memoize access to /etc/ld.so.nohwcap ?

[zimbatm]

Is it really necessary to check for ld.so.nohwcap for each required library of a program ?

See for example: `strace ls /dev/null`, it's called 8 times for no benefits.

-------------

execve("/bin/ls", ["ls", "/dev/null"], [/* 17 vars */]) = 0
brk(0) = 0x8e9b000
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
mmap2(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7712000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=22877, ...}) = 0
mmap2(NULL, 22877, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb770c000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/tls/i686/cmov/librt.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\300\30\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=30684, ...}) = 0
mmap2(NULL, 33364, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7703000
mmap2(0xb770a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6) = 0xb770a000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libselinux.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@G\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=104148, ...}) = 0
mmap2(NULL, 109432, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76e8000
mmap2(0xb7701000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x18) = 0xb7701000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libacl.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\320\26\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=30312, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb76e7000
mmap2(NULL, 28964, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb76df000
mmap2(0xb76e5000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6) = 0xb76e5000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/tls/i686/cmov/libc.so.6", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0000m\1\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=1405508, ...}) = 0
mmap2(NULL, 1415592, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7585000
mprotect(0xb76d8000, 4096, PROT_NONE) = 0
mmap2(0xb76d9000, 12288, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x153) = 0xb76d9000
mmap2(0xb76dc000, 10664, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb76dc000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/tls/i686/cmov/libpthread.so.0", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0 J\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0755, st_size=117086, ...}) = 0
mmap2(NULL, 98792, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb756c000
mmap2(0xb7581000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x14) = 0xb7581000
mmap2(0xb7583000, 4584, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0xb7583000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/tls/i686/cmov/libdl.so.2", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0@\n\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=9736, ...}) = 0
mmap2(NULL, 12408, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7568000
mmap2(0xb756a000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1) = 0xb756a000
close(3) = 0
access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
open("/lib/libattr.so.1", O_RDONLY) = 3
read(3, "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\3\0\3\0\1\0\0\0\360\r\0\0004\0\0\0"..., 512) = 512
fstat64(3, {st_mode=S_IFREG|0644, st_size=17860, ...}) = 0
mmap2(NULL, 20588, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0xb7562000
mmap2(0xb7566000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3) = 0xb7566000
close(3) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7561000
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7560000
set_thread_area({entry_number:-1 -> 6, base_addr:0xb7560720, limit:1048575, seg_32bit:1, contents:0, read_exec_only:0, limit_in_pages:1, seg_not_present:0, useable:1}) = 0
mprotect(0xb7566000, 4096, PROT_READ) = 0
mprotect(0xb756a000, 4096, PROT_READ) = 0
mprotect(0xb7581000, 4096, PROT_READ) = 0
mprotect(0xb76d9000, 8192, PROT_READ) = 0
mprotect(0xb76e5000, 4096, PROT_READ) = 0
mprotect(0xb7701000, 4096, PROT_READ) = 0
mprotect(0xb770a000, 4096, PROT_READ) = 0
mprotect(0x8060000, 4096, PROT_READ) = 0
mprotect(0xb7730000, 4096, PROT_READ) = 0
munmap(0xb770c000, 22877) = 0
set_tid_address(0xb7560788) = 22802
set_robust_list(0xb7560790, 0xc) = 0
futex(0xbfbcdc90, FUTEX_WAKE_PRIVATE, 1) = 0
futex(0xbfbcdc90, FUTEX_WAIT_BITSET_PRIVATE|FUTEX_CLOCK_REALTIME, 1, NULL, bfbcdca0) = -1 EAGAIN (Resource temporarily unavailable)
rt_sigaction(SIGRTMIN, {0xb7570410, [], SA_SIGINFO}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0xb75708f0, [], SA_RESTART|SA_SIGINFO}, NULL, 8) = 0
rt_sigprocmask(SIG_UNBLOCK, [RTMIN RT_1], NULL, 8) = 0
getrlimit(RLIMIT_STACK, {rlim_cur=8192*1024, rlim_max=RLIM_INFINITY}) = 0
uname({sys="Linux", node="vagrantup", ...}) = 0
statfs64("/selinux", 84, {f_type="EXT2_SUPER_MAGIC", f_bsize=4096, f_blocks=9953638, f_bfree=8412886, f_bavail=7907261, f_files=2531328, f_ffree=2419797, f_fsid={866754416, 1089126459}, f_namelen=255, f_frsize=4096}) = 0
