From e401e6769552ab2b536b951958661dc0cded285c Mon Sep 17 00:00:00 2001
From: David Wendt <dcrkid@yahoo.com>
Date: Sun, 24 Oct 2021 22:31:08 -0400
Subject: [PATCH] Implement vectored async IO fallback

---
 kernel/aio.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++---
 kernel/fs.c  |  2 +-
 kernel/fs.h  |  7 +++++--
 3 files changed, 58 insertions(+), 6 deletions(-)

diff --git a/kernel/aio.c b/kernel/aio.c
index b6a15a82db..79d22f0c2d 100644
--- a/kernel/aio.c
+++ b/kernel/aio.c
@@ -2,6 +2,7 @@
 #include "kernel/calls.h"
 #include "kernel/task.h"
 #include "kernel/aio.h"
+#include "kernel/fs.h"
 #include "fs/aio.h"
 #include "fs/fd.h"
 
@@ -186,7 +187,9 @@ dword_t sys_io_cancel(dword_t ctx_id, addr_t iocb, addr_t result) {
  * Do a single PREAD operation, falling back to seek-and-read if necessary.
  * 
  * The return code corresponds to the 'sync error' concept of fallback_submit,
- * while async errors should be flagged by writing to *err.
+ * while async errors should be flagged by writing to `*err`.
+ * 
+ * `*err` also is used to return the total number of bytes read.
  */
 static signed int __aio_fallback_pread(
     struct fd *fd,
@@ -243,7 +246,9 @@ static signed int __aio_fallback_pread(
  * Do a single PWRITE operation, falling back to seek-and-write if necessary.
  * 
  * The return code corresponds to the 'sync error' concept of fallback_submit,
- * while async errors should be flagged by writing to *err.
+ * while async errors should be flagged by writing to `*err`.
+ * 
+ * `*err` also is used to return the total number of bytes written.
  */
 static signed int __aio_fallback_pwrite(
     struct fd *fd,
@@ -316,6 +321,8 @@ int aio_fallback_submit(struct fd *fd, struct aioctx *ctx, unsigned int event_id
         return sync_err;
     }
 
+    struct iovec_ *iov_list = NULL;
+
     char *buf = NULL;
     switch (evt->op) {
         case AIOCTX_PREAD:
@@ -337,7 +344,49 @@ int aio_fallback_submit(struct fd *fd, struct aioctx *ctx, unsigned int event_id
             async_result0 = 0;
             sync_err = 0;
             break;
-        //TODO: AIOCTX_POLL, AIOCTX_PREADV, AIOCTX_PWRITEV
+        case AIOCTX_PREADV:
+            iov_list = read_iovec((addr_t)evt->buf, evt->nbytes);
+            ssize_t total_read = 0;
+
+            for (unsigned int i = 0; i < evt->nbytes; i += 1) {
+                signed int cur_read = 0;
+                sync_err = __aio_fallback_pread(fd, iov_list[i].base, iov_list[i].len, evt->offset + total_read, &cur_read);
+                if (sync_err < 0 || cur_read < 0) {
+                    async_result0 = cur_read;
+                    break;
+                }
+
+                total_read += cur_read;
+
+                if (cur_read < iov_list[i].len) break;
+            }
+
+            if (sync_err < 0 || async_result0 < 0) break;
+
+            async_result0 = total_read;
+            break;
+        case AIOCTX_PWRITEV:
+            iov_list = read_iovec((addr_t)evt->buf, evt->nbytes);
+            ssize_t total_write = 0;
+
+            for (unsigned int i = 0; i < evt->nbytes; i += 1) {
+                signed int cur_write = 0;
+                sync_err = __aio_fallback_pwrite(fd, iov_list[i].base, iov_list[i].len, evt->offset + total_write, &cur_write);
+                if (sync_err < 0 || cur_write < 0) {
+                    async_result0 = cur_write;
+                    break;
+                }
+
+                total_write += cur_write;
+
+                if (cur_write < iov_list[i].len) break;
+            }
+
+            if (sync_err < 0 || async_result0 < 0) break;
+
+            async_result0 = total_write;
+            break;
+        //TODO: AIOCTX_POLL
         default:
             sync_err = _EINVAL;
             break;
diff --git a/kernel/fs.c b/kernel/fs.c
index df1d2aaaa2..af74a57536 100644
--- a/kernel/fs.c
+++ b/kernel/fs.c
@@ -295,7 +295,7 @@ dword_t sys_write(fd_t fd_no, addr_t buf_addr, dword_t size) {
 // that yet because it's more work and the efficiency gain from that is dwarfed
 // by the inefficiency of the emulator.
 
-static struct iovec_ *read_iovec(addr_t iovec_addr, unsigned iovec_count) {
+struct iovec_ *read_iovec(addr_t iovec_addr, unsigned iovec_count) {
     dword_t iovec_size = sizeof(struct iovec_) * iovec_count;
     struct iovec_ *iovec = malloc(iovec_size);
     if (iovec == NULL)
diff --git a/kernel/fs.h b/kernel/fs.h
index 5a8154ccb4..4bbce6fa3d 100644
--- a/kernel/fs.h
+++ b/kernel/fs.h
@@ -1,5 +1,5 @@
-#ifndef FS_H
-#define FS_H
+#ifndef KERNEL_FS_H
+#define KERNEL_FS_H
 
 #include "misc.h"
 #include "util/list.h"
@@ -8,6 +8,7 @@
 #include "fs/fake-db.h"
 #include "fs/fix_path.h"
 #include "emu/memory.h"
+#include "kernel/calls.h"
 #include <dirent.h>
 #include <sqlite3.h>
 
@@ -175,4 +176,6 @@ extern const struct fs_ops devptsfs;
 extern const struct fs_ops tmpfs;
 void fs_register(const struct fs_ops *fs);
 
+struct iovec_ *read_iovec(addr_t iovec_addr, unsigned iovec_count);
+
 #endif