d25877cefcc83..8f898f0150905a 100644
--- a/libc/config/linux/aarch64/headers.txt
+++ b/libc/config/linux/aarch64/headers.txt
@@ -1,6 +1,7 @@
 set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
+    libc.include.dlfcn
     libc.include.errno
     libc.include.features
     libc.include.fenv
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 09f04fb31dfd82..ba60475809853f 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -17,6 +17,12 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.tolower
     libc.src.ctype.toupper
 
+    # dlfcn.h entrypoints
+    libc.src.dlfcn.dlopen
+    libc.src.dlfcn.dlsym
+    libc.src.dlfcn.dlclose
+    libc.src.dlfcn.dlerror
+
     # errno.h entrypoints
     libc.src.errno.errno
 
diff --git a/libc/config/linux/x86_64/headers.txt b/libc/config/linux/x86_64/headers.txt
index 44d640b75e2bf7..df276894246c4c 100644
--- a/libc/config/linux/x86_64/headers.txt
+++ b/libc/config/linux/x86_64/headers.txt
@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
     libc.include.dirent
+    libc.include.dlfcn
     libc.include.errno
     libc.include.fcntl
     libc.include.features
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index 3ab7817d8568b7..f8ef35078a8c46 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -51,6 +51,15 @@ add_gen_header(
     .llvm_libc_common_h
 )
 
+add_gen_header(
+  dlfcn
+  DEF_FILE dlfcn.h.def
+  GEN_HDR dlfcn.h
+  DEPENDS
+    .llvm-libc-macros.dlfcn_macros
+    .llvm_libc_common_h
+)
+
 add_gen_header(
   features
   DEF_FILE features.h.def
diff --git a/libc/include/dlfcn.h.def b/libc/include/dlfcn.h.def
new file mode 100644
index 00000000000000..31395871c6b97e
--- /dev/null
+++ b/libc/include/dlfcn.h.def
@@ -0,0 +1,17 @@
+//===-- C standard library header dlfcn.h ---------------------------------===//
+//
+// 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_DLFCN_H
+#define LLVM_LIBC_DLFCN_H
+
+#include "__llvm-libc-common.h"
+#include "llvm-libc-macros/dlfcn-macros.h"
+
+%%public_api()
+
+#endif // LLVM_LIBC_DLFCN_H
diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
index f6af11abd4dd76..5bf573e4e98dfe 100644
--- a/libc/include/llvm-libc-macros/CMakeLists.txt
+++ b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -277,3 +277,9 @@ add_macro_header(
   HDR
     stdckdint-macros.h
 )
+
+add_macro_header(
+  dlfcn_macros
+  HDR
+    dlfcn-macros.h
+)
\ No newline at end of file
diff --git a/libc/include/llvm-libc-macros/dlfcn-macros.h b/libc/include/llvm-libc-macros/dlfcn-macros.h
new file mode 100644
index 00000000000000..dcd202b9ab435c
--- /dev/null
+++ b/libc/include/llvm-libc-macros/dlfcn-macros.h
@@ -0,0 +1,23 @@
+//===-- Definition of macros from dlfcn.h ---------------------------------===//
+//
+// 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_MACROS_DLFCN_MACROS_H
+#define LLVM_LIBC_MACROS_DLFCN_MACROS_H
+
+#define RTLD_LAZY 0x00001
+#define RTLD_NOW 0x00002
+#define RTLD_GLOBAL 0x00100
+#define RTLD_LOCAL 0
+
+// Non-standard stuff here
+#define RTLD_BINDING_MASK 0x3
+#define RTLD_NOLOAD 0x00004
+#define RTLD_DEEPBIND 0x00008
+#define RTLD_NODELETE 0x01000
+
+#endif // LLVM_LIBC_MACROS_DLFCN_MACROS_H
diff --git a/libc/spec/posix.td b/libc/spec/posix.td
index d14047548e104f..1878b1ee2ae412 100644
--- a/libc/spec/posix.td
+++ b/libc/spec/posix.td
@@ -222,6 +222,40 @@ def POSIX : StandardSpec<"POSIX"> {
       []  // Functions
   >;
 
