[libc][c11] implement ctime

clang-tools-extra/clang-tidy/bugprone/UnsafeFunctionsCheck.cpp

@@ -42,7 +42,7 @@ static StringRef getReplacementFor(StringRef FunctionName,
     // Try to find a better replacement from Annex K first.
     StringRef AnnexKReplacementFunction =
         StringSwitch<StringRef>(FunctionName)
-            .Cases("asctime", "asctime_r", "asctime_s")
+	    .Cases("asctime", "asctime_r", "asctime_s", "ctime", "ctime_r")
             .Case("gets", "gets_s")
             .Default({});
     if (!AnnexKReplacementFunction.empty())

clang/docs/tools/clang-formatted-files.txt

@@ -3062,6 +3062,10 @@ libc/src/time/asctime.cpp
 libc/src/time/asctime.h
 libc/src/time/asctime_r.cpp
 libc/src/time/asctime_r.h
+libc/src/time/ctime.cpp
+libc/src/time/ctime.h
+libc/src/time/ctime_r.cpp
+libc/src/time/ctime_r.h
 libc/src/time/gmtime.cpp
 libc/src/time/gmtime.h
 libc/src/time/gmtime_r.cpp

clang/lib/Tooling/Inclusions/Stdlib/CSymbolMap.inc

@@ -220,6 +220,7 @@ SYMBOL(and, None, <iso646.h>)
 SYMBOL(and_eq, None, <iso646.h>)
 SYMBOL(asctime, None, <time.h>)
 SYMBOL(asctime_s, None, <time.h>)
+SYMBOL(ctime, None, <time.h>)
 SYMBOL(asin, None, <math.h>)
 SYMBOL(asinf, None, <math.h>)
 SYMBOL(asinh, None, <math.h>)

clang/lib/Tooling/Inclusions/Stdlib/StdSymbolMap.inc

@@ -617,6 +617,9 @@ SYMBOL(as_writable_bytes, std::, <span>)
 SYMBOL(asctime, std::, <ctime>)
 SYMBOL(asctime, None, <ctime>)
 SYMBOL(asctime, None, <time.h>)
+SYMBOL(ctime, std::, <ctime>)
+SYMBOL(ctime, None, <ctime>)
+SYMBOL(ctime, None, <time.h>)
 SYMBOL(asin, std::, <cmath>)
 SYMBOL(asin, None, <cmath>)
 SYMBOL(asin, None, <math.h>)

libc/config/baremetal/arm/entrypoints.txt

@@ -203,6 +203,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     # time.h entrypoints
     libc.src.time.asctime
     libc.src.time.asctime_r
+    libc.src.time.ctime
+    libc.src.time.ctime_r
     libc.src.time.difftime
     libc.src.time.gmtime
     libc.src.time.gmtime_r

libc/config/baremetal/riscv/entrypoints.txt

@@ -199,6 +199,8 @@ set(TARGET_LIBC_ENTRYPOINTS
     # time.h entrypoints
     libc.src.time.asctime
     libc.src.time.asctime_r
+    libc.src.time.ctime
+    libc.src.time.ctime_r
     libc.src.time.difftime
     libc.src.time.gmtime
     libc.src.time.gmtime_r

libc/config/linux/aarch64/entrypoints.txt

@@ -948,6 +948,8 @@ if(LLVM_LIBC_FULL_BUILD)
     # time.h entrypoints
     libc.src.time.asctime
     libc.src.time.asctime_r
+    libc.src.time.ctime
+    libc.src.time.ctime_r
     libc.src.time.clock
     libc.src.time.clock_gettime
     libc.src.time.difftime

libc/config/linux/riscv/entrypoints.txt

@@ -883,6 +883,8 @@ if(LLVM_LIBC_FULL_BUILD)
     # time.h entrypoints
     libc.src.time.asctime
     libc.src.time.asctime_r
+    libc.src.time.ctime
+    libc.src.time.ctime_r
     libc.src.time.clock
     libc.src.time.clock_gettime
     libc.src.time.difftime

libc/config/linux/x86_64/entrypoints.txt

@@ -1003,6 +1003,8 @@ if(LLVM_LIBC_FULL_BUILD)
     # time.h entrypoints
     libc.src.time.asctime
     libc.src.time.asctime_r
+    libc.src.time.ctime
+    libc.src.time.ctime_r
     libc.src.time.clock
     libc.src.time.clock_gettime
     libc.src.time.difftime

libc/newhdrgen/yaml/time.yaml

@@ -24,6 +24,19 @@ functions:
     arguments:
       - type: struct tm *
       - type: char *
+  - name: ctime
+    standard:
+      - stdc
+    return_type: char *
+    arguments:
+      - type: const time_t *
+  - name: ctime_r
+    standard:
+      - stdc
+    return_type: char *
+    arguments:
+      - type: const time_t *
+      - type: char *
   - name: clock
     standard:
       - stdc

libc/spec/stdc.td

@@ -3,6 +3,8 @@ def StdC : StandardSpec<"stdc"> {
   NamedType StructTmType = NamedType<"struct tm">;
   PtrType StructTmPtr = PtrType<StructTmType>;
   PtrType TimeTTypePtr = PtrType<TimeTType>;
+  NamedType StructTimeTType = NamedType<"time_t">;
+  PtrType StructTimeTPtr = PtrType<StructTimeTType>;
   NamedType ClockT = NamedType<"clock_t">;
   NamedType LocaleT = NamedType<"locale_t">;
 
