From 366ccf20745b23f1eb8554cbe17e6972271de002 Mon Sep 17 00:00:00 2001
From: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
Date: Sun, 11 Jun 2023 15:40:26 +0200
Subject: libio: remove precache from istream_advance_buffer

Since the user has to call istream_get_buffered_data afterwards anyway,
we can do the precache lazily.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
---
 include/io/istream.h      | 13 ++-----------
 lib/io/src/get_line.c     |  3 +--
 lib/io/src/istream.c      | 12 +++---------
 lib/io/src/xfrm/istream.c |  7 ++-----
 lib/io/test/istream_mem.c |  5 +----
 lib/tar/src/iterator.c    |  4 +---
 6 files changed, 10 insertions(+), 34 deletions(-)

diff --git a/include/io/istream.h b/include/io/istream.h
index 8edd61d..fca1440 100644
--- a/include/io/istream.h
+++ b/include/io/istream.h
@@ -141,24 +141,15 @@ SQFS_INLINE int istream_get_buffered_data(istream_t *strm, const sqfs_u8 **out,
  *
  * This marks the first `count` bytes of the internal buffer as used,
  * forcing @ref istream_get_buffered_data to return data afterwards
- * and potentially to load more data.
+ * and potentially try to load more data.
  *
  * @param strm A pointer to an istream_t implementation.
  * @param count The number of bytes used up.
- *
- * @return Zero on success, a negative error code on failure.
  */
-SQFS_INLINE int istream_advance_buffer(istream_t *strm, size_t count)
+SQFS_INLINE void istream_advance_buffer(istream_t *strm, size_t count)
 {
-	if (count >= strm->buffer_used) {
-		strm->buffer += strm->buffer_used;
-		strm->buffer_used = 0;
-		return strm->precache(strm);
-	}
-
 	strm->buffer += count;
 	strm->buffer_used -= count;
-	return 0;
 }
 
 /**
diff --git a/lib/io/src/get_line.c b/lib/io/src/get_line.c
index 94ae9ce..4dc221a 100644
--- a/lib/io/src/get_line.c
+++ b/lib/io/src/get_line.c
@@ -85,8 +85,7 @@ int istream_get_line(istream_t *strm, char **out,
 		line_len += count;
 		line[line_len] = '\0';
 
-		if (istream_advance_buffer(strm, i))
-			goto fail_free;
+		istream_advance_buffer(strm, i);
 
 		if (have_line) {
 			if (line_len > 0 && line[line_len - 1] == '\r')
diff --git a/lib/io/src/istream.c b/lib/io/src/istream.c
index b4c709c..9340dd6 100644
--- a/lib/io/src/istream.c
+++ b/lib/io/src/istream.c
@@ -29,13 +29,10 @@ sqfs_s32 istream_read(istream_t *strm, void *data, size_t size)
 			diff = size;
 
 		memcpy(data, ptr, diff);
+		istream_advance_buffer(strm, diff);
 		data = (char *)data + diff;
 		size -= diff;
 		total += diff;
-
-		ret = istream_advance_buffer(strm, diff);
-		if (ret)
-			return -1;
 	}
 
 	return total;
@@ -61,9 +58,7 @@ int istream_skip(istream_t *strm, sqfs_u64 size)
 			diff = size;
 
 		size -= diff;
-
-		if (istream_advance_buffer(strm, diff))
-			return -1;
+		istream_advance_buffer(strm, diff);
 	}
 
 	return 0;
@@ -92,11 +87,10 @@ sqfs_s32 istream_splice(istream_t *in, ostream_t *out, sqfs_u32 size)
 
 		if (ostream_append(out, ptr, diff))
 			return -1;
-		if (istream_advance_buffer(in, diff))
-			return -1;
 
 		total += diff;
 		size -= diff;
+		istream_advance_buffer(in, diff);
 	}
 
 	return total;
diff --git a/lib/io/src/xfrm/istream.c b/lib/io/src/xfrm/istream.c
index 8755cb6..bad3e22 100644
--- a/lib/io/src/xfrm/istream.c
+++ b/lib/io/src/xfrm/istream.c
@@ -18,7 +18,7 @@ typedef struct istream_xfrm_t {
 static int xfrm_precache(istream_t *base)
 {
 	istream_xfrm_t *xfrm = (istream_xfrm_t *)base;
-	int ret, sret;
+	int ret;
 
 	assert(base->buffer >= xfrm->uncompressed);
 	assert(base->buffer <= (xfrm->uncompressed + BUFSZ));
@@ -59,10 +59,7 @@ static int xfrm_precache(istream_t *base)
 		}
 
 		base->buffer_used = out_off;
-
-		sret = istream_advance_buffer(xfrm->wrapped, in_off);
-		if (sret != 0)
-			return sret;
+		istream_advance_buffer(xfrm->wrapped, in_off);
 
 		if (ret == XFRM_STREAM_BUFFER_FULL || out_off >= BUFSZ)
 			break;
diff --git a/lib/io/test/istream_mem.c b/lib/io/test/istream_mem.c
index f1849dd..84da9a9 100644
--- a/lib/io/test/istream_mem.c
+++ b/lib/io/test/istream_mem.c
@@ -63,11 +63,8 @@ int main(int argc, char **argv)
 			TEST_EQUAL_UI(ptr[j], byte_at_offset(i + j));
 		}
 
-		diff = eat_all ? size : (size / 2);
+		istream_advance_buffer(in, eat_all ? size : (size / 2));
 		eat_all = !eat_all;
-
-		ret = istream_advance_buffer(in, diff);
-		TEST_EQUAL_I(ret, 0);
 	}
 
 	sqfs_drop(in);
diff --git a/lib/tar/src/iterator.c b/lib/tar/src/iterator.c
index f46a9c2..df5c446 100644
--- a/lib/tar/src/iterator.c
+++ b/lib/tar/src/iterator.c
@@ -109,9 +109,7 @@ static int strm_precache(istream_t *strm)
 		return tar->state;
 
 	if (!tar->parent->last_sparse) {
-		int ret = istream_advance_buffer(tar->parent->stream, diff);
-		if (ret != 0)
-			return ret;
+		istream_advance_buffer(tar->parent->stream, diff);
 		tar->parent->record_size -= diff;
 	}
 
-- 
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