Get information about a server connection
#include <sys/neutrino.h> int ConnectServerInfo( pid_t pid, int coid, struct _server_info* info ); int ConnectServerInfo_r( pid_t pid, int coid, struct _server_info* info );
- The process ID of the owner of the connection.
- The connection ID of the connection.
- NULL, or a pointer to a _server_info structure where the function can store information about the connection. For more information, see below.
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The ConnectServerInfo() and ConnectServerInfo_r() kernel calls get information about the connection coid owned by process pid, and store it in the structure pointed to by info. If the process doesn't have a connection coid, the call scans for the next higher connection and returns it if present. Otherwise, -1 is returned. If you wish to check for the existence of an exact connection, you must compare the returned connection with the coid you requested.
These functions are identical except in the way they indicate errors. See the Returns section for details.
If the info argument is NULL, ConnectServerInfo() ignores connections with dead servers and skips to the next coid. If info is non-NULL, the function fills in the _server_info structure; for connections with dead servers, it turns on the _NTO_COF_DEAD bit in the flags field of the structure.
The _server_info structure that info points to includes at least the following members:
- uint32_t nd
- The server's node descriptor, a temporary numeric description of a remote node; ND_LOCAL_NODE (or 0) is the descriptor for the local node.
- pid_t pid
- The server's process ID.
- int32_t chid
- The server's channel ID.
- int32_t scoid
- The server's connection ID.
- int32_t coid
- The client's connection ID.
- int16_t flags
- Flags that indicate the properties of the connection.
The bits include:
- _NTO_COF_CLOEXEC — the connection will be closed when your process calls an exec*() function to start a new process.
- _NTO_COF_DEAD — the connection is to a dead server.
- _NTO_COF_NOSHARE — some internal data structures aren't shared.
- _NTO_COF_NONBLOCK — don't block waiting if all the send headers are in use; for asynchronous messaging.
- _NTO_COF_ASYNC — the connection is for asynchronous messaging.
- _NTO_COF_GLOBAL — the connection is to a global channel.
The only difference between these functions is the way they indicate errors:
- A matched coid. If an error occurs, the function returns -1 and sets errno .
- A matched coid. This function does NOT set errno. If an error occurs, the function returns the negative of a value from the Errors section.
- A fault occurred when the kernel tried to access the buffers provided.
- Process pid doesn't have a connection >= coid.
- The process indicated by pid doesn't exist.