[libc] implement template functions for localtime

libc/config/baremetal/aarch64/entrypoints.txt

@@ -269,6 +269,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.difftime
     libc.src.time.gmtime
     libc.src.time.gmtime_r
+    libc.src.time.localtime
+    libc.src.time.localtime_r
     libc.src.time.mktime
     libc.src.time.strftime
     libc.src.time.strftime_l

libc/config/linux/x86_64/entrypoints.txt

@@ -1304,6 +1304,8 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.gettimeofday
     libc.src.time.gmtime
     libc.src.time.gmtime_r
+    libc.src.time.localtime
+    libc.src.time.localtime_r
     libc.src.time.mktime
     libc.src.time.nanosleep
     libc.src.time.strftime

libc/docs/headers/time.rst

@@ -87,9 +87,9 @@ Implementation Status
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
 | gmtime_r            | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
-| localtime           |         |         |         |                 |         |         |         |         |         |         |         |         |         |
+| localtime           | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
-| localtime_r         |         |         |         |                 |         |         |         |         |         |         |         |         |         |
+| localtime_r         | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
 | mktime              | |check| | |check| |         |     |check|     |         |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
@@ -112,4 +112,4 @@ Implementation Status
 | timer_settime       |         |         |         |                 |         |         |         |         |         |         |         |         |         |
 +---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
 | tzset               |         |         |         |                 |         |         |         |         |         |         |         |         |         |
-+---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+
++---------------------+---------+---------+---------+-----------------+---------+---------+---------+---------+---------+---------+---------+---------+---------+

libc/hdr/localtime_overlay.h

@@ -0,0 +1,45 @@
+//===-- Including localtime.h in overlay mode -----------------------------===//
+//
+// 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_HDR_LOCALTIME_OVERLAY_H
+#define LLVM_LIBC_HDR_LOCALTIME_OVERLAY_H
+
+#ifdef LIBC_FULL_BUILD
+#error "This header should only be included in overlay mode"
+#endif
+
+// Overlay mode
+
+// glibc <unistd.h> header might provide extern inline definitions for few
+// functions, causing external alias errors.  They are guarded by
+// `__USE_EXTERN_INLINES` macro.
+
+#ifdef __USE_EXTERN_INLINES
+#define LIBC_OLD_USE_EXTERN_INLINES
+#undef __USE_EXTERN_INLINES
+#endif
+
+#ifndef __NO_INLINE__
+#define __NO_INLINE__ 1
+#define LIBC_SET_NO_INLINE
+#endif
+
+#include <localtime.h>
+#include <localtime_r.h>
+
+#ifdef LIBC_SET_NO_INLINE
+#undef __NO_INLINE__
+#undef LIBC_SET_NO_INLINE
+#endif
+
+#ifdef LIBC_OLD_USE_EXTERN_INLINES
+#define __USE_EXTERN_INLINES
+#undef LIBC_OLD_USE_EXTERN_INLINES
+#endif
+
+#endif // LLVM_LIBC_HDR_LOCALTIME_OVERLAY_H

libc/include/time.yaml

@@ -41,6 +41,19 @@ functions:
     arguments:
       - type: const time_t *
       - type: char *
+  - name: localtime
+    standard:
+      - stdc
+    return_type: struct tm *
+    arguments:
+      - type: const time_t *
+  - name: localtime_r
+    standard:
+      - stdc
+    return_type: struct tm *
+    arguments:
+      - type: const time_t *
+      - type: struct tm *
   - name: clock
     standard:
       - stdc

libc/src/time/CMakeLists.txt

@@ -85,6 +85,30 @@ add_entrypoint_object(
     libc.include.time
 )
 
+add_entrypoint_object(
+  localtime
+  SRCS
+    localtime.cpp
+  HDRS
+    localtime.h
+  DEPENDS
+    .time_utils
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
+)
+
+add_entrypoint_object(
+  localtime_r
+  SRCS
+    localtime_r.cpp
+  HDRS
+    localtime_r.h
+  DEPENDS
+    .time_utils
+    libc.hdr.types.time_t
+    libc.hdr.types.struct_tm
+)
+
 add_entrypoint_object(
   difftime
   SRCS

libc/src/time/baremetal/CMakeLists.txt

@@ -19,3 +19,29 @@ add_entrypoint_object(
     libc.hdr.time_macros
     libc.hdr.types.struct_timespec
 )
+
+add_entrypoint_object(
+  localtime
+  SRCS
+    localtime.cpp
+  HDRS
+    ../localtime.h
+    time_utils.h
+  DEPENDS
+    .time_utils
+    libc.hdr.types.struct_tm
+    libc.hdr.types.time_t
+)
+
+add_entrypoint_object(
+  localtime_r
+  SRCS
+    localtime_r.cpp
+  HDRS
+    ../localtime.h
+    time_utils.h
+  DEPENDS
+    .time_utils
+    libc.hdr.types.struct_tm
+    libc.hdr.types.time_t
+)

