[libc-commits] [libc] 2d52283 - [libc] add fgets
Michael Jones via libc-commits
libc-commits at lists.llvm.org
Thu Oct 27 10:27:29 PDT 2022
Author: Michael Jones
Date: 2022-10-27T10:27:24-07:00
New Revision: 2d52283391bc81b1536345a644c30597564c0b1e
URL: https://github.com/llvm/llvm-project/commit/2d52283391bc81b1536345a644c30597564c0b1e
DIFF: https://github.com/llvm/llvm-project/commit/2d52283391bc81b1536345a644c30597564c0b1e.diff
LOG: [libc] add fgets
This adds the fgets function and its unit tests.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D136785
Added:
libc/src/stdio/fgets.cpp
libc/src/stdio/fgets.h
libc/test/src/stdio/fgets_test.cpp
Modified:
libc/config/linux/x86_64/entrypoints.txt
libc/spec/stdc.td
libc/src/stdio/CMakeLists.txt
libc/test/src/stdio/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index b2b617c71aad7..18594e500c936 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -369,6 +369,7 @@ if(LLVM_LIBC_FULL_BUILD)
libc.src.stdio.ferror
libc.src.stdio.ferror_unlocked
libc.src.stdio.fgetc
+ libc.src.stdio.fgets
libc.src.stdio.fflush
libc.src.stdio.fopen
libc.src.stdio.fputc
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index bc3778053ae25..337713e48c152 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -531,6 +531,15 @@ def StdC : StandardSpec<"stdc"> {
RetValSpec<IntType>,
[ArgSpec<FILEPtr>]
>,
+ FunctionSpec<
+ "fgets",
+ RetValSpec<CharPtr>,
+ [
+ ArgSpec<CharRestrictedPtr>,
+ ArgSpec<IntType>,
+ ArgSpec<FILERestrictedPtr>,
+ ]
+ >,
FunctionSpec<
"fflush",
RetValSpec<IntType>,
diff --git a/libc/src/stdio/CMakeLists.txt b/libc/src/stdio/CMakeLists.txt
index 7be2d93ba40bd..6fe3c59311db4 100644
--- a/libc/src/stdio/CMakeLists.txt
+++ b/libc/src/stdio/CMakeLists.txt
@@ -112,6 +112,18 @@ add_entrypoint_object(
libc.src.__support.File.platform_file
)
+add_entrypoint_object(
+ fgets
+ SRCS
+ fgets.cpp
+ HDRS
+ fgets.h
+ DEPENDS
+ libc.include.stdio
+ libc.src.__support.File.file
+ libc.src.__support.File.platform_file
+)
+
add_entrypoint_object(
fflush
SRCS
diff --git a/libc/src/stdio/fgets.cpp b/libc/src/stdio/fgets.cpp
new file mode 100644
index 0000000000000..ddce420450d23
--- /dev/null
+++ b/libc/src/stdio/fgets.cpp
@@ -0,0 +1,50 @@
+//===-- Implementation of fgets -------------------------------------------===//
+//
+// 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/stdio/fgets.h"
+#include "src/__support/File/file.h"
+
+#include <stddef.h>
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(char *, fgets,
+ (char *__restrict str, int count,
+ ::FILE *__restrict raw_stream)) {
+ if (count < 1)
+ return nullptr;
+
+ unsigned char c = '\0';
+ auto stream = reinterpret_cast<__llvm_libc::File *__restrict>(raw_stream);
+ stream->lock();
+
+ // i is an int because it's frequently compared to count, which is also int.
+ int i = 0;
+
+ for (; i < (count - 1) && c != '\n'; ++i) {
+ size_t r = stream->read_unlocked(&c, 1);
+ if (r != 1)
+ break;
+ str[i] = c;
+ }
+
+ bool has_error = stream->error_unlocked();
+ bool has_eof = stream->iseof_unlocked();
+ stream->unlock();
+
+ // If the requested read size makes no sense, an error occured, or no bytes
+ // were read due to an EOF, then return nullptr and don't write the null byte.
