ID: 40749 User updated by: ben at ateor dot com Reported By: ben at ateor dot com -Status: Feedback +Status: Open Bug Type: Unknown/Other Function Operating System: OpenBSD amd64 and sparc64 PHP Version: 5.2.1 Assigned To: iliaa New Comment:
Fix the problem for me, thanks. (ps: meanwhile, I can't verify there's no regressions, given how the testsuite has changed). Previous Comments: ------------------------------------------------------------------------ [2007-04-03 22:00:45] [EMAIL PROTECTED] Please try using this CVS snapshot: http://snaps.php.net/php5.2-latest.tar.gz For Windows: http://snaps.php.net/win32/php5.2-win32-latest.zip ------------------------------------------------------------------------ [2007-03-16 14:03:01] martin at netimage dot dk It appears that the sign bit is taken from LSB instead of MSB > php -r 'print_r( unpack('N',pack('N',127)));' Array ( [1] => 127 ) > php -r 'print_r( unpack('N',pack('N',128)));' Array ( [1] => -2147483520 ) The last number is 2's complement of -128 for 32 bit integers Cheers ------------------------------------------------------------------------ [2007-03-14 20:57:41] pz at mysqlperformanceblog dot com In any case if you call it bug or a feature this is serious behavior change for something which a lot of people could be depending on. It breaks in MySQL 5.2.0 -> 5.2.1 which is minor version upgrade. ------------------------------------------------------------------------ [2007-03-09 09:06:47] windeler at mediafinanz dot de Here is another example of a problem with unpack on 64bit systems. It worked in 5.1.6, but with 5.2.1 the results are bogus. The expected value from the file content is 200, but PHP says -2147483448 when I echo $a['i']. <?php $f = fopen('test.pdf','rb'); //Read a 4-byte integer from file $a = unpack('Ni',fread($f,4)); echo $a['i']; fclose($f); ?> ------------------------------------------------------------------------ [2007-03-07 17:12:58] ben at ateor dot com Description: ------------ This is a follow-up on #40543 (http://bugs.php.net/bug.php?id=40543, since that bug is closed, I can't add comments). Please note : it's not identical to #4053 (other weird behaviors are demonstrated). Iliaa, Not sure why you suggest to use little endian or host conversions routines, but in my standpoint if you reverse twice a number's byte ordering then you should get the original number back (assuming the number don't overflows php's internals). At least, that's the standard behavior for perl and python. Beside, I can't see why php should handles those endianness conversions differently on an i386 (32 bits) and on an x86_64 (64 bits), both having the same byte order. The following on a 64bit, little endian host : x86_64$ uname -mprsv OpenBSD 4.0 GENERIC#0 amd64 AMD Sempron(tm) Processor 3400+ x86_64$ perl -e 'print unpack("N", pack("N", 41445)) ."\n"' 41445 x86_64$ python Python 2.4.3 (#1, Sep 6 2006, 20:33:08) [GCC 3.3.5 (propolice)] on openbsd4 Type "help", "copyright", "credits" or "license" for more information. >>> from struct import * >>> unpack('>L', pack('>L', 41445)) (41445L,) And, indeed : #include <stdio.h> #include <sys/types.h> int main(void) { u_int32_t x, y, z; /* 32 bits unsigned longs */ x = 41445; /* conv host (little) to network (big endian) long : pack("N", 41445) */ y = htonl(x); /* conv network (big endian) to host (little) long : unpack("N", ...) */ z = ntohl(y); printf("Host : %li\nBig : %li\nHost : %li\n", x, y, z); return 0; } x86_64$ gcc conv.c -o conv ; ./conv Host : 41445 Big : -442433536 Host : 41445 But still (PHP 5.2.2-dev (cli) (built: Feb 27 2007 22:10:11)) : x86_64$ php -r 'print_r(unpack("N", pack("N", 41445)));' Array ( [1] => -2147442203 ) While on a plain old x86 little endian host (PHP 4.4.0), we get a different result : i386_32$ uname -mprsv OpenBSD 3.9 GENERIC#0 i386 Intel(R) Pentium(R) 4 CPU 1.70GHz ("GenuineIntel" 686-class) i386_32$ php -r 'print_r(unpack("N", pack("N", 41445)));' Array ( [1] => 41445 ) Still on the 64 bits little endian host : x86_64$ php -r '$a = unpack("N", pack("N", 65536)); printf("$a[1]\n");' 65536 # Ok x86_64$ php -r '$a = unpack("N", pack("N", 65535)); printf("$a[1]\n");' -2147418113 # Weird x86_64$ php -r '$a = unpack("N", pack("N", 0x1234)); printf("0x%x\n", $a[1]);' 0x1234 # Ok x86_64$ php -r '$a = unpack("L", pack("N", 0x1234)); printf("0x%x\n", $a[1]);' 0x34120000 # Ok x86_64$ php -r '$a = unpack("L", pack("L", 0xffff)); printf("0x%x\n", $a[1]);' 0xffff # Ok x86_64$ php -r '$a = unpack("N", pack("N", 0xffff)); printf("0x%x\n", $a[1]);' 0xffffffff8000ffff # The doc says "N" gives you "always 32 bit", and we get # 8 bytes. No wonder why we overflow. x86_64$ php -r '$a = unpack("N", pack("N", 0xff )); printf("0x%x\n", $a[1]);' 0xffffffff800000ff # Same. Don't tell me 0xff is too large. And now, all the following tests are on a 64 bits _big endian_ host (sparc64, running php-5.2.1) : sparc64$ uname -mprsv OpenBSD 3.8 GENERIC#607 sparc64 SUNW,UltraSPARC-IIi @ 440 MHz, version 0 FPU sparc64$ php -r '$a = unpack("N", pack("N", 0xffff)); printf("0x%x\n", $a[1]);' 0xffff # Ok # The same, but prefixing 0000 to the argument : sparc64$ php -r '$a = unpack("N", pack("N", 0x0000ffff)); printf("0x%x\n", $a[1]);' 0xffffffff8000ffff # Weird (and with "N", we stayed on the host byte order this time). # Shouldn't 0xffff == 0x0000ffff, even on big endian ? Apparently, yes : sparc64$ php -r 'printf("0x%x\n", 0x0000ffff);' 0xffff # Also, look at this : sparc64$ php -r '$a = unpack("N", pack("N", 41445)); printf("$a[1]\n");' 41445 # And now let's just remove the line feed (\n) from the above printf : sparc64$ php -r '$a = unpack("N", pack("N", 41445)); printf("$a[1]");' -2147442203 # Same for 2^16 -1 / 65535 / 0xfff : sparc64$ php -r '$a = unpack("N", pack("N", 65535)); printf("$a[1]\n");' 65535 sparc64$ php -r '$a = unpack("N", pack("N", 65535)); printf("$a[1]");' -2147418113 # We get the opposite (bogus with \n, correct without) when converting # to little endian and back to host : sparc64$ php -r '$a = unpack("L", pack("L", 0xffff)); printf( $a[1]);' 65535 sparc64$ php -r '$a = unpack("L", pack("L", 0xffff)); printf( $a[1]."\n");' -2147418113 This doesn't help : SKIP Generic pack()/unpack() tests [ext/standard/tests/strings/pack.phpt] reason: 32bit test only ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=40749&edit=1