+  HeaderSpec DlFcn = HeaderSpec<
+    "dlfcn.h",
+    [
+      Macro<"RTLD_LAZY">,
+      Macro<"RTLD_NOW">,
+      Macro<"RTLD_GLOBAL">,
+      Macro<"RTLD_LOCAL">,
+    ],
+    [],  // Types
+    [], // Enumerations
+    [
+      FunctionSpec<
+          "dlclose",
+          RetValSpec<IntType>,
+          [ArgSpec<VoidPtr>]
+      >,
+      FunctionSpec<
+          "dlerror",
+          RetValSpec<CharPtr>,
+          []
+      >,
+      FunctionSpec<
+          "dlopen",
+          RetValSpec<VoidPtr>,
+          [ArgSpec<ConstCharPtr>, ArgSpec<IntType>]
+      >,
+      FunctionSpec<
+          "dlsym",
+          RetValSpec<VoidPtr>,
+          [ArgSpec<VoidRestrictedPtr>, ArgSpec<ConstCharRestrictedPtr>]
+      >,
+    ]
+  >;
+
   HeaderSpec FCntl = HeaderSpec<
     "fcntl.h",
     [], // Macros
@@ -1690,6 +1724,7 @@ def POSIX : StandardSpec<"POSIX"> {
     ArpaInet,
     CType,
     Dirent,
+    DlFcn,
     Errno,
     FCntl,
     PThread,
diff --git a/libc/src/CMakeLists.txt b/libc/src/CMakeLists.txt
index 09b16be1e2d42e..f011fe25226e55 100644
--- a/libc/src/CMakeLists.txt
+++ b/libc/src/CMakeLists.txt
@@ -11,6 +11,7 @@ add_subdirectory(stdio)
 add_subdirectory(stdlib)
 add_subdirectory(string)
 add_subdirectory(wchar)
+add_subdirectory(dlfcn)
 
 if(${LIBC_TARGET_OS} STREQUAL "linux")
   add_subdirectory(dirent)
diff --git a/libc/src/dlfcn/CMakeLists.txt b/libc/src/dlfcn/CMakeLists.txt
new file mode 100644
index 00000000000000..5534f2dfb88533
--- /dev/null
+++ b/libc/src/dlfcn/CMakeLists.txt
@@ -0,0 +1,43 @@
+add_entrypoint_object(
+  dlclose
+  SRCS
+    dlclose.cpp
+  HDRS
+    dlclose.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dlerror
+  SRCS
+    dlerror.cpp
+  HDRS
+    dlerror.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dlopen
+  SRCS
+    dlopen.cpp
+  HDRS
+    dlopen.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  dlsym
+  SRCS
+    dlsym.cpp
+  HDRS
+    dlsym.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
diff --git a/libc/src/dlfcn/dlclose.cpp b/libc/src/dlfcn/dlclose.cpp
new file mode 100644
index 00000000000000..6dc1892120dddb
--- /dev/null
+++ b/libc/src/dlfcn/dlclose.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation of dlclose -----------------------------------------===//
+//
+// 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 "dlclose.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(int, dlclose, (void *)) { return -1; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlclose.h b/libc/src/dlfcn/dlclose.h
new file mode 100644
index 00000000000000..27c0207d726e49
--- /dev/null
+++ b/libc/src/dlfcn/dlclose.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlclose ------------------------*- 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_DLCLOSE_H
+#define LLVM_LIBC_SRC_DLFCN_DLCLOSE_H
+
+namespace LIBC_NAMESPACE {
+
+int dlclose(void *);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLCLOSE_H
diff --git a/libc/src/dlfcn/dlerror.cpp b/libc/src/dlfcn/dlerror.cpp
new file mode 100644
index 00000000000000..8c3611d9c639e5
--- /dev/null
+++ b/libc/src/dlfcn/dlerror.cpp
@@ -0,0 +1,19 @@
+//===-- Implementation of delerror ----------------------------------------===//
+//
+// 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 "dlerror.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(char *, dlerror, ()) {
+  return const_cast<char *>("unsupported");
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlerror.h b/libc/src/dlfcn/dlerror.h
new file mode 100644
index 00000000000000..966496016d3ebd
--- /dev/null
+++ b/libc/src/dlfcn/dlerror.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlerror ------------------------*- 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_DLERROR_H
+#define LLVM_LIBC_SRC_DLFCN_DLERROR_H
+
+namespace LIBC_NAMESPACE {
+
+char *dlerror();
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLERROR_H
diff --git a/libc/src/dlfcn/dlopen.cpp b/libc/src/dlfcn/dlopen.cpp
new file mode 100644
index 00000000000000..835d981e192371
--- /dev/null
+++ b/libc/src/dlfcn/dlopen.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation of dlopen -----------------------------------------===//
+//
+// 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 "dlopen.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(void *, dlopen, (const char *, int)) { return nullptr; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlopen.h b/libc/src/dlfcn/dlopen.h
new file mode 100644
index 00000000000000..4565953efd4943
--- /dev/null
+++ b/libc/src/dlfcn/dlopen.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlopen -------------------------*- 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_DLOPEN_H
+#define LLVM_LIBC_SRC_DLFCN_DLOPEN_H
+
+namespace LIBC_NAMESPACE {
+
+void *dlopen(const char *, int);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLOPEN_H
diff --git a/libc/src/dlfcn/dlsym.cpp b/libc/src/dlfcn/dlsym.cpp
new file mode 100644
index 00000000000000..98d678caece902
--- /dev/null
+++ b/libc/src/dlfcn/dlsym.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation of dlsym ------------------------------------------===//
+//
+// 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 "dlsym.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(void *, dlsym, (void *, const char *)) { return nullptr; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dlsym.h b/libc/src/dlfcn/dlsym.h
new file mode 100644
index 00000000000000..8157ac3e3fd4ca
--- /dev/null
+++ b/libc/src/dlfcn/dlsym.h
@@ -0,0 +1,18 @@
+//===-- Implementation header of dlsym --------------------------*- 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_DLSYM_H
+#define LLVM_LIBC_SRC_DLFCN_DLSYM_H
+
+namespace LIBC_NAMESPACE {
+
+void *dlsym(void *, const char *);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLSYM_H

