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131 .IX Title "buffer 3"
132 .TH buffer 3 "2009-07-23" "0.9.8k" "OpenSSL"
133 .SH "NAME"
134 BUF_MEM_new, BUF_MEM_free, BUF_MEM_grow, BUF_strdup \- simple
135 character arrays structure
136 .SH "SYNOPSIS"
137 .IX Header "SYNOPSIS"
138 .Vb 1
139 \& #include <openssl/buffer.h>
140 .Ve
141 .PP
142 .Vb 1
143 \& BUF_MEM *BUF_MEM_new(void);
144 .Ve
145 .PP
146 .Vb 1
147 \& void BUF_MEM_free(BUF_MEM *a);
148 .Ve
149 .PP
150 .Vb 1
151 \& int BUF_MEM_grow(BUF_MEM *str, int len);
152 .Ve
153 .PP
154 .Vb 1
155 \& char * BUF_strdup(const char *str);
156 .Ve
157 .SH "DESCRIPTION"
158 .IX Header "DESCRIPTION"
159 The buffer library handles simple character arrays. Buffers are used for
160 various purposes in the library, most notably memory BIOs.
161 .PP
162 The library uses the \s-1BUF_MEM\s0 structure defined in buffer.h:
163 .PP
164 .Vb 6
165 \& typedef struct buf_mem_st
166 \& {
167 \& int length; /* current number of bytes */
168 \& char *data;
169 \& int max; /* size of buffer */
170 \& } BUF_MEM;
171 .Ve
172 .PP
173 \&\fBlength\fR is the current size of the buffer in bytes, \fBmax\fR is the amount of
174 memory allocated to the buffer. There are three functions which handle these
175 and one \*(L"miscellaneous\*(R" function.
176 .PP
177 \&\fIBUF_MEM_new()\fR allocates a new buffer of zero size.
178 .PP
179 \&\fIBUF_MEM_free()\fR frees up an already existing buffer. The data is zeroed
180 before freeing up in case the buffer contains sensitive data.
181 .PP
182 \&\fIBUF_MEM_grow()\fR changes the size of an already existing buffer to
183 \&\fBlen\fR. Any data already in the buffer is preserved if it increases in
184 size.
185 .PP
186 \&\fIBUF_strdup()\fR copies a null terminated string into a block of allocated
187 memory and returns a pointer to the allocated block.
188 Unlike the standard C library \fIstrdup()\fR this function uses \fIOPENSSL_malloc()\fR and so
189 should be used in preference to the standard library \fIstrdup()\fR because it can
190 be used for memory leak checking or replacing the \fImalloc()\fR function.
191 .PP
192 The memory allocated from \fIBUF_strdup()\fR should be freed up using the \fIOPENSSL_free()\fR
193 function.
194 .SH "RETURN VALUES"
195 .IX Header "RETURN VALUES"
196 \&\fIBUF_MEM_new()\fR returns the buffer or \s-1NULL\s0 on error.
197 .PP
198 \&\fIBUF_MEM_free()\fR has no return value.
199 .PP
200 \&\fIBUF_MEM_grow()\fR returns zero on error or the new size (i.e. \fBlen\fR).
201 .SH "SEE ALSO"
202 .IX Header "SEE ALSO"
203 \&\fIbio\fR\|(3)
204 .SH "HISTORY"
205 .IX Header "HISTORY"
206 \&\fIBUF_MEM_new()\fR, \fIBUF_MEM_free()\fR and \fIBUF_MEM_grow()\fR are available in all
207 versions of SSLeay and OpenSSL. \fIBUF_strdup()\fR was added in SSLeay 0.8.