Updated: April 19, 2023 |
Convert a node descriptor into a string
#include <sys/netmgr.h> int netmgr_ndtostr( unsigned flags, int nd, char * buf, size_t maxbuf );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The netmgr_ndtostr() function converts a node descriptor, nd, to a string and stores the string in the buffer pointed to by buf. The size of the buffer is given by maxbuf. If the string is too long to fit into the buffer, netmgr_ndtostr() truncates it. The function null-terminates the string.
A node descriptor is a temporary numeric description of a remote node. For more information, see the Qnet Networking chapter of the System Architecture guide.
The flags argument indicates which part(s) of the Fully Qualified Path Name (FQPN) to adjust. The following diagram shows the components for the FQPN, /net/my_node.qnx.com~preferred:
The Fully Qualified Node Name (FQNN) is my_node.qnx.com.
The default string that netmgr_ndtostr() builds is the FQNN, plus the Quality of Service (QoS) if it isn't the default (~loadbalance). A process on another node can pass this string to netmgr_strtond(), and get a node descriptor that refers to the same node and QoS as nd.
To specify what to include in the string, specify a bitwise OR of the following bits in the flags argument:
netmgr_ndtostr(ND2S_DIR_SHOW, nd, buf, sizeofbuf)
on a node with a default domain of qnx.com using a nd that refers to a FQNN of peterv.qnx.com results in the string, /net/peterv.qnx.com/.
If Qnet isn't active on the node, and netmgr_ndtostr(ND2S_DIR_SHOW, nd, buf, sizeofbuf) has a nd of ND_LOCAL_NODE, then the string is /.
netmgr_ndtostr(ND2S_LOCAL_STR, nd, buf, sizeofbuf)
on a node with a default domain of qnx.com using a nd that refers to an FQPN of /net/peterv.qnx.com results in a string of peterv, whereas a nd that refers to /net/peterv.anotherhost.com results in peterv.anotherhost.com.
netmgr_ndtostr(ND2S_SEP_FORCE | ND2S_DIR_HIDE | ND2S_NAME_HIDE| ND2S_DOMAIN_HIDE | ND2S_QOS_SHOW, nd, buf, sizeofbuf)
with a nd of ND_LOCAL_NODE results in a string of ~loadbalance. This is useful if you want to concatenate each component of the FQPN individually.
By combining the above bits in various combinations, you can extract all sorts of interesting information. For example:
The length of the string including the NUL byte, or -1 if an error occurs (errno is set).
#include <stdio.h> #include <stdlib.h> #include <sys/netmgr.h> int main () { int nd1, nd2, nd3, len; char path1[50] = "/net/dave", path2[50] = "/net/karen", buff[100]; nd1 = netmgr_strtond( path1, NULL); if (nd1 == -1) { perror ("netmgr_strtond" ); return EXIT_FAILURE; } else { printf ("Node id for %s is %d.\n", path1, nd1); } nd2 = netmgr_strtond( path2, NULL); if (nd2 == -1) { perror ("netmgr_strtond" ); return EXIT_FAILURE; } else { printf ("Node id for %s is %d.\n", path2, nd2); } nd3 = netmgr_remote_nd ( nd2, nd1 ); if (nd3 == -1) { perror ("netmgr_strtond" ); return EXIT_FAILURE; } else { printf ("Node id for %s, relative to %s, is %d.\n", path1, path2, nd3); } len = netmgr_ndtostr ( ND2S_DIR_HIDE | ND2S_DOMAIN_SHOW | ND2S_NAME_SHOW | ND2S_QOS_SHOW, nd1, buff, 100 ); if (len == -1) { perror ("netmgr_ndtostr" ); } else { printf ("Node name for %d is %s.\n", nd1, buff); return EXIT_FAILURE; } return EXIT_SUCCESS; }
Safety: | |
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Cancellation point | Yes |
Interrupt handler | No |
Signal handler | Yes |
Thread | Yes |