--- a/src/buffer.c Sun Jan 05 14:03:30 2025 +0100
+++ b/src/buffer.c Sun Jan 05 18:19:42 2025 +0100
@@ -71,12 +71,18 @@
buffer->size = 0;
buffer->pos = 0;
- buffer->flush_func = NULL;
- buffer->flush_target = NULL;
- buffer->flush_blkmax = 0;
- buffer->flush_blksize = 4096;
- buffer->flush_threshold = SIZE_MAX;
+ buffer->flush = NULL;
+
+ return 0;
+}
+int cxBufferEnableFlushing(
+ CxBuffer *buffer,
+ CxBufferFlushConfig config
+) {
+ buffer->flush = malloc(sizeof(CxBufferFlushConfig));
+ if (buffer->flush == NULL) return -1; // LCOV_EXCL_LINE
+ memcpy(buffer->flush, &config, sizeof(CxBufferFlushConfig));
return 0;
}
@@ -84,6 +90,7 @@
if (buffer->flags & CX_BUFFER_FREE_CONTENTS) {
cxFree(buffer->allocator, buffer->bytes);
}
+ free(buffer->flush);
memset(buffer, 0, sizeof(CxBuffer));
}
@@ -196,39 +203,52 @@
}
}
-/**
- * Helps flushing data to the flush target of a buffer.
- *
- * @param buffer the buffer containing the config
- * @param space the data to flush
- * @param size the element size
- * @param nitems the number of items
- * @return the number of items flushed
- */
-static size_t cx_buffer_write_flush_helper(
- CxBuffer *buffer,
- const unsigned char *space,
+static size_t cx_buffer_flush_helper(
+ const CxBuffer *buffer,
size_t size,
+ const unsigned char *src,
size_t nitems
) {
- size_t pos = 0;
- size_t remaining = nitems;
- size_t max_items = buffer->flush_blksize / size;
- while (remaining > 0) {
- size_t items = remaining > max_items ? max_items : remaining;
- size_t flushed = buffer->flush_func(
- space + pos,
- size, items,
- buffer->flush_target);
+ // flush data from an arbitrary source
+ // does not need to be the buffer's contents
+ size_t max_items = buffer->flush->blksize / size;
+ size_t fblocks = 0;
+ size_t flushed_total = 0;
+ while (nitems > 0 && fblocks < buffer->flush->blkmax) {
+ fblocks++;
+ size_t items = nitems > max_items ? max_items : nitems;
+ size_t flushed = buffer->flush->wfunc(
+ src, size, items, buffer->flush->target);
if (flushed > 0) {
- pos += (flushed * size);
- remaining -= flushed;
+ flushed_total += flushed;
+ src += flushed * size;
+ nitems -= flushed;
} else {
// if no bytes can be flushed out anymore, we give up
break;
}
}
- return nitems - remaining;
+ return flushed_total;
+}
+
+static size_t cx_buffer_flush_impl(CxBuffer *buffer, size_t size) {
+ // flush the current contents of the buffer
+ unsigned char *space = buffer->bytes;
+ size_t remaining = buffer->pos / size;
+ size_t flushed_total = cx_buffer_flush_helper(
+ buffer, size, space, remaining);
+
+ // shift the buffer left after flushing
+ // IMPORTANT: up to this point, copy on write must have been
+ // performed already, because we can't do error handling here
+ cxBufferShiftLeft(buffer, flushed_total*size);
+
+ return flushed_total;
+}
+
+size_t cxBufferFlush(CxBuffer *buffer) {
+ if (buffer_copy_on_write(buffer)) return 0;
+ return cx_buffer_flush_impl(buffer, 1);
}
size_t cxBufferWrite(
@@ -249,20 +269,20 @@
}
size_t len;
- size_t nitems_out = nitems;
if (cx_szmul(size, nitems, &len)) {
errno = EOVERFLOW;
return 0;
}
+ if (buffer->pos > SIZE_MAX - len) {
+ errno = EOVERFLOW;
+ return 0;
+ }
size_t required = buffer->pos + len;
- if (buffer->pos > required) {
- return 0;
- }
bool perform_flush = false;
if (required > buffer->capacity) {