@@ -1600,6 +1602,19 @@ def StdC : StandardSpec<"stdc"> {
                   ArgSpec<CharPtr>,
               ]
           >,
+          FunctionSpec<
+              "ctime",
+              RetValSpec<CharPtr>,
+              [ArgSpec<StructTimeTPtr>]
+          >,
+          FunctionSpec<
+              "ctime_r",
+              RetValSpec<CharPtr>,
+              [
+                  ArgSpec<StructTimeTPtr>,
+                  ArgSpec<CharPtr>,
+              ]
+          >,
           FunctionSpec<
               "clock",
               RetValSpec<ClockT>,

libc/src/time/CMakeLists.txt

@@ -36,6 +36,28 @@ add_entrypoint_object(
     libc.include.time
 )
 
+add_entrypoint_object(
+  ctime
+  SRCS
+    ctime.cpp
+  HDRS
+    ctime.h
+  DEPENDS
+    .time_utils
+    libc.include.time
+)
+
+add_entrypoint_object(
+  ctime_r
+  SRCS
+    ctime_r.cpp
+  HDRS
+    ctime_r.h
+  DEPENDS
+    .time_utils
+    libc.include.time
+)
+
 add_entrypoint_object(
   difftime
   SRCS

libc/src/time/ctime.cpp

@@ -0,0 +1,23 @@
+//===-- Implementation of ctime 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/ctime.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+using LIBC_NAMESPACE::time_utils::TimeConstants;
+
+LLVM_LIBC_FUNCTION(char *, ctime, (const time_t *t_ptr)) {
+  static char buffer[TimeConstants::CTIME_BUFFER_SIZE];
+  return time_utils::asctime(localtime(t_ptr), buffer, TimeConstants::CTIME_MAX_BYTES);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/ctime.h

@@ -0,0 +1,21 @@
+//===-- Implementation header of ctime --------------------------*- 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_CTIME_H
+#define LLVM_LIBC_SRC_TIME_CTIME_H
+
+#include "src/__support/macros/config.h"
+#include <time.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+char *ctime(const time_t *t_ptr);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_CTIME_H

libc/src/time/ctime_r.cpp

@@ -0,0 +1,22 @@
+//===-- Implementation of ctime_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/ctime_r.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+#include "src/time/time_utils.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+using LIBC_NAMESPACE::time_utils::TimeConstants;
+
+LLVM_LIBC_FUNCTION(char *, ctime_r, (const time_t *t_ptr, char *buffer)) {
+  return time_utils::asctime(localtime(t_ptr), buffer, TimeConstants::CTIME_MAX_BYTES);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/time/ctime_r.h

@@ -0,0 +1,21 @@
+//===-- Implementation header of ctime_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_CTIME_R_H
+#define LLVM_LIBC_SRC_TIME_CTIME_R_H
+
+#include "src/__support/macros/config.h"
+#include <time.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+char *ctime_r(const time_t *t, char *buffer);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_TIME_CTIME_R_H

libc/src/time/time_utils.h

@@ -62,6 +62,9 @@ struct TimeConstants {
   static constexpr int ASCTIME_BUFFER_SIZE = 256;
   static constexpr int ASCTIME_MAX_BYTES = 26;
 
+  static constexpr int CTIME_BUFFER_SIZE = 256;
+  static constexpr int CTIME_MAX_BYTES = 26;
+
   /* 2000-03-01 (mod 400 year, immediately after feb29 */
   static constexpr int64_t SECONDS_UNTIL2000_MARCH_FIRST =
       (946684800LL + SECONDS_PER_DAY * (31 + 29));

libc/test/src/time/ctime_r_test.cpp

@@ -0,0 +1,60 @@
+//===-- Unittests for ctime_r ---------------------------------------------===//
+//
+// 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/errno/libc_errno.h"
+#include "src/time/ctime_r.h"
+#include "src/time/time_utils.h"
+#include "test/UnitTest/Test.h"
+#include "test/src/time/TmHelper.h"
+
+using LIBC_NAMESPACE::time_utils::TimeConstants;
+
+static inline char *call_ctime_r(time_t *t, int year, int month, int mday,
+                                 int hour, int min, int sec, int wday, int yday,
+                                 char *buffer) {
+  LIBC_NAMESPACE::tmhelper::testing::initialize_tm_data(
+      localtime(t), year, month, mday, hour, min, sec, wday, yday);
+  return LIBC_NAMESPACE::ctime_r(t, buffer);
+}
+
+// ctime and ctime_r share the same code and thus didn't repeat all the
+// tests from ctime. Added couple of validation tests.
+TEST(LlvmLibcCtimeR, Nullptr) {
+  char *result;
+  result = LIBC_NAMESPACE::ctime_r(nullptr, nullptr);
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_STREQ(nullptr, result);
+
+  char buffer[TimeConstants::CTIME_BUFFER_SIZE];
+  result = LIBC_NAMESPACE::ctime_r(nullptr, buffer);
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_STREQ(nullptr, result);
+
+  time_t t;
+  result = LIBC_NAMESPACE::ctime_r(&tm_data, nullptr);
+  ASSERT_ERRNO_EQ(EINVAL);
+  ASSERT_STREQ(nullptr, result);
+}
+
+TEST(LlvmLibcCtimeR, ValidDate) {
+  char buffer[TimeConstants::CTIME_BUFFER_SIZE];
+  struct time_t t;
+  char *result;
+  // 1970-01-01 00:00:00. Test with a valid buffer size.
+  result = call_ctime_r(&t,
+                        1970, // year
+                        1,    // month
+                        1,    // day
+                        0,    // hr
+                        0,    // min
+                        0,    // sec
+                        4,    // wday
+                        0,    // yday
+                        buffer);
+  ASSERT_STREQ("Thu Jan  1 00:00:00 1970\n", result);
+}