syscalls: openat

src/arch/x86_64/syscall.asm

@@ -31,7 +31,8 @@ extern syscall_munmap
 extern syscall_umask
 extern syscall_poll
 extern syscall_fchmodat
-func_count equ 30
+extern syscall_openat
+func_count equ 31
 
 
 func_table:
@@ -65,6 +66,7 @@ func_table:
 	dq syscall_umask
 	dq syscall_poll
 	dq syscall_fchmodat
+	dq syscall_openat
 section .text
 global asm_syscall_entry
 

src/sys/syscalls/open.c

@@ -8,8 +8,7 @@
 #include <kernel/alloc.h>
 #include <stddef.h>
 
-
-syscallret syscall_open(const char* pathname, int flags, mode_t mode){
+syscallret syscall_openat(int dirfd, const char* pathname, int flags, mode_t mode){
 	syscallret retv;
 	retv.ret = -1;
 
@@ -39,6 +38,26 @@ syscallret syscall_open(const char* pathname, int flags, mode_t mode){
 		return retv;	
 	}
 
+	fd_t* targfd;
+	dirnode_t* target;
+
+	if(dirfd != AT_FDCWD){
+
+		err = fd_access(&proc->fdtable, &targfd, dirfd);
+
+		if(err){
+			retv.errno = err;
+			free(name);
+			fd_release(fd);
+			fd_free(&proc->fdtable, fd);
+			return retv;
+		}
+
+		target = targfd->node;
+
+	}
+	else target = proc->cwd;
+
 	fd->flags = flags + 1; // 1 is added to make O_RDONLY etc easier to lookup
 	fd->offset = 0;
 	
@@ -47,8 +66,8 @@ syscallret syscall_open(const char* pathname, int flags, mode_t mode){
 	retry:
 
 	size_t ret = vfs_open(&file, 
-		*name == '/' ? proc->root : proc->cwd,
-		*name == '/' ? name + 1 : name
+		*name == '/' ? proc->root : target,
+		name
 	);
 
 	if(ret == ENOENT && (flags & O_CREAT)){
@@ -93,9 +112,18 @@ syscallret syscall_open(const char* pathname, int flags, mode_t mode){
 	if(file)
 		vfs_close(file);
 
+	if(dirfd != AT_FDCWD)
+		fd_release(targfd);
+
 	fd_release(fd);
 	fd_free(&proc->fdtable,  fd);
 	free(name);
 	return retv;
 
 }
+
+// kept so no ABI breaks happen
+
+syscallret syscall_open(const char* pathname, int flags, mode_t mode){
+	return syscall_openat(AT_FDCWD, pathname, flags, mode);
+}