[libc-commits] [libc] [libc] Enable socket entrypoints in overlay mode (PR #195035)
Pavel Labath via libc-commits
libc-commits at lists.llvm.org
Thu Apr 30 01:13:47 PDT 2026
https://github.com/labath created https://github.com/llvm/llvm-project/pull/195035
This is slightly tricky in that many of these functions depend on types (struct sockaddrs, msghdr, ...) and we cannot overlay types. However, this works because these functions are simple syscall wrappers which simply forward the data to the kernel -- so it's really the kernel that's defining these structures.
This approach is compatible with libraries which implement these functions the same way, this includes at least glibc (on all architectures) and musl (on 32-bit architectures). 64-bit musl repacks the [c]msghdr structures to zero out padding fields, and overlaying that can lead to subtle bugs. However, I believe that overlaying musl is not a very interesting use case, so I'm leaving that as a TODO. If someone is interested in doing that, they can either exclude these entrypoints from the overlay or implement the musl-compatible repacking code.
>From 165708178420f08be926603d0c838b5c4e3652e0 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Tue, 28 Apr 2026 09:55:26 +0000
Subject: [PATCH] [libc] Enable socket entrypoints in overlay mode
This is slightly tricky in that many of these functions depend on types
(struct sockaddrs, msghdr, ...) and we cannot overlay types. However,
this works because these functions are simple syscall wrappers which
simply forward the data to the kernel -- so it's really the kernel
that's defining these structures.
This approach is compatible with libraries which implement these
functions the same way, this includes at least glibc (on all
architectures) and musl (on 32-bit architectures). 64-bit musl repacks
the [c]msghdr structures to zero out padding fields, and overlaying that
can lead to subtle bugs. However, I believe that overlaying musl is not
a very interesting use case, so I'm leaving that as a TODO. If someone
is interested in doing that, they can either exclude these entrypoints
from the overlay or implement the musl-compatible repacking code.
---
libc/config/linux/aarch64/entrypoints.txt | 33 +++++++++------
libc/config/linux/riscv/entrypoints.txt | 40 ++++++++++---------
libc/config/linux/x86_64/entrypoints.txt | 40 ++++++++++---------
.../src/sys/socket/linux/socketopt_test.cpp | 2 +-
4 files changed, 64 insertions(+), 51 deletions(-)
diff --git a/libc/config/linux/aarch64/entrypoints.txt b/libc/config/linux/aarch64/entrypoints.txt
index b15edc5e3e102..1a14d80497a65 100644
--- a/libc/config/linux/aarch64/entrypoints.txt
+++ b/libc/config/linux/aarch64/entrypoints.txt
@@ -278,9 +278,29 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.sys.resource.getrlimit
libc.src.sys.resource.setrlimit
- # sys/sendfile entrypoints
+ # sys/sendfile.h entrypoints
libc.src.sys.sendfile.sendfile
+ # sys/socket.h entrypoints
+ libc.src.sys.socket.accept
+ libc.src.sys.socket.accept4
+ libc.src.sys.socket.bind
+ libc.src.sys.socket.connect
+ libc.src.sys.socket.getsockopt
+ libc.src.sys.socket.listen
+ libc.src.sys.socket.recv
+ libc.src.sys.socket.recvfrom
+ libc.src.sys.socket.send
+ libc.src.sys.socket.sendto
+ libc.src.sys.socket.setsockopt
+ libc.src.sys.socket.shutdown
+ libc.src.sys.socket.socket
+ libc.src.sys.socket.socketpair
+ # TODO: These functions are not compatible with 64-bit musl. They need to
+ # be excluded if overlaying musl.
+ libc.src.sys.socket.recvmsg
+ libc.src.sys.socket.sendmsg
+
# sys/stat.h entrypoints
libc.src.sys.stat.chmod
libc.src.sys.stat.fchmod
@@ -1218,17 +1238,6 @@ if(LLVM_LIBC_FULL_BUILD)
# sys/select.h entrypoints
libc.src.sys.select.select
-
- # sys/socket.h entrypoints
- libc.src.sys.socket.accept
- libc.src.sys.socket.accept4
- libc.src.sys.socket.bind
- libc.src.sys.socket.connect
- libc.src.sys.socket.getsockopt
- libc.src.sys.socket.listen
- libc.src.sys.socket.setsockopt
- libc.src.sys.socket.shutdown
- libc.src.sys.socket.socket
)
endif()
diff --git a/libc/config/linux/riscv/entrypoints.txt b/libc/config/linux/riscv/entrypoints.txt
index 6478aed3b0391..9955c59fc01bf 100644
--- a/libc/config/linux/riscv/entrypoints.txt
+++ b/libc/config/linux/riscv/entrypoints.txt
@@ -278,9 +278,29 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.sys.resource.getrlimit
libc.src.sys.resource.setrlimit
- # sys/sendfile entrypoints
+ # sys/sendfile.h entrypoints
libc.src.sys.sendfile.sendfile
+ # sys/socket.h entrypoints
+ libc.src.sys.socket.accept
+ libc.src.sys.socket.accept4
+ libc.src.sys.socket.bind
+ libc.src.sys.socket.connect
+ libc.src.sys.socket.getsockopt
+ libc.src.sys.socket.listen
+ libc.src.sys.socket.recv
+ libc.src.sys.socket.recvfrom
+ libc.src.sys.socket.send
+ libc.src.sys.socket.sendto
+ libc.src.sys.socket.setsockopt
+ libc.src.sys.socket.shutdown
+ libc.src.sys.socket.socket
+ libc.src.sys.socket.socketpair
+ # TODO: These functions are not compatible with 64-bit musl. They need to
+ # be excluded if overlaying musl.
