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string_utils.h
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1/*
2 * Copyright (C) 2022 Otto-von-Guericke-Universität Magdeburg
3 *
4 * This file is subject to the terms and conditions of the GNU Lesser General
5 * Public License v2.1. See the file LICENSE in the top level directory for more
6 * details.
7 */
8
24#include <assert.h>
25#include <errno.h>
26#include <stdint.h>
27/* if explicit_bzero() is provided by standard C lib, it may be defined in
28 * either `string.h` or `strings.h`, so just include both here */
29#include <string.h>
30#include <strings.h>
31#include <sys/types.h>
32
33#include "flash_utils.h"
34#include "modules.h"
35
36#ifndef STRING_UTILS_H
37#define STRING_UTILS_H
38
39#ifdef __cplusplus
40extern "C" {
41#endif
42
47typedef struct {
48 const char *start;
49 char *position;
50 size_t capacity;
51} string_writer_t;
52
60static inline void string_writer_init(string_writer_t *sw, void *buffer, size_t len)
61{
62 assert(buffer && len);
63
64 sw->start = buffer;
65 sw->position = buffer;
66 sw->capacity = len;
67 sw->position[0] = 0;
68}
69
75static inline size_t string_writer_len(const string_writer_t *sw)
76{
77 return sw->position - sw->start;
78}
79
85static inline const char *string_writer_str(const string_writer_t *sw)
86{
87 return sw->start;
88}
89
93#if IS_ACTIVE(HAS_FLASH_UTILS_ARCH)
94#define __swprintf flash_swprintf
95#else
96#define __swprintf swprintf
97__attribute__ ((format (printf, 2, 3)))
98#endif
111int __swprintf(string_writer_t *sw, FLASH_ATTR const char *restrict format, ...);
112
113#if IS_ACTIVE(HAS_FLASH_UTILS_ARCH)
114#define swprintf(sw, fmt, ...) flash_swprintf(sw, TO_FLASH(fmt), ## __VA_ARGS__)
115#endif
116
117/* explicit_bzero is provided if:
118 * - glibc is used as C lib (only with board natvie)
119 * - newlib is used and __BSD_VISIBILE is set
120 * - except for ESP8266, which is using an old version of newlib without it
121 * - picolibc is used and __BSD_VISIBLE is set
122 *
123 * for all other cases, we provide it here
124 */
125#if !defined(CPU_NATIVE) \
126 && !(IS_USED(MODULE_PICOLIBC) && __BSD_VISIBLE) \
127 && !(IS_USED(MODULE_NEWLIB) && __BSD_VISIBLE && !defined(CPU_ESP8266))
128
141static inline void explicit_bzero(void *dest, size_t n_bytes)
142{
143 volatile uint8_t *tmp = dest;
144 for (size_t i = 0; i < n_bytes; i++) {
145 tmp[i] = 0;
146 }
147}
148#endif
149
168ssize_t strscpy(char *dest, const char *src, size_t count);
169
180const void *memchk(const void *data, uint8_t c, size_t len);
181
182#ifdef __cplusplus
183}
184#endif
185
186#endif /* STRING_UTILS_H */
assert.h
POSIX.1-2008 compliant version of the assert macro.
assert
#define assert(cond)
abort the program if assertion is false
Definition assert.h:136
flash_utils.h
Utility functions, macros, and types for read-only memory.
printf
#define printf(...)
A wrapper for the printf() function that passes arguments through unmodified, but fails to compile if...
Definition stdio.h:60
FLASH_ATTR
#define FLASH_ATTR
C type qualifier required to place a variable in flash.
Definition flash_utils.h:68
strscpy
ssize_t strscpy(char *dest, const char *src, size_t count)
Copy the string, or as much of it as fits, into the dest buffer.
string_writer_len
static size_t string_writer_len(const string_writer_t *sw)
Get the size of the string contained by the string writer.
Definition string_utils.h:75
memchk
const void * memchk(const void *data, uint8_t c, size_t len)
Check if the entire buffer is filled with the same byte.
explicit_bzero
static void explicit_bzero(void *dest, size_t n_bytes)
Like memset(dest, 0, n_bytes), but secure.
Definition string_utils.h:141
__swprintf
#define __swprintf
internal helper macro
Definition string_utils.h:96
string_writer_str
static const char * string_writer_str(const string_writer_t *sw)
Get the string contained by the string writer.
Definition string_utils.h:85
string_writer_init
static void string_writer_init(string_writer_t *sw, void *buffer, size_t len)
Initialize a string writer structure.
Definition string_utils.h:60
modules.h
Common macros and compiler attributes/pragmas configuration.
strings.h
strings.h
string_writer_t
String Writer structure.
Definition string_utils.h:47
string_writer_t::position
char * position
current write pointer
Definition string_utils.h:49
string_writer_t::start
const char * start
start of the target buffer
Definition string_utils.h:48
string_writer_t::capacity
size_t capacity
remaining capacity of the buffer
Definition string_utils.h:50