c++: Basic Traits

Traits:
In C++ "traits" are basically a group of template classes that provide miscellaneous information about another type or data structure.

'Think of a trait as a small object whose main purpose is to carry information used by another object or algorithm to determine "policy" or "implementation details".'
- Bjarne Stroustrup

Traits are very common in C++. One of the more common ones is the string class its self. The string class uses traits to provide information about internationalization and character encoding. Often they are visible in the code and debugger output as a template parameter that has a default initialization via a second template.

In other cases the use of traits is more normal as in the the class "std::numeric_limits" and the other members of the limits.h header.

Boost also offers many interesting and helpful traits classes as an example here is the "is_void" traits class.

template< typename T > 
struct is_void{ 
  static const bool value = false;
};

template<> 
struct is_void< void >{ 
  static const bool value = true; 
};

As you can see this trait template's sole purpose to is provide information about what the input parameter type was. This is only really useful in a parts of the code which the programmer doesn't know what the input type was: Hence inside another template.

For more info refer to:
http://www.cantrip.org/traits.html
http://www.cplusplus.com/reference/std/limits/numeric_limits/

The truth about what movitates people

http://www.youtube.com/watch?v=u6XAPnuFjJc

Three coworkers sharing average salaries

Question:
Three coworkers would like to know their average salary. How can they do it, without disclosing their own salaries?

The key is to scramble the sum with unknown/unshared data. The scramble must be reversible and when reversing it must not effect the sum.

Answer on the web:
So each person adds a random number(Rn) plus there salary(Sn) to the sum(Sum) and hands it to the next one. And then in the second round they each deduce there random number

(round 1)
Sum0 = S1 + R1
Sum1 = S1 + S2 + R1 + R2
Sum2 = S1 + S2 + S3 + R1 + R2 + R3

(round 2)
Sum3 = S1 + S2 + S3 + R2 + R3
Sum4 = S1 + S2 + S3 + R3
Sum5 = S1 + S2 + S3

And final they divide by the number of people
Average(6) = (S1 + S2 + S3)/3

Here is the proof:
For person 1

Starts with:
R1
S1
Sum0 = S1 + R1
Sum2 = S1 + S2 + S3 + R1 + R2 + R3
Sum3 = S1 + S2 + S3 + R2 + R3
Sum5 = S1 + S2 + S3

Can calc
R2 + R3 = Sum3 - Sum5

So he finally knows
R1
S1
R2 + R3
S2 + S3 

For person 2

He starts with:
R2
S2
Sum0 = S1 + R1
Sum1 = S1 + S2 + R1 + R2
Sum3 = S1 + S2 + S3 + R2 + R3
Sum4 = S1 + S2 + S3 + R3
Sum5 = S1 + S2 + S3

He can calc:
R3 = Sum4 - Sum5

He finally knows knows
R2
R3
S2
S1 + R1
S1 + S3

For person 3

He Starts with:
R3
S3
Sum1 = S1 + S2 + R1 + R2
Sum2 = S1 + S2 + S3 + R1 + R2 + R3
Sum4 = S1 + S2 + S3 + R3
Sum5 = S1 + S2 + S3

He can calc:
S1 + S2 = Sum5 - S2
R1 + R2 = Sum2 - S1 + S2 

He finally knows:
R3
S3
S1 + S2
R1 + R2

Here is a much stronger answer
It requires an 2 or more arbitrators in the system, At the end of each Sum stage the summer chooses a random arbitrator who then adds his own random value to the sum.
Once Sum5 stage is complete the arbitrators each in turn recieve the sum and deduct out the total of the random numbers they added in. As a result the computation becomes

(round 1)
Sum0 = S1 + R1 + A0
Sum1 = S1 + S2 + R1 + R2 + A0 + A1
Sum2 = S1 + S2 + S3 + R1 + R2 + R3 + A0 + A1 + A2

(round 2)
Sum3 = S1 + S2 + S3 + R2 + R3 + A0 + A1 + A2 + A3
Sum4 = S1 + S2 + S3 + R3 + A0 + A1 + A2 + A3 + A4
Sum5 = S1 + S2 + S3 + A0 + A1 + A2 + A3 + A4 + A5

Sum6 =  S1 + S2 + S3 + A0 + A2 + A4
Sum7 =  S1 + S2 + S3

Hence its much more harder to break

Nuggets in packs of 6, 9 and 20.

Question:
At a fast food restaurant you can buy chicken nuggets in packs of 6, 9 or 20. Is there such a number N, that for all numbers greater than it, it is possible to buy any number of chicken nuggets?

