ringbuffer, guid, iovec stuff, and mmio

core/lib/iovec.c

@@ -0,0 +1,53 @@
+#include <zinnia/iovec.h>
+#include <zinnia/usercopy.h>
+#include <zinnia/utils.h>
+#include <string.h>
+
+// Copies between `buf` and the iterator. If `to_iter` is set, data flows from `buf` into the iovecs.
+static errno_t iovec_iter_copy(iovec_iter_t* iter, void* buf, size_t len, bool to_iter, size_t* out_copied) {
+    size_t progress = 0;
+    errno_t status = 0;
+
+    while (progress < len && iter->current_idx < iter->iovecs_len) {
+        iovec_t* vec = &iter->iovecs[iter->current_idx];
+        size_t remaining = vec->len - iter->current_offset;
+        if (remaining == 0) {
+            iter->current_idx++;
+            iter->current_offset = 0;
+            continue;
+        }
+
+        size_t chunk = MIN(remaining, len - progress);
+        void* ptr = (void*)(vec->base + iter->current_offset);
+        uint8_t* kbuf = (uint8_t*)buf + progress;
+
+        if (iter->user) {
+            bool ok = to_iter ? usercopy_write((__user void*)ptr, kbuf, chunk)
+                              : usercopy_read(kbuf, (const __user void*)ptr, chunk);
+            if (!ok) {
+                status = EFAULT;
+                break;
+            }
+        } else if (to_iter) {
+            memcpy(ptr, kbuf, chunk);
+        } else {
+            memcpy(kbuf, ptr, chunk);
+        }
+
+        progress += chunk;
+        iter->current_offset += chunk;
+        iter->total_offset += chunk;
+    }
+
+    if (out_copied)
+        *out_copied = progress;
+    return status;
+}
+
+errno_t iovec_iter_copy_to(iovec_iter_t* iter, const void* src, size_t len, size_t* out_copied) {
+    return iovec_iter_copy(iter, (void*)src, len, true, out_copied);
+}
+
+errno_t iovec_iter_copy_from(iovec_iter_t* iter, void* dst, size_t len, size_t* out_copied) {
+    return iovec_iter_copy(iter, dst, len, false, out_copied);
+}