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ipc_check_perms(9) [centos man page]

IPC_CHECK_PERMS(9)					       Kernel IPC facilities						IPC_CHECK_PERMS(9)

NAME
ipc_check_perms - check security and permissions for an IPC SYNOPSIS
int ipc_check_perms(struct ipc_namespace * ns, struct kern_ipc_perm * ipcp, struct ipc_ops * ops, struct ipc_params * params); ARGUMENTS
ns IPC namespace ipcp ipc permission set ops the actual security routine to call params its parameters DESCRIPTION
This routine is called by sys_msgget, sys_semget and sys_shmget when the key is not IPC_PRIVATE and that key already exists in the ids IDR. On success, the IPC id is returned. It is called with ipc_ids.rwsem and ipcp->lock held. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 IPC_CHECK_PERMS(9)

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PMLOOKUPIPC(3)						     Library Functions Manual						    PMLOOKUPIPC(3)

NAME
__pmAddIPC, __pmLookupIPC, __pmFdLookupIPC, __pmOverrideLastFd, __pmPrintIPC, __pmResetIPC - IPC version infrastructure support C SYNOPSIS
#include <pcp/pmapi.h> #include <pcp/impl.h> int __pmAddIPC(int fd, __pmIPC ipc); int __pmLookupIPC(__pmIPC **ipcp); int __pmFdLookupIPC(int fd, __pmIPC **ipcp); void __pmOverrideLastFd(int fd); void __pmPrintIPC(void); void __pmResetIPC(int fd); cc ... -lpcp DESCRIPTION
IPC channels throughout the distributed PCP framework are affected by the PCP 2.0 (and later) PDU changes. These functions are the inter- face to the libpcp IPC connection management global data. This data consists of a hash table of __pmIPC structures (indexed by file descriptor) and a cached, most-recently-used file descriptor. Newly created IPC channels must be registered with the hash table using __pmAddIPC, such that the PDU sending and decoding routines can determine whether they need to perform any PDU version translations or not, for backward compatibility with previous the PCP 1.x IPC proto- col. __pmLookupIPC and __pmFdLookupIPC both provide handles to the __pmIPC structure associated with the given file descriptor, as previously established by a call to __pmAddIPC. The difference between the two is that one allows an explicit file descriptor lookup, and the other uses the cached, most-recently-used file descriptor. So __pmLookupIPC actually calls __pmFdLookupIPC using this cached file descriptor as the argument. The justification for having both is that in some places it is not possible to use __pmFdLookupIPC (which is preferred), since at that particular level of the PMAPI a file descriptor is not available (see the __pmDecodeError code for an example). The __pmOverrideLastFd is an escape mechanism for use in those situations where the last PDU fetch did not go through the usual channels (ie. __pmGetPDU), so as to ensure that the cached file descriptor is the correct file descriptor for the PDU which is currently being pro- cessed. This will typically be used for archive PDU processing or where version information is not available for a given file descriptor (eg. immediately prior to a PDU version exchange). __pmPrintIPC is a useful debugging routine for displaying a table mapping all currently registered file descriptors to their associated PDU version numbers. Unused entries in this table should display the value zero in the version column. __pmResetIPC resets the version information associated with the given file descriptor to some known (invalid) number. Subsequent lookups on this file descriptor will return an UNKNOWN_VERSION embedded within the __pmIPC structure. SEE ALSO
PMAPI(3) DIAGNOSTICS
A negative return value from __pmLookupIPC indicates that the requested file descriptor is not registered in the hash table. This typi- cally indicates closure of an IPC channel, so PM_ERR_IPC is returned if this is the case. Performance Co-Pilot PCP PMLOOKUPIPC(3)
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