libio: move istream buffer logic into interall callbacks

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

4 files changed, 186 insertions, 72 deletions

diff --git a/lib/io/src/mem.c b/lib/io/src/mem.c
index 39e0d6b..bbb186a 100644
--- a/lib/io/src/mem.c
+++ b/lib/io/src/mem.c
@@ -20,38 +20,52 @@ typedef struct {
 
 	const void *data;
 	size_t size;
+	size_t offset;
+	size_t visible;
 
 	char *name;
 } mem_istream_t;
 
-static int mem_in_precache(istream_t *strm)
+static int mem_get_buffered_data(istream_t *strm, const sqfs_u8 **out,
+				 size_t *size, size_t want)
 {
 	mem_istream_t *mem = (mem_istream_t *)strm;
-	size_t diff;
+	size_t have = mem->size - mem->offset;
 
-	assert(strm->buffer >= mem->buffer);
-	assert(strm->buffer <= (mem->buffer + mem->bufsz));
-	assert(strm->buffer_used <= mem->bufsz);
-	assert((size_t)(strm->buffer - mem->buffer) <=
-	       (mem->bufsz - strm->buffer_used));
+	if (have > mem->bufsz)
+		have = mem->bufsz;
 
-	if (strm->buffer_used > 0)
-		memmove(mem->buffer, strm->buffer, strm->buffer_used);
+	if (want > have)
+		want = have;
 
-	strm->buffer = mem->buffer;
+	if (mem->visible == 0 || mem->visible < want) {
+		memcpy(mem->buffer + mem->visible,
+		       (const char *)mem->data + mem->offset + mem->visible,
+		       have - mem->visible);
+		mem->visible = have;
+	}
 
-	diff = mem->bufsz - strm->buffer_used;
-	if (diff > mem->size)
-		diff = mem->size;
+	*out = mem->buffer;
+	*size = mem->visible;
+	return (mem->visible == 0) ? 1 : 0;
+}
 
-	if (diff > 0) {
-		memcpy(mem->buffer + strm->buffer_used, mem->data, diff);
-		strm->buffer_used += diff;
-		mem->data = (const char *)mem->data + diff;
-		mem->size -= diff;
-	}
+static void mem_advance_buffer(istream_t *strm, size_t count)
+{
+	mem_istream_t *mem = (mem_istream_t *)strm;
 
-	return 0;
+	assert(count <= mem->visible);
+
+	if (count > 0 && count < mem->visible)
+		memmove(mem->buffer, mem->buffer + count, mem->visible - count);
+
+	mem->offset += count;
+	mem->visible -= count;
+
+	if (mem->visible < mem->bufsz) {
+		memset(mem->buffer + mem->visible, 0,
+		       mem->bufsz - mem->visible);
+	}
 }
 
 static const char *mem_in_get_filename(istream_t *strm)
@@ -88,8 +102,8 @@ istream_t *istream_memory_create(const char *name, size_t bufsz,
 	mem->data = data;
 	mem->size = size;
 	mem->bufsz = bufsz;
-	strm->buffer = mem->buffer;
-	strm->precache = mem_in_precache;
+	strm->get_buffered_data = mem_get_buffered_data;
+	strm->advance_buffer = mem_advance_buffer;
 	strm->get_filename = mem_in_get_filename;
 	return strm;
 }
diff --git a/lib/io/src/unix/istream.c b/lib/io/src/unix/istream.c
index 8a2dc26..60abff1 100644
--- a/lib/io/src/unix/istream.c
+++ b/lib/io/src/unix/istream.c
@@ -12,30 +12,35 @@ typedef struct {
 	int fd;
 
 	bool eof;
+	size_t buffer_offset;
+	size_t buffer_used;
 	sqfs_u8 buffer[BUFSZ];
 } file_istream_t;
 
-static int file_precache(istream_t *strm)
+static int precache(istream_t *strm)
 {
 	file_istream_t *file = (file_istream_t *)strm;
 
