plist.h File Reference

Linked List for maintaining process id - command line pairs. More...

#include <sys/types.h>

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Functions
int	insertElement (pid_t pid, const char *commandLine)
	Inserts a new pid-command line pair into the linked list.
int	removeElement (pid_t pid, char *commandLineBuffer, size_t bufferSize)
	Remove a specific pid-command line pair from the linked list.
void	rewindPList ()
	Reset the list iterator position to the head of the list.
int	nextElement (const char **cmdLine, pid_t *pid)
	Provides the next element in the list and advances the list iterator.

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Detailed Description

Linked List for maintaining process id - command line pairs.

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Function Documentation

int insertElement	(	pid_t	pid,
		const char *	commandLine
	)

Inserts a new pid-command line pair into the linked list.

During the insert operation, the passed commandLine is copied to an internally allocated buffer. The caller may free or otherwise reuse the memory occupied by commandLine after return from insertElement.

Parameters:

	pid	The process id of the pair that is to be inserted.
	commandLine	The commandLine corresponding to the process with id pid.

Returns:

pid on success, negative value on error

Return values:

	pid	success
	-1	a pair with the given pid already exists
	-2	insufficient memory to complete the operation

int nextElement	(	const char **	cmdLine,
		pid_t *	pid
	)

Provides the next element in the list and advances the list iterator.

This functions returns the command line and the pid of the current position of the list iterator, and advances the iterator to the next element afterwards. The function provides a pointer to the internal storage allocated for the commandLine. This storage must not be used after the element was removed using the removeElement function. The implementation of nextElement is not thread safe. A list traversal must not be interleaved by insertElement or removeElement operations.

Parameters:

	cmdLine	Pointer to a location, where a pointer to the interal storage location of command line can be written to.
	pid	Pointer to a location suitable to store a pid value.

Returns:

0 on success, negative value when the iterator has reached the end of the list

int removeElement	(	pid_t	pid,
		char *	commandLineBuffer,
		size_t	bufferSize
	)

Remove a specific pid-command line pair from the linked list.

The linked list is searched for a pair with the given pid. If such a pair is found, the '\0'-terminated command line is copied to the buffer provided by the caller. If the length of the command line exceeds the size of the buffer, only the first (buffersize-1) characters of the command line are copied to the buffer and terminated with the '\0' character. Upon completion, removeElement deallocates all resources that were occupied by the removed pair.

Parameters:

	pid	The process id of the pair that is to be removed.
	commandLineBuffer	A buffer provided by the caller that the '\0'-terminated commandline is written to.
	bufferSize	The size of commandLineBuffer.

Returns:

actual length of the command line on success, negative value on error.

Return values:

	>0	success, actual length of the command line
	-1	a pair with the given pid does not exist

void rewindPList

(

)

Reset the list iterator position to the head of the list.

This function should be invoked before starting a list traversal with the nextElement() function. The internal position of the list iterator is reset to the head of the list.