syscalls: faccessat

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

@@ -23,6 +23,7 @@ extern syscall_fcntl
 extern syscall_chdir
 extern syscall_pipe2
 extern syscall_isatty
+extern syscall_faccessat
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -48,7 +49,8 @@ dq syscall_fcntl
 dq syscall_chdir
 dq syscall_pipe2
 dq syscall_isatty
-syscallcount equ 24
+dq syscall_faccessat
+syscallcount equ 25
 section .text
 global arch_syscall_entry
 ; on entry:

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

@@ -2,7 +2,7 @@
 #include <arch/e9.h>
 #include <arch/cpu.h>
 
-#define SYSCALL_COUNT 24
+#define SYSCALL_COUNT 25
 #define LOGSTR(x) arch_e9_puts(x)
 
 static char *name[] = {
@@ -29,7 +29,8 @@ static char *name[] = {
 	"fcntl",
 	"chdir",
 	"pipe2",
-	"isatty"
+	"isatty",
+	"faccessat"
 };
 
 static char *args[] = {
@@ -57,6 +58,7 @@ static char *args[] = {
 	"path %s", // chdir
 	"flags %d", // pipe2
 	"fd %d", // isatty
+	"dirfd %d pathname %s mode %d flags %d" // faccessat
 };
 
 __attribute__((no_caller_saved_registers)) void arch_syscall_log(int syscall, uint64_t a1, uint64_t a2, uint64_t a3, uint64_t a4, uint64_t a5, uint64_t a6) {

kernel-src/sys/syscalls/faccessat.c

@@ -0,0 +1,65 @@
+#include <kernel/syscalls.h>
+#include <kernel/file.h>
+#include <kernel/alloc.h>
+#include <kernel/vfs.h>
+#include <arch/cpu.h>
+#include <string.h>
+
+#define AT_SYMLINK_NOFOLLOW 0x100
+
+syscallret_t syscall_faccessat(context_t *, int dirfd, const char *upath, int mode, int flags) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	char *path = alloc(strlen(upath) + 1);
+	if (path == NULL) {
+		ret.errno = ENOMEM;
+		return ret;
+	}
+
+	// TODO safe strcopy
+	strcpy(path, upath);
+
+	vnode_t *dirnode = NULL;
+	file_t *file = NULL;
+	if (*path == '/') {
+		dirnode = sched_getroot();
+	} else if (dirfd == AT_FDCWD) {
+		dirnode = sched_getcwd();
+	} else {
+		file = fd_get(dirfd);
+		if (file == NULL) {
+			ret.errno = EBADF;
+			goto cleanup;
+		}
+
+		dirnode = file->vnode;
+
+		if (dirnode->type != V_TYPE_DIR) {
+			ret.errno = ENOTDIR;
+			goto cleanup;
+		}
+	}
+
+	vnode_t *node = NULL;
+	ret.errno = vfs_lookup(&node, dirnode, path, NULL, flags & AT_SYMLINK_NOFOLLOW ? VFS_LOOKUP_NOLINK : 0);
+	if (ret.errno)
+		goto cleanup;
+
+	ret.errno = VOP_ACCESS(node, mode, &_cpu()->thread->proc->cred);
+	ret.ret = 0;
+
+	cleanup:
+	if (node)
+		VOP_RELEASE(node);
+
+	if (file)
+		fd_release(file);
+	else
+		VOP_RELEASE(dirnode);
+
+	free(path);
+
+	return ret;
+}