kernel: posix: Add POSIX 'uio'

See https://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/uio.h.html

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 156 insertions, 0 deletions

diff --git a/sys/kern/kern_uio.c b/sys/kern/kern_uio.c
new file mode 100644
index 0000000..dd533c2
--- /dev/null
+++ b/sys/kern/kern_uio.c
@@ -0,0 +1,156 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/limits.h>
+#include <sys/errno.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/filedesc.h>
+
+/*
+ * Read data into POSIX.1‐2017 iovec
+ *
+ * @filedes: File descriptor number
+ * @iov: I/O vector to read file into
+ * @iovnt: Number of I/O vectors
+ */
+ssize_t
+readv(int filedes, const struct iovec *iov, int iovcnt)
+{
+    void *base;
+    size_t len;
+    ssize_t tmp, bytes_read = 0;
+
+    if (filedes < 0) {
+        return -EINVAL;
+    }
+
+    /*
+     * Make sure that this conforms to our max
+     * iovec limit.
+     */
+    if (iovcnt > IOVEC_MAX) {
+        return -EINVAL;
+    }
+
+    /*
+     * Go through each I/O vector and read a chunk
+     * of data into one.
+     */
+    for (int i = 0; i < iovcnt; ++i) {
+        base = iov[i].iov_base;
+        len = iov[i].iov_len;
+
+        /*
+         * If we encounter a base that is NULL,
+         * or if the length to read is an invalid
+         * value of zero. We can just assume this
+         * is some sort of weird list termination?
+         */
+        if (base == NULL || len == 0) {
+            break;
+        }
+
+        /* Read the file into this base  */
+        tmp = fd_read(filedes, base, len);
+
+        /* Did anything go wrong? */
+        if (tmp < 0) {
+            return tmp;
+        }
+
+        /* No more data */
+        if (tmp == 0) {
+            break;
+        }
+
+        /* Read more bytes */
+        bytes_read += tmp;
+    }
+
+    return bytes_read;
+}
+
+/*
+ * Write data from POSIX.1‐2017 iovec
+ *
+ * @filedes: File descriptor number
+ * @iov: I/O vector to write to file
+ * @iovnt: Number of I/O vectors
+ */
+ssize_t
+writev(int filedes, const struct iovec *iov, int iovcnt)
+{
+    void *base;
+    size_t len;
+    ssize_t bytes_written = 0;
+    ssize_t tmp;
+
+    if (filedes < 0) {
+        return -EINVAL;
+    }
+
+    /*
+     * Are we within the limits? Return an
+     * error if not.
+     */
+    if (iovcnt > IOVEC_MAX) {
+        return -EINVAL;
+    }
+
+    for (int i = 0; i < iovcnt; ++i) {
+        base = iov[i].iov_base;
+        len = iov[i].iov_len;
+
+        /*
+         * These are invalid, whatever these are,
+         * terminate our walk through.
+         */
+        if (base == NULL || len == 0) {
+            break;
+        }
+
+        /* Write the data from the iovec */
+        tmp = fd_write(filedes, base, len);
+
+        /* Was there an error? */
+        if (tmp < 0) {
+            return tmp;
+        }
+
+        /* No more data to read? */
+        if (tmp == 0) {
+            break;
+        }
+
+        bytes_written += tmp;
+    }
+
+    return bytes_written;
+}