Lines Matching +full:write +full:- +full:to +full:- +full:read

7 BIO_get_mem_ptr, BIO_new_mem_buf - memory BIO
28 written to a memory BIO is stored in a BUF_MEM structure which is extended
29 as appropriate to accommodate the stored data.
34 Any data written to a memory BIO can be recalled by reading from it.
35 Unless the memory BIO is read only any data read from it is deleted from
43 Calling BIO_reset() on a read write memory BIO clears any data in it if the
44 flag BIO_FLAGS_NONCLEAR_RST is not set, otherwise it just restores the read
45 pointer to the state it was just after the last write was performed and the
46 data can be read again. On a read only BIO it similarly restores the BIO to
47 its original state and the read only data can be read again.
56 zero then it will return B<v> when it is empty and it will set the read retry
57 flag (that is BIO_read_retry(b) is true). To avoid ambiguity with a normal
58 positive return value B<v> should be set to a negative value, typically -1.
60 BIO_get_mem_data() sets *B<pp> to a pointer to the start of the memory BIOs data
65 BIO_set_mem_buf() sets the internal BUF_MEM structure to B<bm> and sets the
66 close flag to B<c>, that is B<c> should be either BIO_CLOSE or BIO_NOCLOSE.
73 if B<len> is -1 then the B<buf> is assumed to be nul terminated and its
74 length is determined by B<strlen>. The BIO is set to a read only state and
75 as a result cannot be written to. This is useful when some data needs to be
77 supplied data is read directly from the supplied buffer: it is B<not> copied
82 Writes to memory BIOs will always succeed if memory is available: that is
85 Every write after partial read (not all data in the memory buffer was read)
86 to a read write memory BIO will have to move the unread data with an internal
87 copy operation, if a BIO contains a lot of data and it is read in small
89 a buffering BIO to the chain can speed up the process.
94 Switching the memory BIO from read write to read only is not supported and
96 exceptions to the rule. The first one is to assign a static memory buffer
97 immediately after BIO creation and set the BIO as read only.
99 The other supported sequence is to start with read write BIO then temporarily
100 switch it to read only and call BIO_reset() on the read only BIO immediately
101 before switching it back to read write. Before the BIO is freed it must be
102 switched back to the read write mode.
104 Calling BIO_get_mem_ptr() on read only BIO will return a BUF_MEM that
105 contains only the remaining data to be read. If the close status of the
106 BIO is set to BIO_NOCLOSE, before freeing the BUF_MEM the data pointer
107 in it must be set to NULL as the data pointer does not point to an
110 Calling BIO_reset() on a read write memory BIO with BIO_FLAGS_NONCLEAR_RST
111 flag set can have unexpected outcome when the reads and writes to the
112 BIO are intertwined. As documented above the BIO will be reset to the
113 state after the last completed write operation. The effects of reads
114 preceding that write operation cannot be undone.
116 Calling BIO_get_mem_ptr() prior to a BIO_reset() call with
117 BIO_FLAGS_NONCLEAR_RST set has the same effect as a write operation.
119 Calling BIO_set_close() with BIO_NOCLOSE orphans the BUF_MEM internal to the
125 There should be an option to set the maximum size of a memory BIO.
132 return 1 on success or a value which is less than or equal to 0 if an error occurred.
141 Create a memory BIO and write some data to it:
147 Create a read only memory BIO:
150  BIO *mem = BIO_new_mem_buf(data, -1);
170  bptr->data = NULL; /* Tell BUF_MEM to orphan data */
177 Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.