>From d7610bc1e28b29f6646d63720afac376fe231200 Mon Sep 17 00:00:00 2001
From: Izaak Schroeder <izaak.schroeder at gmail.com>
Date: Mon, 1 Jul 2024 19:40:07 -0700
Subject: [PATCH 2/2] [libc] Add `link.h` and `elf.h`

---
 libc/config/linux/aarch64/entrypoints.txt     |  5 ++++
 libc/config/linux/aarch64/headers.txt         |  2 ++
 libc/config/linux/api.td                      | 13 ++++++++
 libc/config/linux/x86_64/entrypoints.txt      |  5 ++++
 libc/config/linux/x86_64/headers.txt          |  2 ++
 libc/include/CMakeLists.txt                   | 20 +++++++++++++
 libc/include/elf.h.def                        | 14 +++++++++
 libc/include/link.h.def                       | 16 ++++++++++
 libc/include/llvm-libc-macros/CMakeLists.txt  |  8 ++++-
 libc/include/llvm-libc-macros/elf-macros.h    | 18 +++++++++++
 libc/include/llvm-libc-macros/link-macros.h   | 26 ++++++++++++++--
 libc/include/llvm-libc-types/CMakeLists.txt   |  3 ++
 libc/include/llvm-libc-types/Dl_info.h        | 19 ++++++++++++
 .../__dl_iterate_phdr_callback_t.h            | 17 +++++++++++
 .../llvm-libc-types/struct_dl_phdr_info.h     | 26 ++++++++++++++++
 libc/spec/linux.td                            | 30 +++++++++++++++++++
 libc/spec/posix.td                            | 10 ++++++-
 libc/src/CMakeLists.txt                       |  1 +
 libc/src/dlfcn/CMakeLists.txt                 | 11 +++++++
 libc/src/dlfcn/dladdr.cpp                     | 17 +++++++++++
 libc/src/dlfcn/dladdr.h                       | 20 +++++++++++++
 libc/src/link/CMakeLists.txt                  |  9 ++++++
 libc/src/link/dl_iterate_phdr.cpp             | 20 +++++++++++++
 libc/src/link/dl_iterate_phdr.h               | 20 +++++++++++++
 24 files changed, 328 insertions(+), 4 deletions(-)
 create mode 100644 libc/include/elf.h.def
 create mode 100644 libc/include/link.h.def
 create mode 100644 libc/include/llvm-libc-macros/elf-macros.h
 create mode 100644 libc/include/llvm-libc-types/Dl_info.h
 create mode 100644 libc/include/llvm-libc-types/__dl_iterate_phdr_callback_t.h
 create mode 100644 libc/include/llvm-libc-types/struct_dl_phdr_info.h
 create mode 100644 libc/src/dlfcn/dladdr.cpp
 create mode 100644 libc/src/dlfcn/dladdr.h
 create mode 100644 libc/src/link/CMakeLists.txt
 create mode 100644 libc/src/link/dl_iterate_phdr.cpp
 create mode 100644 libc/src/link/dl_iterate_phdr.h

diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 70c588622ec6b2..fe4cec1d7a77ff 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -22,6 +22,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.dlfcn.dlsym
     libc.src.dlfcn.dlclose
     libc.src.dlfcn.dlerror
+    libc.src.dlfcn.dlsym
+    libc.src.dlfcn.dladdr
 
     # errno.h entrypoints
     libc.src.errno.errno
@@ -32,6 +34,9 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.fcntl.open
     libc.src.fcntl.openat
 
+    # link.h entrypoints
+    libc.src.link.dl_iterate_phdr
+
     # sched.h entrypoints
     libc.src.sched.sched_get_priority_max
     libc.src.sched.sched_get_priority_min
diff --git a/libc/config/linux/aarch64/headers.txt b/libc/config/linux/aarch64/headers.txt
index 8f898f0150905a..ebe053af99d803 100644
--- a/libc/config/linux/aarch64/headers.txt
+++ b/libc/config/linux/aarch64/headers.txt
@@ -2,6 +2,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.assert
     libc.include.ctype
     libc.include.dlfcn
+    libc.include.elf
     libc.include.errno
     libc.include.features
     libc.include.fenv
@@ -9,6 +10,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.stdint
     libc.include.inttypes
     libc.include.limits
+    libc.include.link
     libc.include.math
     libc.include.pthread
     libc.include.signal
diff --git a/libc/config/linux/api.td b/libc/config/linux/api.td
index eb0090c80b0da3..3ff99f263f8118 100644
--- a/libc/config/linux/api.td
+++ b/libc/config/linux/api.td
@@ -308,3 +308,16 @@ def SearchAPI : PublicAPI<"search.h"> {
 def SysStatvfsAPI : PublicAPI<"sys/statvfs.h"> {
   let Types = ["fsblkcnt_t", "fsfilcnt_t", "struct statvfs"];
 }
+
+def LinkAPI : PublicAPI<"link.h"> {
+  let Types = [
+    "struct dl_phdr_info",
+    "__dl_iterate_phdr_callback_t"
+  ];
+}
+
+def DlfcnAPI : PublicAPI<"dlfcn.h"> {
+  let Types = [
+    "Dl_info"
+  ];
+}
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index ba60475809853f..18e682e52bb12f 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -22,6 +22,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.dlfcn.dlsym
     libc.src.dlfcn.dlclose
     libc.src.dlfcn.dlerror
+    libc.src.dlfcn.dlsym
+    libc.src.dlfcn.dladdr
 
     # errno.h entrypoints
     libc.src.errno.errno
@@ -32,6 +34,9 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.fcntl.open
     libc.src.fcntl.openat
 
