[libc-commits] [libc] Implement gethostname (PR #128142)
via libc-commits
libc-commits at lists.llvm.org
Thu Feb 20 23:25:54 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: Zaky Hermawan (ZakyHermawan)
<details>
<summary>Changes</summary>
The implementation is based on the specifications from: https://man7.org/linux/man-pages/man2/gethostname.2.html
Closes https://github.com/llvm/llvm-project/issues/126602
---
Full diff: https://github.com/llvm/llvm-project/pull/128142.diff
10 Files Affected:
- (modified) libc/config/linux/aarch64/entrypoints.txt (+1)
- (modified) libc/config/linux/riscv/entrypoints.txt (+1)
- (modified) libc/config/linux/x86_64/entrypoints.txt (+1)
- (modified) libc/include/unistd.yaml (+7)
- (modified) libc/src/unistd/CMakeLists.txt (+7)
- (added) libc/src/unistd/gethostname.h (+22)
- (modified) libc/src/unistd/linux/CMakeLists.txt (+16)
- (added) libc/src/unistd/linux/gethostname.cpp (+62)
- (modified) libc/test/src/unistd/CMakeLists.txt (+11)
- (added) libc/test/src/unistd/gethostname_test.cpp (+28)
``````````diff
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index aac4017a0d845..6450e41b76dfe 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -327,6 +327,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.getcwd
libc.src.unistd.getentropy
libc.src.unistd.geteuid
+ libc.src.unistd.gethostname
libc.src.unistd.getpid
libc.src.unistd.getppid
libc.src.unistd.getsid
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 6b006f0ecca89..10119b5f76d58 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -324,6 +324,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.ftruncate
libc.src.unistd.getcwd
libc.src.unistd.geteuid
+ libc.src.unistd.gethostname
libc.src.unistd.getpid
libc.src.unistd.getppid
libc.src.unistd.getsid
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 35661004663c9..c4c2e1449ef97 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -326,6 +326,7 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.unistd.getcwd
libc.src.unistd.getentropy
libc.src.unistd.geteuid
+ libc.src.unistd.gethostname
libc.src.unistd.getpid
libc.src.unistd.getppid
libc.src.unistd.getsid
diff --git a/libc/include/unistd.yaml b/libc/include/unistd.yaml
index 051e92b006741..3ba3ec71c25ce 100644
--- a/libc/include/unistd.yaml
+++ b/libc/include/unistd.yaml
@@ -141,6 +141,13 @@ functions:
return_type: uid_t
arguments:
- type: void
+ - name: gethostname
+ standards:
+ - POSIX
+ return_type: int
+ arguments:
+ - type: char *
+ - type: size_t
- name: getopt
standards:
- POSIX
diff --git a/libc/src/unistd/CMakeLists.txt b/libc/src/unistd/CMakeLists.txt
index b1a1716aa85c6..c66a3a4d0ed76 100644
--- a/libc/src/unistd/CMakeLists.txt
+++ b/libc/src/unistd/CMakeLists.txt
@@ -111,6 +111,13 @@ add_entrypoint_object(
.${LIBC_TARGET_OS}.getcwd
)
+add_entrypoint_object(
+ gethostname
+ ALIAS
+ DEPENDS
+ .${LIBC_TARGET_OS}.gethostname
+)
+
add_entrypoint_object(
getpid
ALIAS
diff --git a/libc/src/unistd/gethostname.h b/libc/src/unistd/gethostname.h
new file mode 100644
index 0000000000000..ef1b2d5381de6
--- /dev/null
+++ b/libc/src/unistd/gethostname.h
@@ -0,0 +1,22 @@
+//===-- Implementation header for gethostname -------------------*- 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_GETHOSTNAME_H
+#define LLVM_LIBC_SRC_UNISTD_GETHOSTNAME_H
+
+#include "hdr/types/size_t.h"
+#include "hdr/unistd_macros.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+int gethostname(char *name, size_t len);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC_UNISTD_GETHOSTNAME_H
diff --git a/libc/src/unistd/linux/CMakeLists.txt b/libc/src/unistd/linux/CMakeLists.txt
index 368593a3bb7b5..6ea8068a6f39c 100644
--- a/libc/src/unistd/linux/CMakeLists.txt
+++ b/libc/src/unistd/linux/CMakeLists.txt
@@ -193,6 +193,22 @@ add_entrypoint_object(
libc.src.errno.errno
)
+add_entrypoint_object(
+ gethostname
+ SRCS
+ gethostname.cpp
+ HDRS
+ ../gethostname.h
+ DEPENDS
+ libc.hdr.types.size_t
+ libc.include.sys_syscall
+ libc.include.sys_utsname
+ libc.src.__support.OSUtil.osutil
+ libc.src.errno.errno
+ libc.src.string.strlen
+ libc.src.string.strncpy
+)
+
add_entrypoint_object(
geteuid
SRCS
diff --git a/libc/src/unistd/linux/gethostname.cpp b/libc/src/unistd/linux/gethostname.cpp
new file mode 100644
index 0000000000000..617d0197c73c7
--- /dev/null
+++ b/libc/src/unistd/linux/gethostname.cpp
@@ -0,0 +1,62 @@
+//===-- Linux implementation of gethostname -------------------------------===//
+//
+// 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/gethostname.h"
+
+#include "hdr/types/size_t.h"
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+#include "src/string/strlen.h"
+#include "src/string/strncpy.h"
+#include "src/errno/libc_errno.h"
+
+#include <sys/syscall.h> // For syscall numbers.
