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

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

#define DTOP_MEM_SIZE 8192
#define DTOP_MEM_LINE (DTOP_MEM_SIZE>>2)

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

/**
 * @brief Parses lines with data in "/proc/meminfo"
 *
 * @param line1 Line to parse to find datapoint names and values.
 * @param len1 Length of line1.
 * @param l Index in the dictionary the key/value pair is added to.
 * @param dict Dictionary the keys and values are added to.
 */
int dt_meminfo_parse(char *line1, int len1,
			int l, struct dt_procdict *dict)
{
	int i, k, n;
	if (len1 < 1)
		return 0;

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

	k = l;
	dict->key[k] = &line1[0];
	for (i = 0; i < len1 && k < DTOP_DICT_SIZE; i++) {
		if (line1[i] == ' ' || line1[i] == '	') {
			line1[i] = 0;
			n = i+1;
			while (line1[n] == '	' || line1[n] == ' ')
				n++;
			dict->val[k] = &line1[n];
			while (line1[n] != ' ')
				n++;
			line1[n] = 0;
			break;
		}
	}
	k++;
	dict->max = k;
	return k;
}

/**
 * @brief Stores the data collected from a "/proc/meminfo"
 *
 * @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_meminfo_poll(struct dtop_data_point_gatherer *dpg)
{
	char *data;
	int *line_len = malloc(sizeof(int) *
			((struct dtop_meminfo_vars *)
			(dpg->priv))->line_count);
	int read;
	struct dt_procdict dict;
	int i, j, n, sum;

	read = dt_read_file(dpg->file, &data, DTOP_MEM_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_meminfo_vars *)
				(dpg->priv))->line_count; n++) {
		line_len[n] = dt_read_line(((struct dtop_meminfo_vars *)
					(dpg->priv))->line[n],
					   DTOP_MEM_LINE, data,
					   DTOP_MEM_SIZE, sum);
		if (n <= (((struct dtop_meminfo_vars *)
			(dpg->priv))->line_count - 1)) {
			sum += (line_len[n] + 1);
		}

	}

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

	/* Assigns the dp value to the dp struct */
	for (j = 0; j < dpg->data_points_len; j++) {
		i = dt_find_dict_idx(dpg->data_points[j].name, &dict);
		if (i >= 0 && i < dict.max) {
			sscanf(dict.val[i], "%" PRIu64,
			       &(dpg->data_points[i].data.d_ulong));
			dpg->data_points[i].data.d_ulong *= 1024;
			if (dpg->data_points[i].
				initial_data_populated == NOT_POPULATED) {
				dpg->data_points[i].initial_data.d_ulong
					= dpg->data_points[i].data.d_ulong;
				dpg->data_points[i].initial_data_populated
					= POPULATED;
			}
		}
	}

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

/**
 * @brief Frees dynamically allocated "/proc/meminfo" 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_meminfo_dpg_deconstructor
			(struct dtop_data_point_gatherer *dpset)
{
	int i;
	free(dpset->data_points);
	for (i = 0; i < ((struct dtop_meminfo_vars *)
				(dpset->priv))->line_count; i++)
		free(((struct dtop_meminfo_vars *)(dpset->priv))->line[i]);
	free(((struct dtop_meminfo_vars *)(dpset->priv))->line);
	free(((struct dtop_meminfo_vars *)(dpset->priv)));
	free(dpset);
}

/**
 * @brief Creates a dpg for "/proc/meminfo" 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_meminfo_vars struct that holds relevant dpg variables.
 */
static void construct_meminfo_file_dpg(struct dtop_data_point
		*data_points, struct dtop_meminfo_vars *storage)
{
	struct dtop_data_point_gatherer *dpg = malloc
		(sizeof(struct dtop_data_point_gatherer));
	dpg->prefix = "/proc/meminfo";
	dpg->file = "/proc/meminfo";
	dpg->poll = dtop_meminfo_poll;
	dpg->data_points = data_points;
	dpg->priv = (struct dtop_meminfo_vars *)storage;
	dpg->data_points_len = storage->line_count;
	dpg->deconstruct = dtop_meminfo_dpg_deconstructor;

	dtop_register(dpg);
}

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

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

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

	read = dt_read_file("/proc/meminfo", &data, DTOP_MEM_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_MEM_LINE, data,
					   DTOP_MEM_SIZE, sum);
		if (n < (storage->line_count - 1))
			sum += (line_len[n] + 1);
	}

	/* Stores dp names in dictionary */
	for (i = 0; i < (storage->line_count); i++)
		dt_parse_proc_same_line_key_and_val(storage->line[i],
						line_len[i], i, &dict);

	data_points = malloc
		       (storage->line_count * sizeof(struct dtop_data_point));

	k = 0;
	/* Creates a dtop_data_point struct for each dp found in the file */
	for (i = 0; i < dict.max; i++) {
		data_points[i].name = dict.key[i];
		data_points[i].prefix = NULL;
		data_points[i].type = DTOP_ULONG;
		k++;
	}

	/* Calls dpg constructor, dpg will point to the dp struct */
	construct_meminfo_file_dpg(data_points, storage);

	free(line_len);
	dt_free(&data);

	return DTOP_POLL_OK;
}

/**
 * @brief Calls dtop_search for "/proc/meminfo" file.
 */
void dtop_meminfo_init(void)
{
	struct dtop_meminfo_vars *storage = malloc
			(sizeof(struct dtop_meminfo_vars));
	storage->line_count = dtop_get_file_line_amount("/proc/meminfo");
	dtop_meminfo_search(storage);
}