/**
* @brief Sorts list using mergesort algorithms.
* @param[in] i_head Pointer to the head of list.
*/
Node * p_mergesort(Node * i_head)
{
// list is empty or has only one node
if (i_head == nullptr || i_head->next == nullptr)
{
return i_head;
}
// split list into two halfs
Node * half = p_split(i_head);
// recursively sort two halfs
i_head = p_mergesort(i_head);
half = p_mergesort(half);
// merge sorted lists
return p_merge(i_head, half);
}
/*
This function specifies readPipe and writePipe, but in the prototype
the names are reversed: there writePipe and readPipe are used.
The prototype is given from the point of view of the parent code,
which first specifies the writePipe.
Here, we're in the child-process itself, and the parent's writePipe
becomes the child's readPipe.
*/
int p_child(Process *pp, int *readPipe, int *writePipe)
{
char **argv = p_split(pp); /* construct argv */
close(readPipe[WRITE]); /* Close unused pipe-ends */
close(writePipe[READ]);
if /* Use our descriptors for */
( /* standard streams */
dup2(readPipe[READ], STDIN_FILENO) < 0
||
dup2(writePipe[WRITE], STDOUT_FILENO) < 0
)
if (message_show(MSG_ALERT))
message("%s: Can't redirect STDIN and/or STDOUT");
close(readPipe[READ]); /* close superfluous original */
close(writePipe[WRITE]); /* parts */
return execvp(*argv, argv); /* exec the program */
/* (program exits or -1 is */
/* returned when exec fails */
}
