[ptxdist] [PATCH] Fixed broken httpd build (undefined reference to crypt_r)

[ptxdist] [PATCH] Fixed broken httpd build (undefined reference to crypt_r)

[Stefan Kratochwil]

Hi,

I fixed a problem regarding the httpd build. Without this fix, the build crashes during linking several binaries from the <httpd-basedir>/support subdir, including htdigest etc. The error message was 'undefined reference to crypt_r'.

This has been introduced by a changed behaviour in newer gcc versions, which by default set the linker option -Wl--as-needed. This results in WEAK symbol references not being resolved properly in certain situations. Linking against libcrypt turned out to be a main trigger for this problem.

The solution is to add -Wl--no-as-needed to ALL_LDFLAGS:


commit 8ecb56b24b57a0b2aca1470f48f60a34f518beaf
Author: Stefan Kratochwil <stefankratochwil@inovel.de>
Date:   Wed Jul 8 16:02:23 2015 +0200

    Fixed undefined reference to crypt_r.

    Newer gcc versions used the linker option -Wl--no-as-needed by default.
    This behaviour was changed in newer versions, which default to
    -Wl--as-needed.

    This leads to WEAK symbols not being resolved properly, which itself
    leads to linking errors, especially if libcrypt is involved.

    This patch restores the original behaviour by adding the linker option
    -Wl--no-as-needed to ALL_LDFLAGS.

diff --git a/patches/httpd-2.0.64/0005-fix-undefined-reference-to-crypt_r-by-no-as-needed.patch b/patches/httpd-2.0.64/0005-fix-undefined-reference-to-crypt_r-by-no-as-needed.patch
new file mode 100755
index 0000000..e80637f
--- /dev/null
+++ b/patches/httpd-2.0.64/0005-fix-undefined-reference-to-crypt_r-by-no-as-needed.patch
                
+Index: httpd-2.0.64/build/rules.mk.in
+===================================================================
+--- httpd-2.0.64.orig/build/rules.mk.in    2006-07-12 09:40:55.000000000 +0200
++++ httpd-2.0.64/build/rules.mk.in 2015-07-08 11:16:05.521218188 +0200
+                 
+ ALL_CFLAGS   = $(EXTRA_CFLAGS) $(NOTEST_CFLAGS) $(CFLAGS)
+ ALL_CPPFLAGS = $(DEFS) $(EXTRA_CPPFLAGS) $(NOTEST_CPPFLAGS) $(CPPFLAGS)
+ ALL_CXXFLAGS = $(EXTRA_CXXFLAGS) $(NOTEST_CXXFLAGS) $(CXXFLAGS)
+-ALL_LDFLAGS  = $(EXTRA_LDFLAGS) $(NOTEST_LDFLAGS) $(LDFLAGS)
++ALL_LDFLAGS  = -Wl,--no-as-needed $(EXTRA_LDFLAGS) $(NOTEST_LDFLAGS) $(LDFLAGS)
+ ALL_LIBS     = $(EXTRA_LIBS) $(NOTEST_LIBS) $(LIBS)
+ ALL_INCLUDES = $(INCLUDES) $(EXTRA_INCLUDES)
+ 
diff --git a/patches/httpd-2.0.64/series b/patches/httpd-2.0.64/series
index ff12a99..ff03f1f 100644
--- a/patches/httpd-2.0.64/series
+++ b/patches/httpd-2.0.64/series
               
 0003-HACK-support-apxs-don-t-execute-httpd.patch
 0004-HACK-support-apxs-don-t-try-to-modify-the-config-fil.patch
 # 160b9c105b4f55538cd0ce5c82eda8fd  - git-ptx-patches magic
+0005-fix-undefined-reference-to-crypt_r-by-no-as-needed.patch

I have no idea since when this problem occurs, but I recall a posting her on the mailinglist from a few years ago, stating that the build worked with OSELAS.Toolchain() 2012.xx.yy, but got broken with a later version.


Note: this problem also occurs in lighthttpd, and possibly in several other packages! I do not have a patch for lighthttpd and also didn't look for other affected packages.


I would be happy about a few comments.

 
Mit freundlichen Grüßen / with best regards


stefan kratochwil  
future master of software engineering

inovel elektronik gmbh 
inovel systeme AG 
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Re: [ptxdist] [PATCH] Fixed broken httpd build (undefined reference to crypt_r)

[Juergen Borleis]

Hi Stefan,

On Thursday 09 July 2015 11:35:40 Stefan Kratochwil wrote:
> I fixed a problem regarding the httpd build. Without this fix, the build
> crashes during linking several binaries from the <httpd-basedir>/support
> subdir, including htdigest etc. The error message was 'undefined reference
> to crypt_r'.
>
> This has been introduced by a changed behaviour in newer gcc versions,
> which by default set the linker option -Wl--as-needed. This results in WEAK
> symbol references not being resolved properly in certain situations.
> Linking against libcrypt turned out to be a main trigger for this problem.
>
> The solution is to add -Wl--no-as-needed to ALL_LDFLAGS:

After a discussion here your fix isn't a real fix, it is just a workaround.

Alternatively you can add a

APACHE2_WRAPPER_BLACKLIST := TARGET_LINKER_AS_NEEDED

to your apache rule file. This will prevent the compiler wrappers from 
forwarding the global "-Wl--as-needed" option to this specific package.

But:

With the "-Wl--as-needed" switch each component is linked against only those 
libraries it really uses. In the reported build failure from February 6th 2015 
the main program "httxt2dbm" was linked against "libcrypt" and "libaprutil-0".

In the "--no-as-needed" case "httxt2dbm" gets linked against "libcrypt", even 
if it *does not* use any symbol from this library:

httxt2dbm
  -> libcrypt
  -> libaprutil-0
     -> calls "crypt_r()" from libcrypt

In the "--as-needed" case the linker sorts out libcrypt, because "httxt2dbm" 
does not use any symbol from this library:

httxt2dbm
  -> libaprutil-0
     -> calls "crypt_r()" and fails

Using "--as-needed" is a correct approach, because it forces you to do things 
right: ensure your component is linked agains everything it needs.

httxt2dbm
  -> libaprutil-0
     -> libcrypt
     -> calls "crypt_r()" from libcrypt

The correct fix is: ensure the component libaprutil-0 is linked 
against "libcrypt" because it uses "crypt_r()".

Regards,
Juergen

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