kernel: vfs: Refactor fd related code

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

3 files changed, 244 insertions, 177 deletions

diff --git a/sys/include/sys/filedesc.h b/sys/include/sys/filedesc.h
index dbac349..f5f24db 100644
--- a/sys/include/sys/filedesc.h
+++ b/sys/include/sys/filedesc.h
@@ -43,4 +43,11 @@ struct filedesc {
     struct spinlock lock;
 };
 
+int fd_close(unsigned int fd);
+int fd_read(unsigned int fd, void *buf, size_t count);
+
+int fd_alloc(struct filedesc **fd_out);
+int fd_open(const char *pathname, int flags);
+struct filedesc *fd_get(unsigned int fdno);
+
 #endif  /* !_SYS_FILEDESC_H_ */
diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
new file mode 100644
index 0000000..adc5027
--- /dev/null
+++ b/sys/kern/kern_descrip.c
@@ -0,0 +1,233 @@
+/*
+ * Copyright (c) 2023-2024 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/atomic.h>
+#include <sys/errno.h>
+#include <sys/proc.h>
+#include <sys/limits.h>
+#include <sys/namei.h>
+#include <sys/filedesc.h>
+#include <sys/systm.h>
+#include <vm/dynalloc.h>
+#include <string.h>
+
+/*
+ * Allocate a file descriptor.
+ *
+ * @fd_out: Pointer to allocated file descriptor output.
+ *
+ * This routine will create a new file descriptor
+ * table entry.
+ *
+ * Returns 0 on success.
+ */
+int
+fd_alloc(struct filedesc **fd_out)
+{
+    struct filedesc *fd;
+    struct proc *td = this_td();
+
+    /* Find free fd table entry */
+    for (size_t i = 3; i < PROC_MAX_FILEDES; ++i) {
+        if (td->fds[i] != NULL) {
+            /* In use */
+            continue;
+        }
+
+        fd = dynalloc(sizeof(struct filedesc));
+        memset(fd, 0, sizeof(struct filedesc));
+
+        if (fd == NULL) {
+            return -ENOMEM;
+        }
+
+        fd->refcnt = 1;
+        fd->fdno = i;
+        td->fds[i] = fd;
+
+        if (fd_out != NULL)
+            *fd_out = fd;
+
+        return 0;
+    }
+
+    return -EMFILE;
+}
+
+/*
+ * Fetch a file descriptor from a file descriptor
+ * number.
+ *
+ * @fdno: File descriptor to fetch
+ */
+struct filedesc *
+fd_get(unsigned int fdno)
+{
+    struct proc *td = this_td();
+
+    if (fdno > PROC_MAX_FILEDES) {
+        return NULL;
+    }
+
+    return td->fds[fdno];
+}
+
+/*
+ * Close a file descriptor with a file
+ * descriptor number.
+ *
+ * @fd: File descriptor number to close.
+ */
+int
+fd_close(unsigned int fd)
+{
+    struct filedesc *filedes;
+    struct proc *td;
+
+    if ((filedes = fd_get(fd)) == NULL) {
+        return -EBADF;
+    }
+
