s3: VFS: Add SMB_VFS_READLINKAT().

Currently identical to SMB_VFS_READLINK().

Next, add to all VFS modules that implement
readlink and eventually remove readlink.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Böhme <slow@samba.org>

examples/VFS/skel_opaque.c

@@ -473,6 +473,16 @@ static int skel_vfs_readlink(vfs_handle_struct *handle,
 	return -1;
 }
 
+static int skel_vfs_readlinkat(vfs_handle_struct *handle,
+			files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
 static int skel_linkat(vfs_handle_struct *handle,
 			files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,
@@ -1090,6 +1100,7 @@ static struct vfs_fn_pointers skel_opaque_fns = {
 	.getlock_fn = skel_getlock,
 	.symlink_fn = skel_symlink,
 	.readlink_fn = skel_vfs_readlink,
+	.readlinkat_fn = skel_vfs_readlinkat,
 	.linkat_fn = skel_linkat,
 	.mknodat_fn = skel_mknodat,
 	.realpath_fn = skel_realpath,

examples/VFS/skel_transparent.c

@@ -571,6 +571,19 @@ static int skel_vfs_readlink(vfs_handle_struct *handle,
 	return SMB_VFS_NEXT_READLINK(handle, smb_fname, buf, bufsiz);
 }
 
+static int skel_vfs_readlinkat(vfs_handle_struct *handle,
+			files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz)
+{
+	return SMB_VFS_NEXT_READLINKAT(handle,
+			dirfsp,
+			smb_fname,
+			buf,
+			bufsiz);
+}
+
 static int skel_linkat(vfs_handle_struct *handle,
 			files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,
@@ -1365,6 +1378,7 @@ static struct vfs_fn_pointers skel_transparent_fns = {
 	.getlock_fn = skel_getlock,
 	.symlink_fn = skel_symlink,
 	.readlink_fn = skel_vfs_readlink,
+	.readlinkat_fn = skel_vfs_readlinkat,
 	.linkat_fn = skel_linkat,
 	.mknodat_fn = skel_mknodat,
 	.realpath_fn = skel_realpath,

source3/include/smbprofile.h

@@ -83,6 +83,7 @@ struct tevent_context;
 	SMBPROFILE_STATS_BASIC(syscall_linux_setlease) \
 	SMBPROFILE_STATS_BASIC(syscall_fcntl_getlock) \
 	SMBPROFILE_STATS_BASIC(syscall_readlink) \
+	SMBPROFILE_STATS_BASIC(syscall_readlinkat) \
 	SMBPROFILE_STATS_BASIC(syscall_symlink) \
 	SMBPROFILE_STATS_BASIC(syscall_linkat) \
 	SMBPROFILE_STATS_BASIC(syscall_mknodat) \

source3/include/vfs.h

@@ -275,6 +275,7 @@
 /* Version 42 - Move SMB_VFS_RENAME -> SMB_VFS_RENAMEAT */
 /* Version 42 - Move SMB_VFS_LINK -> SMB_VFS_LINKAT. */
 /* Version 42 - Move SMB_VFS_MKNOD -> SMB_VFS_MKDNODAT. */
+/* Version 42 - Add SMB_VFS_READLINKAT. */
 
 #define SMB_VFS_INTERFACE_VERSION 42
 
@@ -801,6 +802,11 @@ struct vfs_fn_pointers {
 				const struct smb_filename *smb_fname,
 				char *buf,
 				size_t bufsiz);
+	int (*readlinkat_fn)(struct vfs_handle_struct *handle,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				char *buf,
+				size_t bufsiz);
 	int (*linkat_fn)(struct vfs_handle_struct *handle,
 				struct files_struct *srcfsp,
 				const struct smb_filename *old_smb_fname,
@@ -1334,6 +1340,11 @@ int smb_vfs_call_readlink(struct vfs_handle_struct *handle,
 			const struct smb_filename *smb_fname,
 			char *buf,
 			size_t bufsiz);
+int smb_vfs_call_readlinkat(struct vfs_handle_struct *handle,
+			struct files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz);
 int smb_vfs_call_linkat(struct vfs_handle_struct *handle,
 			struct files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,
@@ -1764,6 +1775,11 @@ int vfs_not_implemented_vfs_readlink(vfs_handle_struct *handle,
 				     const struct smb_filename *smb_fname,
 				     char *buf,
 				     size_t bufsiz);
+int vfs_not_implemented_vfs_readlinkat(vfs_handle_struct *handle,
+			struct files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz);
 int vfs_not_implemented_linkat(vfs_handle_struct *handle,
 			struct files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,

source3/include/vfs_macros.h

@@ -306,6 +306,11 @@
 #define SMB_VFS_NEXT_READLINK(handle, smb_fname, buf, bufsiz) \
 	smb_vfs_call_readlink((handle)->next, (smb_fname), (buf), (bufsiz))
 
