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px4_daemon server: fix packet reading

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By reading sizeof(packet), it could have happened that 2 packets at once
were read, and the second one was then ignored.
This makes sure that only one packet at a time is read.

The other 2 changes are for efficiency.
This commit is contained in:
Beat Küng
2018-08-06 08:10:43 +02:00
committed by Lorenz Meier
parent 1f0655302c
commit e6d71680ab
1 changed files with 23 additions and 5 deletions
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28
platforms/posix/src/px4_daemon/server.cpp
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@@ -124,12 +124,30 @@ Server::_server_main(void *arg)
client_send_packet_s packet;
int bytes_read = read(client_send_pipe_fd, &packet, sizeof(packet));
// We only read as much as we need, otherwise we might get out of
// sync with packets.
int bytes_read = read(client_send_pipe_fd, &packet, sizeof(client_send_packet_s::header));
if (bytes_read > 0) {
_parse_client_send_packet(packet);
} else if (bytes_read == 0) {
// Using the header we can determine how big the payload is.
int payload_to_read = sizeof(packet)
- sizeof(packet.header)
- sizeof(packet.payload)
+ packet.header.payload_length;
// Again, we only read as much as we need because otherwise we need
// hold a buffer and parse it.
bytes_read = read(client_send_pipe_fd, ((uint8_t *)&packet) + bytes_read, payload_to_read);
if (bytes_read > 0) {
_parse_client_send_packet(packet);
}
}
if (bytes_read == 0) {
// 0 means the pipe has been closed by all clients
// and we need to re-open it.
close(client_send_pipe_fd);
@@ -169,7 +187,7 @@ Server::_execute_cmd_packet(const client_send_packet_s &packet)
// We open the client's specific pipe to write the return value and stdout back to.
// The pipe's path is created knowing the UUID of the client.
char path[RECV_PIPE_PATH_LEN] = {};
char path[RECV_PIPE_PATH_LEN];
int ret = get_client_recv_pipe_path(packet.header.client_uuid, path, RECV_PIPE_PATH_LEN);
if (ret < 0) {
@@ -190,7 +208,7 @@ Server::_execute_cmd_packet(const client_send_packet_s &packet)
// We need to copy everything that the new thread needs because we will go
// out of scope.
RunCmdArgs *args = new RunCmdArgs;
memcpy(args->cmd, packet.payload.execute_msg.cmd, sizeof(args->cmd));
strncpy(args->cmd, (char *)packet.payload.execute_msg.cmd, sizeof(args->cmd));
args->client_uuid = packet.header.client_uuid;
args->pipe_fd = pipe_fd;
args->is_atty = packet.payload.execute_msg.is_atty;