Unable to List Files Attributes on EXT2

The code is well commented, the compiler isn't pointing anything really great, so I'm kinda lost, it is an exercise on a book I'm reading...

Code:

---

/*check flags.c - display info on ext2 extended attributes*/

/* For each file name on the command line, display information on that
file's ext2 attributes */

#include<errno.h>
#include<fcntl.h>
#include<linux/ext2_fs.h>
#include<stdio.h>
#include<sys/ioctl.h>
#include<unistd.h>

int main(int argc, char **argv){
       
        char **filename = argv + 1;
        int fd;
        int flags;
       
/*Iterate over each file name on the command line. The last pointer in argv[]
        is NULL, so this while() loop is legal*/
        while (*filename){

/*Unlike normal attributes, ext2 attributes can only be queried if
we have a file descriptor (a file name is not sufficient). We
dont need write acces to query the ext2 attributes, so O_RDONLY is ok*/
               
                fd = open(*filename, O_RDONLY);
                        if (fd < 0) {
                                fprintf(stderr,"cannot open %s: %s\n", *filename,
                                                strerror(errno));
                                return 1;
                        }
/*This gets the attributes, and puts them into flags*/
                               
                        if (ioctl(fd, EXT2_IOC_GETFLAGS, &flags)){
                                fprintf(stderr,"ioctl failed on %s: %s\n", *filename,
                                                strerror(errno));
                                return 1;
                        }
                       
                        printf("%s:", *filename++);

/*Check for each attribute, and display a message for each one wich is returned
on*/
                        if (flags & EXT2_APPEND_FL) printf("Append");
                        if (flags & EXT2_IMMUTABLE_FL) printf("Immutable");
                        if (flags & EXT2_SYNC_FL) printf("Sync");
                        if (flags & EXT2_NODUMP_FL) printf("No dump");
                       
                        printf("\n");
                        close(fd);                       
        }
       
        return 0;
}

---

The problem is simple, the program does nothing... :(

Are you supplying any filenames on the command line (i.e.: flags file1 file2 file3)?

Quote:

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Originally Posted by itsme86

Are you supplying any filenames on the command line (i.e.: flags file1 file2 file3)?

---

yes, but I now I thing I might be doing it wrong in Anjuta (the IDE I'm using) could you plase give an example of call to the program to check one file? I would be very gratefull! :D

You can't just hit the "run" button in the IDE to get it to display anything. Compile it, then go to a shell (command line prompt, whatever you want to call it) and type in: flags file where flags is the name of the program and file is the name of the file.

Well I think I'm doing right, but I got no output anyways:
imanewbie@blah:~/Projects/Junk Code$ ./checkflags random.c
random.c:

I've called the program checkgflags.

Woops I might figured out now:

EXECUTING:
/home/imanewbie/Projects/Junk Code/checkflags flags senha.c
----------------------------------------------
cannot open flags: No such file or directory

----------------------------------------------
Program exited successfully with errcode (1)
Press the Enter key to close this terminal ...


No idea about what is wrong :(

Quote:

---

Originally Posted by Maragato

cannot open flags: No such file or directory

---

It is trying to open flags as a file, it is not finding it.

EXECUTING:
/home/imanewbie/Projects/Junk Code/checkflags checkflags.c
----------------------------------------------
checkflags.c:

----------------------------------------------
Program exited successfully with errcode (0)
Press the Enter key to close this terminal ...


Suggestions? :confused:

>>Program exited successfully
What's the problem exactly? :confused:

Quote:

---

Originally Posted by Hammer

>>Program exited successfully
What's the problem exactly? :confused:

---

The program exited (didn't crash) but also did'nt displayed the info I was waiting for:

Code:

---

/*check flags.c - display info on ext2 extended attributes*/

/* For each file name on the command line, display information on that
file's ext2 attributes */

#include<errno.h>
#include<fcntl.h>
#include<linux/ext2_fs.h>
#include<stdio.h>
#include<sys/ioctl.h>
#include<unistd.h>

int main(int argc, char **argv){
       
        char **filename = argv + 1;
        int fd;
        int flags;
       
/*Iterate over each file name on the command line. The last pointer in argv[]
        is NULL, so this while() loop is legal*/
        while (*filename){

