Re: What happened to libtool transitive DSOs?

2018-06-28 Thread Tim Mooney

In regard to: Re: What happened to libtool transitive DSOs?, Bob...:


On Thu, 21 Jun 2018, John Calcote wrote:


Hi Bob. It's an ubuntu distro release - Linux Mint 18. Why would they do
that?


GNU Linux and the GNU linker support implicit library dependencies.


Sorry to jump into this discussion late, but I wanted to point out
that at least RHEL seems to be moving away from using implicit library
dependencies.

In the RHEL 7.5 (current latest) release notes, chapter 53, on deprecated
functionality:


https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/7.5_release_notes/chap-red_hat_enterprise_linux-7.5_release_notes-deprecated_functionality

there's this note:

Symbols from libraries linked as dependencies no longer resolved by ld

Previously, the ld linker resolved any symbols present in any linked
library, even if some libraries were linked only implicitly as
dependencies of other libraries. This allowed developers to use symbols
from the implicitly linked libraries in application code and omit
explicitly specifying these libraries for linking.

For security reasons, ld has been changed to not resolve references to
symbols in libraries linked implicitly as dependencies.

As a result, linking with ld fails when application code attempts to use
symbols from libraries not declared for linking and linked only implicitly
as dependencies. To use symbols from libraries linked as dependencies,
developers must explicitly link against these libraries as well.

To restore the previous behavior of ld, use the -copy-dt-needed-entries
command-line option. (BZ#1292230)


- end excerpt from RHEL release notes

Tim
--
Tim Mooney tim.moo...@ndsu.edu
Enterprise Computing & Infrastructure  701-231-1076 (Voice)
Room 242-J6, Quentin Burdick Building  701-231-8541 (Fax)
North Dakota State University, Fargo, ND 58105-5164

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Re: Does libtool need to escape plus signs in egrep expressions?

2018-06-28 Thread Bob Friesenhahn

On Thu, 28 Jun 2018, Roumen Petrov wrote:

May be I misunderstand issue.

$ echo ' _head_ABC_a'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
 _head_ABC_a

$ echo ' _head_ABC_al'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
 _head_ABC_al

but:
$ echo ' _head__al'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
$ echo ' __head_ABC_al'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
$ echo ' _head_ABC_zl'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'




Are you sure this actually works?
I'm not expert in regular expressions but according above tests "plus" in RE 
works - see case _head__al .


It should match a run of alpha-numeric characters including 
underscores.  However, I do see that the expression includes a match 
of literal underscore and then there is a literal underscore so there 
might be something going on with that.  Greedy matching would likely 
absorb a final underscore so it might not be possible to match on that 
final literal underscore.  This might expose differences in behaviors 
between egreps.


Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
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Re: Does libtool need to escape plus signs in egrep expressions?

2018-06-28 Thread Roumen Petrov

Hello,

LRN wrote:

While looking though ltmain source code i've stumbled upon this egrep 
invocation:
$EGREP ' (_head_[A-Za-z0-9_]+_[ad]l*|[A-Za-z0-9_]+_[ad]l*_iname)$'
I've tried to see how it behaves on some import libraries that i have, and it
turned out that i could never get it to detect the iname lines, unless i escape
the plus sign.

May be I misunderstand issue.

$ echo ' _head_ABC_a'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
 _head_ABC_a

$ echo ' _head_ABC_al'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
 _head_ABC_al

but:
$ echo ' _head__al'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
$ echo ' __head_ABC_al'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'
$ echo ' _head_ABC_zl'  | egrep ' _head_[A-Za-z0-9_]+_[ad]l*$'




Are you sure this actually works?
I'm not expert in regular expressions but according above tests "plus" 
in RE works - see case _head__al .



Note that the function that does this is only
used in rather exotic corner-cases (old dlltool and/or ms dumpbin being in
use), so it's plausible that it could have been broken since 2010, when it was
added.



Regards,
Roumen Petrov


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