okay, maybe i am missing the point totally with structures. here is my code, let
me know whats wrong with it:
struct utsname *host_uname;
host_uname = (struct utsname *)malloc(sizeof(struct utsname));
uname(host_uname);
system_os = malloc(strlen(host_uname->sysname)+1);
strncpy(system_os, (host_uname->sysname), sizeof(system_os));
system_os is type char *. i cant see anything wrong with this code, but then
again ive never worked extensively with structs.
thanks for any help
Benjamin Scott wrote:
> On Thu, 22 Feb 2001, Tony Lambiris wrote:
> > when I set a pointer to the structure, and say, get the OS version:
> >
> > struct utsname *host_uname;
>
> Are you allocating a memory buffer and pointing host_uname to it before
> invoking uname:
>
> struct utsname buf;
> uname(&buf);
>
> > os_version = malloc(strlen(host_uname->release));
>
> You do not declare os_version in the code sample you give. I will assume
> you mean:
>
> char * os_version;
>
> If you intend to copy the string pointed to by host_uname->release, then you
> need to malloc one extra byte for the terminating NUL byte:
>
> os_version = malloc( strlen(buf->release) + 1 );
>
> > os_version = (host_uname->release);
>
> Be aware that this does *NOT* copy the string pointed to by
> host_uname->release to the buffer pointed to by os_version. Instead, it
> copies the *pointer* contained in host_uname to os_version (which, hopefully,
> is also a pointer). This is fine, but it means that if you destroy
> host_uname, os_version will no longer be valid.
>
> If you intended to copy the string, you need to use:
>
> strcpy (os_version, host_uname->release);
>
> But you should really use:
>
> strncpy (os_version, host_uname->release, SIZE_OF_OS_VERSION_BUFFER);
>
> That will prevent buffer overflow bugs.
>
> > or perhaps I just suck at coding??
>
> I would not go that far, but it is apparent you do not fully understand
> string handling in C. That is pretty common; C string handling is notoriously
> hard to master for new users, especially those used to other languages with a
> built-in "string" type. I recommend _The C Programming Language_, Second
> Edition, by Kernighan and Ritchie. Actually, I recommend two copies: One to
> use, and one to place in a shrine. ;-)
>
> --
> Ben Scott <[EMAIL PROTECTED]>
> Net Technologies, Inc. <http://www.ntisys.com>
> Voice: (800)905-3049 x18 Fax: (978)499-7839
>
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