[libc-commits] [libc] 6e675fb - [libc] Add POSIX functions pread and pwrite.
Siva Chandra Reddy via libc-commits
libc-commits at lists.llvm.org
Wed Sep 14 13:52:46 PDT 2022
Author: Siva Chandra Reddy
Date: 2022-09-14T20:52:20Z
New Revision: 6e675fba3a51faf87bc9df2bcb4e2d6ede1dd167
URL: https://github.com/llvm/llvm-project/commit/6e675fba3a51faf87bc9df2bcb4e2d6ede1dd167
DIFF: https://github.com/llvm/llvm-project/commit/6e675fba3a51faf87bc9df2bcb4e2d6ede1dd167.diff
LOG: [libc] Add POSIX functions pread and pwrite.
Reviewed By: michaelrj
Differential Revision: https://reviews.llvm.org/D133888
Added:
libc/src/unistd/linux/pread.cpp
libc/src/unistd/linux/pwrite.cpp
libc/src/unistd/pread.h
libc/src/unistd/pwrite.h
libc/test/src/unistd/pread_pwrite_test.cpp
Modified:
libc/config/linux/aarch64/entrypoints.txt
libc/config/linux/x86_64/entrypoints.txt
libc/spec/posix.td
libc/src/unistd/CMakeLists.txt
libc/src/unistd/linux/CMakeLists.txt
libc/test/src/unistd/CMakeLists.txt
Removed:
################################################################################
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index 34f3978647a5..3331a118e874 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -123,6 +123,8 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.link
libc.src.unistd.linkat
libc.src.unistd.lseek
+ libc.src.unistd.pread
+ libc.src.unistd.pwrite
libc.src.unistd.read
libc.src.unistd.readlink
libc.src.unistd.readlinkat
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index f6816bce4496..9119704cc7cb 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -123,6 +123,8 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.link
libc.src.unistd.linkat
libc.src.unistd.lseek
+ libc.src.unistd.pread
+ libc.src.unistd.pwrite
libc.src.unistd.read
libc.src.unistd.readlink
libc.src.unistd.readlinkat
diff --git a/libc/spec/posix.td b/libc/spec/posix.td
index 877ae614fce5..b0520dbfcb2b 100644
--- a/libc/spec/posix.td
+++ b/libc/spec/posix.td
@@ -321,6 +321,16 @@ def POSIX : StandardSpec<"POSIX"> {
RetValSpec<OffTType>,
[ArgSpec<IntType>, ArgSpec<OffTType>, ArgSpec<IntType>]
>,
+ FunctionSpec<
+ "pread",
+ RetValSpec<SSizeTType>,
+ [ArgSpec<IntType>, ArgSpec<VoidPtr>, ArgSpec<SizeTType>, ArgSpec<OffTType>]
+ >,
+ FunctionSpec<
+ "pwrite",
+ RetValSpec<SSizeTType>,
+ [ArgSpec<IntType>, ArgSpec<ConstVoidPtr>, ArgSpec<SizeTType>, ArgSpec<OffTType>]
+ >,
FunctionSpec<
"read",
RetValSpec<SSizeTType>,
diff --git a/libc/src/unistd/CMakeLists.txt b/libc/src/unistd/CMakeLists.txt
index 0f8fffaeb2aa..bc501570ccd8 100644
--- a/libc/src/unistd/CMakeLists.txt
+++ b/libc/src/unistd/CMakeLists.txt
@@ -86,6 +86,20 @@ add_entrypoint_object(
.${LIBC_TARGET_OS}.lseek
)
+add_entrypoint_object(
+ pread
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.pread
+)
+
+add_entrypoint_object(
+ pwrite
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.pwrite
+)
+
add_entrypoint_object(
read
ALIAS
diff --git a/libc/src/unistd/linux/CMakeLists.txt b/libc/src/unistd/linux/CMakeLists.txt
index 8b2f44c56116..186fdc263100 100644
--- a/libc/src/unistd/linux/CMakeLists.txt
+++ b/libc/src/unistd/linux/CMakeLists.txt
@@ -157,6 +157,32 @@ add_entrypoint_object(
