Configure mangles hex values

Configure mangles hex values

[Nick Pollitt]

When doing a make oldconfig, the hex function strips the leading '0x' from hex 
values.  The '0x' is needed in the final autoconf.h, and its absence causes 
the following problem.

If I start with a hex value in my config file like this:
CONFIG_LOWMEM_SIZE=0x40000000
When I run make oldconfig, it strips out the '0x' leaving this:
CONFIG_LOWMEM_SIZE=40000000
Then if I run make xconfig, this is not considered a valid hex value, so it
replaces my value with the default:
CONFIG_LOWMEM_SIZE=0x20000000

The following patch removes the lines that strip the 0x from the hex value.  
It also checks the result for the leading 0x and inserts it if necessary.

--- scripts/Configure.orig 2005-01-24 13:31:55.000000000 -0800
+++ scripts/Configure 2005-01-24 13:34:20.000000000 -0800
@@ -378,15 +378,18 @@
 function hex () {
  old=$(eval echo "\${$2}")
  def=${old:-$3}
- def=${def#*[x,X]}
  while :; do
    readln "$1 ($2) [$def] " "$def" "$old"
-   ans=${ans#*[x,X]}
-   if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
-     define_hex "$2" "0x$ans"
+   if expr "$ans" : '0x[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
+     define_hex "$2" "$ans"
      break
    else
-     help "$2"
+     if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
+       define_hex "$2" "0x$ans"
+       break
+     else
+       help "$2"
+     fi
    fi
  done
 }

Re: Configure mangles hex values

[Nick Pollitt]

Sorry about previous message.

The hex function in scripts/Configure strips the leading 0x from hex values.  
The 0x needs to be there in autoconf.h, and stripping it out causes the 
following problematic scenario:

If I start with a hex value in my config file like this:
CONFIG_LOWMEM_SIZE=0x40000000
and then run make oldconfig, it strips out the '0x' so I end up with this:
CONFIG_LOWMEM_SIZE=40000000
Then if I run make xconfig, it doesn't think this is a valid hex value, so it
replaces my value with the default:
CONFIG_LOWMEM_SIZE=0x20000000

The following patch removes the lines that strip out 0x, and inserts the 0x if 
appropriate.

--- scripts/Configure.orig 2005-01-24 13:31:55.000000000 -0800
+++ scripts/Configure 2005-01-24 13:34:20.000000000 -0800
@@ -378,15 +378,18 @@
 function hex () {
  old=$(eval echo "\${$2}")
  def=${old:-$3}
- def=${def#*[x,X]}
  while :; do
    readln "$1 ($2) [$def] " "$def" "$old"
-   ans=${ans#*[x,X]}
-   if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
-     define_hex "$2" "0x$ans"
+   if expr "$ans" : '0x[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
+     define_hex "$2" "$ans"
      break
    else
-     help "$2"
+     if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
+       define_hex "$2" "0x$ans"
+       break
+     else
+       help "$2"
+     fi
    fi
  done
 }

Re: Configure mangles hex values

[Marcelo Tosatti]

Hi Nick,

Curiosity: What was the reason for stripping the leading 0x? 

On Mon, Jan 24, 2005 at 02:41:56PM -0800, Nick Pollitt wrote:
> Sorry about previous message.
> 
> The hex function in scripts/Configure strips the leading 0x from hex values.  
> The 0x needs to be there in autoconf.h, and stripping it out causes the 
> following problematic scenario:
> 
> If I start with a hex value in my config file like this:
> CONFIG_LOWMEM_SIZE=0x40000000
> and then run make oldconfig, it strips out the '0x' so I end up with this:
> CONFIG_LOWMEM_SIZE=40000000
> Then if I run make xconfig, it doesn't think this is a valid hex value, so it
> replaces my value with the default:
> CONFIG_LOWMEM_SIZE=0x20000000
> 
> The following patch removes the lines that strip out 0x, and inserts the 0x if 
> appropriate.
> 
> --- scripts/Configure.orig 2005-01-24 13:31:55.000000000 -0800
> +++ scripts/Configure 2005-01-24 13:34:20.000000000 -0800
> @@ -378,15 +378,18 @@
>  function hex () {
>   old=$(eval echo "\${$2}")
>   def=${old:-$3}
> - def=${def#*[x,X]}
>   while :; do
>     readln "$1 ($2) [$def] " "$def" "$old"
> -   ans=${ans#*[x,X]}
> -   if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
> -     define_hex "$2" "0x$ans"
> +   if expr "$ans" : '0x[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
> +     define_hex "$2" "$ans"
>       break
>     else
> -     help "$2"
> +     if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
> +       define_hex "$2" "0x$ans"
> +       break
> +     else
> +       help "$2"
> +     fi
>     fi
>   done
>  }

Re: Configure mangles hex values

[Nick Pollitt]

Hello.  I'm thinking that the 0x was stripped for purely cosmetic reasons 
rather than anything functional.  I had originally thought that the readln 
function might need the formatting, but taking a closer look at it now I 
don't see any need.

Nick

On Tuesday 25 January 2005 1:20 am, Marcelo Tosatti wrote:
> Hi Nick,
>
> Curiosity: What was the reason for stripping the leading 0x?
>
> On Mon, Jan 24, 2005 at 02:41:56PM -0800, Nick Pollitt wrote:
> > Sorry about previous message.
> >
> > The hex function in scripts/Configure strips the leading 0x from hex
> > values. The 0x needs to be there in autoconf.h, and stripping it out
> > causes the following problematic scenario:
> >
> > If I start with a hex value in my config file like this:
> > CONFIG_LOWMEM_SIZE=0x40000000
> > and then run make oldconfig, it strips out the '0x' so I end up with
> > this: CONFIG_LOWMEM_SIZE=40000000
> > Then if I run make xconfig, it doesn't think this is a valid hex value,
> > so it replaces my value with the default:
> > CONFIG_LOWMEM_SIZE=0x20000000
> >
> > The following patch removes the lines that strip out 0x, and inserts the
> > 0x if appropriate.
> >
> > --- scripts/Configure.orig 2005-01-24 13:31:55.000000000 -0800
> > +++ scripts/Configure 2005-01-24 13:34:20.000000000 -0800
> > @@ -378,15 +378,18 @@
> >  function hex () {
> >   old=$(eval echo "\${$2}")
> >   def=${old:-$3}
> > - def=${def#*[x,X]}
> >   while :; do
> >     readln "$1 ($2) [$def] " "$def" "$old"
> > -   ans=${ans#*[x,X]}
> > -   if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
> > -     define_hex "$2" "0x$ans"
> > +   if expr "$ans" : '0x[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
> > +     define_hex "$2" "$ans"
> >       break
> >     else
> > -     help "$2"
> > +     if expr "$ans" : '[0-9a-fA-F][0-9a-fA-F]*$' > /dev/null; then
> > +       define_hex "$2" "0x$ans"
> > +       break
> > +     else
> > +       help "$2"
> > +     fi
> >     fi
> >   done
> >  }

Re: Configure mangles hex values

[Keith Owens]

On Tue, 25 Jan 2005 09:25:57 -0800, 
Nick Pollitt <npollitt@mvista.com> wrote:
>Hello.  I'm thinking that the 0x was stripped for purely cosmetic reasons 
>rather than anything functional.  I had originally thought that the readln 
>function might need the formatting, but taking a closer look at it now I 
>don't see any need.

Agreed.  Apply the patch.