[libc] Add strftime_l (#127767)

This is a (no-op) locale version of strftime.

Fixes: #106630

Author: petrhosek

libc/config/baremetal/aarch64/entrypoints.txt

@@ -248,6 +248,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.gmtime
     libc.src.time.gmtime_r
     libc.src.time.mktime
+    libc.src.time.strftime
+    libc.src.time.strftime_l
     libc.src.time.timespec_get
 
     # internal entrypoints

libc/config/baremetal/arm/entrypoints.txt

@@ -248,6 +248,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.gmtime
     libc.src.time.gmtime_r
     libc.src.time.mktime
+    libc.src.time.strftime
+    libc.src.time.strftime_l
     libc.src.time.timespec_get
 
     # internal entrypoints

libc/config/baremetal/riscv/entrypoints.txt

@@ -244,6 +244,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.time.gmtime
     libc.src.time.gmtime_r
     libc.src.time.mktime
+    libc.src.time.strftime
+    libc.src.time.strftime_l
     libc.src.time.timespec_get
 
     # internal entrypoints

libc/config/linux/x86_64/entrypoints.txt

@@ -1129,6 +1129,7 @@ if(LLVM_LIBC_FULL_BUILD)
     libc.src.time.mktime
     libc.src.time.nanosleep
     libc.src.time.strftime
+    libc.src.time.strftime_l
     libc.src.time.time
     libc.src.time.timespec_get
 

libc/include/time.yaml

@@ -9,6 +9,7 @@ types:
   - type_name: time_t
   - type_name: clock_t
   - type_name: size_t
+  - type_name: locale_t
 enums: []
 objects: []
 functions:
@@ -100,6 +101,16 @@ functions:
       - type: size_t
       - type: const char *__restrict
       - type: const struct tm *__restrict
+  - name: strftime_l
+    standard:
+      - stdc
+    return_type: size_t
+    arguments:
+      - type: char *__restrict
+      - type: size_t
+      - type: const char *__restrict
+      - type: const struct tm *__restrict
+      - type: locale_t
   - name: time
     standard:
       - stdc

libc/src/time/CMakeLists.txt

@@ -150,6 +150,20 @@ add_entrypoint_object(
     libc.src.time.strftime_core.strftime_main
 )
 
+add_entrypoint_object(
+  strftime_l
+  SRCS
+    strftime_l.cpp
+  HDRS
+    strftime_l.h
+  DEPENDS
+    libc.hdr.types.locale_t
+    libc.hdr.types.size_t
+    libc.hdr.types.struct_tm
+    libc.src.stdio.printf_core.writer
+    libc.src.time.strftime_core.strftime_main
+)
+
 add_entrypoint_object(
   time
   SRCS

libc/src/time/strftime.cpp

@@ -19,7 +19,6 @@ namespace LIBC_NAMESPACE_DECL {
 LLVM_LIBC_FUNCTION(size_t, strftime,
                    (char *__restrict buffer, size_t buffsz,
                     const char *__restrict format, const tm *timeptr)) {
-
   printf_core::WriteBuffer wb(buffer, (buffsz > 0 ? buffsz - 1 : 0));
   printf_core::Writer writer(&wb);
   int ret = strftime_core::strftime_main(&writer, format, timeptr);

libc/src/time/strftime_l.cpp

@@ -0,0 +1,33 @@
+//===-- Implementation of strftime_l 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/strftime_l.h"
+#include "hdr/types/locale_t.h"
+#include "hdr/types/size_t.h"
+#include "hdr/types/struct_tm.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/stdio/printf_core/writer.h"
+#include "src/time/strftime_core/strftime_main.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+// TODO: Add support for locales.
+LLVM_LIBC_FUNCTION(size_t, strftime_l,
+                   (char *__restrict buffer, size_t buffsz,
+                    const char *__restrict format, const tm *timeptr,
+                    locale_t)) {
+  printf_core::WriteBuffer wb(buffer, (buffsz > 0 ? buffsz - 1 : 0));
+  printf_core::Writer writer(&wb);
+  int ret = strftime_core::strftime_main(&writer, format, timeptr);
+  if (buffsz > 0) // if the buffsz is 0 the buffer may be a null pointer.
+    wb.buff[wb.buff_cur] = '\0';
+  return (ret < 0 || static_cast<size_t>(ret) > buffsz) ? 0 : ret;
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/strftime_l.h

@@ -0,0 +1,24 @@
+//===-- Implementation header for strftime_l --------------------*- 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_STRFTIME_L_H
+#define LLVM_LIBC_SRC_TIME_STRFTIME_L_H
+
+#include "hdr/types/locale_t.h"
+#include "hdr/types/size_t.h"
+#include "hdr/types/struct_tm.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+size_t strftime_l(char *__restrict buffer, size_t count,
+                  const char *__restrict format, const tm *timeptr, locale_t);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_STRFTIME_L_H