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On 6/9/2013 7:53 PM, Philip Goetz wrote:
I tried but was unable to find any documentation on peflags other than
that provided by
peflags --help
This documentation indicates that I should be able to do something like this:
$ peflags --bigaddr `which perl`
but instead of getting a zero or one back, I get this, and have no
idea how to interpret it:
/usr/bin/perl: coff(0x0326[+bigaddr]) pe(0x8000)
See below.
The documentation also indicates I should be able to do this, but I cannot:
$ peflags --bigaddr 1 `which perl`
1: skipped because nonexistent
/usr/bin/perl: coff(0x0326[+bigaddr]) pe(0x8000)
I think you need to say "--bigaddr=1" but I could be wrong there.
Neither does this work:
$ peflags -l1 `which perl`
/usr/bin/perl: skipped because could not open
I have write permission on /usr/bin/perl .
No explanation here, but your followup seems to indicate it was a cygwin
version problem.
Can you point me to some documentation that will explain how to use
peflags to view and set this --bigaddr bit?
The existing documentation says:
"For each numerical value, if an argument is given, the specified value
will be overwritten; if no argument is given, the numerical value will
be displayed in decimal and hexadecimal notation."
The cryptic output "/usr/bin/perl: coff(0x0326[+bigaddr]) pe(0x8000)"
contains the actual values of the Characteristics fields of the COFF
File Header, and the PE OptionalHeader records in the on-disk file,
expressed in hex notation.
*coff_characteristics = pep->ntheaderNN->FileHeader.Characteristics;
*pe_characteristics = pep->ntheaderNN->OptionalHeader.DllCharacteristics;
It's really for debugging. By setting a particular flag true then false,
and checking the output, you can tell which bit corresponds to that flag
AND you can verify that the on-disk file actually got changed.
I had this whole big scheme to extensibly express all the flag values in
readable english, but it was a maintenance nightmare and cgf rightly
nixed it.
Instead, you get english output for JUST the value(s) you query. If you
query -d then the hex output is augmented with a string for dynamic base
-- but nothing else. If you query -l, then the hex output is augmented
with a string for big address -- but nothing else. There's a "+" if the
flag is turned "on", and a "-" if the flag is turned "off".
E.g.
$ peflags -l /usr/bin/perl
/usr/bin/perl: coff(0x0326[+bigaddr]) pe(0x8000)
Means you have bigaddr on.
$ peflags -d /usr/bin/perl
/usr/bin/perl: coff(0x0326) pe(0x8000[-dynamicbase])
Means you have dynamicbase off.
You can combine multiple queries:
$ peflags -d -l /usr/bin/perl
/usr/bin/perl: coff(0x0326[+bigaddr]) pe(0x8000[-dynamicbase])
So, what you do is grep the output for "+bigaddr" -- if that doesn't
appear when you query -l, then bigaddr is not set.
$ peflags -l /usr/bin/perl | grep '+bigaddr' >/dev/null &&\
echo has_bigaddr
has_bigaddr
$ peflags -d /usr/bin/perl | grep '+dynamicbase' >/dev/null &&\
echo has_dynamicbase
$
--
Chuck
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