kernel: vfs_syscalls: Add sys_open()

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

2 files changed, 125 insertions, 0 deletions

diff --git a/sys/kern/kern_syscall.c b/sys/kern/kern_syscall.c
index 1a750cc..2c81d2c 100644
--- a/sys/kern/kern_syscall.c
+++ b/sys/kern/kern_syscall.c
@@ -30,10 +30,12 @@
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <sys/proc.h>
+#include <sys/vfs.h>
 
 scret_t(*g_sctab[])(struct syscall_args *) = {
     NULL,       /* SYS_none */
     sys_exit,   /* SYS_exit */
+    sys_open,   /* SYS_open */
 };
 
 const size_t MAX_SYSCALLS = NELEM(g_sctab);
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
new file mode 100644
index 0000000..477bc81
--- /dev/null
+++ b/sys/kern/vfs_syscalls.c
@@ -0,0 +1,123 @@
+/*
+ * 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/vfs.h>
+#include <sys/vnode.h>
+#include <sys/types.h>
+#include <sys/systm.h>
+#include <sys/errno.h>
+#include <sys/filedesc.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>
+
+/*
+ * 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->fdno = i;
+        td->fds[i] = fd;
+
+        if (fd_out != NULL)
+            *fd_out = fd;
+
+        return 0;
+    }
+
+    return -EMFILE;
+}
+
+/*
+ * arg0: pathname
+ * arg1: oflags
+ *
+ * TODO: Use oflags.
+ */
+scret_t
+sys_open(struct syscall_args *scargs)
+{
+    int error;
+    const char *pathname;
+    char pathbuf[PATH_MAX];
+    struct proc *td;
+    struct filedesc *filedes;
+    struct nameidata nd;
+
+    pathname = (char *)scargs->arg0;
+    td = this_td();
+
+    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;
+}