[Bug 1829980] [NEW] sscanf %02x and "0x" behaviour

[Zibri Soft]

Public bug reported:

I wrote this routine to convert a hex string to binary:

https://gist.github.com/Zibri/992b38baa520eb478ef7fa15fd950a7a/raw/2ea3634b31d6c90d74dc2a987a3dfe3b57e6fbcc/hex2bin_by_zibri.c

The routine works nicely but I noticed one thing:

sscanf("%02x",&char)

accepts:

1
02
Aa
aA

but it also accepts

0x which it translates to 00

There's no real harm in that, but I think that should be corrected.
In a loop if the input string (check my routine) is
"0x 0x 12 34 0x 1x 12 34"
The routine translates
00 00 12 34 00

Because for sscanf 0x is not an error but 1x is.
IMHO they should both be treated the same way in "%x"...

Regards,
Zibri

** Affects: glibc (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: input sscanf unintended

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https://bugs.launchpad.net/bugs/1829980

Title:
  sscanf %02x  and "0x" behaviour

Status in glibc package in Ubuntu:
  New

Bug description:
  I wrote this routine to convert a hex string to binary:

  https://gist.github.com/Zibri/992b38baa520eb478ef7fa15fd950a7a/raw/2ea3634b31d6c90d74dc2a987a3dfe3b57e6fbcc/hex2bin_by_zibri.c

  The routine works nicely but I noticed one thing:

  sscanf("%02x",&char)

  accepts:

  1
  02
  Aa
  aA

  but it also accepts

  0x which it translates to 00

  There's no real harm in that, but I think that should be corrected.
  In a loop if the input string (check my routine) is
  "0x 0x 12 34 0x 1x 12 34"
  The routine translates
  00 00 12 34 00

  Because for sscanf 0x is not an error but 1x is.
  IMHO they should both be treated the same way in "%x"...

  Regards,
  Zibri

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