+ libc.src.sys.socket.recvmsg
+ libc.src.sys.socket.sendmsg
+
# sys/stat.h entrypoints
libc.src.sys.stat.chmod
libc.src.sys.stat.fchmod
@@ -1352,24 +1372,6 @@ if(LLVM_LIBC_FULL_BUILD)
# sys/select.h entrypoints
libc.src.sys.select.select
-
- # sys/socket.h entrypoints
- libc.src.sys.socket.accept
- libc.src.sys.socket.accept4
- libc.src.sys.socket.bind
- libc.src.sys.socket.connect
- libc.src.sys.socket.getsockopt
- libc.src.sys.socket.listen
- libc.src.sys.socket.setsockopt
- libc.src.sys.socket.shutdown
- libc.src.sys.socket.socket
- libc.src.sys.socket.socketpair
- libc.src.sys.socket.send
- libc.src.sys.socket.sendto
- libc.src.sys.socket.sendmsg
- libc.src.sys.socket.recv
- libc.src.sys.socket.recvfrom
- libc.src.sys.socket.recvmsg
)
endif()
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index d1c1d9496af67..ee60f1764a9f2 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -294,9 +294,29 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.sys.sem.semctl
libc.src.sys.sem.semop
- # sys/sendfile entrypoints
+ # sys/sendfile.h entrypoints
libc.src.sys.sendfile.sendfile
+ # sys/socket.h entrypoints
+ libc.src.sys.socket.accept
+ libc.src.sys.socket.accept4
+ libc.src.sys.socket.bind
+ libc.src.sys.socket.connect
+ libc.src.sys.socket.getsockopt
+ libc.src.sys.socket.listen
+ libc.src.sys.socket.recv
+ libc.src.sys.socket.recvfrom
+ libc.src.sys.socket.send
+ libc.src.sys.socket.sendto
+ libc.src.sys.socket.setsockopt
+ libc.src.sys.socket.shutdown
+ libc.src.sys.socket.socket
+ libc.src.sys.socket.socketpair
+ # TODO: These functions are not compatible with 64-bit musl. They need to
+ # be excluded if overlaying musl.
+ libc.src.sys.socket.recvmsg
+ libc.src.sys.socket.sendmsg
+
# sys/stat.h entrypoints
libc.src.sys.stat.chmod
libc.src.sys.stat.fchmod
@@ -1429,24 +1449,6 @@ if(LLVM_LIBC_FULL_BUILD)
# sys/select.h entrypoints
libc.src.sys.select.select
- # sys/socket.h entrypoints
- libc.src.sys.socket.accept
- libc.src.sys.socket.accept4
- libc.src.sys.socket.socket
- libc.src.sys.socket.bind
- libc.src.sys.socket.connect
- libc.src.sys.socket.getsockopt
- libc.src.sys.socket.listen
- libc.src.sys.socket.shutdown
- libc.src.sys.socket.socketpair
- libc.src.sys.socket.setsockopt
- libc.src.sys.socket.send
- libc.src.sys.socket.sendto
- libc.src.sys.socket.sendmsg
- libc.src.sys.socket.recv
- libc.src.sys.socket.recvfrom
- libc.src.sys.socket.recvmsg
-
# wchar.h entrypoints
libc.src.wchar.mblen
libc.src.wchar.mbrlen
diff --git a/libc/test/src/sys/socket/linux/socketopt_test.cpp b/libc/test/src/sys/socket/linux/socketopt_test.cpp
index e069a7bd35fa6..0e132a877d0c7 100644
--- a/libc/test/src/sys/socket/linux/socketopt_test.cpp
+++ b/libc/test/src/sys/socket/linux/socketopt_test.cpp
@@ -48,7 +48,7 @@ TEST_F(LlvmLibcSocketOptTest, BasicSocketOpt) {
ASSERT_THAT(
LIBC_NAMESPACE::getsockopt(sock, SOL_SOCKET, SO_TYPE, &optval, &optlen),
Succeeds(0));
- ASSERT_EQ(optval, SOCK_STREAM);
+ ASSERT_EQ(optval, static_cast<int>(SOCK_STREAM));
ASSERT_EQ(optlen, static_cast<socklen_t>(sizeof(optval)));
optval = SOCK_DGRAM;
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