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/**
 * @file datatop_stat_poll.c
 * @brief Adds ability for data collection from /proc/stat
 *
 * File contains methods for searching and polling data from
 * "/proc/stat"
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "datatop_interface.h"
#include "datatop_fileops.h"
#include "datatop_str.h"

#define DTOP_STAT_SIZE 16384
#define DTOP_STAT_LINE (DTOP_STAT_SIZE>>2)

/**
* @struct dtop_stat_vars
* @brief Struct used to hold necessary variables for /proc/stat dpg
*
* @var dtop_stat_vars::line
* Array of strings where necessary dp names and values are held.
* @var dtop_stat_vars::line_count
* Number of lines the file is that the dpg represents.
*/
struct dtop_stat_vars {
	char **line;
	int line_count;
};

/**
 * @brief Parses lines with data in "/proc/stat"
 *
 * @param line1 Line to parse to find datapoint names and values.
 * @param len1 Length of line1.
 * @param n_index Index in the dictionary the key (name) is added to.
 * @param v_index Index in the dictionary the value is added to.
 * @param dict Dictionary the keys and values are added to.
 */
static int dt_stat_parse(char *line1, int len1,
			int n_index, int v_index, struct dt_procdict *dict)
{
	int i, k, j, start = 0;
	if (len1 < 1)
		return 0;

	if (line1 == 0 || dict == 0)
		return 0;

	dict->key[n_index] = &line1[0];
	for (i = 0; i < len1; i++) {
		if (line1[i] == ' ') {
			line1[i] = 0;
			start = (i+1);
			break;
		}
	}

	k = v_index;
	for (i = start; i < len1 && k < DTOP_DICT_SIZE; i++) {
		if (line1[i] != ' ') {
			dict->val[k] = &line1[i];
			for (j = i; j < len1; j++) {
				if (line1[j] == ' ') {
					line1[j] = 0;
					break;
				}
			}
			i = j;
			k++;
		}
	}

	dict->max = k;
	return k;
}

/**
 * @brief Stores the data collected from "/proc/stat"
 *
 * @param dpg Struct that polled data is added to.
 * @return DTOP_POLL_IO_ERR - Poll of dpg unsuccessful.
 * @return DTOP_POLL_OK - Poll of dpg successful.
 */
int dtop_stat_poll(struct dtop_data_point_gatherer *dpg)
{
	char *data;
	int *line_len = malloc(sizeof(int) *
			((struct dtop_stat_vars *)
			(dpg->priv))->line_count);
	int read;
	struct dt_procdict dict;
	int i, n, sum;
	int dp_count = 0;

	read = dt_read_file(dpg->file, &data, DTOP_STAT_SIZE);
	if (read == 0 || data == 0)
		return DTOP_POLL_IO_ERR;

	sum = 0;
	/* Assigns each line read from the file, a length */
	for (n = 0; n < ((struct dtop_stat_vars *)
				(dpg->priv))->line_count; n++) {
		line_len[n] = dt_read_line(((struct dtop_stat_vars *)
					(dpg->priv))->line[n],
					   DTOP_STAT_LINE, data,
					   DTOP_STAT_SIZE, sum);
		if (n <= (((struct dtop_stat_vars *)
			(dpg->priv))->line_count - 1)) {
			sum += (line_len[n] + 1);
		}

	}

	/* Stores dp names and values in dictionary */
	for (i = 0; i < ((struct dtop_stat_vars *)(dpg->priv))->line_count; i++)
		dp_count = dt_stat_parse(((struct dtop_stat_vars *)
			(dpg->priv))->line[i], line_len[i], i, dp_count, &dict);

	/* Assigns the dp value to the dp struct */
	for (n = 0; n < dp_count; n++) {
		dtop_store_dp(&(dpg->data_points[n]),
				dict.val[n]);
	}

	dt_free(&data);
	free(line_len);
	return DTOP_POLL_OK;
}

/**
 * @brief Frees dynamically allocated "/proc/stat" dpg.
 *
 * Frees the memory of the dpg along with it's data_points
 * and other malloc'd memory no longer needed.
 *
 * @param dpg Dpg to deconstruct and deallocate memory for.
 */
static void dtop_stat_dpg_deconstructor
			(struct dtop_data_point_gatherer *dpset)
{
	int i;
	for (i = 0; i < dpset->data_points_len; i++)
		free(dpset->data_points[i].name);
	free(dpset->data_points);
	for (i = 0; i < ((struct dtop_stat_vars *)
				(dpset->priv))->line_count; i++)
		free(((struct dtop_stat_vars *)(dpset->priv))->line[i]);
	free(((struct dtop_stat_vars *)(dpset->priv))->line);
	free(((struct dtop_stat_vars *)(dpset->priv)));

