[libc][c11] Add stdio.h's rename() function (#85068)

Adds stdio.h's rename() function as defined in n3096. Fixes  #84980.

Author: aniplcc

libc/config/linux/aarch64/entrypoints.txt

@@ -195,6 +195,7 @@ set(TARGET_LIBC_ENTRYPOINTS
 
     # stdio.h entrypoints
     libc.src.stdio.remove
+    libc.src.stdio.rename
     libc.src.stdio.sprintf
     libc.src.stdio.snprintf
     libc.src.stdio.vsprintf

libc/config/linux/riscv/entrypoints.txt

@@ -196,6 +196,7 @@ set(TARGET_LIBC_ENTRYPOINTS
 
     # stdio.h entrypoints
     libc.src.stdio.remove
+    libc.src.stdio.rename
     libc.src.stdio.sprintf
     libc.src.stdio.snprintf
     libc.src.stdio.fprintf

libc/config/linux/x86_64/entrypoints.txt

@@ -198,6 +198,7 @@ set(TARGET_LIBC_ENTRYPOINTS
 
     # stdio.h entrypoints
     libc.src.stdio.remove
+    libc.src.stdio.rename
     libc.src.stdio.sprintf
     libc.src.stdio.snprintf
     libc.src.stdio.fprintf

libc/docs/stdio.rst

@@ -68,7 +68,7 @@ These functions operate on files on the host's system, without using the
 Function_Name  Available
 =============  =========
 remove         |check|
-rename
+rename         |check|
 tmpnam
 =============  =========
 

libc/spec/stdc.td

@@ -706,6 +706,11 @@ def StdC : StandardSpec<"stdc"> {
               RetValSpec<IntType>,
               [ArgSpec<ConstCharPtr>]
           >,
+          FunctionSpec<
+              "rename",
+              RetValSpec<IntType>,
+              [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>]
+          >,
           FunctionSpec<
               "setbuf",
               RetValSpec<VoidType>,

libc/src/stdio/CMakeLists.txt

@@ -256,6 +256,13 @@ add_entrypoint_object(
     .${LIBC_TARGET_OS}.remove
 )
 
+add_entrypoint_object(
+  rename
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.rename
+)
+
 # These entrypoints have multiple potential implementations.
 add_stdio_entrypoint_object(feof)
 add_stdio_entrypoint_object(feof_unlocked)

libc/src/stdio/linux/CMakeLists.txt

@@ -12,3 +12,15 @@ add_entrypoint_object(
     libc.src.__support.OSUtil.osutil
     libc.src.errno.errno
 )
+
+add_entrypoint_object(
+  rename
+  SRCS
+    rename.cpp
+  HDRS
+    ../rename.h
+  DEPENDS
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)

libc/src/stdio/linux/rename.cpp

@@ -0,0 +1,26 @@
+//===-- Linux implementation of rename ------------------------------------===//
+//
+// 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 "src/stdio/rename.h"
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/errno/libc_errno.h"
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(int, rename, (const char *oldpath, const char *newpath)) {
+  int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_rename, oldpath, newpath);
+
+  if (ret >= 0)
+    return 0;
+  libc_errno = -ret;
+  return -1;
+}
+
+} // namespace LIBC_NAMESPACE

libc/src/stdio/rename.h

@@ -0,0 +1,18 @@
+//===-- Implementation header of rename -------------------------*- 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_STDIO_RENAME_H
+#define LLVM_LIBC_SRC_STDIO_RENAME_H
+
+namespace LIBC_NAMESPACE {
+
+int rename(const char *oldpath, const char *newpath);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDIO_RENAME_H

libc/test/src/stdio/CMakeLists.txt

@@ -354,6 +354,21 @@ if(${LIBC_TARGET_OS} STREQUAL "linux")
       libc.src.unistd.access
       libc.src.unistd.close
   )
+  
+  add_libc_test(
+    rename_test
+    SUITE
+      libc_stdio_unittests
+    SRCS
+      rename_test.cpp
+    DEPENDS
+      libc.src.errno.errno
+      libc.src.fcntl.open
+      libc.src.stdio.rename
+      libc.src.unistd.access
+      libc.src.unistd.close
+      libc.test.UnitTest.ErrnoSetterMatcher
+  )
 endif()
 
 add_libc_test(