RE: Use of fgets, puts, rewind in Gtk+
Thanks a lot, it was indeed a security problem, now it is solved.
Sucheta
On Fri, 13 Oct 2006, Madhusudan E wrote:
Hi,
There is absolutely no problem in doing file operations in
GTK based applications.
Just check the validity of your operations.
Check the validity of your file name , path, Security options ( Read only
etc).
Always remember to close the file.
Nothing to worry much, some silly thing has gone wrong.
Rgds,
Madhusudan E
Hello,
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
Thanks regards,
Sucheta Ghosh
Indian Statistical Institute, Kolkata
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Re: Use of fgets, puts, rewind in Gtk+
Let me clarify the situation one by one:
I can see some problems here, but that's not really GTK-related;
Then my question is: how the same code works fine as a simple c file, when
I am not using this inside Gtk+?
1) no error checking for fopen(), fgets() - You don't to anything
if they fail (and that's most probable)
What I have written is only a small piece of code, where I had written the
extract only to explain the problem in short. I have done the error
checking, the result is fopen() is not getting the null value, but fgets()
is getting the null value.
And I have declared all the variables unless it would not compile, as I
said earlier this is a runtime problem.
2) can't see any fclose() - multiple fopen()s without closing
the file is BAD :)
I have done it in my Gtk+ coding only did not shown it here.
And all the other things I have done due to the demand of my application.
Thanks regards,
Sucheta Ghosh
On Thu, 12 Oct 2006, Progss wrote:
Sucheta Ghosh napisa?(a):
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
I can see some problems here, but that's not really GTK-related;
well - there's also a change that included snippet was simply
too short
1) no error checking for fopen(), fgets() - You don't to anything
if they fail (and that's most probable)
2) can't see any fclose() - multiple fopen()s without closing
the file is BAD :)
3) You're reading the same file 8 times - and that's *at least*
non-optimal - of course that depends on what exactly you're going
to achieve, however I'm quite convinced
4) I'd be really careful about placing some external file operations
nside of a callback function. but this depends on your overall
application purpose and design.
Best regards
Waldek
--
Czas pozegnac finansowe problemy.
Kredyt Citibank - prosty kredyt na wszystkie potrzeby.
Sprawdz: http://link.interia.pl/f19a5
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Re: Use of fgets, puts, rewind in Gtk+
On 10/12/06, Sucheta Ghosh [EMAIL PROTECTED] wrote:
Hello,
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Please, copy-paste the error.
Do you have any idea that how to overcome this problem?
Thanks regards,
Sucheta Ghosh
Indian Statistical Institute, Kolkata
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Re: Use of fgets, puts, rewind in Gtk+
On Fri, 2006-10-13 at 10:16 +0530, Sucheta Ghosh wrote:
Let me clarify the situation one by one:
I can see some problems here, but that's not really GTK-related;
Then my question is: how the same code works fine as a simple c file, when
I am not using this inside Gtk+?
Probably because you are just lucky. Often times code that's not quite
correct can work fine in a small, standalone test case but fails when
run in another context.
By the way you never did post the runtime error message you got.
Unfortunately without knowing what that error was we cannot help you.
1) no error checking for fopen(), fgets() - You don't to anything
if they fail (and that's most probable)
What I have written is only a small piece of code, where I had written the
extract only to explain the problem in short. I have done the error
checking, the result is fopen() is not getting the null value, but fgets()
is getting the null value.
And I have declared all the variables unless it would not compile, as I
said earlier this is a runtime problem.
2) can't see any fclose() - multiple fopen()s without closing
the file is BAD :)
I have done it in my Gtk+ coding only did not shown it here.
And all the other things I have done due to the demand of my application.
Thanks regards,
Sucheta Ghosh
On Thu, 12 Oct 2006, Progss wrote:
Sucheta Ghosh napisa?(a):
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
I can see some problems here, but that's not really GTK-related;
well - there's also a change that included snippet was simply
too short
1) no error checking for fopen(), fgets() - You don't to anything
if they fail (and that's most probable)
2) can't see any fclose() - multiple fopen()s without closing
the file is BAD :)
3) You're reading the same file 8 times - and that's *at least*
non-optimal - of course that depends on what exactly you're going
to achieve, however I'm quite convinced
4) I'd be really careful about placing some external file operations
nside of a callback function. but this depends on your overall
application purpose and design.
