Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / buffer.3
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124.\" ========================================================================
125.\"
126.IX Title "buffer 3"
e3261593 127.TH buffer 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
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132.SH "NAME"
133BUF_MEM_new, BUF_MEM_free, BUF_MEM_grow, BUF_strdup \- simple
134character arrays structure
135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 1
138\& #include <openssl/buffer.h>
e257b235 139\&
984263bc 140\& BUF_MEM *BUF_MEM_new(void);
e257b235 141\&
984263bc 142\& void BUF_MEM_free(BUF_MEM *a);
e257b235 143\&
984263bc 144\& int BUF_MEM_grow(BUF_MEM *str, int len);
e257b235 145\&
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146\& char * BUF_strdup(const char *str);
147.Ve
148.SH "DESCRIPTION"
8b0cefbb 149.IX Header "DESCRIPTION"
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150The buffer library handles simple character arrays. Buffers are used for
151various purposes in the library, most notably memory BIOs.
152.PP
8b0cefbb 153The library uses the \s-1BUF_MEM\s0 structure defined in buffer.h:
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154.PP
155.Vb 6
156\& typedef struct buf_mem_st
157\& {
158\& int length; /* current number of bytes */
159\& char *data;
160\& int max; /* size of buffer */
161\& } BUF_MEM;
162.Ve
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163.PP
164\&\fBlength\fR is the current size of the buffer in bytes, \fBmax\fR is the amount of
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165memory allocated to the buffer. There are three functions which handle these
166and one \*(L"miscellaneous\*(R" function.
167.PP
8b0cefbb 168\&\fIBUF_MEM_new()\fR allocates a new buffer of zero size.
984263bc 169.PP
8b0cefbb 170\&\fIBUF_MEM_free()\fR frees up an already existing buffer. The data is zeroed
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171before freeing up in case the buffer contains sensitive data.
172.PP
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173\&\fIBUF_MEM_grow()\fR changes the size of an already existing buffer to
174\&\fBlen\fR. Any data already in the buffer is preserved if it increases in
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175size.
176.PP
8b0cefbb 177\&\fIBUF_strdup()\fR copies a null terminated string into a block of allocated
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178memory and returns a pointer to the allocated block.
179Unlike the standard C library \fIstrdup()\fR this function uses \fIOPENSSL_malloc()\fR and so
180should be used in preference to the standard library \fIstrdup()\fR because it can
181be used for memory leak checking or replacing the \fImalloc()\fR function.
182.PP
183The memory allocated from \fIBUF_strdup()\fR should be freed up using the \fIOPENSSL_free()\fR
184function.
185.SH "RETURN VALUES"
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186.IX Header "RETURN VALUES"
187\&\fIBUF_MEM_new()\fR returns the buffer or \s-1NULL\s0 on error.
984263bc 188.PP
8b0cefbb 189\&\fIBUF_MEM_free()\fR has no return value.
984263bc 190.PP
8b0cefbb 191\&\fIBUF_MEM_grow()\fR returns zero on error or the new size (i.e. \fBlen\fR).
984263bc 192.SH "SEE ALSO"
74dab6c2 193.IX Header "SEE ALSO"
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194\&\fIbio\fR\|(3)
195.SH "HISTORY"
74dab6c2 196.IX Header "HISTORY"
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197\&\fIBUF_MEM_new()\fR, \fIBUF_MEM_free()\fR and \fIBUF_MEM_grow()\fR are available in all
198versions of SSLeay and OpenSSL. \fIBUF_strdup()\fR was added in SSLeay 0.8.