fgets problems Post: 302397207

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Top Forums Programming fgets problems Post 302397207 by achenle on Sunday 21st of February 2010 10:49:56 AM

02-21-2010

Registered User

Let me get this straight: you have a custom memory management library, and your code using that library crashes?

OK.

You need all the help you can get. But there's not much out there.

Your only hope is to do something like download a demo copy of Purify and use it. And then pray that you don't have any bugs in your custom library.

And good luck.

You're going to need it.

There's a reason why nobody writes their own memory management libraries. First off, the multiple libraries available for free on your OS of choice are almost certainly fast enough. If they're not, you're most likely doing something wrong, like an over-reliance on malloc()/free() and/or new/delete. And if the OS libaries truly aren't fast enough (and if you're not multithreaded on a massively parallel application, they ARE fast enough!), there are third-party memory management libraries available.

Go price something like Smartheap. Then calculate all the hours spent on your custom memory library and how much those hours cost. Want to bet Smartheap is cheaper? If you even need it in the first place.

There are probably literally thousands of man-years invested by many absolutely brilliant computer scientists and programmers in all the memory-management libraries available in today's operating systems. And those products have been thoroughly tested - for literally decades.

You want a car analogy? Writing your own memory management library is like chiseling out a stone wheel for a sports car. The only reason to do it is for the sake of doing it - as a hobby or academic learning experience. Because there's no way you can duplicate the engineering history behind a "normal" wheel. Even if you do manage to chisel out a wheel that manages to outperform a "normal" wheel in a tiny operating range, you'll never really know how durable your wheel is because it's totally untested.

achenle

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LEARN ABOUT CENTOS

pam_wheel

PAM_WHEEL(8)							 Linux-PAM Manual						      PAM_WHEEL(8)

NAME

       pam_wheel - Only permit root access to members of group wheel

SYNOPSIS

       pam_wheel.so [debug] [deny] [group=name] [root_only] [trust] [use_uid]

DESCRIPTION

       The pam_wheel PAM module is used to enforce the so-called wheel group. By default it permits root access to the system if the applicant
       user is a member of the wheel group. If no group with this name exist, the module is using the group with the group-ID 0.

OPTIONS

       debug
	   Print debug information.

       deny
	   Reverse the sense of the auth operation: if the user is trying to get UID 0 access and is a member of the wheel group (or the group of
	   the group option), deny access. Conversely, if the user is not in the group, return PAM_IGNORE (unless trust was also specified, in
	   which case we return PAM_SUCCESS).

       group=name
	   Instead of checking the wheel or GID 0 groups, use the name group to perform the authentication.

       root_only
	   The check for wheel membership is done only.

       trust
	   The pam_wheel module will return PAM_SUCCESS instead of PAM_IGNORE if the user is a member of the wheel group (thus with a little play
	   stacking the modules the wheel members may be able to su to root without being prompted for a passwd).

       use_uid
	   The check for wheel membership will be done against the current uid instead of the original one (useful when jumping with su from one
	   account to another for example).

MODULE TYPES PROVIDED

       The auth and account module types are provided.

RETURN VALUES

       PAM_AUTH_ERR
	   Authentication failure.

       PAM_BUF_ERR
	   Memory buffer error.

       PAM_IGNORE
	   The return value should be ignored by PAM dispatch.

       PAM_PERM_DENY
	   Permission denied.

       PAM_SERVICE_ERR
	   Cannot determine the user name.

       PAM_SUCCESS
	   Success.

       PAM_USER_UNKNOWN
	   User not known.

EXAMPLES

       The root account gains access by default (rootok), only wheel members can become root (wheel) but Unix authenticate non-root applicants.

	   su	   auth     sufficient	   pam_rootok.so
	   su	   auth     required	   pam_wheel.so
	   su	   auth     required	   pam_unix.so

SEE ALSO

       pam.conf(5), pam.d(5), pam(8)

AUTHOR

       pam_wheel was written by Cristian Gafton <gafton@redhat.com>.

Linux-PAM Manual						    09/19/2013							      PAM_WHEEL(8)

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