-	assert(strm->buffer >= file->buffer);
-	assert(strm->buffer <= (file->buffer + BUFSZ));
-	assert(strm->buffer_used <= BUFSZ);
-	assert((size_t)(strm->buffer - file->buffer) <=
-	       (BUFSZ - strm->buffer_used));
+	if (file->eof)
+		return 0;
 
-	if (strm->buffer_used > 0)
-		memmove(file->buffer, strm->buffer, strm->buffer_used);
+	if (file->buffer_offset > 0 &&
+	    file->buffer_offset < file->buffer_used) {
+		memmove(file->buffer, file->buffer + file->buffer_offset,
+			file->buffer_used - file->buffer_offset);
+	}
 
-	strm->buffer = file->buffer;
+	file->buffer_used -= file->buffer_offset;
+	file->buffer_offset = 0;
 
-	while (!file->eof && strm->buffer_used < BUFSZ) {
-		ssize_t ret = read(file->fd, file->buffer + strm->buffer_used,
-				   BUFSZ - strm->buffer_used);
+	while (file->buffer_used < BUFSZ) {
+		ssize_t ret = read(file->fd, file->buffer + file->buffer_used,
+				   BUFSZ - file->buffer_used);
 
-		if (ret == 0)
+		if (ret == 0) {
 			file->eof = true;
+			break;
+		}
 
 		if (ret < 0) {
 			if (errno == EINTR)
@@ -45,12 +50,43 @@ static int file_precache(istream_t *strm)
 			return -1;
 		}
 
-		strm->buffer_used += ret;
+		file->buffer_used += ret;
 	}
 
 	return 0;
 }
 
+static int file_get_buffered_data(istream_t *strm, const sqfs_u8 **out,
+				  size_t *size, size_t want)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	if (want > BUFSZ)
+		want = BUFSZ;
+
+	if (file->buffer_used == 0 ||
+	    (file->buffer_used - file->buffer_offset) < want) {
+		int ret = precache(strm);
+		if (ret)
+			return ret;
+	}
+
+	*out = file->buffer + file->buffer_offset;
+	*size = file->buffer_used - file->buffer_offset;
+	return (file->eof && *size == 0) ? 1 : 0;
+}
+
+static void file_advance_buffer(istream_t *strm, size_t count)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	assert(count <= file->buffer_used);
+
+	file->buffer_offset += count;
+
+	assert(file->buffer_offset <= file->buffer_used);
+}
+
 static const char *file_get_filename(istream_t *strm)
 {
 	file_istream_t *file = (file_istream_t *)strm;
@@ -93,8 +129,8 @@ istream_t *istream_open_file(const char *path)
 		goto fail_path;
 	}
 
-	strm->buffer = file->buffer;
-	strm->precache = file_precache;
+	strm->get_buffered_data = file_get_buffered_data;
+	strm->advance_buffer = file_advance_buffer;
 	strm->get_filename = file_get_filename;
 	return strm;
 fail_path:
@@ -119,8 +155,8 @@ istream_t *istream_open_stdin(void)
 		goto fail;
 
 	file->fd = STDIN_FILENO;
-	strm->buffer = file->buffer;
-	strm->precache = file_precache;
+	strm->get_buffered_data = file_get_buffered_data;
+	strm->advance_buffer = file_advance_buffer;
 	strm->get_filename = file_get_filename;
 	return strm;
 fail:
diff --git a/lib/io/src/win32/istream.c b/lib/io/src/win32/istream.c
index c4d7458..9bc32a0 100644
--- a/lib/io/src/win32/istream.c
+++ b/lib/io/src/win32/istream.c
@@ -15,10 +15,12 @@ typedef struct {
 	HANDLE hnd;
 
 	bool eof;
+	size_t buffer_offset;
+	size_t buffer_used;
 	sqfs_u8 buffer[BUFSZ];
 } file_istream_t;
 
-static int file_precache(istream_t *strm)
+static int precache(istream_t *strm)
 {
 	file_istream_t *file = (file_istream_t *)strm;
 	DWORD diff, actual;
@@ -27,22 +29,21 @@ static int file_precache(istream_t *strm)
 	if (file->eof)
 		return 0;
 
