reader: introduce struct archive_read_filter_vtable

As before - move the dispatch/function pointer so a const data segment.
Separating it from the RW data section.

Note: the close function is _not_ optional - remove the NULL check.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

libarchive/archive_read.c

@@ -451,6 +451,12 @@ archive_read_prepend_callback_data(struct archive *_a, void *client_data)
 	return archive_read_add_callback_data(_a, client_data, 0);
 }
 
+static const struct archive_read_filter_vtable
+none_reader_vtable = {
+	.read = client_read_proxy,
+	.close = client_close_proxy,
+};
+
 int
 archive_read_open1(struct archive *_a)
 {
@@ -486,8 +492,7 @@ archive_read_open1(struct archive *_a)
 	filter->upstream = NULL;
 	filter->archive = a;
 	filter->data = a->client.dataset[0].data;
-	filter->read = client_read_proxy;
-	filter->close = client_close_proxy;
+	filter->vtable = &none_reader_vtable;
 	filter->name = "none";
 	filter->code = ARCHIVE_FILTER_NONE;
 	filter->can_skip = 1;
@@ -599,10 +604,9 @@ choose_filters(struct archive_read *a)
 int
 __archive_read_header(struct archive_read *a, struct archive_entry *entry)
 {
-	if (a->filter->read_header)
-		return a->filter->read_header(a->filter, entry);
-	else
+	if (!a->filter->vtable->read_header)
 		return (ARCHIVE_OK);
+	return a->filter->vtable->read_header(a->filter, entry);
 }
 
 /*
@@ -991,8 +995,8 @@ close_filters(struct archive_read *a)
 	/* Close each filter in the pipeline. */
 	while (f != NULL) {
 		struct archive_read_filter *t = f->upstream;
-		if (!f->closed && f->close != NULL) {
-			int r1 = (f->close)(f);
+		if (!f->closed && f->vtable != NULL) {
+			int r1 = (f->vtable->close)(f);
 			f->closed = 1;
 			if (r1 < r)
 				r = r1;
@@ -1382,7 +1386,7 @@ __archive_read_filter_ahead(struct archive_read_filter *filter,
 					*avail = 0;
 				return (NULL);
 			}
-			bytes_read = (filter->read)(filter,
+			bytes_read = (filter->vtable->read)(filter,
 			    &filter->client_buff);
 			if (bytes_read < 0) {		/* Read error. */
 				filter->client_total = filter->client_avail = 0;
@@ -1576,7 +1580,7 @@ advance_file_pointer(struct archive_read_filter *filter, int64_t request)
 
 	/* Use ordinary reads as necessary to complete the request. */
 	for (;;) {
-		bytes_read = (filter->read)(filter, &filter->client_buff);
+		bytes_read = (filter->vtable->read)(filter, &filter->client_buff);
 		if (bytes_read < 0) {
 			filter->client_buff = NULL;
 			filter->fatal = 1;

libarchive/archive_read_private.h

@@ -75,6 +75,15 @@ struct archive_read_filter_bidder {
 	const struct archive_read_filter_bidder_vtable *vtable;
 };
 
+struct archive_read_filter_vtable {
+	/* Return next block. */
+	ssize_t (*read)(struct archive_read_filter *, const void **);
+	/* Close (just this filter) and free(self). */
+	int (*close)(struct archive_read_filter *self);
+	/* Read any header metadata if available. */
+	int (*read_header)(struct archive_read_filter *self, struct archive_entry *entry);
+};
+
 /*
  * This structure is allocated within the archive_read core
  * and initialized by archive_read and the init() method of the
@@ -87,12 +96,7 @@ struct archive_read_filter {
 	struct archive_read_filter_bidder *bidder; /* My bidder. */
 	struct archive_read_filter *upstream; /* Who I read from. */
 	struct archive_read *archive; /* Associated archive. */
-	/* Return next block. */
-	ssize_t (*read)(struct archive_read_filter *, const void **);
-	/* Close (just this filter) and free(self). */
-	int (*close)(struct archive_read_filter *self);
-	/* Read any header metadata if available. */
-	int (*read_header)(struct archive_read_filter *self, struct archive_entry *entry);
+	const struct archive_read_filter_vtable *vtable;
 	/* My private data. */
 	void *data;
 

libarchive/archive_read_support_filter_bzip2.c

@@ -173,6 +173,12 @@ bzip2_reader_init(struct archive_read_filter *self)
 