+    # link.h entrypoints
+    libc.src.link.dl_iterate_phdr
+
     # sched.h entrypoints
     libc.src.sched.sched_get_priority_max
     libc.src.sched.sched_get_priority_min
diff --git a/libc/config/linux/x86_64/headers.txt b/libc/config/linux/x86_64/headers.txt
index df276894246c4c..903771c5f96a6a 100644
--- a/libc/config/linux/x86_64/headers.txt
+++ b/libc/config/linux/x86_64/headers.txt
@@ -3,6 +3,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.ctype
     libc.include.dirent
     libc.include.dlfcn
+    libc.include.elf
     libc.include.errno
     libc.include.fcntl
     libc.include.features
@@ -11,6 +12,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.stdint
     libc.include.inttypes
     libc.include.limits
+    libc.include.link
     libc.include.math
     libc.include.pthread
     libc.include.sched
diff --git a/libc/include/CMakeLists.txt b/libc/include/CMakeLists.txt
index f8ef35078a8c46..a39c1c118165fa 100644
--- a/libc/include/CMakeLists.txt
+++ b/libc/include/CMakeLists.txt
@@ -56,6 +56,7 @@ add_gen_header(
   DEF_FILE dlfcn.h.def
   GEN_HDR dlfcn.h
   DEPENDS
+    .llvm-libc-types.Dl_info
     .llvm-libc-macros.dlfcn_macros
     .llvm_libc_common_h
 )
@@ -367,6 +368,25 @@ add_gen_header(
     .llvm-libc-types.posix_spawn_file_actions_t
 )
 