+#include <sys/utsname.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+// Matching the behavior of glibc version 2.2 and later.
+// Copies up to len bytes from the returned nodename field into name.
+LLVM_LIBC_FUNCTION(int, gethostname, (char *name, size_t len)) {
+
+ // Check for invalid pointer
+ if (name == nullptr) {
+ libc_errno = EFAULT;
+ return -1;
+ }
+
+ struct utsname unameData;
+ int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_uname, &unameData);
+
+ // Checks if the length of the nodename was greater than or equal to len, and if it is,
+ // then the function returns -1 with errno set to ENAMETOOLONG.
+ // In this case, a terminating null byte is not included in the returned name.
+ if (strlen(unameData.nodename) >= len)
+ {
+ strncpy(name, unameData.nodename, len);
+ libc_errno = ENAMETOOLONG;
+ return -1;
+ }
+
+ // If the size of the array name is not large enough (less than the size of nodename with null termination), then anything might happen.
+ // In this case, what happens to the array name will be determined by the implementation of LIBC_NAMESPACE_DECL::strncpy
+ strncpy(name, unameData.nodename, len);
+
+ if (ret < 0) {
+ libc_errno = static_cast<int>(-ret);
+ return -1;
+ }
+
+ return 0;
+}
+
+} // namespace LIBC_NAMESPACE_DECL
+
+
diff --git a/libc/test/src/unistd/CMakeLists.txt b/libc/test/src/unistd/CMakeLists.txt
index d1f3050e6cccf..0f01104044e34 100644
--- a/libc/test/src/unistd/CMakeLists.txt
+++ b/libc/test/src/unistd/CMakeLists.txt
@@ -374,6 +374,17 @@ add_libc_unittest(
libc.src.unistd.unlinkat
)
+add_libc_unittest(
+ gethostname_test
+ SUITE
+ libc_unistd_unittests
+ SRCS
+ gethostname_test.cpp
+ DEPENDS
+ libc.src.unistd.gethostname
+ libc.src.errno.errno
+)
+
add_libc_unittest(
getpid_test
SUITE
diff --git a/libc/test/src/unistd/gethostname_test.cpp b/libc/test/src/unistd/gethostname_test.cpp
new file mode 100644
index 0000000000000..777f9664e7ee6
--- /dev/null
+++ b/libc/test/src/unistd/gethostname_test.cpp
@@ -0,0 +1,28 @@
+//===-- Unittests for gethostname -----------------------------------------===//
+//
+// 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/unistd/gethostname.h"
+#include "test/UnitTest/Test.h"
+
+TEST(LlvmLibcGetHostNameTest, GetCurrHostName) {
+ char hostbuffer[1024];
+ int ret = LIBC_NAMESPACE::gethostname(hostbuffer, sizeof(hostbuffer));
+ ASSERT_NE(ret, -1);
+ ASSERT_ERRNO_SUCCESS();
+
+ ret = LIBC_NAMESPACE::gethostname(hostbuffer, 0);
+ ASSERT_EQ(ret, -1);
+ ASSERT_ERRNO_EQ(ENAMETOOLONG);
+
+ // test for invalid pointer
+ char* nptr = nullptr;
+ ret = LIBC_NAMESPACE::gethostname(nptr, 1);
+ ASSERT_EQ(ret, -1);
+ ASSERT_ERRNO_EQ(EFAULT);
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/128142
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