From 24d77bf5161c1936951a76fead13a92f57557929 Mon Sep 17 00:00:00 2001
From: Pompolic <pompolic@special-circumstanc.es>
Date: Wed, 19 Feb 2020 18:27:18 +0100
Subject: [PATCH] Fix bug that would have added extra 0 bytes in partial groups
---
pdf.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/pdf.c b/pdf.c
index 1db9e37..e130384 100644
--- a/pdf.c
+++ b/pdf.c
@@ -373,16 +373,21 @@ HParsedToken *
act_a85partialgroup(const HParseResult *p, void *u)
{
uint8_t bytes_helper[4];
- size_t bytes_used = 1;
+ size_t bytes_used = 0;
uint8_t *bytes;
uint32_t fourbytes = H_CAST_UINT(p->ast);
- for (size_t i; i < 4; ++i)
+ /* Scan the uint backwards to find the first non-zero byte */
+ for (size_t i = 3; i > 0; --i)
{
- bytes_helper[i] = (fourbytes >> (3-i * 8)) & 0xFF;
- bytes_used += 1;
+ /* Shift by 0, 8, 16 and 24 to get the correct byte */
+ bytes_helper[i] = (fourbytes >> ((3-i) * 8)) & 0xFF;
+ /* If we haven't set bytes_used yet, and the particular byte is nonzero */
+ if (!bytes_used && bytes_helper[i])
+ bytes_used = i;
}
+ assert(bytes_used > 0);
bytes = h_arena_malloc(p->arena, bytes_used);
return H_MAKE_BYTES(bytes, bytes_used);
--
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