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Add BUF_MEM_reserve.

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BUF_MEM is actually a rather silly API for the SSL stack. There's separate
length and max fields, but init_buf effectively treats length as max and max as
nothing.

We possibly don't want to be using it long-term anyway (if nothing else, the
char*/uint8_t* thing is irritating), but in the meantime, it'll be easier to
separately fix up get_message's book-keeping and state tracking from where the
handshake gets its messages from.

Change-Id: I9e56ea008173991edc8312ec707505ead410a9ee
Reviewed-on: https://boringssl-review.googlesource.com/7947
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2016-05-13 17:00:49 -04:00 committed by Adam Langley
parent 4d559617cd
commit 1f9329aaf5
2 changed files with 29 additions and 21 deletions
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46
crypto/buf/buf.c
View File

@ -88,34 +88,26 @@ void BUF_MEM_free(BUF_MEM *buf) {
OPENSSL_free(buf);
}
static size_t buf_mem_grow(BUF_MEM *buf, size_t len, char clean) {
char *new_buf;
size_t n, alloc_size;
if (buf->length >= len) {
buf->length = len;
return len;
}
if (buf->max >= len) {
memset(&buf->data[buf->length], 0, len - buf->length);
buf->length = len;
return len;
static int buf_mem_reserve(BUF_MEM *buf, size_t cap, int clean) {
if (buf->max >= cap) {
return 1;
}
n = len + 3;
if (n < len) {
size_t n = cap + 3;
if (n < cap) {
/* overflow */
OPENSSL_PUT_ERROR(BUF, ERR_R_MALLOC_FAILURE);
return 0;
}
n = n / 3;
alloc_size = n * 4;
size_t alloc_size = n * 4;
if (alloc_size / 4 != n) {
/* overflow */
OPENSSL_PUT_ERROR(BUF, ERR_R_MALLOC_FAILURE);
return 0;
}
char *new_buf;
if (buf->data == NULL) {
new_buf = OPENSSL_malloc(alloc_size);
} else {
@ -128,14 +120,26 @@ static size_t buf_mem_grow(BUF_MEM *buf, size_t len, char clean) {
if (new_buf == NULL) {
OPENSSL_PUT_ERROR(BUF, ERR_R_MALLOC_FAILURE);
len = 0;
} else {
buf->data = new_buf;
buf->max = alloc_size;
memset(&buf->data[buf->length], 0, len - buf->length);
buf->length = len;
return 0;
}
buf->data = new_buf;
buf->max = alloc_size;
return 1;
}
int BUF_MEM_reserve(BUF_MEM *buf, size_t cap) {
return buf_mem_reserve(buf, cap, 0 /* don't clear old buffer contents. */);
}
static size_t buf_mem_grow(BUF_MEM *buf, size_t len, int clean) {
if (!buf_mem_reserve(buf, len, clean)) {
return 0;
}
if (buf->length < len) {
memset(&buf->data[buf->length], 0, len - buf->length);
}
buf->length = len;
return len;
}

4
include/openssl/buf.h
View File

@ -80,6 +80,10 @@ OPENSSL_EXPORT BUF_MEM *BUF_MEM_new(void);
/* BUF_MEM_free frees |buf->data| if needed and then frees |buf| itself. */
OPENSSL_EXPORT void BUF_MEM_free(BUF_MEM *buf);
/* BUF_MEM_reserve ensures |buf| has capacity |cap| and allocates memory if
* needed. It returns one on success and zero on error. */
OPENSSL_EXPORT int BUF_MEM_reserve(BUF_MEM *buf, size_t cap);
/* BUF_MEM_grow ensures that |buf| has length |len| and allocates memory if
* needed. If the length of |buf| increased, the new bytes are filled with
* zeros. It returns the length of |buf|, or zero if there's an error. */