brk(0) = 0x8e9b000
brk(0x8ebc000) = 0x8ebc000
open("/proc/filesystems", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7711000
read(3, "nodev\tsysfs\nnodev\trootfs\nnodev\tb"..., 1024) = 326
read(3, "", 1024) = 0
close(3) = 0
munmap(0xb7711000, 4096) = 0
open("/usr/lib/locale/locale-archive", O_RDONLY|O_LARGEFILE) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/locale.alias", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=2570, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7711000
read(3, "# Locale name alias data base.\n#"..., 4096) = 2570
read(3, "", 4096) = 0
close(3) = 0
munmap(0xb7711000, 4096) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_IDENTIFICATION", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_IDENTIFICATION", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=373, ...}) = 0
mmap2(NULL, 373, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7711000
close(3) = 0
open("/usr/lib/gconv/gconv-modules.cache", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=26048, ...}) = 0
mmap2(NULL, 26048, PROT_READ, MAP_SHARED, 3, 0) = 0xb7559000
close(3) = 0
futex(0xb76dba8c, FUTEX_WAKE_PRIVATE, 2147483647) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_MEASUREMENT", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_MEASUREMENT", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=23, ...}) = 0
mmap2(NULL, 23, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7710000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_TELEPHONE", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_TELEPHONE", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=59, ...}) = 0
mmap2(NULL, 59, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb770f000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_ADDRESS", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_ADDRESS", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=155, ...}) = 0
mmap2(NULL, 155, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb770e000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_NAME", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_NAME", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=77, ...}) = 0
mmap2(NULL, 77, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb770d000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_PAPER", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_PAPER", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=34, ...}) = 0
mmap2(NULL, 34, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb770c000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_MESSAGES", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_MESSAGES", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
close(3) = 0
open("/usr/lib/locale/en_US.utf8/LC_MESSAGES/SYS_LC_MESSAGES", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=57, ...}) = 0
mmap2(NULL, 57, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7558000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_MONETARY", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_MONETARY", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=286, ...}) = 0
mmap2(NULL, 286, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7557000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_COLLATE", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_COLLATE", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=1170770, ...}) = 0
mmap2(NULL, 1170770, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7439000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_TIME", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_TIME", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=2454, ...}) = 0
mmap2(NULL, 2454, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7438000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_NUMERIC", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_NUMERIC", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=54, ...}) = 0
mmap2(NULL, 54, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb7437000
close(3) = 0
open("/usr/lib/locale/en_US.UTF-8/LC_CTYPE", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib/locale/en_US.utf8/LC_CTYPE", O_RDONLY) = 3
fstat64(3, {st_mode=S_IFREG|0644, st_size=256324, ...}) = 0
mmap2(NULL, 256324, PROT_READ, MAP_PRIVATE, 3, 0) = 0xb73f8000
close(3) = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbfbcdb28) = -1 ENOTTY (Inappropriate ioctl for device)
ioctl(1, TIOCGWINSZ, 0xbfbcdc80) = -1 ENOTTY (Inappropriate ioctl for device)
stat64("/dev/null", {st_mode=S_IFCHR|0666, st_rdev=makedev(1, 3), ...}) = 0
lstat64("/dev/null", {st_mode=S_IFCHR|0666, st_rdev=makedev(1, 3), ...}) = 0
fstat64(1, {st_mode=S_IFREG|0644, st_size=11716, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb73f7000
write(1, "/dev/null\n", 10/dev/null
) = 10
close(1) = 0
munmap(0xb73f7000, 4096) = 0
close(2) = 0
exit_group(0) = ?