+    /* Return if other threads still hold a ref */
+    if (atomic_dec_int(&filedes->refcnt) > 0) {
+        return 0;
+    }
+
+    td = this_td();
+
+    /*
+     * Each file descriptor structure references a vnode,
+     * we want to reclaim it or at the very least drop
+     * one of its references. After we've cleaned up within
+     * the file descriptor, we can clear it from the fd table
+     * and free up the memory for it.
+     */
+    vfs_release_vnode(filedes->vp);
+    td->fds[fd] = NULL;
+    dynfree(filedes);
+    return 0;
+}
+
+/*
+ * Read bytes from a file using a file
+ * descriptor number.
+ *
+ * @fd: File descriptor number.
+ * @buf: Buffer to read into.
+ * @count: Number of bytes to read.
+ */
+int
+fd_read(unsigned int fd, void *buf, size_t count)
+{
+    char *kbuf = NULL;
+    struct filedesc *filedes;
+    struct sio_txn sio;
+    scret_t retval = 0;
+
+    if (count > SSIZE_MAX) {
+        retval = -EINVAL;
+        goto done;
+    }
+
+    filedes = fd_get(fd);
+    kbuf = dynalloc(count);
+
+    if (kbuf == NULL) {
+        retval = -ENOMEM;
+        goto done;
+    }
+
+    if (filedes == NULL) {
+        retval = -EBADF;
+        goto done;
+    }
+
+    if (filedes->is_dir) {
+        retval = -EISDIR;
+        goto done;
+    }
+
+    sio.len = count;
+    sio.buf = kbuf;
+    sio.offset = filedes->offset;
+
+    if ((count = vfs_vop_read(filedes->vp, &sio)) < 0) {
+        retval = -EIO;
+        goto done;
+    }
+
+    if (copyout(kbuf, buf, count) < 0) {
+        retval = -EFAULT;
+        goto done;
+    }
+
+    retval = count;
+done:
+    if (kbuf != NULL) {
+        dynfree(kbuf);
+    }
+    return retval;
+}
+
+/*
+ * Open a file and get a file descriptor
+ * number.
+ *
+ * @pathname: Path of file to open.
+ * @flags: Flags to use.
+ *
+ * TODO: Use of flags.
+ */
+int
+fd_open(const char *pathname, int flags)
+{
+    int error;
+    char pathbuf[PATH_MAX];
+    struct filedesc *filedes;
+    struct nameidata nd;
+
+    nd.path = pathbuf;
+    nd.flags = 0;
+
+    if (copyinstr(pathname, pathbuf, PATH_MAX) < 0) {
+        return -EFAULT;
+    }
+
+    if ((error = namei(&nd)) < 0) {
+        return error;
+    }
+
+    if ((error = fd_alloc(&filedes)) != 0) {
+        vfs_release_vnode(nd.vp);
+        return error;
+    }
+
+    filedes->vp = nd.vp;
+    return filedes->fdno;
+}
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index 77070ab..f4c5c59 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -28,83 +28,11 @@
  */
 