-	assert(strm->buffer >= file->buffer);
-	assert(strm->buffer <= (file->buffer + BUFSZ));
-	assert(strm->buffer_used <= BUFSZ);
-	assert((size_t)(strm->buffer - file->buffer) <=
-	       (BUFSZ - strm->buffer_used));
+	if (file->buffer_offset > 0 &&
+	    file->buffer_offset < file->buffer_used) {
+		memmove(file->buffer, file->buffer + file->buffer_offset,
+			file->buffer_used - file->buffer_offset);
+	}
 
-	if (strm->buffer_used > 0)
-		memmove(file->buffer, strm->buffer, strm->buffer_used);
+	file->buffer_used -= file->buffer_offset;
+	file->buffer_offset = 0;
 
-	strm->buffer = file->buffer;
 	hnd = file->path == NULL ? GetStdHandle(STD_INPUT_HANDLE) : file->hnd;
 
-	while (strm->buffer_used < sizeof(file->buffer)) {
-		diff = sizeof(file->buffer) - strm->buffer_used;
+	while (file->buffer_used < sizeof(file->buffer)) {
+		diff = sizeof(file->buffer) - file->buffer_used;
 
-		if (!ReadFile(hnd, file->buffer + strm->buffer_used,
+		if (!ReadFile(hnd, file->buffer + file->buffer_used,
 			      diff, &actual, NULL)) {
 			DWORD error = GetLastError();
 
@@ -63,12 +64,43 @@ static int file_precache(istream_t *strm)
 			break;
 		}
 
-		strm->buffer_used += actual;
+		file->buffer_used += actual;
 	}
 
 	return 0;
 }
 
+static int file_get_buffered_data(istream_t *strm, const sqfs_u8 **out,
+				  size_t *size, size_t want)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	if (want > BUFSZ)
+		want = BUFSZ;
+
+	if (file->buffer_used == 0 ||
+	    (file->buffer_used - file->buffer_offset) < want) {
+		int ret = precache(strm);
+		if (ret)
+			return ret;
+	}
+
+	*out = file->buffer + file->buffer_offset;
+	*size = file->buffer_used - file->buffer_offset;
+	return (file->eof && *size == 0) ? 1 : 0;
+}
+
+static void file_advance_buffer(istream_t *strm, size_t count)
+{
+	file_istream_t *file = (file_istream_t *)strm;
+
+	assert(count <= file->buffer_used);
+
+	file->buffer_offset += count;
+
+	assert(file->buffer_offset <= file->buffer_used);
+}
+
 static const char *file_get_filename(istream_t *strm)
 {
 	file_istream_t *file = (file_istream_t *)strm;
@@ -122,7 +154,8 @@ istream_t *istream_open_file(const char *path)
 	free(wpath);
 
 	strm->buffer = file->buffer;
-	strm->precache = file_precache;
+	strm->get_buffered_data = file_get_buffered_data;
+	strm->advance_buffer = file_advance_buffer;
 	strm->get_filename = file_get_filename;
 	return strm;
 fail_path:
@@ -146,7 +179,8 @@ istream_t *istream_open_stdin(void)
 	sqfs_object_init(file, file_destroy, NULL);
 
 	strm->buffer = file->buffer;
-	strm->precache = file_precache;
+	strm->get_buffered_data = file_get_buffered_data;
+	strm->advance_buffer = file_advance_buffer;
 	strm->get_filename = file_get_filename;
 	return strm;
 }
diff --git a/lib/io/src/xfrm/istream.c b/lib/io/src/xfrm/istream.c
index bad3e22..c9bc41a 100644
--- a/lib/io/src/xfrm/istream.c
+++ b/lib/io/src/xfrm/istream.c
@@ -12,27 +12,28 @@ typedef struct istream_xfrm_t {
 	istream_t *wrapped;
 	xfrm_stream_t *xfrm;
 
+	size_t buffer_offset;
+	size_t buffer_used;
 	sqfs_u8 uncompressed[BUFSZ];
 } istream_xfrm_t;
 
