Add few docs and implementation of strcpy and strcat.

Summary:
This patch illustrates some of the features like modularity we want
in the new libc. Few other ideas like different kinds of testing, redirectors
etc are not yet present.

Reviewers: dlj, hfinkel, theraven, jfb, alexshap, jdoerfert

Subscribers: mgorny, dexonsmith, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67867

llvm-svn: 373764

13 files changed, 252 insertions, 0 deletions

diff --git a/libc/src/CMakeLists.txt b/libc/src/CMakeLists.txt
new file mode 100644
index 00000000000..b661a65d900
--- /dev/null
+++ b/libc/src/CMakeLists.txt
@@ -0,0 +1,3 @@
+add_subdirectory(string)
+
+add_subdirectory(__support)
diff --git a/libc/src/__support/CMakeLists.txt b/libc/src/__support/CMakeLists.txt
new file mode 100644
index 00000000000..a536e9025d7
--- /dev/null
+++ b/libc/src/__support/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_gen_header(
+  support_common_h
+  DEF_FILE common.h.def
+  PARAMS
+    entrypoint_macro=${LIBC_TARGET_OS}/entrypoint_macro.h.inc
+  GEN_HDR common.h
+  DATA_FILES
+    ${LIBC_TARGET_OS}/entrypoint_macro.h.inc
+)
diff --git a/libc/src/__support/common.h.def b/libc/src/__support/common.h.def
new file mode 100644
index 00000000000..b2605a712d8
--- /dev/null
+++ b/libc/src/__support/common.h.def
@@ -0,0 +1,18 @@
+//===-------------------- Common internal contructs ---------------------*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SUPPORT_COMMON_H
+#define LLVM_LIBC_SUPPORT_COMMON_H
+
+#define INLINE_ASM __asm__ __volatile__
+
+<!> The entrypoint macro has a platform specific definition. So, we include the
+<!> right definition at build time.
+%%include_file(${entrypoint_macro})
+
+#endif // LLVM_LIBC_SUPPORT_COMMON_H
diff --git a/libc/src/__support/linux/entrypoint_macro.h.inc b/libc/src/__support/linux/entrypoint_macro.h.inc
new file mode 100644
index 00000000000..8f873f90b48
--- /dev/null
+++ b/libc/src/__support/linux/entrypoint_macro.h.inc
@@ -0,0 +1,13 @@
+//===---- Definition of LLVM_LIBC_ENTRYPOINT macro for ELF paltforms ----*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+%%begin()
+
+#define ENTRYPOINT_SECTION_ATTRIBUTE(name) \
+    __attribute__((section(".llvm.libc.entrypoint."#name)))
+#define LLVM_LIBC_ENTRYPOINT(name) ENTRYPOINT_SECTION_ATTRIBUTE(name) name
diff --git a/libc/src/string/CMakeLists.txt b/libc/src/string/CMakeLists.txt
new file mode 100644
index 00000000000..a8984f6ee9f
--- /dev/null
+++ b/libc/src/string/CMakeLists.txt
@@ -0,0 +1,4 @@
+add_custom_target(libc_string_unittests)
+
+add_subdirectory(strcpy)
+add_subdirectory(strcat)
diff --git a/libc/src/string/strcat/CMakeLists.txt b/libc/src/string/strcat/CMakeLists.txt
new file mode 100644
index 00000000000..790d77bbb1a
--- /dev/null
+++ b/libc/src/string/strcat/CMakeLists.txt
@@ -0,0 +1,21 @@
+add_entrypoint_object(
+  strcat
+  SRCS
+    strcat.cpp
+  HDRS
+    strcat.h
+  DEPENDS
+    strcpy
+    string_h
+)
+
+add_libc_unittest(
+  strcat_test
+  SUITE
+    libc_string_unittests
+  SRCS
+    strcat_test.cpp
+  DEPENDS
+    strcat
+    strcpy
+)
diff --git a/libc/src/string/strcat/strcat.cpp b/libc/src/string/strcat/strcat.cpp
new file mode 100644
index 00000000000..09cc62d25e2
--- /dev/null
+++ b/libc/src/string/strcat/strcat.cpp
@@ -0,0 +1,23 @@
+//===-------------------- Implementation of strcat -----------------------===//
+//
+// 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/string/strcat/strcat.h"
+
+#include "src/__support/common.h"
+#include "src/string/strcpy/strcpy.h"
+
+namespace __llvm_libc {
+
+char *LLVM_LIBC_ENTRYPOINT(strcat)(char *dest, const char *src) {
+  // We do not yet have an implementaion of strlen in so we will use strlen
+  // from another libc.
+  __llvm_libc::strcpy(dest + ::strlen(dest), src);
+  return dest;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/string/strcat/strcat.h b/libc/src/string/strcat/strcat.h
new file mode 100644
index 00000000000..d3023e9757c
--- /dev/null
+++ b/libc/src/string/strcat/strcat.h
@@ -0,0 +1,20 @@
+//===----------------- Implementation header for strcat -------------------===//
+//