Answer:
Keep in mind the key fact we need to prove that numbers are not possible. The equation we have is 6x + 9y + 20z = n. The minimum step we can take is 6 so lets work from there.
If we assume y and z are 0 then the equation becomes 6x = n. Hence the possible numbers become

 1  2  3  4  5  x
 7  8  9 10 11  x
13 14 15 16 17  x 
19 20 21 22 23  x 

If we assume y=1, z=0 then the equation becomes 9 + 6x = n. Hence the possible numbers become

 1  2  3  4  5  x
 7  8  x 10 11  x
13 14  x 16 17  x 
19 20  x 22 23  x 

Any further 9s will take us back to the same used columns so more 9s is pointless that leaves 20. If we assume y=0, z=1 then the equation becomes 20 + 6x = n

 1  2  3  4  5  x
 7  8  x 10 11  x
13 14  x 16 17  x
19  x  x 22 23  x
25  x  x 28 29  x
31  x  x 34 35  x
37  x  x 40 41  x
43  x  x 46 47  x

If we assume y=1, z=1 then the equation becomes 20 + 9 + 6x = 29 + 6n = n

 1  2  3  4  5  x
 7  8  x 10 11  x
13 14  x 16 17  x
19  x  x 22 23  x
25  x  x 28  x  x
31  x  x 34  x  x
37  x  x 40  x  x
43  x  x 46  x  x

If we go y=2,z=1 now then it becomes 38 + 6n which is already taken. So we try another 20 If we assume y=0, z=2 then the equation becomes 40 + 6x = n

 1  2  3  4  5  x
 7  8  x 10 11  x
13 14  x 16 17  x
19  x  x 22 23  x
25  x  x 28  x  x
31  x  x 34  x  x
37  x  x  x  x  x
43  x  x  x  x  x
 x  x  x  x  x  x

If we assume y=1, z=2 then the equation becomes 40 + 9 + 6x = 49 + 6x = n

Hence N = 43.

fork: basic child processes - creating, waiting for and ending children

Here is basic example program demonstrating the use of forks and child processes.

The key points are;

• Children processes are created with a call to fork, Fork returns:
  
  • A number less than 0(the Error code) on an error.
  • A number equal to 0 in the thread.
  • A number greater than to 0(the childs pid) in the main process.
• A call to getpid() will return the pid of the child or parent process.


• Keep in might the differences between a thread and process. The fundamental difference is that a thread shares all regions of memory except the stack where as a process shares none. In general memory is copied over the the child process as needed by the kernel.

//complie with; g++ fork.cpp
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <time.h>

struct BaseA
{
 pid_t pid;
 int number;
};

//The thread core...
void child_worker(BaseA* data)
{
 data->pid = getpid();

 for(int i = 0; i < 10; i++)
   {
     printf("Child %d @ %d \n", data->pid, data->number++);
     sleep(rand()%3000/1000);
   }

 printf("Child %d DONE!\n", data->pid);
 exit(0);
}

int main()
{
 srand(time(NULL));

 pid_t childPid;
 BaseA data;

 //setup the process
 data.number = 1;

 // create the threads
 childPid = fork();
 if (childPid >= 0) // fork ok
    if (childPid == 0) // Am I the kid
       child_worker(&data);
 childPid = fork();
 if (childPid >= 0) // fork ok
    if (childPid == 0) // Am I the kid
       child_worker(&data);

 //wait for all kids to complete
 wait(NULL);
 wait(NULL);

 printf("Parent %d DONE!\n", data.number);

 exit(0);
}

pthread: basic threading - creating, waiting for and ending threads

Here is basic example program demonstrating threads using the posfix threads library.

The key points are;

• Threads are created with a call to pthread_create, the parameters are:
  
  • The threads handle, consider it to be the equivalent of a file handle.
  • The threads attributes. Normally the defaults are sufficient so use NULL, otherwise you might end up having to allocate the stack for it too.
  • The function pointer to the threads "main", if this routine exits or returns it will implicitly end the thread just like the pthread_exit call.
  • And a generic chunk of memory that is passed to the threads "main".
• pthread_join; this takes the threads handle and simply blocks until it gets the signal that the thread has ended. The second parameter is a pointer to the location of where to store the pointer for the threads exit.. gezz look at the function definition its more easy to understand than a written description of it.
• pthread_exit: This is the thread equivalent of exit but it can return a pointer to a complex piece of data.