 #include <sys/vfs.h>
-#include <sys/vnode.h>
 #include <sys/types.h>
-#include <sys/systm.h>
-#include <sys/errno.h>
-#include <sys/sio.h>
 #include <sys/filedesc.h>
-#include <sys/atomic.h>
-#include <sys/namei.h>
-#include <sys/proc.h>
-#include <sys/limits.h>
-#include <sys/syslog.h>
-#include <vm/dynalloc.h>
-#include <assert.h>
 #include <string.h>
 
 /*
- * Fetch a file descriptor from a file descriptor
- * number.
- *
- * @fdno: File descriptor to fetch
- */
-static struct filedesc *
-fd_get(int fdno)
-{
-    struct proc *td = this_td();
-
-    if (fdno < 0 || fdno > PROC_MAX_FILEDES) {
-        return NULL;
-    }
-
-    return td->fds[fdno];
-}
-
-/*
- * Allocate a file descriptor.
- *
- * @fd_out: Pointer to allocated file descriptor output.
- *
- * This routine will create a new file descriptor
- * table entry.
- *
- * Returns 0 on success.
- */
-static int
-fd_alloc(struct filedesc **fd_out)
-{
-    struct filedesc *fd;
-    struct proc *td = this_td();
-
-    /* Find free fd table entry */
-    for (size_t i = 3; i < PROC_MAX_FILEDES; ++i) {
-        if (td->fds[i] != NULL) {
-            /* In use */
-            continue;
-        }
-
-        fd = dynalloc(sizeof(struct filedesc));
-        memset(fd, 0, sizeof(struct filedesc));
-
-        if (fd == NULL) {
-            return -ENOMEM;
-        }
-
-        fd->refcnt = 1;
-        fd->fdno = i;
-        td->fds[i] = fd;
-
-        if (fd_out != NULL)
-            *fd_out = fd;
-
-        return 0;
-    }
-
-    return -EMFILE;
-}
-
-/*
  * arg0: pathname
  * arg1: oflags
  *
@@ -113,31 +41,7 @@ fd_alloc(struct filedesc **fd_out)
 scret_t
 sys_open(struct syscall_args *scargs)
 {
-    int error;
-    const char *pathname;
-    char pathbuf[PATH_MAX];
-    struct filedesc *filedes;
-    struct nameidata nd;
-
-    pathname = (char *)scargs->arg0;
-    nd.path = pathbuf;
-    nd.flags = 0;
-
-    if (copyinstr(pathname, pathbuf, PATH_MAX) < 0) {
-        return -EFAULT;
-    }
-
-    if ((error = namei(&nd)) < 0) {
-        return error;
-    }
-
-    if ((error = fd_alloc(&filedes)) != 0) {
-        vfs_release_vnode(nd.vp);
-        return error;
-    }
-
-    filedes->vp = nd.vp;
-    return filedes->fdno;
+    return fd_open((char *)scargs->arg0, scargs->arg1);
 }
 
 /*
@@ -146,32 +50,7 @@ sys_open(struct syscall_args *scargs)
 scret_t
 sys_close(struct syscall_args *args)
 {
-    struct filedesc *filedes;
-    struct proc *td;
-    int fd = args->arg0;
-
-    if ((filedes = fd_get(fd)) == NULL) {
-        return -EBADF;
-    }
-
-    /* Return if other threads still hold a ref */
-    if (atomic_dec_int(&filedes->refcnt) > 0) {
-        return 0;
-    }
-
-    td = this_td();
-
-    /*
-     * Each file descriptor structure references a vnode,
-     * we want to reclaim it or at the very least drop
-     * one of its references. After we've cleaned up within
-     * the file descriptor, we can clear it from the fd table
-     * and free up the memory for it.
-     */
-    vfs_release_vnode(filedes->vp);
-    td->fds[fd] = NULL;
-    dynfree(filedes);
-    return 0;
+    return fd_close(args->arg0);
 }
 
 /*
@@ -182,58 +61,6 @@ sys_close(struct syscall_args *args)
 scret_t
 sys_read(struct syscall_args *scargs)
 {
-    int fd;
-    char *buf, *kbuf = NULL;
-    size_t count;
-    struct filedesc *filedes;
-    struct sio_txn sio;
-    scret_t retval = 0;
-
-    fd = scargs->arg0;
-    buf = (char *)scargs->arg1;
-    count = scargs->arg2;
-
-    if (count > SSIZE_MAX) {
-        retval = -EINVAL;
-        goto done;
-    }
-
-    filedes = fd_get(fd);
-    kbuf = dynalloc(count);
-
-    if (kbuf == NULL) {
-        retval = -ENOMEM;
-        goto done;
-    }
-
-    if (filedes == NULL) {
-        retval = -EBADF;
-        goto done;
-    }
-
-    if (filedes->is_dir) {
-        retval = -EISDIR;
-        goto done;
-    }
-
-    sio.len = count;
-    sio.buf = kbuf;
-    sio.offset = filedes->offset;
-
-    if ((count = vfs_vop_read(filedes->vp, &sio)) < 0) {
-        retval = -EIO;
-        goto done;
-    }
-
-    if (copyout(kbuf, buf, count) < 0) {
-        retval = -EFAULT;
-        goto done;
-    }
-
-    retval = count;
-done:
-    if (kbuf != NULL) {
-        dynfree(kbuf);
-    }
-    return retval;
+    return fd_read(scargs->arg0, (void *)scargs->arg1,
+        scargs->arg2);
 }