Cross compile PHP with UCLIBC

Question

THIS IS A REPOST, PREVIOUS POST GOT CLOSED, MOVED TO SERVERFAULT AND CLOSED AGAIN. I think this post is a valid stackoverflow problem because i think its caused by some automake/compile/linking error. This is a programming problem not a server admin problem.

Cross compile PHP

https://serverfault.com/questions/418521/cross-compile-php

Start of post

I have downloaded the PHP 5.4.0 source, extracted it and moved into the source folder.

I do a configure with:

./configure --build=x86_64-unknown-linux-gnu --host=arm-linux-uclibcgnueabi --prefix=/usr/arm/www CC="arm-linux-uclibcgnueabi-gcc --sysroot=/toolchains/gnu_cortex-a9_tools/"  --disable-libxml --disable-dom  --without-iconv --without-openssl --disable-simplexml --disable-xml --disable-xmlreader --disable-xmlwriter --without-pear --without-sqlite3 --disable-pdo --without-pdo-sqlite --disable-phar  --with-config-file-path=/etc/

Followed by

make

no errors, everything runs fine. Next i do a make install.

make install

Again everything runs fine. i move it to the target platform and run

/usr/arm/www/bin/php -v
PHP 5.4.0 (cli) (built: Aug 15 2012 16:07:41) 
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies

I test a simple home page with my webserver and directly with php.

<?php echo "hello" ?>
# php index.php
hello

it works as expected. next i test:

<?php
$output = shell_exec('ls -lart');
echo "<pre>$output</pre>";
?>

oh noes~

# php shell.php 

Segmentation fault

I teset another script:

#!/bin/php
<?php

echo "hello";
$handle = fopen("info.txt", "r");
echo $handle;
?>

Same result:

# php index.php 
helloSegmentation fault

do i have a php.ini?

# /usr/arm/www/bin/php --ini
Configuration File (php.ini) Path: /etc/
Loaded Configuration File:         /etc/php.ini

yes, and no disabled functions. testing strace /usr/arm/www/bin/php index.php

lstat("/srv/www/info.txt", {st_mode=S_IFREG|0644, st_size=20, ...}) = 0
open("/srv/www/info.txt", O_RDONLY)     = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=20, ...}) = 0
lseek(3, 10, SEEK_CUR)                  = 0
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++

the file info.txt exists and it got premission to read/write to it.

Testing strace /usr/arm/www/bin/php shell.php

fcntl64(3, F_GETFL)                     = 0 (flags O_RDONLY)
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0x7e31fddc) = -1 EINVAL (Invalid argument)
vfork()                                 = 3324
close(4)                                = 0
fstat(3, {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
read(3, "total 24\n-rw-rw-r--    1 1001    "..., 8192) = 468
read(3, ""..., 8192)                    = 0
--- SIGCHLD (Child exited) @ 0 (0) ---
close(3)                                = 0
wait4(3324, [{WIFEXITED(s) && WEXITSTATUS(s) == 0}], 0, NULL) = 3324
--- SIGSEGV (Segmentation fault) @ 0 (0) ---
+++ killed by SIGSEGV +++

if i run the index.php through gdb it gives me:

Starting program: /usr/arm/www/bin/php index.php
hello
Program received signal SIGSEGV, Segmentation fault.
zend_do_fcall_common_helper_SPEC (execute_data=0x2ac7a040) at /home/maiden/Downloads/php-5.4.0/Zend/zend.h:391
391 /home/maiden/Downloads/php-5.4.0/Zend/zend.h: No such file or directory.
    in /home/maiden/Downloads/php-5.4.0/Zend/zend.h

gdb gives me this from shell.php Starting program: /usr/arm/www/bin/php shell.php

Program received signal SIGSEGV, Segmentation fault.

zend_do_fcall_common_helper_SPEC (execute_data=0x2ab76040) at /home/maiden/Downloads/php-5.4.0/Zend/zend.h:391
391 in /home/maiden/Downloads/php-5.4.0/Zend/zend.h

zend.h is located in /usr/arm/www/include/php/Zend/ obviously something went wrong during cross compilation. what have i missed? i do not find any configure flag to correct this and creating a symlink to the desired location removes the gdb output but php still segfaults.

Thanks for any help!

UPDATE:

# valgrind php test.php
==2181== Memcheck, a memory error detector
==2181== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==2181== Using Valgrind-3.8.0 and LibVEX; rerun with -h for copyright info
==2181== Command: php test.php
==2181==
==2181== Conditional jump or move depends on uninitialised value(s)
==2181==    at 0x4004EC8: ??? (in /lib/ld-uClibc-0.9.30-nptl.so)
==2181==
==2181== Invalid read of size 4
==2181==    at 0x4004D48: _dl_get_ready_to_run (in /lib/ld-uClibc-0.9.30-nptl.so)
==2181==  Address 0x7d4cc304 is just below the stack ptr.  To suppress, use: --workaround-gcc296-bugs=yes
==2181==
==2181== Invalid read of size 4
==2181==    at 0x48C348C: __uClibc_main (in /lib/libuClibc-0.9.30-nptl.so)
==2181==  Address 0x7d4cc554 is just below the stack ptr.  To suppress, use: --workaround-gcc296-bugs=yes
==2181==
==2181== Invalid write of size 4
==2181==    at 0x233010: __eqdf2 (ieee754-df.S:1120)
==2181==  Address 0x7d4cb0bc is just below the stack ptr.  To suppress, use: --workaround-gcc296-bugs=yes
==2181==
Warning: shell_exec(): Unable to execute 'ls -lart' in /test.php on line 3
==2181== Invalid read of size 4
==2181==    at 0x1FF1AC: zend_do_fcall_common_helper_SPEC (zend.h:391)
==2181==    by 0x1F3D17: execute (zend_vm_execute.h:410)
==2181==    by 0x18B217: zend_execute_scripts (zend.c:1279)
==2181==    by 0x1365BB: php_execute_script (main.c:2473)
==2181==    by 0x22B52B: do_cli (php_cli.c:988)
==2181==    by 0x22BD4B: main (php_cli.c:1364)
==2181==  Address 0x8 is not stack'd, malloc'd or (recently) free'd
==2181==
Segmentation fault

Update2

re-run valgrind with memcheck, got about the same output as before but this was new:

php: can't resolve symbol '__libc_freeres'

Update3

While valgrind have failed me, i continued with gdb, i created the folder /home/maiden/..etc on my target system and copied over the content of my php/include folder and re-run gdb. now i get this error message:

(gdb) run index.php 
Starting program: /bin/php index.php
hello
Program received signal SIGSEGV, Segmentation fault.
zend_do_fcall_common_helper_SPEC (execute_data=0x2ab34040) at /home/maiden/Downloads/php-5.4.5/Zend/zend.h:391
warning: Source file is more recent than executable.
391     return --pz->refcount__gc;

this is very similar to what sixeightzero wrote in the comments yesterday. I have now tried PHP version 5.3.5, 5.4.0, 5.4.5 same error on all.

Update4

I downloaded a new toolchain for glibc, cross compiled a new busybox with glibc, created a chroot jail, cross compiled php with glibc instead of uclibc and tested it inside my chroot jail on my uclibc box, and it works! But i still need to get php to work in my uclibc environment....

Answer 1

i would check configure.log of uClibc to see if ARCH_USE_MMU and fork is enabled. if not vfork is replaced with fork which is likely to be used by shell_exec. the main problem with vfork is, parent and child uses same memory space which leads to weird crashes.