libc.src.errno.errno
)
+add_entrypoint_object(
+ pread
+ SRCS
+ pread.cpp
+ HDRS
+ ../pread.h
+ DEPENDS
+ libc.include.unistd
+ libc.include.sys_syscall
+ libc.src.__support.OSUtil.osutil
+ libc.src.errno.errno
+)
+
+add_entrypoint_object(
+ pwrite
+ SRCS
+ pwrite.cpp
+ HDRS
+ ../pwrite.h
+ DEPENDS
+ libc.include.unistd
+ libc.include.sys_syscall
+ libc.src.__support.OSUtil.osutil
+ libc.src.errno.errno
+)
+
add_entrypoint_object(
read
SRCS
diff --git a/libc/src/unistd/linux/pread.cpp b/libc/src/unistd/linux/pread.cpp
new file mode 100644
index 000000000000..24f4d472e84f
--- /dev/null
+++ b/libc/src/unistd/linux/pread.cpp
@@ -0,0 +1,29 @@
+//===-- Linux implementation of pread -------------------------------------===//
+//
+// 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/unistd/pread.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(ssize_t, pread,
+ (int fd, void *buf, size_t count, off_t offset)) {
+ long ret = __llvm_libc::syscall(SYS_pread64, fd, buf, count, offset);
+ if (ret < 0) {
+ errno = -ret;
+ return -1;
+ }
+ return ret;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/unistd/linux/pwrite.cpp b/libc/src/unistd/linux/pwrite.cpp
new file mode 100644
index 000000000000..d26f87660de9
--- /dev/null
+++ b/libc/src/unistd/linux/pwrite.cpp
@@ -0,0 +1,29 @@
+//===-- Linux implementation of pwrite ------------------------------------===//
+//
+// 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/unistd/pwrite.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <errno.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(ssize_t, pwrite,
+ (int fd, const void *buf, size_t count, off_t offset)) {
+ long ret = __llvm_libc::syscall(SYS_pwrite64, fd, buf, count, offset);
+ if (ret < 0) {
+ errno = -ret;
+ return -1;
+ }
+ return ret;
+}
+
+} // namespace __llvm_libc
diff --git a/libc/src/unistd/pread.h b/libc/src/unistd/pread.h
new file mode 100644
index 000000000000..5ddf32eae4f8
--- /dev/null
+++ b/libc/src/unistd/pread.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for pread -------------------------*- 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_UNISTD_PREAD_H
+#define LLVM_LIBC_SRC_UNISTD_PREAD_H
+
+#include <unistd.h>
+
+namespace __llvm_libc {
+
+ssize_t pread(int fd, void *buf, size_t count, off_t offset);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_UNISTD_PREAD_H
diff --git a/libc/src/unistd/pwrite.h b/libc/src/unistd/pwrite.h
new file mode 100644
index 000000000000..4286314abee0
--- /dev/null
+++ b/libc/src/unistd/pwrite.h
@@ -0,0 +1,20 @@
+//===-- Implementation header for pwrite ------------------------*- 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_UNISTD_PWRITE_H
+#define LLVM_LIBC_SRC_UNISTD_PWRITE_H
+
+#include <unistd.h>
+
+namespace __llvm_libc {
+
+ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_UNISTD_PWRITE_H
diff --git a/libc/test/src/unistd/CMakeLists.txt b/libc/test/src/unistd/CMakeLists.txt
index f848d8d340e5..c4ad96b9eeba 100644
--- a/libc/test/src/unistd/CMakeLists.txt
+++ b/libc/test/src/unistd/CMakeLists.txt
@@ -119,6 +119,25 @@ add_libc_unittest(
libc.src.__support.CPP.string_view
)
+add_libc_unittest(
+ pread_pwrite_test
