php-src/main/snprintf.h at master · php/php-src · GitHub

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+----------------------------------------------------------------------+

| This source file is subject to the Modified BSD License that is |

| bundled with this package in the file LICENSE, and is available |

| through the World Wide Web at <https://www.php.net/license/>. |

| |

| SPDX-License-Identifier: BSD-3-Clause |

+----------------------------------------------------------------------+

| Author: Stig Sæther Bakken <ssb@php.net> |

| Marcus Boerger <helly@php.net> |

+----------------------------------------------------------------------+

Comparing: sprintf, snprintf, slprintf, spprintf

sprintf offers the ability to make a lot of failures since it does not know

the size of the buffer it uses. Therefore usage of sprintf often

results in possible entries for buffer overrun attacks. So please

use this version only if you are sure the call is safe. sprintf

always terminates the buffer it writes to.

snprintf knows the buffers size and will not write behind it. But you will

have to use either a static buffer or allocate a dynamic buffer

before being able to call the function. In other words you must

be sure that you really know the maximum size of the buffer required.

A bad thing is having a big maximum while in most cases you would

only need a small buffer. If the size of the resulting string is

longer or equal to the buffer size than the buffer is not terminated.

The function also returns the number of chars not including the

terminating \0 that were needed to fully comply to the print request.

slprintf same as snprintf with the difference that it actually returns the

length printed not including the terminating \0.

spprintf is the dynamical version of snprintf. It allocates the buffer in size

as needed and allows a maximum setting as snprintf (turn this feature

off by setting max_len to 0). spprintf is a little bit slower than

snprintf and offers possible memory leaks if you miss freeing the

buffer allocated by the function. Therefore this function should be

used where either no maximum is known or the maximum is much bigger

than normal size required. spprintf always terminates the buffer.

Example:

#define MAX 1024 | #define MAX 1024 | #define MAX 1024

char buffer[MAX] | char buffer[MAX] | char *buffer;

| |

| | // No need to initialize buffer:

| | // spprintf ignores value of buffer

sprintf(buffer, "test"); | snprintf(buffer, MAX, "test"); | spprintf(&buffer, MAX, "text");

| | if (!buffer)

| | return OUT_OF_MEMORY

// sprintf always terminates | // manual termination of | // spprintf allays terminates buffer

// buffer | // buffer *IS* required |

| buffer[MAX-1] = 0; |

action_with_buffer(buffer); | action_with_buffer(buffer); | action_with_buffer(buffer);

| | efree(buffer);

#ifndef SNPRINTF_H

#define SNPRINTF_H

#include <stdbool.h>

BEGIN_EXTERN_C()

PHPAPI int ap_php_slprintf(char *buf, size_t len, const char *format,...) ZEND_ATTRIBUTE_FORMAT(printf, 3, 4);

PHPAPI int ap_php_vslprintf(char *buf, size_t len, const char *format, va_list ap);

PHPAPI int ap_php_snprintf(char *, size_t, const char *, ...) ZEND_ATTRIBUTE_FORMAT(printf, 3, 4);

PHPAPI int ap_php_vsnprintf(char *, size_t, const char *, va_list ap);

PHPAPI int ap_php_vasprintf(char **buf, const char *format, va_list ap);

PHPAPI int ap_php_asprintf(char **buf, const char *format, ...) ZEND_ATTRIBUTE_FORMAT(printf, 2, 3);

PHPAPI char * php_0cvt(double value, int ndigit, char dec_point, char exponent, char *buf);

PHPAPI char * php_conv_fp(char format, double num,

bool add_dp, int precision, char dec_point, bool * is_negative, char *buf, size_t *len);

END_EXTERN_C()

#define php_gcvt zend_gcvt

#ifdef slprintf

#undef slprintf

#endif

#define slprintf ap_php_slprintf

#ifdef vslprintf

#undef vslprintf

#endif

#define vslprintf ap_php_vslprintf

#ifdef snprintf

#undef snprintf

#endif

#define snprintf ap_php_snprintf

#ifdef vsnprintf

#undef vsnprintf

#endif

#define vsnprintf ap_php_vsnprintf

#ifndef HAVE_VASPRINTF

#define vasprintf ap_php_vasprintf

#endif

#ifndef HAVE_ASPRINTF

#define asprintf ap_php_asprintf

#endif

typedef enum {

LM_STD = 0,

LM_INTMAX_T,

LM_PTRDIFF_T,

#if SIZEOF_LONG_LONG

LM_LONG_LONG,

#endif

LM_SIZE_T,

LM_LONG,

LM_LONG_DOUBLE,

} length_modifier_e;

PHPAPI char * ap_php_conv_10(int64_t num, bool is_unsigned,

bool * is_negative, char *buf_end, size_t *len);

PHPAPI char * ap_php_conv_p2(uint64_t num, int nbits,

char format, char *buf_end, size_t *len);

#endif /* SNPRINTF_H */

php-src/main/snprintf.h at master · php/php-src · GitHub

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