-static int xfrm_precache(istream_t *base)
+static int precache(istream_t *base)
 {
 	istream_xfrm_t *xfrm = (istream_xfrm_t *)base;
 	int ret;
 
-	assert(base->buffer >= xfrm->uncompressed);
-	assert(base->buffer <= (xfrm->uncompressed + BUFSZ));
-	assert(base->buffer_used <= BUFSZ);
-	assert((size_t)(base->buffer - xfrm->uncompressed) <=
-	       (BUFSZ - base->buffer_used));
-
-	if (base->buffer_used > 0)
-		memmove(xfrm->uncompressed, base->buffer, base->buffer_used);
+	if (xfrm->buffer_offset > 0 &&
+	    xfrm->buffer_offset < xfrm->buffer_used) {
+		memmove(xfrm->uncompressed,
+			xfrm->uncompressed + xfrm->buffer_offset,
+			xfrm->buffer_used - xfrm->buffer_offset);
+	}
 
-	base->buffer = xfrm->uncompressed;
+	xfrm->buffer_used -= xfrm->buffer_offset;
+	xfrm->buffer_offset = 0;
 
 	for (;;) {
-		sqfs_u32 in_off = 0, out_off = base->buffer_used;
+		sqfs_u32 in_off = 0, out_off = xfrm->buffer_used;
 		int mode = XFRM_STREAM_FLUSH_NONE;
 		const sqfs_u8 *ptr;
 		size_t avail;
@@ -41,10 +42,8 @@ static int xfrm_precache(istream_t *base)
 						sizeof(xfrm->uncompressed));
 		if (ret < 0)
 			return ret;
-		if (ret > 0) {
+		if (ret > 0)
 			mode = XFRM_STREAM_FLUSH_FULL;
-			avail = 0;
-		}
 
 		ret = xfrm->xfrm->process_data(xfrm->xfrm,
 					       ptr, avail,
@@ -58,7 +57,7 @@ static int xfrm_precache(istream_t *base)
 			return -1;
 		}
 
-		base->buffer_used = out_off;
+		xfrm->buffer_used = out_off;
 		istream_advance_buffer(xfrm->wrapped, in_off);
 
 		if (ret == XFRM_STREAM_BUFFER_FULL || out_off >= BUFSZ)
@@ -71,6 +70,37 @@ static int xfrm_precache(istream_t *base)
 	return 0;
 }
 
+static int xfrm_get_buffered_data(istream_t *strm, const sqfs_u8 **out,
+				  size_t *size, size_t want)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
+
+	if (want > BUFSZ)
+		want = BUFSZ;
+
+	if (xfrm->buffer_used == 0 ||
+	    (xfrm->buffer_used - xfrm->buffer_offset) < want) {
+		int ret = precache(strm);
+		if (ret)
+			return ret;
+	}
+
+	*out = xfrm->uncompressed + xfrm->buffer_offset;
+	*size = xfrm->buffer_used - xfrm->buffer_offset;
+	return (*size == 0) ? 1 : 0;
+}
+
+static void xfrm_advance_buffer(istream_t *strm, size_t count)
+{
+	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
+
+	assert(count <= xfrm->buffer_used);
+
+	xfrm->buffer_offset += count;
+
+	assert(xfrm->buffer_offset <= xfrm->buffer_used);
+}
+
 static const char *xfrm_get_filename(istream_t *strm)
 {
 	istream_xfrm_t *xfrm = (istream_xfrm_t *)strm;
@@ -100,9 +130,9 @@ istream_t *istream_xfrm_create(istream_t *strm, xfrm_stream_t *xfrm)
 	stream->wrapped = sqfs_grab(strm);
 	stream->xfrm = sqfs_grab(xfrm);
 
-	base->precache = xfrm_precache;
+	base->get_buffered_data = xfrm_get_buffered_data;
+	base->advance_buffer = xfrm_advance_buffer;
 	base->get_filename = xfrm_get_filename;
-	base->buffer = stream->uncompressed;
 	return base;
 fail:
 	fprintf(stderr, "%s: error initializing decompressor stream.\n",