px_sbuf.h : Safe buffer string appending functions that avoid overflow

Description

Safe buffer string appending functions that avoid overflow.

File(s):

• utils/inc/px_sbuf.h
• utils/src/px_sbuf.c

This module provides a mechanism to provide a fixed size character buffer and append characters and strings safely and avoiding buffer overflows.

Example:

#include <stdio.h>
#include <string.h>
 
#include "px_sbuf.h"
 
int main(void)
{
    px_sbuf_t sbuf;
    char      buf[16];
 
    // Test 1. Fill buffer with magic values to detect buffer overflow
    memset(buf, 0xcc, sizeof(buf));
    // Initialise safe buffer
    px_sbuf_init(&sbuf, buf, 8);
    // Append formatted strings
    px_sbuf_printf(&sbuf, "%u", 1234);
    px_sbuf_printf(&sbuf, "%u", 56789);
    // Report result
    printf("%s\n", sbuf.buf);
 
    // Test 2. Fill buffer with magic values to detect buffer overflow
    memset(buf, 0xcc, sizeof(buf));
    // Reset safe buffer
    px_sbuf_reset(&sbuf);
    // Append characters
    for(int i = 0; i < 16; i++)
    {
        px_sbuf_putchar(&sbuf, '0' + i);
    }
    // Report result
    printf("%s\n", sbuf.buf);
 
    // Test 3. Fill buffer with magic values to detect buffer overflow
    memset(buf, 0xcc, sizeof(buf));
    // Reset safe buffer
    px_sbuf_reset(&sbuf);
    // Append strings
    px_sbuf_print(&sbuf, "01234");
    px_sbuf_print(&sbuf, "56789");
    // Report result
    printf("%s\n", sbuf.buf);
 
    // Loop forever
    while(true) {;}
}

Data Structures
struct	px_sbuf_t

Functions
void	px_sbuf_init (px_sbuf_t *sbuf, char *buf, size_t buf_size)
	Initialise safe buffer. More...
void	px_sbuf_reset (px_sbuf_t *sbuf)
	Reset safe buffer. More...
bool	px_sbuf_is_empty (const px_sbuf_t *sbuf)
	Is safe buffer empty? More...
bool	px_sbuf_is_full (const px_sbuf_t *sbuf)
	Is safe buffer full. More...
void	px_sbuf_putchar (px_sbuf_t *sbuf, char c)
	Append a character to safe buffer. More...
void	px_sbuf_puts (px_sbuf_t *sbuf, const char *str)
	Append a string and newline character to safe buffer. More...
void	px_sbuf_print (px_sbuf_t *sbuf, const char *str)
	Append a string to safe buffer. More...
void	px_sbuf_printf (px_sbuf_t *sbuf, const char *format,...)
	Append a formatted string to safe buffer. More...

---

Data Structure Documentation

px_sbuf_t

struct px_sbuf_t

Definition at line 52 of file px_sbuf.h.

Data Fields
char *	buf	Pointer to character buffer.
size_t	buf_size	Size of character buffer.
size_t	index	Index of next character to be copied into buffer.

Function Documentation

px_sbuf_init()

void px_sbuf_init	(	px_sbuf_t *	sbuf,
		char *	buf,
		size_t	buf_size
	)

Initialise safe buffer.

Parameters

sbuf	Pointer to safe buffer object
buf	Pointer to character buffer
buf_size	Size of character buffer

Definition at line 39 of file px_sbuf.c.

px_sbuf_reset()

void px_sbuf_reset

(

px_sbuf_t *

sbuf

)

Reset safe buffer.

Parameters

sbuf	Pointer to buffer object

Definition at line 47 of file px_sbuf.c.

px_sbuf_is_empty()

bool px_sbuf_is_empty

(

const px_sbuf_t *

sbuf

)

Is safe buffer empty?

Parameters

sbuf	Pointer to safe buffer object

Return values

true	safe buffer is empty
false	safe buffer is not empty

Definition at line 53 of file px_sbuf.c.

px_sbuf_is_full()

bool px_sbuf_is_full

(

const px_sbuf_t *

sbuf

)

Is safe buffer full.

Parameters

sbuf	Pointer to safe buffer object

Return values

true	safe buffer is full
false	safe buffer is empty

Definition at line 65 of file px_sbuf.c.

px_sbuf_putchar()

void px_sbuf_putchar	(	px_sbuf_t *	sbuf,
		char	c
	)

Append a character to safe buffer.

Parameters

sbuf	Pointer to safe buffer object
c	Character to append

Definition at line 77 of file px_sbuf.c.

px_sbuf_puts()

void px_sbuf_puts	(	px_sbuf_t *	sbuf,
		const char *	str
	)

Append a string and newline character to safe buffer.

Parameters

sbuf	Pointer to safe buffer object
str	String to append

Definition at line 92 of file px_sbuf.c.

px_sbuf_print()

void px_sbuf_print	(	px_sbuf_t *	sbuf,
		const char *	str
	)

Append a string to safe buffer.

Parameters

sbuf	Pointer to safe buffer object
str	String to append

Definition at line 98 of file px_sbuf.c.

px_sbuf_printf()

void px_sbuf_printf	(	px_sbuf_t *	sbuf,
		const char *	format,
			...
	)

Append a formatted string to safe buffer.

Parameters

sbuf	Pointer to safe buffer object
format	Printf format string

Definition at line 131 of file px_sbuf.c.