 #else
 
+static const struct archive_read_filter_vtable
+bzip2_reader_vtable = {
+	.read = bzip2_filter_read,
+	.close = bzip2_filter_close,
+};
+
 /*
  * Setup the callbacks.
  */
@@ -199,8 +205,7 @@ bzip2_reader_init(struct archive_read_filter *self)
 	self->data = state;
 	state->out_block_size = out_block_size;
 	state->out_block = out_block;
-	self->read = bzip2_filter_read;
-	self->close = bzip2_filter_close;
+	self->vtable = &bzip2_reader_vtable;
 
 	return (ARCHIVE_OK);
 }

libarchive/archive_read_support_filter_compress.c

@@ -198,6 +198,12 @@ compress_bidder_bid(struct archive_read_filter_bidder *self,
 	return (bits_checked);
 }
 
+static const struct archive_read_filter_vtable
+compress_reader_vtable = {
+	.read = compress_filter_read,
+	.close = compress_filter_close,
+};
+
 /*
  * Setup the callbacks.
  */
@@ -226,8 +232,7 @@ compress_bidder_init(struct archive_read_filter *self)
 	self->data = state;
 	state->out_block_size = out_block_size;
 	state->out_block = out_block;
-	self->read = compress_filter_read;
-	self->close = compress_filter_close;
+	self->vtable = &compress_reader_vtable;
 
 	/* XXX MOVE THE FOLLOWING OUT OF INIT() XXX */
 

libarchive/archive_read_support_filter_gzip.c

@@ -288,6 +288,15 @@ gzip_read_header(struct archive_read_filter *self, struct archive_entry *entry)
 	return (ARCHIVE_OK);
 }
 
+static const struct archive_read_filter_vtable
+gzip_reader_vtable = {
+	.read = gzip_filter_read,
+	.close = gzip_filter_close,
+#ifdef HAVE_ZLIB_H
+	.read_header = gzip_read_header,
+#endif
+};
+
 /*
  * Initialize the filter object.
  */
@@ -314,11 +323,7 @@ gzip_bidder_init(struct archive_read_filter *self)
 	self->data = state;
 	state->out_block_size = out_block_size;
 	state->out_block = out_block;
-	self->read = gzip_filter_read;
-	self->close = gzip_filter_close;
-#ifdef HAVE_ZLIB_H
-	self->read_header = gzip_read_header;
-#endif
+	self->vtable = &gzip_reader_vtable;
 
 	state->in_stream = 0; /* We're not actually within a stream yet. */
 

libarchive/archive_read_support_filter_lz4.c

@@ -208,6 +208,12 @@ lz4_reader_init(struct archive_read_filter *self)
 
 #else
 
+static const struct archive_read_filter_vtable
+lz4_reader_vtable = {
+	.read = lz4_filter_read,
+	.close = lz4_filter_close,
+};
+
 /*
  * Setup the callbacks.
  */
@@ -228,8 +234,7 @@ lz4_reader_init(struct archive_read_filter *self)
 
 	self->data = state;
 	state->stage = SELECT_STREAM;
-	self->read = lz4_filter_read;
-	self->close = lz4_filter_close;
+	self->vtable = &lz4_reader_vtable;
 
 	return (ARCHIVE_OK);
 }

libarchive/archive_read_support_filter_lzop.c

@@ -169,6 +169,13 @@ lzop_bidder_init(struct archive_read_filter *self)
 	return (r);
 }
 #else
+
+static const struct archive_read_filter_vtable
+lzop_reader_vtable = {
+	.read = lzop_filter_read,
+	.close = lzop_filter_close.
+};
+
 /*
  * Initialize the filter object.
  */
@@ -188,8 +195,7 @@ lzop_bidder_init(struct archive_read_filter *self)
 	}
 
 	self->data = state;
-	self->read = lzop_filter_read;
-	self->close = lzop_filter_close;
+	self->vtable = &lzop_reader_vtable;
 
 	return (ARCHIVE_OK);
 }

libarchive/archive_read_support_filter_program.c

@@ -382,6 +382,12 @@ child_read(struct archive_read_filter *self, char *buf, size_t buf_len)
 	}
 }
 
