doc/crypto/buffer.pod

=pod

=head1 NAME

BUF_MEM_new, BUF_MEM_new_ex, BUF_MEM_free, BUF_MEM_grow - simple
character array structure

BUF_strdup, BUF_strndup, BUF_memdup, BUF_strlcpy, BUF_strlcat -
standard C library equivalents

=head1 SYNOPSIS

 #include <openssl/buffer.h>

 BUF_MEM *BUF_MEM_new(void);

 #define BUF_MEM_FLAG_SECURE

 BUF_MEM *BUF_MEM_new_ex(unsigned long flags);

 void	BUF_MEM_free(BUF_MEM *a);

 int	BUF_MEM_grow(BUF_MEM *str, int len);

 char *BUF_strdup(const char *str);

 char *BUF_strndup(const char *str, size_t siz);

 void *BUF_memdup(const void *data, size_t siz);

 size_t BUF_strlcpy(char *dst, const char *src, size_t size);

 size_t BUF_strlcat(char *dst, const char *src, size_t size);

 size_t BUF_strnlen(const char *str, size_t maxlen);

=head1 DESCRIPTION

The buffer library handles simple character arrays. Buffers are used for
various purposes in the library, most notably memory BIOs.

BUF_MEM_new() allocates a new buffer of zero size.

BUF_MEM_new_ex() allocates a buffer with the specified flags.
The flag B<BUF_MEM_FLAG_SECURE> specifies that the B<data> pointer
should be allocated on the secure heap; see L<CRYPTO_secure_malloc(3)>.

BUF_MEM_free() frees up an already existing buffer. The data is zeroed
before freeing up in case the buffer contains sensitive data.

BUF_MEM_grow() changes the size of an already existing buffer to
B<len>. Any data already in the buffer is preserved if it increases in
size.

BUF_strdup(), BUF_strndup(), BUF_memdup(), BUF_strlcpy(),
BUF_strlcat() and BUF_strnlen are equivalents of the standard C
library functions. The dup() functions use OPENSSL_malloc() underneath
and so should be used in preference to the standard library for memory
leak checking or replacing the malloc() function.

Memory allocated from these functions should be freed up using the
OPENSSL_free() function.

BUF_strndup makes the explicit guarantee that it will never read past
the first B<siz> bytes of B<str>.

=head1 RETURN VALUES

BUF_MEM_new() returns the buffer or NULL on error.

BUF_MEM_free() has no return value.

BUF_MEM_grow() returns zero on error or the new size (i.e. B<len>).

=head1 SEE ALSO

L<bio(3)>,
L<CRYPTO_secure_malloc(3)>.

=head1 HISTORY

BUF_MEM_new_ex() was added in OpenSSL 1.1.0.

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