	free(dpset);
}

/**
 * @brief Creates a dpg for "/proc/stat" file
 *
 * Dynamically allocates memory for dpg which is then added to a linked list
 * via the dtop_register(dpg) function call.
 *
 * @param data_points dtop_data_point struct that dpg points to.
 * @param storage dtop_stat_vars struct that holds relevant dpg variables.
 * @param dp_count Number of data_points in data_points array
 */
static void construct_stat_file_dpg(struct dtop_data_point
		*data_points, struct dtop_stat_vars *storage, int dp_count)
{
	struct dtop_data_point_gatherer *dpg = malloc
		(sizeof(struct dtop_data_point_gatherer));
	dpg->prefix = "/proc/stat";
	dpg->file = "/proc/stat";
	dpg->poll = dtop_stat_poll;
	dpg->data_points = data_points;
	dpg->priv = (struct dtop_stat_vars *)storage;
	dpg->data_points_len = dp_count;
	dpg->deconstruct = dtop_stat_dpg_deconstructor;

	dtop_register(dpg);
}

/**
 * @brief Scans "/proc/stat" in order to autodetect dps.
 *
 * Searches through "/proc/stat" file for all available data
 * points to create as dp structs.
 *
 * @param storage dtop_stat_vars struct where relevant variables are stored.
 */
int dtop_stat_search(struct dtop_stat_vars *storage)
{
	int i, n, sum;
	char *data;
	int *line_len = malloc(sizeof(int) * storage->line_count);
	int read;
	struct dt_procdict dict;
	int dp_count = 0;
	int end;
	int *dp_per_line;
	struct dtop_data_point *data_points;
	int count = 0;

	storage->line = malloc(storage->line_count * sizeof(*storage->line));

	for (i = 0; i < storage->line_count; i++)
		storage->line[i] = malloc(sizeof(char) * DTOP_STAT_LINE);

	read = dt_read_file("/proc/stat", &data, DTOP_STAT_SIZE);
	if (read == 0 || data == 0)
		return DTOP_POLL_IO_ERR;

	sum = 0;
	/* Assigns each line read from the file, a length */
	for (n = 0; n < storage->line_count; n++) {
		line_len[n] = dt_read_line(storage->line[n],
					   DTOP_STAT_LINE, data,
					   DTOP_STAT_SIZE, sum);
		if (n < (storage->line_count - 1))
			sum += (line_len[n] + 1);
	}

	dp_per_line = malloc(sizeof(int) * (storage->line_count));
	/* Stores dp names in dictionary */

	for (i = 0; i < (storage->line_count); i++) {
		end = dp_count;
		dp_count = dt_stat_parse(storage->line[i],
				line_len[i], i, dp_count, &dict);
		dp_per_line[i] = (dp_count - end);
	}

	data_points = malloc(dp_count * sizeof(struct dtop_data_point));

	for (i = 0; i < (storage->line_count); i++) {
		for (n = 0; n < dp_per_line[i]; n++) {
			if (dp_per_line[i] == 1) {
				int dk_len = strlen(dict.key[i]) + 1;
				int dp_len;
				char *newname = malloc(dk_len);
				strlcpy(newname, dict.key[i], dk_len);
				dp_len = strlen(newname) + 1;
				data_points[count].name = malloc(dp_len);
				strlcpy(data_points[count].name, newname,
					dp_len);
				free(newname);
			} else {
				char *add = malloc(15 * sizeof(char));
				char *newname;
				int nn_len, dpn_len;
				snprintf(add, 15 * sizeof(char), "[%d]:", n);
				nn_len = strlen(dict.key[i]) + strlen(add) + 1;
				newname = malloc(nn_len);
				strlcpy(newname, dict.key[i], nn_len);
				strlcat(newname, add, nn_len);
				dpn_len = strlen(newname) + 1;
				data_points[count].name = malloc(dpn_len);
				strlcpy(data_points[count].name, newname,
					dpn_len);
				free(newname);
				free(add);
			}
			data_points[count].prefix = NULL;
			data_points[count].type = DTOP_ULONG;
			data_points[count].initial_data_populated
						= NOT_POPULATED;
			data_points[count].skip = DO_NOT_SKIP;
			count++;
		}
	}

	/* Calls dpg constructor, dpg will point to the dp struct */
	construct_stat_file_dpg(data_points, storage, dp_count);
	free(dp_per_line);
	free(line_len);
	dt_free(&data);

	return DTOP_POLL_OK;
}

/**
 * @brief Calls dtop_search for "/proc/stat" file.
 */
void dtop_stat_init(void)
{
	struct dtop_stat_vars *storage = malloc
			(sizeof(struct dtop_stat_vars));
	storage->line_count = dtop_get_file_line_amount("/proc/stat");
	dtop_stat_search(storage);
}