libc/src/time/baremetal/localtime.cpp

@@ -0,0 +1,22 @@
+//===-- Implementation of localtime for baremetal -------------------------===//
+//
+// 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/time/localtime.h"
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(struct tm *, localtime, (time_t *timer)) {
+  static struct tm tm_out;
+
+  return time_utils::localtime_internal(timer, &tm_out);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/baremetal/localtime_r.cpp

@@ -0,0 +1,24 @@
+//===-- Implementation of localtime_r for baremetal -----------------------===//
+//
+// 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/time/localtime_r.h"
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
+#include "src/__support/macros/null_check.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(struct tm *, localtime_r,
+                   (const time_t *timer, struct tm *buf)) {
+  LIBC_CRASH_ON_NULLPTR(timer);
+
+  return time_utils::localtime_internal(timer, buf);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/localtime.cpp

@@ -0,0 +1,24 @@
+//===-- Linux implementation of the localtime function --------------------===//
+//
+// 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/time/localtime.h"
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
+#include "src/__support/macros/null_check.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(struct tm *, localtime, (const time_t *timer)) {
+  LIBC_CRASH_ON_NULLPTR(timer);
+
+  static struct tm tm_out;
+  return time_utils::localtime_internal(timer, &tm_out);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/localtime.h

@@ -0,0 +1,22 @@
+//===-- Implementation header of localtime ----------------------*- 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_TIME_LOCALTIME_H
+#define LLVM_LIBC_SRC_TIME_LOCALTIME_H
+
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+struct tm *localtime(const time_t *timer);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_LOCALTIME_H

libc/src/time/localtime_r.cpp

@@ -0,0 +1,25 @@
+//===-- Linux implementation of localtime_r function ----------------------===//
+//
+// 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/time/localtime_r.h"
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
+#include "src/__support/macros/null_check.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(struct tm *, localtime_r,
+                   (const time_t *timer, struct tm *buf)) {
+  LIBC_CRASH_ON_NULLPTR(timer);
+  LIBC_CRASH_ON_NULLPTR(buf);
+
+  return time_utils::localtime_internal(timer, buf);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/localtime_r.h

@@ -0,0 +1,22 @@
+//===-- Implementation header of localtime_r --------------------*- 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_TIME_LOCALTIME_R_H
+#define LLVM_LIBC_SRC_TIME_LOCALTIME_R_H
+
+#include "hdr/types/struct_tm.h"
+#include "hdr/types/time_t.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+struct tm *localtime_r(const time_t *timer, struct tm *buf);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_LOCALTIME_R_H

libc/src/time/time_utils.h

@@ -93,11 +93,22 @@ LIBC_INLINE tm *gmtime_internal(const time_t *timer, tm *result) {
   return result;
 }
 
-// TODO: localtime is not yet implemented and a temporary solution is to
-//       use gmtime, https://github.com/llvm/llvm-project/issues/107597
+LIBC_INLINE tm *localtime_internal(const time_t *timer, tm *result) {
+  time_t seconds = *timer;
+  // Update the tm structure's year, month, day, etc. from seconds.
+  if (update_from_seconds(seconds, result) < 0) {
+    out_of_range();
+    return nullptr;
+  }
+
+  // TODO(zimirza): implement timezone database
+
+  return result;
+}
+
 LIBC_INLINE tm *localtime(const time_t *t_ptr) {
   static tm result;
-  return time_utils::gmtime_internal(t_ptr, &result);
+  return time_utils::localtime_internal(t_ptr, &result);
 }
 
 // Returns number of years from (1, year).

libc/test/src/time/CMakeLists.txt

@@ -72,6 +72,29 @@ add_libc_unittest(
     libc.hdr.types.struct_tm
 )
 
+add_libc_unittest(
+  localtime_test
+  SUITE
+    libc_time_unittests
+  SRCS
+    localtime_test.cpp
+  DEPENDS
+    libc.hdr.types.time_t
+    libc.src.time.localtime
+)
+
+add_libc_unittest(
+  localtime_r_test
+  SUITE
+    libc_time_unittests
+  SRCS
+    localtime_r_test.cpp
+  DEPENDS
+    libc.hdr.types.struct_tm
+    libc.hdr.types.time_t
+    libc.src.time.localtime_r
+)
+
 add_libc_test(
   clock_gettime_test
   SUITE