+static const struct archive_read_filter_vtable
+program_reader_vtable = {
+	.read = program_filter_read,
+	.close = program_filter_close,
+};
+
 int
 __archive_read_program(struct archive_read_filter *self, const char *cmd)
 {
@@ -428,8 +434,7 @@ __archive_read_program(struct archive_read_filter *self, const char *cmd)
 	}
 
 	self->data = state;
-	self->read = program_filter_read;
-	self->close = program_filter_close;
+	self->vtable = &program_reader_vtable;
 
 	/* XXX Check that we can read at least one byte? */
 	return (ARCHIVE_OK);

libarchive/archive_read_support_filter_rpm.c

@@ -127,6 +127,12 @@ rpm_bidder_bid(struct archive_read_filter_bidder *self,
 	return (bits_checked);
 }
 
+static const struct archive_read_filter_vtable
+rpm_reader_vtable = {
+	.read = rpm_filter_read,
+	.close = rpm_filter_close,
+};
+
 static int
 rpm_bidder_init(struct archive_read_filter *self)
 {
@@ -134,8 +140,6 @@ rpm_bidder_init(struct archive_read_filter *self)
 
 	self->code = ARCHIVE_FILTER_RPM;
 	self->name = "rpm";
-	self->read = rpm_filter_read;
-	self->close = rpm_filter_close;
 
 	rpm = (struct rpm *)calloc(sizeof(*rpm), 1);
 	if (rpm == NULL) {
@@ -146,6 +150,7 @@ rpm_bidder_init(struct archive_read_filter *self)
 
 	self->data = rpm;
 	rpm->state = ST_LEAD;
+	self->vtable = &rpm_reader_vtable;
 
 	return (ARCHIVE_OK);
 }

libarchive/archive_read_support_filter_uu.c

@@ -351,6 +351,12 @@ uudecode_bidder_bid(struct archive_read_filter_bidder *self,
 	return (0);
 }
 
+static const struct archive_read_filter_vtable
+uudecode_reader_vtable = {
+	.read = uudecode_filter_read,
+	.close = uudecode_filter_close,
+};
+
 static int
 uudecode_bidder_init(struct archive_read_filter *self)
 {
@@ -360,8 +366,6 @@ uudecode_bidder_init(struct archive_read_filter *self)
 
 	self->code = ARCHIVE_FILTER_UU;
 	self->name = "uu";
-	self->read = uudecode_filter_read;
-	self->close = uudecode_filter_close;
 
 	uudecode = (struct uudecode *)calloc(sizeof(*uudecode), 1);
 	out_buff = malloc(OUT_BUFF_SIZE);
@@ -381,6 +385,7 @@ uudecode_bidder_init(struct archive_read_filter *self)
 	uudecode->in_allocated = IN_BUFF_SIZE;
 	uudecode->out_buff = out_buff;
 	uudecode->state = ST_FIND_HEAD;
+	self->vtable = &uudecode_reader_vtable;
 
 	return (ARCHIVE_OK);
 }

libarchive/archive_read_support_filter_xz.c

@@ -461,6 +461,12 @@ set_error(struct archive_read_filter *self, int ret)
 	}
 }
 
+static const struct archive_read_filter_vtable
+xz_lzma_reader_vtable = {
+	.read = xz_filter_read,
+	.close = xz_filter_close,
+};
+
 /*
  * Setup the callbacks.
  */
@@ -485,8 +491,7 @@ xz_lzma_bidder_init(struct archive_read_filter *self)
 	self->data = state;
 	state->out_block_size = out_block_size;
 	state->out_block = out_block;
-	self->read = xz_filter_read;
-	self->close = xz_filter_close;
+	self->vtable = &xz_lzma_reader_vtable;
 
 	state->stream.avail_in = 0;
 

libarchive/archive_read_support_filter_zstd.c

@@ -157,6 +157,12 @@ zstd_bidder_init(struct archive_read_filter *self)
 
 #else
 
+static const struct archive_read_filter_vtable
+zstd_reader_vtable = {
+	.read = zstd_filter_read,
+	.close = zstd_filter_close,
+};
+
 /*
  * Initialize the filter object
  */
@@ -189,8 +195,7 @@ zstd_bidder_init(struct archive_read_filter *self)
 	state->out_block_size = out_block_size;
 	state->out_block = out_block;
 	state->dstream = dstream;
-	self->read = zstd_filter_read;
-	self->close = zstd_filter_close;
+	self->vtable = &zstd_reader_vtable;
 
 	state->eof = 0;
 	state->in_frame = 0;