
#include <sys/types.h>
#include <sys/sysctl.h>

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include <WINGs/WUtil.h>

#include "wconfig.h"

/*
 * copy argc and argv for an existing process identified by `pid'
 * into suitable storage given in ***argv and *argc.
 *
 * subsequent calls use the same static area for argv and argc.
 *
 * returns 0 for failure, in which case argc := 0 and argv := NULL
 * returns 1 for success
 */
Bool GetCommandForPid(int pid, char ***argv, int *argc)
#ifdef KERN_PROCARGS2
{
	int j, mib[4];
	unsigned int i, idx;
	size_t count;
	static char *args = NULL;
	static int argmax = 0;

	*argv = NULL;
	*argc = 0;

	/* the system-wide limit */
	if (argmax == 0) { /* it hopefully doesn't change at runtime *g* */
		mib[0] = CTL_KERN;
		mib[1] = KERN_ARGMAX;
		mib[2] = 0;
		mib[3] = 0;

		count = sizeof(argmax);
		if (sysctl(mib, 2, &argmax, &count, NULL, 0) == -1)
			return False;
	}

	/* if argmax is still 0, something went very seriously wrong */
	assert(argmax > 0);

	/* space for args; no need to free before returning even on errors */
	if (args == NULL)
		args = (char *)wmalloc(argmax);

	/* get process args */
	mib[0] = CTL_KERN;
	mib[1] = KERN_PROCARGS2;
	mib[2] = pid;

	count = argmax;
	if (sysctl(mib, 3, args, &count, NULL, 0) == -1 || count == 0)
		return False;

	/* get argc, skip */
	memcpy(argc, args, sizeof(*argc));
	idx = sizeof(*argc);

	while (args[idx++] != '\0')		/* skip execname */
		;
	while (args[idx] == '\0')		/* padding too */
		idx++;
	/* args[idx] is at at begininng of args now */

	*argv = (char **)wmalloc(sizeof(char *) * (*argc + 1 /* term. null ptr */));
	(*argv)[0] = args + idx;

	/* go through args, set argv[$next] to the beginning of each string */
	for (i = 0, j = 1; i < count - idx /* do not overrun */; i++) {
		if (args[idx + i] != '\0')
			continue;
		if (args[idx + i] == '\0')
			(*argv)[j++] = &args[idx + i + 1];
		if (j == *argc)
			break;
	}

	/* the list of arguments must be terminated by a null pointer */
	(*argv)[j] = NULL;
	return True;
}
#else /* !KERN_PROCARGS2 */
{
	*argv = NULL;
	*argc = 0;

	return False;
}
#endif