+ if (has_error || (i == 0 && has_eof))
+ return nullptr;
+
+ str[i] = '\0';
+ return str;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/stdio/fgets.h b/libc/src/stdio/fgets.h
new file mode 100644
index 0000000000000..6f4ed93ff03dc
--- /dev/null
+++ b/libc/src/stdio/fgets.h
@@ -0,0 +1,20 @@
+//===-- Implementation header of fgets --------------------------*- 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_FGETS_H
+#define LLVM_LIBC_SRC_STDIO_FGETS_H
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+char *fgets(char *__restrict str, int count, ::FILE *__restrict raw_stream);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_STDIO_FGETS_H
diff --git a/libc/test/src/stdio/CMakeLists.txt b/libc/test/src/stdio/CMakeLists.txt
index 3bd3ec575f530..1ab174290a1b7 100644
--- a/libc/test/src/stdio/CMakeLists.txt
+++ b/libc/test/src/stdio/CMakeLists.txt
@@ -170,5 +170,22 @@ add_libc_unittest(
libc.src.stdio.fwrite
)
+add_libc_unittest(
+ fgets_test
+ SUITE
+ libc_stdio_unittests
+ SRCS
+ fgets_test.cpp
+ DEPENDS
+ libc.include.errno
+ libc.include.stdio
+ libc.src.stdio.fclose
+ libc.src.stdio.feof
+ libc.src.stdio.ferror
+ libc.src.stdio.fgets
+ libc.src.stdio.fopen
+ libc.src.stdio.fwrite
+)
+
add_subdirectory(printf_core)
add_subdirectory(testdata)
diff --git a/libc/test/src/stdio/fgets_test.cpp b/libc/test/src/stdio/fgets_test.cpp
new file mode 100644
index 0000000000000..bd2271b832a61
--- /dev/null
+++ b/libc/test/src/stdio/fgets_test.cpp
@@ -0,0 +1,88 @@
+//===-- Unittests for fgets -----------------------------------------------===//
+//
+// 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/stdio/fclose.h"
+#include "src/stdio/feof.h"
+#include "src/stdio/ferror.h"
+#include "src/stdio/fgets.h"
+#include "src/stdio/fopen.h"
+#include "src/stdio/fwrite.h"
+#include "utils/UnitTest/Test.h"
+
+#include <errno.h>
+#include <stdio.h>
+
+TEST(LlvmLibcFgetsTest, WriteAndReadCharacters) {
+ constexpr char FILENAME[] = "testdata/fgets.test";
+ ::FILE *file = __llvm_libc::fopen(FILENAME, "w");
+ ASSERT_FALSE(file == nullptr);
+ constexpr char CONTENT[] = "123456789\n"
+ "1234567\n"
+ "123456\n"
+ "1";
+ constexpr size_t WRITE_SIZE = sizeof(CONTENT) - 1;
+
+ char buff[8];
+ char *output;
+
+ ASSERT_EQ(WRITE_SIZE, __llvm_libc::fwrite(CONTENT, 1, WRITE_SIZE, file));
+ // This is a write-only file so reads should fail.
+ ASSERT_TRUE(__llvm_libc::fgets(buff, 8, file) == nullptr);
+ // This is an error and not a real EOF.
+ ASSERT_EQ(__llvm_libc::feof(file), 0);
+ ASSERT_NE(__llvm_libc::ferror(file), 0);
+ errno = 0;
+
+ ASSERT_EQ(0, __llvm_libc::fclose(file));
+
+ file = __llvm_libc::fopen(FILENAME, "r");
+ ASSERT_FALSE(file == nullptr);
+
+ // If we request just 1 byte, it should return just a null byte and not
+ // advance the read head. This is implementation defined.
+ output = __llvm_libc::fgets(buff, 1, file);
+ ASSERT_TRUE(output == buff);
+ ASSERT_EQ(buff[0], '\0');
+ ASSERT_EQ(errno, 0);
+
+ // If we request less than 1 byte, it should do nothing and return nullptr.
+ // This is also implementation defined.
+ output = __llvm_libc::fgets(buff, 0, file);
+ ASSERT_TRUE(output == nullptr);
+
+ const char *output_arr[] = {
+ "1234567", "89\n", "1234567", "\n", "123456\n", "1",
+ };
+
+ constexpr size_t ARR_SIZE = sizeof(output_arr) / sizeof(char *);
+
+ for (size_t i = 0; i < ARR_SIZE; ++i) {
+ output = __llvm_libc::fgets(buff, 8, file);
+
+ // This pointer comparison is intentional, fgets should return a pointer to
+ // buff when it succeeds.
+ ASSERT_TRUE(output == buff);
+ ASSERT_EQ(__llvm_libc::ferror(file), 0);
+
+ EXPECT_STREQ(buff, output_arr[i]);
+ }
+
+ // This should have hit the end of the file, but that isn't an error unless it
+ // fails to read anything.
+ ASSERT_NE(__llvm_libc::feof(file), 0);
+ ASSERT_EQ(__llvm_libc::ferror(file), 0);
+ ASSERT_EQ(errno, 0);
+
+ // Reading more should be an EOF, but not an error.
+ output = __llvm_libc::fgets(buff, 8, file);
+ ASSERT_TRUE(output == nullptr);
+ ASSERT_NE(__llvm_libc::feof(file), 0);
+ ASSERT_EQ(errno, 0);
+
+ ASSERT_EQ(0, __llvm_libc::fclose(file));
+}
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