+add_gen_header(
+  link
+  DEF_FILE link.h.def
+  GEN_HDR link.h
+  DEPENDS
+    .llvm_libc_common_h
+    .llvm-libc-types.struct_dl_phdr_info
+    .llvm-libc-types.__dl_iterate_phdr_callback_t
+    .llvm-libc-macros.link_macros
+)
+
+add_gen_header(
+  elf
+  DEF_FILE elf.h.def
+  GEN_HDR elf.h
+  DEPENDS
+    .llvm-libc-macros.elf_macros
+)
+
 # TODO: Not all platforms will have a include/sys directory. Add the sys
 # directory and the targets for sys/*.h files conditional to the OS requiring
 # them.
diff --git a/libc/include/elf.h.def b/libc/include/elf.h.def
new file mode 100644
index 00000000000000..1c9d11929029f4
--- /dev/null
+++ b/libc/include/elf.h.def
@@ -0,0 +1,14 @@
+//===-- C standard library header elf.h -----------------------------------===//
+//
+// 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_ELF_H
+#define LLVM_LIBC_ELF_H
+
+#include "llvm-libc-macros/elf-macros.h"
+
+#endif // LLVM_LIBC_ELF_H
diff --git a/libc/include/link.h.def b/libc/include/link.h.def
new file mode 100644
index 00000000000000..353398e4f3c887
--- /dev/null
+++ b/libc/include/link.h.def
@@ -0,0 +1,16 @@
+//===-- C standard library header link.h ----------------------------------===//
+//
+// 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_LINK_H
+#define LLVM_LIBC_LINK_H
+
+#include "llvm-libc-macros/link-macros.h"
+
+%%public_api()
+
+#endif // LLVM_LIBC_LINK_H
diff --git a/libc/include/llvm-libc-macros/CMakeLists.txt b/libc/include/llvm-libc-macros/CMakeLists.txt
index 5bf573e4e98dfe..60c8f5a9cd3de4 100644
--- a/libc/include/llvm-libc-macros/CMakeLists.txt
+++ b/libc/include/llvm-libc-macros/CMakeLists.txt
@@ -282,4 +282,10 @@ add_macro_header(
   dlfcn_macros
   HDR
     dlfcn-macros.h
-)
\ No newline at end of file
+)
+
+add_macro_header(
+  elf_macros
+  HDR
+    elf-macros.h
+)
diff --git a/libc/include/llvm-libc-macros/elf-macros.h b/libc/include/llvm-libc-macros/elf-macros.h
new file mode 100644
index 00000000000000..fa4442abf0f5ce
--- /dev/null
+++ b/libc/include/llvm-libc-macros/elf-macros.h
@@ -0,0 +1,18 @@
+//===-- Definition of macros from elf.h -----------------------------------===//
+//
+// 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_MACROS_ELF_MACROS_H
+#define LLVM_LIBC_MACROS_ELF_MACROS_H
+
+#if __has_include(<linux/elf.h>)
+#include <linux/elf.h>
+#else
+#error "cannot use <sys/elf.h> without proper system headers."
+#endif
+
+#endif // LLVM_LIBC_MACROS_ELF_MACROS_H
diff --git a/libc/include/llvm-libc-macros/link-macros.h b/libc/include/llvm-libc-macros/link-macros.h
index 5c8cadab8e71cb..f7461d9527a47b 100644
--- a/libc/include/llvm-libc-macros/link-macros.h
+++ b/libc/include/llvm-libc-macros/link-macros.h
@@ -6,8 +6,30 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifndef LLVM_LIBC_MACROS_LINK_MACROS_H
+#define LLVM_LIBC_MACROS_LINK_MACROS_H
+
+#include "elf-macros.h"
+
 #ifdef __LP64__
-#define ElfW(type) Elf64_ ## type
+#define ElfW(type) Elf64_##type
 #else
-#define ElfW(type) Elf32_ ## type
+#define ElfW(type) Elf32_##type
+#endif
+
+struct link_map {
+  ElfW(Addr) l_addr;
+  char *l_name;
+  ElfW(Dyn) * l_ld;
+  struct link_map *l_next, *l_prev;
+};
+
+struct r_debug {
+  int r_version;
+  struct link_map *r_map;
+  ElfW(Addr) r_brk;
+  enum { RT_CONSISTENT, RT_ADD, RT_DELETE } r_state;
+  ElfW(Addr) r_ldbase;
+};
+
 #endif
diff --git a/libc/include/llvm-libc-types/CMakeLists.txt b/libc/include/llvm-libc-types/CMakeLists.txt
index d8b975572e0dd3..016ec14b077e8d 100644
--- a/libc/include/llvm-libc-types/CMakeLists.txt
+++ b/libc/include/llvm-libc-types/CMakeLists.txt
@@ -89,6 +89,9 @@ add_header(thrd_t HDR thrd_t.h DEPENDS .__thread_type)
 add_header(tss_t HDR tss_t.h)
 add_header(tss_dtor_t HDR tss_dtor_t.h)
 add_header(__atexithandler_t HDR __atexithandler_t.h)
+add_header(Dl_info HDR Dl_info.h)
+add_header(struct_dl_phdr_info HDR struct_dl_phdr_info.h)
+add_header(__dl_iterate_phdr_callback_t HDR __dl_iterate_phdr_callback_t.h)
 add_header(speed_t HDR speed_t.h)
 add_header(tcflag_t HDR tcflag_t.h)
 add_header(struct_termios HDR struct_termios.h DEPENDS .cc_t .speed_t .tcflag_t)
diff --git a/libc/include/llvm-libc-types/Dl_info.h b/libc/include/llvm-libc-types/Dl_info.h
new file mode 100644
index 00000000000000..613976a54bd612
--- /dev/null
+++ b/libc/include/llvm-libc-types/Dl_info.h
@@ -0,0 +1,19 @@
+//===-- Definition of type Dl_info ----------------------------------------===//
+//
+// 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_TYPES_DL_INFO_H
+#define LLVM_LIBC_TYPES_DL_INFO_H
+
+typedef struct {
+  const char *dli_fname;
+  void *dli_fbase;
+  const char *dli_sname;
+  void *dli_saddr;
+} Dl_info;
+
+#endif // LLVM_LIBC_TYPES_DL_INFO_H
diff --git a/libc/include/llvm-libc-types/__dl_iterate_phdr_callback_t.h b/libc/include/llvm-libc-types/__dl_iterate_phdr_callback_t.h
new file mode 100644
index 00000000000000..9d73e88076e00c
--- /dev/null
+++ b/libc/include/llvm-libc-types/__dl_iterate_phdr_callback_t.h
@@ -0,0 +1,17 @@
+//===-- Definition of __dl_iterate_phdr_callback_t type -------------------===//
+//
+// 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_TYPES___DL_ITERATE_PHDR_CALLBACK_T_H
+#define LLVM_LIBC_TYPES___DL_ITERATE_PHDR_CALLBACK_T_H
+
+#include "llvm-libc-types/size_t.h"
+
+typedef int (*__dl_iterate_phdr_callback_t)(struct dl_phdr_info *info,
+                                            size_t size, void *data);
+
+#endif // LLVM_LIBC_TYPES___DL_ITERATE_PHDR_CALLBACK_T_H
diff --git a/libc/include/llvm-libc-types/struct_dl_phdr_info.h b/libc/include/llvm-libc-types/struct_dl_phdr_info.h
new file mode 100644
index 00000000000000..66512b368e1904
--- /dev/null
+++ b/libc/include/llvm-libc-types/struct_dl_phdr_info.h
@@ -0,0 +1,26 @@
+//===-- Definition of type struct dl_phdr_info ----------------------------===//
+//
+// 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_TYPES_STRUCT_DL_PHDR_INFO_H
+#define LLVM_LIBC_TYPES_STRUCT_DL_PHDR_INFO_H
+
+#include "llvm-libc-macros/link-macros.h"
+#include "llvm-libc-types/size_t.h"
+
+struct dl_phdr_info {
+  ElfW(Addr) dlpi_addr;
+  const char *dlpi_name;
+  const ElfW(Phdr) * dlpi_phdr;
+  ElfW(Half) dlpi_phnum;
+  unsigned long long int dlpi_adds;
+  unsigned long long int dlpi_subs;
+  size_t dlpi_tls_modid;
+  void *dlpi_tls_data;
+};
+
+#endif // LLVM_LIBC_TYPES_STRUCT_DL_PHDR_INFO_H
diff --git a/libc/spec/linux.td b/libc/spec/linux.td
index 82630ff413c73d..bd13dd17a85cdb 100644
--- a/libc/spec/linux.td
+++ b/libc/spec/linux.td
@@ -3,6 +3,9 @@ def StructEpollEventPtr : PtrType<StructEpollEvent>;
 
