From 25461d1d5df8f6d1cf415eeb7d8d7c073171def5 Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 6 Oct 2025 21:25:02 -0400
Subject: kern: filedesc: Add fd_open() function

Introduce the fd_open() function as apart of the kernel file
descriptor API to open a file and get a file descriptor.

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 src/sys/os/os_filedes.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 44 insertions(+), 1 deletion(-)

(limited to 'src/sys/os/os_filedes.c')

diff --git a/src/sys/os/os_filedes.c b/src/sys/os/os_filedes.c
index e7cc83a..dde7f22 100644
--- a/src/sys/os/os_filedes.c
+++ b/src/sys/os/os_filedes.c
@@ -31,10 +31,12 @@
 #include <sys/syslog.h>
 #include <sys/errno.h>
 #include <sys/limits.h>
+#include <sys/proc.h>
+#include <sys/namei.h>
 #include <os/filedesc.h>
 #include <os/kalloc.h>
 #include <io/cons/cons.h>
-#include <sys/proc.h>
+#include <compat/unix/syscall.h>
 #include <string.h>
 
 #define STDOUT_FILENO 1
@@ -86,6 +88,47 @@ fd_alloc(struct proc *procp, struct filedesc **fd_res)
     return -EMFILE;
 }
 
+int
+fd_open(const char *path, mode_t mode)
+{
+    struct filedesc *fd;
+    struct nameidata nd;
+    struct proc *self = proc_self();
+    struct vnode *vp;
+    int error;
+
+    /* We need the current proc */
+    if (self == NULL) {
+        return -ESRCH;
+    }
+
+    if (path == NULL) {
+        return -ESRCH;
+    }
+
+    /* Allocate a new file descriptor */
+    error = fd_alloc(self, &fd);
+    if (error < 0) {
+        return error;
+    }
+
+    /*
+     * Now we try to do the lookup, we'll need
+     * the vnode for file references to be
+     * useful
+     */
+    nd.path = path;
+    nd.flags = 0;
+    nd.vp_res = &vp;
+    error = namei(&nd);
+    if (error < 0) {
+        return error;
+    }
+
+    fd->vp = vp;
+    return fd->fdno;
+}
+
 /*
  * Initialize file descriptor table
  */
-- 
cgit v1.2.3


From 6ce9297e61d5dbc1640392ed6d253d9769953dcf Mon Sep 17 00:00:00 2001
From: Ian Moffett <ian@osmora.org>
Date: Mon, 6 Oct 2025 21:52:15 -0400
Subject: kern: filedes: Add SYS_open system call

Signed-off-by: Ian Moffett <ian@osmora.org>
---
 src/sys/include/compat/unix/syscall.h |  5 +++++
 src/sys/include/sys/syscall.h         |  1 +
 src/sys/os/os_filedes.c               | 21 +++++++++++++++++++++
 3 files changed, 27 insertions(+)

(limited to 'src/sys/os/os_filedes.c')

diff --git a/src/sys/include/compat/unix/syscall.h b/src/sys/include/compat/unix/syscall.h
index ab464c4..1b51d26 100644
--- a/src/sys/include/compat/unix/syscall.h
+++ b/src/sys/include/compat/unix/syscall.h
@@ -54,6 +54,11 @@ scret_t sys_cross(struct syscall_args *scargs);
  */
 scret_t sys_query(struct syscall_args *scargs);
 
+/*
+ * Open a file
+ */
+scret_t sys_open(struct syscall_args *scargs);
+
 #ifdef _NEED_UNIX_SCTAB
 scret_t(*g_unix_sctab[])(struct syscall_args *) = {
     [SYS_none]   = NULL,
diff --git a/src/sys/include/sys/syscall.h b/src/sys/include/sys/syscall.h
index c1c06bb..7dcd266 100644
--- a/src/sys/include/sys/syscall.h
+++ b/src/sys/include/sys/syscall.h
@@ -49,6 +49,7 @@
 #define SYS_sigaction   0x04
 #define SYS_query       0x05    /* query a border (mandatory) */
 #define SYS_spawn       0x06    /* spawn a process */
+#define SYS_open        0x07    /* open a file */
 
 typedef __ssize_t scret_t;
 typedef __ssize_t scarg_t;
diff --git a/src/sys/os/os_filedes.c b/src/sys/os/os_filedes.c
index dde7f22..3353a5f 100644
--- a/src/sys/os/os_filedes.c
+++ b/src/sys/os/os_filedes.c
@@ -35,6 +35,7 @@
 #include <sys/namei.h>
 #include <os/filedesc.h>
 #include <os/kalloc.h>
+#include <os/systm.h>
 #include <io/cons/cons.h>
 #include <compat/unix/syscall.h>
 #include <string.h>
@@ -181,3 +182,23 @@ write(int fd, const void *buf, size_t count)
 
     return count;
 }
+
+/*
+ * ARG0: Path
+ * ARG1: Mode
+ */
+scret_t
+sys_open(struct syscall_args *scargs)
+{
+    const char *u_path = SCARG(scargs, const char *, 0);
+    mode_t mode = SCARG(scargs, mode_t, 1);
+    char pathbuf[PATH_MAX];
+    int error;
+
+    error = copyinstr(u_path, pathbuf, sizeof(PATH_MAX));
+    if (error < 0) {
+        return error;
+    }
+
+    return fd_open(pathbuf, mode);
+}
-- 
cgit v1.2.3