if (buffer->flags & CX_BUFFER_AUTO_EXTEND) {
- if (buffer->flush_blkmax > 0 && required > buffer->flush_threshold) {
+ if (buffer->flush != NULL && required > buffer->flush->threshold) {
perform_flush = true;
} else {
if (cxBufferMinimumCapacity(buffer, required)) {
@@ -270,71 +290,57 @@
}
}
} else {
- if (buffer->flush_blkmax > 0) {
+ if (buffer->flush != NULL) {
perform_flush = true;
} else {
- // truncate data to be written, if we can neither extend nor flush
+ // truncate data, if we can neither extend nor flush
len = buffer->capacity - buffer->pos;
if (size > 1) {
len -= len % size;
}
- nitems_out = len / size;
+ nitems = len / size;
}
}
}
+ // check here and not above because of possible truncation
if (len == 0) {
- return len;
+ return 0;
}
- if (perform_flush) {
- size_t flush_max;
- if (cx_szmul(buffer->flush_blkmax, buffer->flush_blksize, &flush_max)) {
- errno = EOVERFLOW;
- return 0;
- }
- size_t flush_pos = buffer->flush_func == NULL || buffer->flush_target == NULL
- ? buffer->pos
- : cx_buffer_write_flush_helper(buffer, buffer->bytes, 1, buffer->pos);
- if (flush_pos == buffer->pos) {
- // entire buffer has been flushed, we can reset
- buffer->size = buffer->pos = 0;
-
- size_t items_flush; // how many items can also be directly flushed
- size_t items_keep; // how many items have to be written to the buffer
+ // check if we need to copy
+ if (buffer_copy_on_write(buffer)) return 0;
- items_flush = flush_max >= required ? nitems : (flush_max - flush_pos) / size;
- if (items_flush > 0) {
- items_flush = cx_buffer_write_flush_helper(buffer, ptr, size, items_flush / size);
- // in case we could not flush everything, keep the rest
+ // perform the operation
+ if (perform_flush) {
+ size_t items_flush;
+ if (buffer->pos == 0) {
+ // if we don't have data in the buffer, but are instructed
+ // to flush, it means that we are supposed to relay the data
+ items_flush = cx_buffer_flush_helper(buffer, size, ptr, nitems);
+ if (items_flush == 0) {
+ // we needed to flush, but could not flush anything
+ // give up and avoid endless trying
+ return 0;
}
- items_keep = nitems - items_flush;
- if (items_keep > 0) {
- // try again with the remaining stuff
- const unsigned char *new_ptr = ptr;
- new_ptr += items_flush * size;
- // report the directly flushed items as written plus the remaining stuff
- return items_flush + cxBufferWrite(new_ptr, size, items_keep, buffer);
- } else {
- // all items have been flushed - report them as written
- return nitems;
+ size_t ritems = nitems - items_flush;
+ const unsigned char *rest = ptr;
+ rest += items_flush * size;
+ return items_flush + cxBufferWrite(rest, size, ritems, buffer);
+ } else {
+ items_flush = cx_buffer_flush_impl(buffer, size);
+ if (items_flush == 0) {
+ return 0;
}
- } else if (flush_pos == 0) {
- // nothing could be flushed at all, we immediately give up without writing any data
- return 0;
- } else {
- // we were partially successful, we shift left and try again
- cxBufferShiftLeft(buffer, flush_pos);
return cxBufferWrite(ptr, size, nitems, buffer);
}
} else {
- if (buffer_copy_on_write(buffer)) return 0;
memcpy(buffer->bytes + buffer->pos, ptr, len);
buffer->pos += len;
if (buffer->pos > buffer->size) {
buffer->size = buffer->pos;
}
- return nitems_out;
+ return nitems;
}
}