 def StructEpollData : NamedType<"struct epoll_data">;
 
+def StructDlPhdrInfo : NamedType<"struct dl_phdr_info">;
+def DlIteratePhdrCallback : NamedType<"__dl_iterate_phdr_callback_t">;
+
 def Linux : StandardSpec<"Linux"> {
   HeaderSpec Errno = HeaderSpec<
       "errno.h",
@@ -264,8 +267,35 @@ def Linux : StandardSpec<"Linux"> {
       ]
   >;
 
+  HeaderSpec Link = HeaderSpec<
+     "link.h",
+      [], // Macros
+      [StructDlPhdrInfo, DlIteratePhdrCallback], // Types
+      [], // Enumerations
+      [
+        FunctionSpec<
+          "dl_iterate_phdr",
+          RetValSpec<IntType>,
+          [
+            ArgSpec<DlIteratePhdrCallback>,
+            ArgSpec<VoidPtr>
+          ]
+        >,
+      ]  // Functions
+  >;
+
+  HeaderSpec Elf = HeaderSpec<
+     "elf.h",
+      [], // Macros
+      [], // Types
+      [], // Enumerations
+      []  // Functions
+  >;
+
   let Headers = [
+    Elf,
     Errno,
+    Link,
     SysEpoll,
     SysMMan,
     SysPrctl,
diff --git a/libc/spec/posix.td b/libc/spec/posix.td
index 1878b1ee2ae412..1a829704c06672 100644
--- a/libc/spec/posix.td
+++ b/libc/spec/posix.td
@@ -21,6 +21,9 @@ def PThreadOnceT : NamedType<"pthread_once_t">;
 def PThreadOnceTPtr : PtrType<PThreadOnceT>;
 def PThreadOnceCallback : NamedType<"__pthread_once_func_t">;
 
+def DlInfo : NamedType<"Dl_info">;
+def DlInfoPtr : PtrType<DlInfo>;
+
 def InoT : NamedType<"ino_t">;
 def UidT : NamedType<"uid_t">;
 def GidT : NamedType<"gid_t">;
@@ -230,9 +233,14 @@ def POSIX : StandardSpec<"POSIX"> {
       Macro<"RTLD_GLOBAL">,
       Macro<"RTLD_LOCAL">,
     ],
-    [],  // Types
+    [DlInfo],  // Types
     [], // Enumerations
     [
+      FunctionSpec<
+          "dladdr",
+          RetValSpec<IntType>,
+          [ArgSpec<ConstVoidPtr>, ArgSpec<DlInfoPtr>]
+      >,
       FunctionSpec<
           "dlclose",
           RetValSpec<IntType>,
diff --git a/libc/src/CMakeLists.txt b/libc/src/CMakeLists.txt
index f011fe25226e55..9ff88cffc487c8 100644
--- a/libc/src/CMakeLists.txt
+++ b/libc/src/CMakeLists.txt
@@ -12,6 +12,7 @@ add_subdirectory(stdlib)
 add_subdirectory(string)
 add_subdirectory(wchar)
 add_subdirectory(dlfcn)
+add_subdirectory(link)
 