Best regards
Waldek
--
Czas pozegnac finansowe problemy.
Kredyt Citibank - prosty kredyt na wszystkie potrzeby.
Sprawdz: http://link.interia.pl/f19a5
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Use of fgets, puts, rewind in Gtk+
Hello,
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
Thanks regards,
Sucheta Ghosh
Indian Statistical Institute, Kolkata
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Re: Use of fgets, puts, rewind in Gtk+
Sucheta Ghosh napisał(a):
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
I can see some problems here, but that's not really GTK-related;
well - there's also a change that included snippet was simply
too short
1) no error checking for fopen(), fgets() - You don't to anything
if they fail (and that's most probable)
2) can't see any fclose() - multiple fopen()s without closing
the file is BAD :)
3) You're reading the same file 8 times - and that's *at least*
non-optimal - of course that depends on what exactly you're going
to achieve, however I'm quite convinced
4) I'd be really careful about placing some external file operations
nside of a callback function. but this depends on your overall
application purpose and design.
Best regards
Waldek
--
Czas pozegnac finansowe problemy.
Kredyt Citibank - prosty kredyt na wszystkie potrzeby.
Sprawdz: http://link.interia.pl/f19a5
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gtk-app-devel-list@gnome.org
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Re: Use of fgets, puts, rewind in Gtk+
-BEGIN PGP SIGNED MESSAGE-
Hash: SHA1
On Thu, Oct 12, 2006 at 08:14:50PM +0200, Progss wrote:
Let me add some cents to Progss' two dollars :-)
Sucheta Ghosh napisa?(a):
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
I can see some problems here, but that's not really GTK-related;
well - there's also a change that included snippet was simply
too short
Exactly. Where are n, a[], s and all of them declared?
1) no error checking for fopen(), fgets() - You don't to anything
if they fail (and that's most probable)
If fopen() fails, it returns NULL. An fread() or fgets() or whatever
will core dump on that.
2) can't see any fclose() - multiple fopen()s without closing
the file is BAD :)
No crash, but a memory leak. Your program will accumulate file
descriptors until it runs out of them. This is what they call file
descriptor leak.
3) You're reading the same file 8 times - and that's *at least*
non-optimal - of course that depends on what exactly you're going
to achieve, however I'm quite convinced
Yes, this looked strange to me as well. But who knows -- may be
something is changing the file (but it must be very quickly indeed). Or
it may be a special file in /proc, yielding different results for each
read pass.
4) I'd be really careful about placing some external file operations
nside of a callback function. but this depends on your overall
application purpose and design.
Basically I don't see a problem in that -- besides the feeling that
file operations are often taking longer time. And of course, things
that take longer time shouldn't go in a callback, if you don't want your
app to freeze some times.
Regards
- -- tomas
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RE: Use of fgets, puts, rewind in Gtk+
Hi,
There is absolutely no problem in doing file operations in
GTK based applications.
Just check the validity of your operations.
Check the validity of your file name , path, Security options ( Read only
etc).
Always remember to close the file.
Nothing to worry much, some silly thing has gone wrong.
Rgds,
Madhusudan E
Hello,
I wished to read a file and get some lines from there like this:
-
fp=fopen(filename, r);
for(k=0; k8; k++){
n=a[k];
for (i=1; i=n; i++) //Here 'n' is the line number
fgets(s, 100, fp);
puts(s);
rewind(fp);
}
-
-
This is the code snippet, which is working so well after compiling with
'gcc' compiler, but when I added this code inside Gtk+ callback.c, a
runtime error is occuring before execution of 'fgets'. I have already
included 'stdio.h', but even then it is not executing.
Do you have any idea that how to overcome this problem?
Thanks regards,
Sucheta Ghosh
Indian Statistical Institute, Kolkata
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