Tools

Helper utility functions. More...

Functions
static bool	eif_strempty (const char *const str)
	Checks if a string is empty. More...
static size_t	eif_strnlen (const char *const str, size_t max_allowed)
	Computes the length of string. More...

Detailed Description

This module contains inline helper utilities designed for secure and defensive manipulation of strings, preventing common buffer overflows and null-pointer dereferences.

Function Documentation

eif_strempty()

static bool eif_strempty ( const char *const  str )

inlinestatic

Evaluates the provided string to determine if it is either a NULL pointer or points directly to a null-terminator (\0).

Parameters

str	Pointer to the string. Can be NULL.

Returns

• true: The string pointer is NULL or the string is empty ("").
• false: The string is valid and contains at least one character.

Example of use:

#include <esp_log.h>
#include <esp_iot_framework_core_ext.h>
 
#define TAG "STR_UTIL"
 
void validate_json_payload(const char * const payload) {
    const bool is_empty = eif_strempty(payload);
    if (is_empty == true) {
        ESP_LOGE(TAG, "Payload is completely empty or NULL.");
    } else {
        ESP_LOGI(TAG, "Payload validation passed.");
    }
}

eif_strnlen()

static size_t eif_strnlen ( const char *const  str, size_t  max_allowed  )

inlinestatic

Calculates the length of the string str, up to a maximum allowed bound specified by max_allowed.

Parameters

str	Constant pointer to the constant string to measure.
max_allowed	Maximum number of characters to examine, excluding the null-terminator.

Returns

• The number of characters in str if a null-terminator is found within the boundary. If str is NULL, returns 0U. If no null-terminator is found within the limit, returns the internal bounded limit.

Example of use:

#include <esp_log.h>
#include <esp_iot_framework_core_ext.h>
 
#define TAG "STR_UTIL"
#define MAX_BUFFER_SIZE 64U
 
void check_string_bounds(const char * const user_input) {
    const size_t calculated_len = eif_strnlen(user_input, MAX_BUFFER_SIZE);
   
    if (calculated_len > MAX_BUFFER_SIZE) {
        ESP_LOGE(TAG, "Input string exceeds maximum allowed limit of %u.", MAX_BUFFER_SIZE);
    } else {
        ESP_LOGI(TAG, "String length is safe: %zu bytes.", calculated_len);
    }
}