[libc] add printf pointer conv

[michaelrj]

Summary

The pointer converter handles the %p conversion. It uses the hex
converter for most of the conversion.

[michaelrj]

add converter test

[lntue]

Is the new header ptr_converter.h needed to be added to converter object library in CMakeLists.txt?

[michaelrj]

yes, I've added ptr_converter to the CMake now

[sivachandra]

libc/test/src/stdio/sprintf_test.cpp

361

Whats the point of this test?

[michaelrj]

libc/test/src/stdio/sprintf_test.cpp

361

I want to make sure it writes something for a real pointer, but since I don't know the value of the pointer before runtime I can't fix the return value. I use the other cases to check that it actually returns correct values.

libc/src/stdio/printf_core/CMakeLists.txt

add_object_library(
   HDRS
     converter.h
     converter_atlas.h
     converter_utils.h
     string_converter.h
     char_converter.h
     int_converter.h
     hex_converter.h
+    ptr_converter.h
   DEPENDS
     .writer
     .core_structs
 )
 
 
 add_object_library(
   printf_main

libc/src/stdio/printf_core/converter.cpp

case 'A':
     // return convert_float_hex_exp(writer, to_conv);
   case 'g':
   case 'G':
     // return convert_float_mixed(writer, to_conv);
   // TODO(michaelrj): add a flag to disable writing an int here
   case 'n':
     // return convert_write_int(writer, to_conv);
   case 'p':
-    // return convert_pointer(writer, to_conv);
+    return convert_pointer(writer, to_conv);
   default:
     return writer->write(to_conv.raw_string, to_conv.raw_len);
   }
   return -1;
 }
 
 } // namespace printf_core
 } // namespace __llvm_libc

libc/src/stdio/printf_core/converter_atlas.h

 // defines convert_float_dec_exp
 // defines convert_float_hex_exp
 // defines convert_float_mixed
 
 // TODO(michaelrj): add a flag to disable writing an int here
 // defines convert_write_int
 
 // defines convert_pointer
+#include "src/stdio/printf_core/ptr_converter.h"
 
 #endif // LLVM_LIBC_SRC_STDIO_PRINTF_CORE_CONVERTER_ATLAS_H

libc/src/stdio/printf_core/ptr_converter.h

+//===-- Pointer Converter for printf ----------------------------*- 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_PRINTF_CORE_PTR_CONVERTER_H
+#define LLVM_LIBC_SRC_STDIO_PRINTF_CORE_PTR_CONVERTER_H
+
+#include "src/stdio/printf_core/converter_utils.h"
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/hex_converter.h"
+#include "src/stdio/printf_core/writer.h"
+
+namespace __llvm_libc {
+namespace printf_core {
+
+int inline convert_pointer(Writer *writer, const FormatSection &to_conv) {
+  if (to_conv.conv_val_ptr == (void *)(nullptr)) {
+    const char ZERO_STR[] = "(nullptr)";
+    // subtract 1 from sizeof to remove the null byte at the end.
+    RET_IF_RESULT_NEGATIVE(writer->write(ZERO_STR, sizeof(ZERO_STR) - 1));
+  } else {
+    FormatSection hex_conv;
+    hex_conv.has_conv = true;
+    hex_conv.conv_name = 'x';
+    hex_conv.flags = FormatFlags::ALTERNATE_FORM;
+    hex_conv.conv_val_raw = reinterpret_cast<uintptr_t>(to_conv.conv_val_ptr);
+    return convert_hex(writer, hex_conv);
+  }
+  return 0;
+}
+
+} // namespace printf_core
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STDIO_PRINTF_CORE_PTR_CONVERTER_H

libc/test/src/stdio/printf_core/converter_test.cpp

TEST(LlvmLibcPrintfConverterTest, HexConversion) {
   left_justified_conv.min_width = 18;
   left_justified_conv.conv_val_raw = 0x123456ab;
   __llvm_libc::printf_core::convert(&writer, left_justified_conv);
 
   str_writer.terminate();
   ASSERT_STREQ(str, "0x00000000123456ab");
   ASSERT_EQ(writer.get_chars_written(), 18);
 }
+
+TEST(LlvmLibcPrintfConverterTest, PointerConversion) {
+  char str[20];
+  __llvm_libc::printf_core::StringWriter str_writer(str);
+  __llvm_libc::printf_core::Writer writer(
+      reinterpret_cast<void *>(&str_writer),
+      __llvm_libc::printf_core::write_to_string);
+
+  __llvm_libc::printf_core::FormatSection section;
+  section.has_conv = true;
+  section.raw_string = "%p";
+  section.raw_len = 2;
+  section.conv_name = 'p';
+  section.conv_val_ptr = (void *)(0x123456ab);
+  __llvm_libc::printf_core::convert(&writer, section);
+
+  str_writer.terminate();
+  ASSERT_STREQ(str, "0x123456ab");
+  ASSERT_EQ(writer.get_chars_written(), 10);
+}

libc/test/src/stdio/sprintf_test.cpp

TEST(LlvmLibcSPrintfTest, HexConv) {
   ASSERT_STREQ(buff, "0075 0x0025");
 
   written = __llvm_libc::sprintf(buff, "%04hhX %#.5llx %-6.3zX", 256 + 0x7f,
                                  0x1000000000ll, size_t(2));
   EXPECT_EQ(written, 24);
   ASSERT_STREQ(buff, "007F 0x1000000000 002   ");
 }
 
+TEST(LlvmLibcSPrintfTest, PointerConv) {
+  char buff[64];
+  int written;
+
+  written = __llvm_libc::sprintf(buff, "%p", nullptr);
+  EXPECT_EQ(written, 9);
+  ASSERT_STREQ(buff, "(nullptr)");
+
+  written = __llvm_libc::sprintf(buff, "%p", 0x1a2b3c4d);
+  EXPECT_EQ(written, 10);
+  ASSERT_STREQ(buff, "0x1a2b3c4d");
+
+  written = __llvm_libc::sprintf(buff, "%p", buff);
+  EXPECT_GT(written, 0);
+}
+
 #ifndef LLVM_LIBC_PRINTF_DISABLE_INDEX_MODE
 TEST(LlvmLibcSPrintfTest, IndexModeParsing) {
   char buff[64];
   int written;
 
   written = __llvm_libc::sprintf(buff, "%1$s", "abcDEF123");
   EXPECT_EQ(written, 9);
   ASSERT_STREQ(buff, "abcDEF123");