+// 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_STRING_STRCAT_H
+#define LLVM_LIBC_SRC_STRING_STRCAT_H
+
+#include <string.h>
+
+namespace __llvm_libc {
+
+char *strcat(char *dest, const char *src);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRCAT_H
diff --git a/libc/src/string/strcat/strcat_test.cpp b/libc/src/string/strcat/strcat_test.cpp
new file mode 100644
index 00000000000..26bcae2373e
--- /dev/null
+++ b/libc/src/string/strcat/strcat_test.cpp
@@ -0,0 +1,43 @@
+//===---------------------- Unittests for strcat --------------------------===//
+//
+// 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 <string>
+
+#include "src/string/strcat/strcat.h"
+#include "gtest/gtest.h"
+
+TEST(StrCatTest, EmptyDest) {
+  std::string abc = "abc";
+  char *dest = new char[4];
+
+  dest[0] = '\0';
+
+  char *result = __llvm_libc::strcat(dest, abc.c_str());
+  ASSERT_EQ(dest, result);
+  ASSERT_EQ(std::string(dest), abc);
+  ASSERT_EQ(std::string(dest).size(), abc.size());
+
+  delete[] dest;
+}
+
+TEST(StrCatTest, NonEmptyDest) {
+  std::string abc = "abc";
+  char *dest = new char[4];
+
+  dest[0] = 'x';
+  dest[1] = 'y';
+  dest[2] = 'z';
+  dest[3] = '\0';
+
+  char *result = __llvm_libc::strcat(dest, abc.c_str());
+  ASSERT_EQ(dest, result);
+  ASSERT_EQ(std::string(dest), std::string("xyz") + abc);
+  ASSERT_EQ(std::string(dest).size(), abc.size() + 3);
+
+  delete[] dest;
+}
diff --git a/libc/src/string/strcpy/CMakeLists.txt b/libc/src/string/strcpy/CMakeLists.txt
new file mode 100644
index 00000000000..9f2791139ee
--- /dev/null
+++ b/libc/src/string/strcpy/CMakeLists.txt
@@ -0,0 +1,19 @@
+add_entrypoint_object(
+  strcpy
+  SRCS
+    strcpy.cpp
+  HDRS
+    strcpy.h
+  DEPENDS
+    string_h
+)
+
+add_libc_unittest(
+  strcpy_test
+  SUITE
+    libc_string_unittests
+  SRCS
+    strcpy_test.cpp
+  DEPENDS
+    strcpy
+)
diff --git a/libc/src/string/strcpy/strcpy.cpp b/libc/src/string/strcpy/strcpy.cpp
new file mode 100644
index 00000000000..0dfb1e35e41
--- /dev/null
+++ b/libc/src/string/strcpy/strcpy.cpp
@@ -0,0 +1,19 @@
+//===-------------------- Implementation of strcpy -----------------------===//
+//
+// 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/string/strcpy/strcpy.h"
+
+#include "src/__support/common.h"
+
+namespace __llvm_libc {
+
+char *LLVM_LIBC_ENTRYPOINT(strcpy)(char *dest, const char *src) {
+  return reinterpret_cast<char *>(::memcpy(dest, src, ::strlen(src) + 1));
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/string/strcpy/strcpy.h b/libc/src/string/strcpy/strcpy.h
new file mode 100644
index 00000000000..67710d8c84b
--- /dev/null
+++ b/libc/src/string/strcpy/strcpy.h
@@ -0,0 +1,20 @@
+//===----------------- Implementation header for strcpy -------------------===//
+//
+// 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_STRING_STRCPY_H
+#define LLVM_LIBC_SRC_STRING_STRCPY_H
+
+#include <string.h>
+
+namespace __llvm_libc {
+
+char *strcpy(char *dest, const char *src);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STRING_STRCPY_H
diff --git a/libc/src/string/strcpy/strcpy_test.cpp b/libc/src/string/strcpy/strcpy_test.cpp
new file mode 100644
index 00000000000..48f55f24649
--- /dev/null
+++ b/libc/src/string/strcpy/strcpy_test.cpp
@@ -0,0 +1,40 @@
+//===----------------------- Unittests for strcpy -------------------------===//
+//
+// 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 <string>
+
+#include "src/string/strcpy/strcpy.h"
+#include "gtest/gtest.h"
+
+TEST(StrCpyTest, EmptyDest) {
+  std::string abc = "abc";
+  char *dest = new char[4];
+
+  char *result = __llvm_libc::strcpy(dest, abc.c_str());
+  ASSERT_EQ(dest, result);
+  ASSERT_EQ(std::string(dest), abc);
+  ASSERT_EQ(std::string(dest).size(), abc.size());
+
+  delete[] dest;
+}
+
+TEST(StrCpyTest, OffsetDest) {
+  std::string abc = "abc";
+  char *dest = new char[7];
+
+  dest[0] = 'x';
+  dest[1] = 'y';
+  dest[2] = 'z';
+
+  char *result = __llvm_libc::strcpy(dest + 3, abc.c_str());
+  ASSERT_EQ(dest + 3, result);
+  ASSERT_EQ(std::string(dest), std::string("xyz") + abc);
+  ASSERT_EQ(std::string(dest).size(), abc.size() + 3);
+
+  delete[] dest;
+}