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sd-bus/bus-socket: reinstate MSG_TRUNC handling in bus_socket_read_message()

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We switched away from recvmsg_safe() in order to gracefully
handle MSG_CTRUNC. But MSG_TRUNC really shouldn't happen.

While at it, do not use RET_NERRNO with ssize_t.
This commit is contained in:
Mike Yuan
2026-01-28 03:34:25 +01:00
parent 43e08aea6e
commit f452c324e7
1 changed files with 22 additions and 24 deletions
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src/libsystemd/sd-bus/bus-socket.c
+22 -24
View File
@@ -1397,14 +1397,8 @@ static int bus_socket_make_message(sd_bus *bus, size_t size) {
}
int bus_socket_read_message(sd_bus *bus) {
struct msghdr mh;
struct iovec iov = {};
ssize_t k;
size_t need;
int r;
void *b;
CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)) control;
bool handle_cmsg = false;
assert(bus);
assert(IN_SET(bus->state, BUS_RUNNING, BUS_HELLO));
@@ -1416,19 +1410,18 @@ int bus_socket_read_message(sd_bus *bus) {
if (bus->rbuffer_size >= need)
return bus_socket_make_message(bus, need);
b = realloc(bus->rbuffer, need);
void *b = realloc(bus->rbuffer, need);
if (!b)
return -ENOMEM;
bus->rbuffer = b;
iov = IOVEC_MAKE((uint8_t *)bus->rbuffer + bus->rbuffer_size, need - bus->rbuffer_size);
struct iovec iov = IOVEC_MAKE((uint8_t*) bus->rbuffer + bus->rbuffer_size, need - bus->rbuffer_size);
CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int) * BUS_FDS_MAX)) control;
struct msghdr mh;
bool handle_cmsg = false;
ssize_t k;
if (bus->prefer_readv) {
k = readv(bus->input_fd, &iov, 1);
if (k < 0)
k = -errno;
} else {
if (!bus->prefer_readv) {
mh = (struct msghdr) {
.msg_iov = &iov,
.msg_iovlen = 1,
@@ -1436,24 +1429,29 @@ int bus_socket_read_message(sd_bus *bus) {
.msg_controllen = sizeof(control),
};
k = RET_NERRNO(recvmsg(bus->input_fd, &mh, MSG_DONTWAIT|MSG_CMSG_CLOEXEC));
if (k == -ENOTSOCK) {
k = recvmsg(bus->input_fd, &mh, MSG_DONTWAIT|MSG_CMSG_CLOEXEC);
if (k < 0 && errno == ENOTSOCK)
bus->prefer_readv = true;
k = readv(bus->input_fd, &iov, 1);
if (k < 0)
k = -errno;
} else
else
handle_cmsg = true;
}
if (ERRNO_IS_NEG_TRANSIENT(k))
return 0;
if (k < 0)
return (int) k;
if (bus->prefer_readv)
k = readv(bus->input_fd, &iov, 1);
if (k < 0) {
if (ERRNO_IS_TRANSIENT(errno))
return 0;
return -errno;
}
if (k == 0) {
if (handle_cmsg)
cmsg_close_all(&mh); /* On EOF we shouldn't have gotten an fd, but let's make sure */
return -ECONNRESET;
}
if (handle_cmsg && FLAGS_SET(mh.msg_flags, MSG_TRUNC)) {
cmsg_close_all(&mh);
return -EXFULL;
}
bus->rbuffer_size += k;