And here is the sample code its really simple and just a brush up on threads for now

//complie with; g++ thread.cpp -lpthread
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

struct BaseA
{
 pthread_t handler; //the handle to the thread.. a little dangerous!
 int number;
};

//The thread core...
void* thread_worker( void *ptr )
{
 BaseA *data = (BaseA*)ptr;

 for(int i = 0; i < 10; i++)
   {
     printf("Thread %d @ %d \n", data->number, i);
     sleep(rand()%3000/1000);
   }

 printf("Thread %d DONE!\n", data->number);
 pthread_exit(NULL);
}

int main()
{
 srand(time(NULL));

 BaseA data[2];

 //setup the threads
 data[0].number = 1;
 data[1].number = 2;

 // create the threads
 pthread_create (&data[0].handler, NULL, &thread_worker, (void *) &data[0]);
 pthread_create (&data[1].handler, NULL, &thread_worker, (void *) &data[1]);

 //wait for all kids to complete
 pthread_join(data[0].handler, NULL);
 pthread_join(data[1].handler, NULL);

 exit(0);
}

strace - Debugging a live misbehaving process.

Often when a server is live you dont have the luxury of installing a debug-able version and stepping through its code when the problem appears. Other times you need to get a hold on whatever is killing a program that you never even wrote.

Enter "strace" this tool watches the system calls of a process and dumps it to your console for analysis. strace is not for the faint at heart. You need to know about how shells operate, how dynamic linked libraries are loaded and based and how kernel system calls pass in and out of system. On the flip side if you have never seen it before its a real eye opener. The average programmer most likely just doesn't realize how involved the kernel is with your little program.

To execute it on a program from scratch

strace -v <filename>

Note the "-v" gives you information about the environment variables that are passed from the shell to the new process.

To attach to a live process (you'll need to match the processes privilege level or better)

strace -p <process_id>

Here are some more resources on it:
http://www.redhat.com/magazine/010aug05/features/strace/
http://linux.die.net/man/1/strace

ok and here is an strace of ls in an empty directory so you can clearly see that simple isnt really that simple! (PS I seem to have a problem with my locales is polluting the result)

