syscalls: linkat

kernel-src/arch/x86-64/syscall.asm

@@ -28,6 +28,7 @@ extern syscall_unlinkat
 extern syscall_ioctl
 extern syscall_mkdirat
 extern syscall_clockget
+extern syscall_linkat
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -58,7 +59,8 @@ dq syscall_unlinkat
 dq syscall_ioctl
 dq syscall_mkdirat
 dq syscall_clockget
-syscallcount equ 29
+dq syscall_linkat
+syscallcount equ 30
 section .text
 global arch_syscall_entry
 ; on entry:

kernel-src/arch/x86-64/syscalllog.c

@@ -4,7 +4,7 @@
 
 #ifdef SYSCALL_LOGGING
 
-#define SYSCALL_COUNT 29
+#define SYSCALL_COUNT 30
 #define LOGSTR(x) arch_e9_puts(x)
 
 static char *name[] = {
@@ -36,7 +36,8 @@ static char *name[] = {
 	"unlinkat",
 	"ioctl",
 	"mkdirat",
-	"clockget"
+	"clockget",
+	"linkat"
 };
 
 static char *args[] = {
@@ -68,7 +69,8 @@ static char *args[] = {
 	"dirfd %d pathname %d flags %d", // unlinkat
 	"fd %d request %lu argument %d", // ioctl
 	"dirfd %d path %s mode %o", // mkdirat
-	"clockid %d timespec %p" // clockget
+	"clockid %d timespec %p", // clockget
+	"olddirfd %d oldpath %s newdirfd %d oldpath %s flags %d type %d" // linkat
 };
 
 #endif

kernel-src/include/kernel/syscalls.h

@@ -3,10 +3,41 @@
 
 #include <stdint.h>
 #include <arch/context.h>
+#include <kernel/vfs.h>
+#include <kernel/file.h>
+#include <kernel/scheduler.h>
 
 typedef struct {
 	uint64_t ret;
 	uint64_t errno;
 } syscallret_t;
 
+static inline int dirfd_enter(char *path, int dirfd, file_t **file, vnode_t **dirnode) {
+	if (*path == '/') {
+		*dirnode = sched_getroot();
+	} else if (dirfd == AT_FDCWD) {
+		*dirnode = sched_getcwd();
+	} else {
+		*file = fd_get(dirfd);
+		if (file == NULL) {
+			return EBADF;
+		}
+
+		*dirnode = (*file)->vnode;
+
+		if ((*dirnode)->type != V_TYPE_DIR) {
+			fd_release(*file);
+			return ENOTDIR;
+		}
+	}
+	return 0;
+}
+
+static inline void dirfd_leave(vnode_t *dirnode, file_t *file) {
+	if (file)
+		fd_release(file);
+	else
+		VOP_RELEASE(dirnode);
+}
+
 #endif

kernel-src/sys/syscalls/linkat.c

@@ -0,0 +1,61 @@
+#include <kernel/syscalls.h>
+#include <kernel/alloc.h>
+
+
+syscallret_t syscall_linkat(context_t *, int olddirfd, const char *uoldpath, int newdirfd, const char *unewpath, int flags, int type) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	char *oldpath = alloc(strlen(uoldpath) + 1);
+	if (oldpath == NULL) {
+		ret.errno = ENOMEM;
+		return ret;
+	}
+
+	char *newpath = alloc(strlen(unewpath) + 1);
+	if (newpath == NULL) {
+		free(oldpath);
+		ret.errno = ENOMEM;
+		return ret;
+	}
+
+	// TODO safe strcopy
+	strcpy(oldpath, uoldpath);
+	strcpy(newpath, unewpath);
+
+	vnode_t *olddirnode = NULL;
+	file_t *oldfile = NULL;
+	vnode_t *newdirnode = NULL;
+	file_t *newfile = NULL;
+	ret.errno = dirfd_enter(oldpath, olddirfd, &oldfile, &olddirnode);
+
+	if (ret.errno)
+		goto cleanup;
+
+	ret.errno = dirfd_enter(newpath, newdirfd, &newfile, &newdirnode);
+
+	if (ret.errno)
+		goto cleanup;
+
+	vattr_t attr = {
+		.gid = _cpu()->thread->proc->cred.gid,
+		.uid = _cpu()->thread->proc->cred.uid
+	};
+
+	ret.errno = vfs_link(olddirnode, oldpath, newdirnode, newpath, type == 0 ? V_TYPE_REGULAR : V_TYPE_LINK, &attr);
+	ret.ret = ret.errno ? -1 : 0;
+
+	cleanup:
+
+	if (olddirnode)
+		dirfd_leave(olddirnode, oldfile);
+
+	if (newdirnode)
+		dirfd_leave(newdirnode, newfile);
+
+	free(oldpath);
+	free(newpath);
+
+	return ret;
+}