/*Unlike normal attributes, ext2 attributes can only be queried if
we have a file descriptor (a file name is not sufficient). We
dont need write acces to query the ext2 attributes, so O_RDONLY is ok*/
               
                fd = open(*filename, O_RDONLY);
                        if (fd < 0) {
                                fprintf(stderr,"cannot open %s: %s\n", *filename,
                                                strerror(errno));
                                return 1;
                        }
/*This gets the attributes, and puts them into flags*/
                               
                        if (ioctl(fd, EXT2_IOC_GETFLAGS, &flags)){
                                fprintf(stderr,"ioctl failed on %s: %s\n", *filename,
                                                strerror(errno));
                                return 1;
                        }
                       
                        printf("%s:", *filename++);

/*Check for each attribute, and display a message for each one wich is returned
on*/
                        if (flags & EXT2_APPEND_FL) printf("Append");
                        if (flags & EXT2_IMMUTABLE_FL) printf("Immutable");
                        if (flags & EXT2_SYNC_FL) printf("Sync");
                        if (flags & EXT2_NODUMP_FL) printf("No dump");
                       
                        printf("\n");
                        close(fd);                       
        }
       
        return 0;
}

---

Did you pass it any parameters?

Quote:

---

Originally Posted by Hammer

Did you pass it any parameters?

---

I think this piece of code should do it:

Code:

---

/*This gets the attributes, and puts them into flags*/
                               
                        if (ioctl(fd, EXT2_IOC_GETFLAGS, &flags)){
                                fprintf(stderr,"ioctl failed on %s: %s\n", *filename,
                                                strerror(errno));
                                return 1;
                        }

---

No, they mean, are you calling your program correctly? You see, unless you supply command line arguments, then there will be nothing for filename to point at. IE:

Code:

---

./myfunction arg1 arg2 arg3

---

Those arguments would end up being stored in argc. Unless you call your program correctly, there will be nothing for your pointer to point at. Here, add this to your code:

Code:

---

int main(int argc, char **argv){
       
        char **filename = argv + 1;
        int fd;
        int flags;
       
        if( argc < 2 )
        {
                printf("Nope, you didn't call your program correctly.\n"
                printf("Next time try some command line parameters, eh?\n");
                exit( 0 );
        }

/*Iterate over each file name on the command line. The last pointer in argv[]
        is NULL, so this while() loop is legal*/
        while (*filename){

---

You see, this part of your code only works if you supply command line parameters. If you don't, well...

Quote:

---

Originally Posted by Maragato

The problem is simple, the program does nothing...

---

Quote:

---

Originally Posted by Maragato

The program exited (didn't crash) but also did'nt displayed the info I was waiting for:

---

But then, you've already been told that:

Quote:

---

Originally Posted by itsme86

Are you supplying any filenames on the command line (i.e.: flags file1 file2 file3)?

---

Quote:

---

Originally Posted by Hammer

Did you pass it any parameters?

---

I mean really, we can only point out the obvious so many times before it ceases to be amusing. And when it ceases to be amusing, I cease replying.



Quzah.
[edit]Tidying up color tags.[/edit]

Well I added you piece of code to check for the parameters but it goes trought without printing the error advices... :mad: But still not working. :(

Depends what you mean by not working.
The code you posted a couple of posts ago works just fine - it prints a list of filenames passed on the command line.
As for printing the flags, well that really depends on finding files with those attributes set.

Quote:

---

Originally Posted by Salem

Depends what you mean by not working.
The code you posted a couple of posts ago works just fine - it prints a list of filenames passed on the command line.
As for printing the flags, well that really depends on finding files with those attributes set.

---

Salem, I've read on Google about passing the parameters on command line, but the code didn't worked the way they told me to call it, could you please, just type the way I must call it on shell?

MyUser@blah:~here follows the call that I don't know how to do?
Thx a lot by the attention.

Same as you

Code:

---

$ gcc hello.c
$ ./a.out *.c
hello-back.c:
hello.c:
hello-old.c:

---

Nothing wrong with your code - its just that you don't have any files with the extended attributes set.

Quote:

---

Originally Posted by Salem

Same as you

Code:

---

$ gcc hello.c
$ ./a.out *.c
hello-back.c:
hello.c:
hello-old.c:

---

Nothing wrong with your code - its just that you don't have any files with the extended attributes set.

---

Oh now I figured out! Thx a lot! I've just created some tolist the attributes :p, now Imma happy child :D