+#define SMB_VFS_READLINKAT(conn, dirfsp, smb_fname, buf, bufsiz) \
+	smb_vfs_call_readlinkat((conn)->vfs_handles, (dirfsp), (smb_fname), (buf), (bufsiz))
+#define SMB_VFS_NEXT_READLINKAT(handle, dirfsp, smb_fname, buf, bufsiz) \
+	smb_vfs_call_readlinkat((handle)->next, (dirfsp), (smb_fname), (buf), (bufsiz))
+
 #define SMB_VFS_LINKAT(conn, srcfsp, oldpath, dstfsp, newpath, flags) \
 	smb_vfs_call_linkat((conn)->vfs_handles, (srcfsp), (oldpath), (dstfsp), (newpath), (flags))
 #define SMB_VFS_NEXT_LINKAT(handle, srcfsp, oldpath, dstfsp, newpath, flags) \

source3/modules/vfs_default.c

@@ -2663,6 +2663,27 @@ static int vfswrap_readlink(vfs_handle_struct *handle,
 	return result;
 }
 
+static int vfswrap_readlinkat(vfs_handle_struct *handle,
+			files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz)
+{
+	int result;
+
+	START_PROFILE(syscall_readlinkat);
+
+	SMB_ASSERT(dirfsp == dirfsp->conn->cwd_fsp);
+
+	result = readlinkat(dirfsp->fh->fd,
+			smb_fname->base_name,
+			buf,
+			bufsiz);
+
+	END_PROFILE(syscall_readlinkat);
+	return result;
+}
+
 static int vfswrap_linkat(vfs_handle_struct *handle,
 			files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,
@@ -3487,6 +3508,7 @@ static struct vfs_fn_pointers vfs_default_fns = {
 	.getlock_fn = vfswrap_getlock,
 	.symlink_fn = vfswrap_symlink,
 	.readlink_fn = vfswrap_readlink,
+	.readlinkat_fn = vfswrap_readlinkat,
 	.linkat_fn = vfswrap_linkat,
 	.mknodat_fn = vfswrap_mknodat,
 	.realpath_fn = vfswrap_realpath,

source3/modules/vfs_not_implemented.c

@@ -471,6 +471,16 @@ int vfs_not_implemented_vfs_readlink(vfs_handle_struct *handle,
 	return -1;
 }
 
+int vfs_not_implemented_vfs_readlinkat(vfs_handle_struct *handle,
+			files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz)
+{
+	errno = ENOSYS;
+	return -1;
+}
+
 int vfs_not_implemented_linkat(vfs_handle_struct *handle,
 			files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,
@@ -1094,6 +1104,7 @@ static struct vfs_fn_pointers vfs_not_implemented_fns = {
 	.getlock_fn = vfs_not_implemented_getlock,
 	.symlink_fn = vfs_not_implemented_symlink,
 	.readlink_fn = vfs_not_implemented_vfs_readlink,
+	.readlinkat_fn = vfs_not_implemented_vfs_readlinkat,
 	.linkat_fn = vfs_not_implemented_linkat,
 	.mknodat_fn = vfs_not_implemented_mknodat,
 	.realpath_fn = vfs_not_implemented_realpath,

source3/smbd/vfs.c

@@ -2210,6 +2210,20 @@ int smb_vfs_call_readlink(struct vfs_handle_struct *handle,
 	return handle->fns->readlink_fn(handle, smb_fname, buf, bufsiz);
 }
 
+int smb_vfs_call_readlinkat(struct vfs_handle_struct *handle,
+			struct files_struct *dirfsp,
+			const struct smb_filename *smb_fname,
+			char *buf,
+			size_t bufsiz)
+{
+	VFS_FIND(readlinkat);
+	return handle->fns->readlinkat_fn(handle,
+				dirfsp,
+				smb_fname,
+				buf,
+				bufsiz);
+}
+
 int smb_vfs_call_linkat(struct vfs_handle_struct *handle,
 			struct files_struct *srcfsp,
 			const struct smb_filename *old_smb_fname,