From 4cfb83f4fef3b16f0f1119effc3b2e01bcc2ec0c Mon Sep 17 00:00:00 2001
From: Matheus <matheusuky@gmail.com>
Date: Tue, 9 May 2023 23:25:29 -0300
Subject: [PATCH] syscall: openat

---
 kernel-src/arch/x86-64/syscall.asm     |  4 +-
 kernel-src/sys/syscalls/open.c         | 98 ++++++++++++++++++++++++++
 patches/mlibc/jinx-working-patch.patch | 16 +++--
 3 files changed, 112 insertions(+), 6 deletions(-)
 create mode 100644 kernel-src/sys/syscalls/open.c

diff --git a/kernel-src/arch/x86-64/syscall.asm b/kernel-src/arch/x86-64/syscall.asm
index fabfbfa5..5d9d5ecb 100644
--- a/kernel-src/arch/x86-64/syscall.asm
+++ b/kernel-src/arch/x86-64/syscall.asm
@@ -1,11 +1,13 @@
 section .rodata
 extern syscall_print
 extern syscall_mmap
+extern syscall_openat
 syscalltab:
 dq syscall_print
 dq syscall_mmap
+dq syscall_openat
 
-syscallcount equ 2
+syscallcount equ 3
 section .text
 global arch_syscall_entry
 ; on entry:
diff --git a/kernel-src/sys/syscalls/open.c b/kernel-src/sys/syscalls/open.c
new file mode 100644
index 00000000..65262a75
--- /dev/null
+++ b/kernel-src/sys/syscalls/open.c
@@ -0,0 +1,98 @@
+#include <kernel/syscalls.h>
+#include <kernel/file.h>
+#include <kernel/abi.h>
+#include <kernel/alloc.h>
+#include <errno.h>
+#include <logging.h>
+
+syscallret_t syscall_openat(context_t *context, int dirfd, const char *path, int flags, mode_t mode) {
+	syscallret_t ret = {
+		.ret = -1,
+		.errno = 0
+	};
+
+	// transform O_RDONLY, O_WRONLY, O_RDWR into FILE_READ and FILE_WRITE
+	++flags;
+
+	__assert((~FILE_KNOWN_FLAGS & flags) == 0);
+
+	vnode_t *dirnode = NULL;
+	file_t *dirfile;
+
+	size_t pathsize = strlen(path); // TODO u_strlen
+	char *pathbuf = alloc(pathsize + 1);
+	strcpy(pathbuf, path); // TODO u_strcpy
+
+	if (*pathbuf == '/') {
+		dirnode = sched_getroot();
+		dirfile = NULL;
+	} else if (dirfd == AT_FDCWD) {
+		dirnode = sched_getcwd();
+		dirfile = NULL;
+	} else {
+		dirfile = fd_get(dirfd);
+		if (dirfile == NULL) {
+			ret.errno = EBADF;
+			goto cleanup;
+		}
+
+		dirnode = dirfile->vnode;
+		if (dirnode->type != V_TYPE_DIR) {
+			ret.errno = ENOTDIR;
+			goto cleanup;
+		}
+	}
+
+	// TODO pass CLOEXEC to fd
+	file_t *newfile = NULL;
+	int newfd;
+	ret.errno = fd_new(0, &newfile, &newfd);
+	if (ret.errno)
+		goto cleanup;
+
+	vnode_t *vnode = NULL;
+	ret.errno = vfs_open(dirnode, pathbuf, fileflagstovnodeflags(flags), &vnode);
+	if (ret.errno)
+		goto cleanup;
+
+	vattr_t attr;
+	VOP_LOCK(vnode);
+	ret.errno = VOP_GETATTR(vnode, &attr, &_cpu()->thread->proc->cred);
+	VOP_UNLOCK(vnode);
+	if (ret.errno)
+		goto cleanup;
+
+	// node refcount is already increased by open
+	newfile->vnode = vnode;
+	newfile->flags = flags;
+	newfile->offset = 0;
+	newfile->mode = attr.mode;
+
+	ret.errno = 0;
+	ret.ret = newfd;
+
+	cleanup:
+	if (vnode && ret.errno) {
+		vfs_close(vnode, fileflagstovnodeflags(flags));
+		VOP_RELEASE(vnode);
+	}
+
+	if (newfile) {
+		if (ret.errno) {
+			__assert(fd_close(newfd) == 0);
+		} else {
+			fd_release(newfile);
+		}
+	}
+
+	if (pathbuf)
+		free(pathbuf);
+
+	if (dirfile) {
+		fd_release(dirfile);
+	} else if (dirnode){
+		VOP_RELEASE(dirnode);
+	}
+
+	return ret;
+}
diff --git a/patches/mlibc/jinx-working-patch.patch b/patches/mlibc/jinx-working-patch.patch
index 9c820067..d06e4905 100644
--- a/patches/mlibc/jinx-working-patch.patch
+++ b/patches/mlibc/jinx-working-patch.patch
@@ -113,10 +113,10 @@ index 0000000..e5b087a
 +
 diff --git mlibc-workdir/sysdeps/astral/generic/generic.cpp mlibc-workdir/sysdeps/astral/generic/generic.cpp
 new file mode 100644
-index 0000000..4d9555e
+index 0000000..6715503
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/generic/generic.cpp
-@@ -0,0 +1,138 @@
+@@ -0,0 +1,143 @@
 +#include <bits/ensure.h>
 +#include <mlibc/debug.hpp>
 +#include <mlibc/all-sysdeps.hpp>
@@ -218,7 +218,12 @@ index 0000000..4d9555e
 +	}
 +	
 +	int sys_open(const char *pathname, int flags, mode_t mode, int *fd) {
-+		return ENOSYS;
++		long ret;
++		long err = syscall(SYSCALL_OPENAT, &ret, AT_FDCWD, (uint64_t)pathname, flags, mode);
++		if (err)
++			return err;
++		*fd = ret;
++		return 0;
 +	};
 +	int sys_read(int fd, void *buff, size_t count, ssize_t *bytes_read) {
 +		return ENOSYS;
@@ -274,15 +279,16 @@ index 0000000..990eca0
 +#endif
 diff --git mlibc-workdir/sysdeps/astral/include/astral/syscall.h mlibc-workdir/sysdeps/astral/include/astral/syscall.h
 new file mode 100644
-index 0000000..8f1ee3c
+index 0000000..6ef92cd
 --- /dev/null
 +++ mlibc-workdir/sysdeps/astral/include/astral/syscall.h
-@@ -0,0 +1,25 @@
+@@ -0,0 +1,26 @@
 +#ifndef _SYSCALL_H_INCLUDE
 +#define _SYSCALL_H_INCLUDE
 +
 +#define SYSCALL_PRINT 0
 +#define SYSCALL_MMAP 1
++#define SYSCALL_OPENAT 2
 +
 +#include <stddef.h>
 +#include <stdint.h>