reduced empty_filename.php on x86 machine

25129 access("/nfs/causers2/swalk/.hhvm.hhbc-wal", F_OK) = -1 ENOENT (No such file or directory)
25130 fstat(7, {st_mode=S_IFREG|0644, st_size=14180352, ...}) = 0
25131 lseek(7, 9594880, SEEK_SET)             = 9594880
25132 read(7, "\5\0\0\0\22\3\224\0\0\0004\264\3\372\3\364\3\356\3\350\3\342\3\334\3\326\3\320\3\312\3\304"..., 1024) = 1024
25133 lseek(7, 13814784, SEEK_SET)            = 13814784
25134 read(7, "\5\0\0\0}\1\22\0\0\0005\216\1*\0010\0016\1<\1B\1H\1N\1T\1Z\1`"..., 1024) = 1024
25135 lseek(7, 14038016, SEEK_SET)            = 14038016
25136 read(7, "\r\0\0\0\7\0\274\0\3\205\0032\3\5\2\33\1A\0\355\0\274\0\0\0\0\0\0\0\0\0\0"..., 1024) = 1024
25137 fcntl(7, F_SETLK, {type=F_UNLCK, whence=SEEK_SET, start=0, len=0}) = 0
25138 mmap(NULL, 67108864, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f55c7c00000
25139 mmap(0x7f55cac00000, 16777216, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 5, 0) = 0x7f55cac00000
25140 mprotect(0x7f55c7c01000, 50327552, PROT_READ) = 0
25141 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 236000}, ru_stime={0, 220000}, ...}) = 0
25142 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 236000}, ru_stime={0, 220000}, ...}) = 0
25143 write(6, "de00421 56 PHP::/data/swalk/try0"..., 55) = 55
25144 write(6, "15a0081d 2f PHP::/data/swalk/try"..., 56) = 56
25145 statfs("", 0x7ffda23550a0)              = -1 ENOENT (No such file or directory)
25146 fcntl(7, F_SETLK, {type=F_RDLCK, whence=SEEK_SET, start=1073741824, len=1}) = 0
25147 fcntl(7, F_SETLK, {type=F_RDLCK, whence=SEEK_SET, start=1073741826, len=510}) = 0
25148 fcntl(7, F_SETLK, {type=F_UNLCK, whence=SEEK_SET, start=1073741824, len=1}) = 0
25149 access("/nfs/causers2/swalk/.hhvm.hhbc-journal", F_OK) = -1 ENOENT (No such file or directory)
25150 fstat(7, {st_mode=S_IFREG|0644, st_size=14180352, ...}) = 0
25151 lseek(7, 24, SEEK_SET)                  = 24
25152 read(7, "\0\0\3\217\0\0006\30\0\0\0\0\0\0\0\0", 16) = 16
25153 fstat(7, {st_mode=S_IFREG|0644, st_size=14180352, ...}) = 0
25154 access("/nfs/causers2/swalk/.hhvm.hhbc-wal", F_OK) = -1 ENOENT (No such file or directory)
25155 fstat(7, {st_mode=S_IFREG|0644, st_size=14180352, ...}) = 0
25156 fcntl(7, F_SETLK, {type=F_UNLCK, whence=SEEK_SET, start=0, len=0}) = 0
25157 fstat(1, {st_mode=S_IFREG|0644, st_size=1802258, ...}) = 0
25158 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f55e2063000
25159 write(1, "\nWarning: disk_free_space(): No "..., 93
25160 Warning: disk_free_space(): No such file or directory in /data/swalk/try009/t.php on line 2
25161 ) = 93
25162 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 248000}, ru_stime={0, 220000}, ...}) = 0
25163 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 252000}, ru_stime={0, 220000}, ...}) = 0
25164 write(6, "de00477 6e PHP::/data/swalk/try0"..., 55) = 55
25165 write(6, "15a00864 4d PHP::/data/swalk/try"..., 56) = 56
25166 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 260000}, ru_stime={0, 220000}, ...}) = 0
25167 mmap(NULL, 16777216, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f55c6c00000
25168 write(6, "11a00000 49 PHP::systemlib.phpst"..., 62) = 62
25169 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 264000}, ru_stime={0, 220000}, ...}) = 0
25170 getrusage(0x1 /* RUSAGE_??? */, {ru_utime={1, 264000}, ru_stime={0, 220000}, ...}) = 0
25171 write(6, "11a00049 89 PHP::systemlib.phpst"..., 53) = 53
25172 write(6, "17200183 fa PHP::systemlib.phpst"..., 53) = 53
25173 write(1, "bool(false)\n", 12bool(false)
25174 )           = 12
25175 madvise(0x7f55d2552000, 2097152, MADV_DONTNEED) = 0

test case
<?php
var_dump(disk_free_space(''));
?>

swalk@jjones-lnx1:/data/swalk/try009$ uname -a
Linux jjones-lnx1 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3 (2016-07-02) x86_64 GNU/Linux

swalk@jjones-lnx1:/data/swalk/try009$ file ../hhvm/hphp/hhvm/hhvm
../hhvm/hphp/hhvm/hhvm: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 2.6.32, BuildID[sha1]=ec4ab5bb20f5176cd2dd64155deb452227dc9f01, not stripped