+ SUITE
+ libc_unistd_unittests
+ SRCS
+ pread_pwrite_test.cpp
+ DEPENDS
+ libc.include.errno
+ libc.include.unistd
+ libc.src.fcntl.open
+ libc.src.unistd.close
+ libc.src.unistd.fsync
+ libc.src.unistd.pread
+ libc.src.unistd.pwrite
+ libc.src.unistd.unlink
+ libc.src.unistd.write
+ libc.test.errno_setter_matcher
+)
+
add_libc_unittest(
read_write_test
SUITE
diff --git a/libc/test/src/unistd/pread_pwrite_test.cpp b/libc/test/src/unistd/pread_pwrite_test.cpp
new file mode 100644
index 000000000000..bccdaffd7f4f
--- /dev/null
+++ b/libc/test/src/unistd/pread_pwrite_test.cpp
@@ -0,0 +1,74 @@
+//===-- Unittests for pread and pwrite ------------------------------------===//
+//
+// 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/fcntl/open.h"
+#include "src/unistd/close.h"
+#include "src/unistd/fsync.h"
+#include "src/unistd/pread.h"
+#include "src/unistd/pwrite.h"
+#include "src/unistd/unlink.h"
+#include "src/unistd/write.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+
+TEST(LlvmLibcUniStd, PWriteAndPReadBackTest) {
+ // The strategy here is that we first create a file and write to it. Next,
+ // we open that file again and write at an offset. Finally, we open the
+ // file again and pread at an offset and make sure that only expected data
+ // is being read back. This also confirms that pwrite happened successfully.
+ constexpr const char HELLO[] = "hello";
+ constexpr int HELLO_SIZE = sizeof(HELLO);
+ constexpr off_t OFFSET = 3;
+ constexpr const char OFFSET_TEXT[] = "helhello";
+ constexpr int OFFSET_TEXT_SIZE = sizeof(OFFSET_TEXT);
+
+ using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+
+ constexpr const char *TEST_FILE = "testdata/pread_pwrite.test";
+ int fd = __llvm_libc::open(TEST_FILE, O_WRONLY | O_CREAT, S_IRWXU);
+ ASSERT_EQ(errno, 0);
+ ASSERT_GT(fd, 0);
+ ASSERT_THAT(__llvm_libc::write(fd, HELLO, HELLO_SIZE), Succeeds(HELLO_SIZE));
+ ASSERT_THAT(__llvm_libc::fsync(fd), Succeeds(0));
+ ASSERT_THAT(__llvm_libc::close(fd), Succeeds(0));
+
+ fd = __llvm_libc::open(TEST_FILE, O_WRONLY);
+ ASSERT_EQ(errno, 0);
+ ASSERT_GT(fd, 0);
+ ASSERT_THAT(__llvm_libc::pwrite(fd, HELLO, HELLO_SIZE, OFFSET),
+ Succeeds(HELLO_SIZE));
+ ASSERT_THAT(__llvm_libc::fsync(fd), Succeeds(0));
+ ASSERT_THAT(__llvm_libc::close(fd), Succeeds(0));
+
+ fd = __llvm_libc::open(TEST_FILE, O_RDONLY);
+ ASSERT_EQ(errno, 0);
+ ASSERT_GT(fd, 0);
+ char read_buf[OFFSET_TEXT_SIZE];
+ ASSERT_THAT(__llvm_libc::pread(fd, read_buf, HELLO_SIZE, OFFSET),
+ Succeeds(HELLO_SIZE));
+ EXPECT_STREQ(read_buf, HELLO);
+ ASSERT_THAT(__llvm_libc::pread(fd, read_buf, OFFSET_TEXT_SIZE, 0),
+ Succeeds(OFFSET_TEXT_SIZE));
+ EXPECT_STREQ(read_buf, OFFSET_TEXT);
+ ASSERT_THAT(__llvm_libc::close(fd), Succeeds(0));
+
+ ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcUniStd, PWriteFails) {
+ using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+ EXPECT_THAT(__llvm_libc::pwrite(-1, "", 1, 0), Fails(EBADF));
+}
+
+TEST(LlvmLibcUniStd, PReadFails) {
+ using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+ EXPECT_THAT(__llvm_libc::pread(-1, nullptr, 1, 0), Fails(EBADF));
+}
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