On Wed, 14 Jul 2021, o...@eigenstate.org wrote:
Yes, but your patch doesn't apply cleanly to 9front, and
it would be useful to check whether I fuck up porting it
manually.
Ok, but I told you already how to create one.
http://adr.freeshell.org/files/turner_ovid_banished_from_rome.png
Quoth adr via 9fans <9fans@9fans.net>:
> On Mon, 12 Jul 2021, o...@eigenstate.org wrote:
> > Do you have an example?
>
> I could upload it in some place but you don't need it, really. The
> specification is clear
Yes, but your patch doesn't apply cleanly to 9front, and
it would be useful to
By the way, the lenght should be checked to not exceed 0x7FFF
so a corrupt chunk can be detected early.
--- /n/dump/2021/0627/sys/src/cmd/jpg/readpng.c Thu Jan 24 23:39:55 2013
+++ /sys/src/cmd/jpg/readpng.c Tue Jul 13 11:16:50 2021
@@ -10,8 +10,6 @@
enum
{
- IDATSIZE = 100,
-
On Tue, 13 Jul 2021, hiro wrote:
you seem to propose that if the png tells us to then we should
allocate 2GB per chunk, just bec. the spec allows it
even if the spec doesn't tell us a limit, we might want to have a limit.
No. The system should constrain the allocation. If you have enough
you seem to propose that if the png tells us to then we should
allocate 2GB per chunk, just bec. the spec allows it
even if the spec doesn't tell us a limit, we might want to have a limit.
On 7/13/21, adr via 9fans <9fans@9fans.net> wrote:
> On Tue, 13 Jul 2021, hiro wrote:
>> are you saying
On Tue, 13 Jul 2021, hiro wrote:
are you saying this is a purely synthetic error, it doesn't happen in
the wild bec. these sizes are normally more sane?
No, no... you got it wrong. You have to follow the specification
of the format, unless you want to have surprises like this one.
The file
are you saying this is a purely synthetic error, it doesn't happen in
the wild bec. these sizes are normally more sane?
On 7/13/21, adr via 9fans <9fans@9fans.net> wrote:
> On Mon, 12 Jul 2021, adr via 9fans wrote:
> [...]
>> the length of a data chunk must be less than 2^31 - 1
> [...]
>> can't
On Mon, 12 Jul 2021, adr via 9fans wrote:
[...]
the length of a data chunk must be less than 2^31 - 1
[...]
can't be fixed (At least you want to allocate more than 2GB...)
[...]
Well... to be exact here, it can't be bigger than 2^31 - 1, so there
are "almost" 2GB.
On Mon, 12 Jul 2021, hiro wrote:
Date: Mon, 12 Jul 2021 20:04:23 +0200
From: hiro <23h...@gmail.com>
Reply-To: 9fans <9fans@9fans.net>
To: 9fans <9fans@9fans.net>
Subject: Re: [9fans] pngread: alloc chunk's length
it's always useful to have the testcase available, for other
it's always useful to have the testcase available, for others and for
possible future regressions
On 7/12/21, adr via 9fans <9fans@9fans.net> wrote:
> On Mon, 12 Jul 2021, o...@eigenstate.org wrote:
>> Do you have an example?
>
> I could upload it in some place but you don't need it, really. The
On Mon, 12 Jul 2021, o...@eigenstate.org wrote:
Do you have an example?
I could upload it in some place but you don't need it, really. The
specification is clear, the length of a data chunk must be less
than 2^31 - 1, and the complete image data is represented by a
single zlib datastream that
On Mon, 12 Jul 2021, o...@eigenstate.org wrote:
Why not make getchunk allocate? Somethign like:
---
//.git/fs/object/e8259861da3a55c03491904e4d11c5c15b7577c5/tree/sys/src/cmd/jpg/readpng.c
+++ sys/src/cmd/jpg/readpng.c
@@ -94,7 +94,7 @@
}
static int
-getchunk(Biobuf *b, char *type, uchar *d,
Quoth adr via 9fans <9fans@9fans.net>:
> because it couldn't open some png files
Do you have an example?
--
9fans: 9fans
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https://9fans.topicbox.com/groups/9fans/T4a714ed14c50767a-Mfc030872ffba9972709a61bd
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Quoth adr via 9fans <9fans@9fans.net>:
> Checking the sent mail I noticed that I forgot to remove mag...
Why not make getchunk allocate? Somethign like:
---
//.git/fs/object/e8259861da3a55c03491904e4d11c5c15b7577c5/tree/sys/src/cmd/jpg/readpng.c
+++ sys/src/cmd/jpg/readpng.c
@@ -94,7 +94,7 @@
Checking the sent mail I noticed that I forgot to remove mag...
--- sys/src/cmd/jpg/readpng.c Thu Jan 24 23:39:55 2013
+++ /sys/src/cmd/jpg/readpng.c Sat Jul 10 13:09:13 2021
@@ -10,8 +10,6 @@
enum
{
- IDATSIZE = 100,
-
/* filtering algorithms */
FilterNone =
Hi,
Png is using a fix size to allocate space for the chunks. I noticed
it because it couldn't open some png files (the chunk size was
bigger than IDATSIZE).
This patch removes IDATSIZE and instead makes png to allocate the
size of the chunk before reading it.
--- sys/src/cmd/jpg/readpng.c
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