1 files changed, 272 insertions, 0 deletions
diff --git a/sys/kern/kern_uio.c b/sys/kern/kern_uio.c
new file mode 100644
index 0000000..2ec1532
--- /dev/null
+++ b/sys/kern/kern_uio.c
@@ -0,0 +1,272 @@
+/*
+ * 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/systm.h>
+#include <sys/errno.h>
+#include <sys/types.h>
+#include <sys/uio.h>
+#include <sys/filedesc.h>
+
+/*
+ * Clean up after a UIO copyin() operation
+ *
+ * @iov: iovec copy to clean up
+ * @iovcnt: Number of iovec entries
+ */
+void
+uio_copyin_clean(struct iovec *iov, int iovcnt)
+{
+    for (int i = 0; i < iovcnt; ++i) {
+        if (iov[i].iov_base == NULL) {
+            continue;
+        }
+
+        dynfree(iov[i].iov_base);
+        iov[i].iov_base = NULL;
+    }
+}
+
+/*
+ * 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;
+}
+
+/*
+ * Validate iovecs coming in from userland
+ * and copy it to a kernel buffer.
+ *
+ * XXX: A new buffer is allocated in k_iov[i]->iov_base
+ *      and must be freed with dynfree() after use.
+ *
+ * @u_iov: Userspace source iovecs
+ * @k_iov: Kernel destination iovec
+ * @iovcnt: Number of iovecs to copy
+ */
+int
+uio_copyin(const struct iovec *u_iov, struct iovec *k_iov, int iovcnt)
+{
+    struct iovec *iov_dest;
+    const struct iovec *iov_src;
+    size_t len;
+    void *old_base;
+    int error;
+
+    if (u_iov == NULL || k_iov == NULL) {
+        return -EINVAL;
+    }
+
+    for (int i = 0; i < iovcnt; ++i) {
+        iov_dest = &k_iov[i];
+        iov_src = &u_iov[i];
+        error = copyin(iov_src, iov_dest, sizeof(*iov_dest));
+
+        if (error < 0) {
+            uio_copyin_clean(iov_dest, i + 1);
+            return error;
+        }
+
+        /*
+         * Save the old base so that we may copy the data to
+         * the new kernel buffer. First we'd need to allocate
+         * one of course.
+         */
+        old_base = iov_dest->iov_base;
+        len = iov_dest->iov_len;
+        iov_dest->iov_base = dynalloc(len);
+
+        /* Did it fail? */
+        if (iov_dest->iov_base == NULL) {
+            uio_copyin_clean(iov_dest, i + 1);
+            return -ENOMEM;
+        }
+
+        /* Copy actual data in */
+        error = copyin(old_base, iov_dest->iov_base, len);
+        if (error < 0) {
+            uio_copyin_clean(iov_dest, i + 1);
+            return error;
+        }
+    }
+
+    return 0;
+}
+
+
+/*
+ * Validate iovecs going out from kernel space (us)
+ * before actually sending it out.
+ *
+ * @k_iov: Kernel iovec to copyout
+ * @u_iov: Userspace destination
+ * @iovcnt: Number of iovecs
+ */
+int
+uio_copyout(const struct iovec *k_iov, struct iovec *u_iov, int iovcnt)
+{
+    struct iovec iov_shadow, *iov_dest;
+    const struct iovec *iov_src;
+    int error;
+
+    for (int i = 0; i < iovcnt; ++i) {
+        iov_dest = &u_iov[i];
+        iov_src = &k_iov[i];
+
+        /* Grab a shadow copy */
+        error = copyin(iov_src, &iov_shadow, sizeof(iov_shadow));
+        if (error < 0) {
+            return error;
+        }
+
+        /* Copy out actual data */
+        error = copyout(iov_src->iov_base, iov_dest->iov_base, iov_dest->iov_len);
+        if (error < 0) {
+            return error;
+        }
+    }
+
+    return 0;
+}