 if(${LIBC_TARGET_OS} STREQUAL "linux")
   add_subdirectory(dirent)
diff --git a/libc/src/dlfcn/CMakeLists.txt b/libc/src/dlfcn/CMakeLists.txt
index 5534f2dfb88533..5321499b2e3349 100644
--- a/libc/src/dlfcn/CMakeLists.txt
+++ b/libc/src/dlfcn/CMakeLists.txt
@@ -1,3 +1,14 @@
+add_entrypoint_object(
+  dladdr
+  SRCS
+    dladdr.cpp
+  HDRS
+    dladdr.h
+  DEPENDS
+    libc.include.dlfcn
+    libc.src.errno.errno
+)
+
 add_entrypoint_object(
   dlclose
   SRCS
diff --git a/libc/src/dlfcn/dladdr.cpp b/libc/src/dlfcn/dladdr.cpp
new file mode 100644
index 00000000000000..00ff1845fbe3e1
--- /dev/null
+++ b/libc/src/dlfcn/dladdr.cpp
@@ -0,0 +1,17 @@
+//===-- Implementation of dladdr -----------------------------------------===//
+//
+// 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 "dladdr.h"
+
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(int, dladdr, (const void *, Dl_info *)) { return 0; }
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/dlfcn/dladdr.h b/libc/src/dlfcn/dladdr.h
new file mode 100644
index 00000000000000..b86f3fdea0ddef
--- /dev/null
+++ b/libc/src/dlfcn/dladdr.h
@@ -0,0 +1,20 @@
+//===-- Implementation header of dladdr ------------------------*- 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_DLADDR_H
+#define LLVM_LIBC_SRC_DLFCN_DLADDR_H
+
+namespace LIBC_NAMESPACE {
+
+#include "include/llvm-libc-types/Dl_info.h"
+
+int dladdr(const void *, Dl_info *);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_DLFCN_DLADDR_H
diff --git a/libc/src/link/CMakeLists.txt b/libc/src/link/CMakeLists.txt
new file mode 100644
index 00000000000000..06f5e05e624fd6
--- /dev/null
+++ b/libc/src/link/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_entrypoint_object(
+  dl_iterate_phdr
+  SRCS
+    dl_iterate_phdr.cpp
+  HDRS
+    dl_iterate_phdr.h
+  DEPENDS
+    libc.src.__support.common
+)
diff --git a/libc/src/link/dl_iterate_phdr.cpp b/libc/src/link/dl_iterate_phdr.cpp
new file mode 100644
index 00000000000000..7a723c097c47bc
--- /dev/null
+++ b/libc/src/link/dl_iterate_phdr.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of dl_iterate_phdr ---------------------------------===//
+//
+// 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 "dl_iterate_phdr.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(int, dl_iterate_phdr,
+                   (__dl_iterate_phdr_callback_t, void *)) {
+  // HACK(@izaakschroeder): Not implemented
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/link/dl_iterate_phdr.h b/libc/src/link/dl_iterate_phdr.h
new file mode 100644
index 00000000000000..b7f7951e883a87
--- /dev/null
+++ b/libc/src/link/dl_iterate_phdr.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for dl_iterate_phdr ---------------*- 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_LINK_DL_ITERATE_PHDR_H
+#define LLVM_LIBC_SRC_LINK_DL_ITERATE_PHDR_H
+
+namespace LIBC_NAMESPACE {
+
+#include "include/llvm-libc-types/__dl_iterate_phdr_callback_t.h"
+
+int dl_iterate_phdr(__dl_iterate_phdr_callback_t, void *);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_LINK_DL_ITERATE_PHDR_H



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