~/tmp> strace ls ./

execve("/bin/ls", ["ls", "./"], [/* 42 vars */]) = 0
brk(0)                                  = 0x61a000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f51000
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f4f000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-release-NDEBUG/dist/bin/tls/x86_64/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-release-NDEBUG/dist/bin/tls/x86_64", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-release-NDEBUG/dist/bin/tls/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-release-NDEBUG/dist/bin/tls", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-release-NDEBUG/dist/bin/x86_64/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-release-NDEBUG/dist/bin/x86_64", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-release-NDEBUG/dist/bin/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-release-NDEBUG/dist/bin", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-debug/dist/lib/tls/x86_64/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-debug/dist/lib/tls/x86_64", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-debug/dist/lib/tls/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-debug/dist/lib/tls", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-debug/dist/lib/x86_64/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-debug/dist/lib/x86_64", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/home/ashley/obj-mail-debug/dist/lib/librt.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat("/home/ashley/obj-mail-debug/dist/lib", 0x7fff25ef42d0) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=102124, ...}) = 0
mmap(NULL, 102124, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f36000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/librt.so.1", O_RDONLY)       = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240#\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=35784, ...}) = 0
mmap(NULL, 2132968, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7da0b2c000
mprotect(0x7f7da0b34000, 2093056, PROT_NONE) = 0
mmap(0x7f7da0d33000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x7000) = 0x7f7da0d33000
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\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\240Q\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=109368, ...}) = 0
mmap(NULL, 2209176, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7da0910000
mprotect(0x7f7da0929000, 2097152, PROT_NONE) = 0
mmap(0x7f7da0b29000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x19000) = 0x7f7da0b29000
mmap(0x7f7da0b2b000, 1432, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f7da0b2b000
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\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\220\33\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=27600, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f35000
mmap(NULL, 2122744, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7da0709000
mprotect(0x7f7da070f000, 2097152, PROT_NONE) = 0
mmap(0x7f7da090f000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x6000) = 0x7f7da090f000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libc.so.6", O_RDONLY)        = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\340\342"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1436976, ...}) = 0
mmap(NULL, 3543672, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7da03a7000
mprotect(0x7f7da04ff000, 2097152, PROT_NONE) = 0
mmap(0x7f7da06ff000, 20480, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x158000) = 0x7f7da06ff000
mmap(0x7f7da0704000, 17016, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f7da0704000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libpthread.so.0", O_RDONLY)  = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\260W\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=130224, ...}) = 0
mmap(NULL, 2208624, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7da018b000
mprotect(0x7f7da01a1000, 2097152, PROT_NONE) = 0
mmap(0x7f7da03a1000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x16000) = 0x7f7da03a1000
mmap(0x7f7da03a3000, 13168, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f7da03a3000
close(3)                                = 0
access("/etc/ld.so.nohwcap", F_OK)      = -1 ENOENT (No such file or directory)
open("/lib/libdl.so.2", O_RDONLY)       = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \16\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=14624, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f34000
mmap(NULL, 2109728, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7d9ff87000
mprotect(0x7f7d9ff89000, 2097152, PROT_NONE) = 0
mmap(0x7f7da0189000, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x2000) = 0x7f7da0189000
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\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0000\21\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0644, st_size=16128, ...}) = 0
mmap(NULL, 2111240, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f7d9fd83000
mprotect(0x7f7d9fd87000, 2093056, PROT_NONE) = 0
mmap(0x7f7d9ff86000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x3000) = 0x7f7d9ff86000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f33000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f32000
arch_prctl(ARCH_SET_FS, 0x7f7da0f32780) = 0
mprotect(0x7f7da06ff000, 12288, PROT_READ) = 0
munmap(0x7f7da0f36000, 102124)          = 0
set_tid_address(0x7f7da0f32810)         = 15691
set_robust_list(0x7f7da0f32820, 0x18)   = 0
futex(0x7fff25ef4e0c, 0x81 /* FUTEX_??? */, 1) = 0
rt_sigaction(SIGRTMIN, {0x7f7da01902d0, [], SA_RESTORER|SA_SIGINFO, 0x7f7da01997d0}, NULL, 8) = 0
rt_sigaction(SIGRT_1, {0x7f7da0190350, [], SA_RESTORER|SA_RESTART|SA_SIGINFO, 0x7f7da01997d0}, 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
brk(0)                                  = 0x61a000
brk(0x63b000)                           = 0x63b000
open("/etc/selinux/config", O_RDONLY)   = -1 ENOENT (No such file or directory)
statfs("/selinux", 0x7fff25ef3d30)      = -1 ENOENT (No such file or directory)
open("/proc/mounts", O_RDONLY)          = 3
fstat(3, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f4e000
read(3, "rootfs / rootfs rw 0 0\nnone /sys"..., 1024) = 1024
read(3, "server1/public /home/ashley/file"..., 1024) = 537
read(3, "", 1024)                       = 0
close(3)                                = 0
munmap(0x7f7da0f4e000, 4096)            = 0
open("/usr/lib/locale/locale-archive", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/locale.alias", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=2586, ...}) = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7da0f4e000
read(3, "# Locale name alias data base.\n#"..., 4096) = 2586
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0x7f7da0f4e000, 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
fstat(3, {st_mode=S_IFREG|0644, st_size=373, ...}) = 0
mmap(NULL, 373, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f4e000
close(3)                                = 0
open("/usr/lib/gconv/gconv-modules.cache", O_RDONLY) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=25700, ...}) = 0
mmap(NULL, 25700, PROT_READ, MAP_SHARED, 3, 0) = 0x7f7da0f47000
close(3)                                = 0
futex(0x7f7da0703f40, 0x81 /* FUTEX_??? */, 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
fstat(3, {st_mode=S_IFREG|0644, st_size=23, ...}) = 0
mmap(NULL, 23, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f46000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=59, ...}) = 0
mmap(NULL, 59, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f45000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=155, ...}) = 0
mmap(NULL, 155, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f44000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=77, ...}) = 0
mmap(NULL, 77, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f43000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=34, ...}) = 0
mmap(NULL, 34, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f42000
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
fstat(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
fstat(3, {st_mode=S_IFREG|0644, st_size=52, ...}) = 0
mmap(NULL, 52, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f41000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=286, ...}) = 0
mmap(NULL, 286, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f40000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=921214, ...}) = 0
mmap(NULL, 921214, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0e51000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=2451, ...}) = 0
mmap(NULL, 2451, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f3f000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=54, ...}) = 0
mmap(NULL, 54, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0f3e000
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
fstat(3, {st_mode=S_IFREG|0644, st_size=254076, ...}) = 0
mmap(NULL, 254076, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f7da0e12000
close(3)                                = 0
ioctl(1, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon echo ...}) = 0
ioctl(1, TIOCGWINSZ, {ws_row=46, ws_col=156, ws_xpixel=0, ws_ypixel=0}) = 0
stat("./", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
open("./", O_RDONLY|O_NONBLOCK|O_DIRECTORY|0x80000) = 3
fstat(3, {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
fcntl(3, F_GETFD)                       = 0x1 (flags FD_CLOEXEC)
getdents(3, /* 2 entries */, 4096)      = 48
getdents(3, /* 0 entries */, 4096)      = 0
close(3)                                = 0
close(1)                                = 0
close(2)                                = 0
exit_group(0)                           = ?
Process 15691 detached