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[xferbuf] Simplify and generalise data transfer buffers

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Since all data transfer buffer contents are now accessible via direct
pointer dereferences, remove the unnecessary abstractions for read and
write operations and create two new data transfer buffer types: a
fixed-size buffer, and a void buffer that records its size but can
never receive non-zero lengths of data.  These replace the custom data
buffer types currently implemented for EFI PXE TFTP downloads and for
block device translations.

A new operation xferbuf_detach() is required to take ownership of the
data accumulated in the data transfer buffer, since we no longer rely
on the existence of an independently owned external data pointer for
data transfer buffers allocated via umalloc().

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2025-04-29 09:16:41 +01:00
parent 43fc516298
commit 837b77293b
7 changed files with 130 additions and 245 deletions
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146
src/core/xferbuf.c
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@@ -50,6 +50,21 @@ static struct profiler xferbuf_write_profiler __profiler =
static struct profiler xferbuf_read_profiler __profiler =
{ .name = "xferbuf.read" };
/**
* Detach data from data transfer buffer
*
* @v xferbuf Data transfer buffer
*
* The caller assumes responsibility for eventually freeing the data
* previously owned by the data transfer buffer.
*/
void xferbuf_detach ( struct xfer_buffer *xferbuf ) {
xferbuf->data = NULL;
xferbuf->len = 0;
xferbuf->pos = 0;
}
/**
* Free data transfer buffer
*
@@ -58,8 +73,7 @@ static struct profiler xferbuf_read_profiler __profiler =
void xferbuf_free ( struct xfer_buffer *xferbuf ) {
xferbuf->op->realloc ( xferbuf, 0 );
xferbuf->len = 0;
xferbuf->pos = 0;
xferbuf_detach ( xferbuf );
}
/**
@@ -109,9 +123,13 @@ int xferbuf_write ( struct xfer_buffer *xferbuf, size_t offset,
if ( ( rc = xferbuf_ensure_size ( xferbuf, max_len ) ) != 0 )
return rc;
/* Check that buffer is non-void */
if ( len && ( ! xferbuf->data ) )
return -ENOTTY;
/* Copy data to buffer */
profile_start ( &xferbuf_write_profiler );
xferbuf->op->write ( xferbuf, offset, data, len );
memcpy ( ( xferbuf->data + offset ), data, len );
profile_stop ( &xferbuf_write_profiler );
return 0;
@@ -133,9 +151,13 @@ int xferbuf_read ( struct xfer_buffer *xferbuf, size_t offset,
( len > ( xferbuf->len - offset ) ) )
return -ENOENT;
/* Check that buffer is non-void */
if ( len && ( ! xferbuf->data ) )
return -ENOTTY;
/* Copy data from buffer */
profile_start ( &xferbuf_read_profiler );
xferbuf->op->read ( xferbuf, offset, data, len );
memcpy ( data, ( xferbuf->data + offset ), len );
profile_stop ( &xferbuf_read_profiler );
return 0;
@@ -178,7 +200,7 @@ int xferbuf_deliver ( struct xfer_buffer *xferbuf, struct io_buffer *iobuf,
}
/**
* Reallocate malloc()-based data buffer
* Reallocate malloc()-based data transfer buffer
*
* @v xferbuf Data transfer buffer
* @v len New length (or zero to free buffer)
@@ -194,94 +216,76 @@ static int xferbuf_malloc_realloc ( struct xfer_buffer *xferbuf, size_t len ) {
return 0;
}
/**
* Write data to malloc()-based data buffer
*
* @v xferbuf Data transfer buffer
* @v offset Starting offset
* @v data Data to copy
* @v len Length of data
*/
static void xferbuf_malloc_write ( struct xfer_buffer *xferbuf, size_t offset,
const void *data, size_t len ) {
memcpy ( ( xferbuf->data + offset ), data, len );
}
/**
* Read data from malloc()-based data buffer
*
* @v xferbuf Data transfer buffer
* @v offset Starting offset
* @v data Data to read
* @v len Length of data
*/
static void xferbuf_malloc_read ( struct xfer_buffer *xferbuf, size_t offset,
void *data, size_t len ) {
memcpy ( data, ( xferbuf->data + offset ), len );
}
/** malloc()-based data buffer operations */
struct xfer_buffer_operations xferbuf_malloc_operations = {
.realloc = xferbuf_malloc_realloc,
.write = xferbuf_malloc_write,
.read = xferbuf_malloc_read,
};
/**
* Reallocate umalloc()-based data buffer
* Reallocate umalloc()-based data transfer buffer
*
* @v xferbuf Data transfer buffer
* @v len New length (or zero to free buffer)
* @ret rc Return status code
*/
static int xferbuf_umalloc_realloc ( struct xfer_buffer *xferbuf, size_t len ) {
void **udata = xferbuf->data;
void *new_udata;
new_udata = urealloc ( *udata, len );
new_udata = urealloc ( xferbuf->data, len );
if ( ! new_udata )
return -ENOSPC;
*udata = new_udata;
xferbuf->data = new_udata;
return 0;
}
/**
* Write data to umalloc()-based data buffer
*
* @v xferbuf Data transfer buffer
* @v offset Starting offset
* @v data Data to copy
* @v len Length of data
*/
static void xferbuf_umalloc_write ( struct xfer_buffer *xferbuf, size_t offset,
const void *data, size_t len ) {
void **udata = xferbuf->data;
memcpy ( ( *udata + offset ), data, len );
}
/**
* Read data from umalloc()-based data buffer
*
* @v xferbuf Data transfer buffer
* @v offset Starting offset
* @v data Data to read
* @v len Length of data
*/
static void xferbuf_umalloc_read ( struct xfer_buffer *xferbuf, size_t offset,
void *data, size_t len ) {
void **udata = xferbuf->data;
memcpy ( data, ( *udata + offset ), len );
}
/** umalloc()-based data buffer operations */
struct xfer_buffer_operations xferbuf_umalloc_operations = {
.realloc = xferbuf_umalloc_realloc,
.write = xferbuf_umalloc_write,
.read = xferbuf_umalloc_read,
};
/**
* Reallocate fixed-size data transfer buffer
*
* @v xferbuf Data transfer buffer
* @v len New length (or zero to free buffer)
* @ret rc Return status code
*/
static int xferbuf_fixed_realloc ( struct xfer_buffer *xferbuf, size_t len ) {
/* Refuse to allocate extra space */
if ( len > xferbuf->len ) {
/* Note that EFI relies upon this error mapping to
* EFI_BUFFER_TOO_SMALL.
*/
return -ERANGE;
}
return 0;
}
/** Fixed-size data buffer operations */
struct xfer_buffer_operations xferbuf_fixed_operations = {
.realloc = xferbuf_fixed_realloc,
};
/**
* Reallocate void data transfer buffer
*
* @v xferbuf Data transfer buffer
* @v len New length (or zero to free buffer)
* @ret rc Return status code
*/
static int xferbuf_void_realloc ( struct xfer_buffer *xferbuf,
size_t len __unused ) {
/* Succeed without ever allocating data */
assert ( xferbuf->data == NULL );
return 0;
}
/** Void data buffer operations */
struct xfer_buffer_operations xferbuf_void_operations = {
.realloc = xferbuf_void_realloc,
};
/**