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Operating Systems Linux C++ Code to Access Linux Hard Disk Sectors (with a LoopBack Virtual Hard Disk) Post 302491389 by Corona688 on Thursday 27th of January 2011 09:43:40 AM
Old 01-27-2011
Why are you opening and closing the file every time you do something?

This especially becomes useless:
Code:
/**
Seek out a Particular Block In the Disk
Block_SIZE=512bytes
*/
int seekDisk()
{
    cout<<"Seeking the File Disk..."<<endl;
    int fd=open(DISK_NAME, O_RDWR);
	if(lseek(fd, 0L, SEEK_SET) != 0L)
        {
                perror("Couldn't seek");
                close(fd);
                return(1);
        }
    close(fd);
    return 0;
}

...because the seek position gets reset every time you open it anyway. You should open it once and keep using the number it gives you. Your read code would end up looking like int readFromDisk(int fd, char *buffer,int length) { ... } iow exactly like normal read...so you might as well get used to ordinary read call instead.

You should also be doing something more with the number of bytes written and read than just printing it. read() and write() will occasionally surprise you with less than you asked for.
 

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FBB::Hostname(3bobcat)						     Host Info						    FBB::Hostname(3bobcat)

NAME
FBB::Hostname - Contains name/address info about a host SYNOPSIS
#include <bobcat/hostname> Linking option: -lbobcat DESCRIPTION
FBB::Hostname objects inherit from Hostent, and offers information about a host, like Hostent. Apart from being initialized by a hostname or host address, they can also be initialized by a FBB::InetAddress object. Most of the functionality of an FBB::Hostname object is avail- able through its parent-class FBB::Hostent. NAMESPACE
FBB All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace FBB. INHERITS FROM
FBB::Hostent CONSTRUCTORS
o Hostname(): The default constructor initializes an empty FBB::Hostname object. o Hostname((std::string const &host)): This constructor initializes an FBB::Hostname object from a string representing the name or dotted decimal address of a host. An FBB::Errno object is thrown if the hostname information could not be retrieved. o Hostname(InetAddress const &inetAddress): This constructor initializes an FBB::Hostname object from an InetAddress object. An FBB::Errno object is thrown if the hostname information could not be retrieved. The copy constructor is available. MEMBER FUNCTIONS
All members of FBB::Hostent are available, as FBB::Hostname inherits from this class. There are no additional members. EXAMPLE
#include <iostream> #include <bobcat/hostname> #include <bobcat/errno> using namespace std; using namespace FBB; int main(int argc, char **argv) { while (true) { cout << "Enter name or address: "; string str; if (!getline(cin, str)) return 0; if (str == "") break; try { Hostname h(str); cout << "Official name: "; cout << h.hostname() << endl; cout << "Aliases: "; for (size_t idx = 0; idx < h.nAliases(); idx++) cout << h.alias(idx) << " "; cout << endl; cout << "Adresses: "; for (size_t idx = 0; idx < h.nAddresses(); idx++) cout << h.dottedDecimalAddress(idx) << " "; cout << endl; } catch (Errno const &err) { cout << err.why() << endl; } } return 0; } FILES
bobcat/hostname - defines the class interface SEE ALSO
bobcat(7), hostent(3bobcat) BUGS
None Reported. DISTRIBUTION FILES
o bobcat_3.01.00-x.dsc: detached signature; o bobcat_3.01.00-x.tar.gz: source archive; o bobcat_3.01.00-x_i386.changes: change log; o libbobcat1_3.01.00-x_*.deb: debian package holding the libraries; o libbobcat1-dev_3.01.00-x_*.deb: debian package holding the libraries, headers and manual pages; o http://sourceforge.net/projects/bobcat: public archive location; BOBCAT
Bobcat is an acronym of `Brokken's Own Base Classes And Templates'. COPYRIGHT
This is free software, distributed under the terms of the GNU General Public License (GPL). AUTHOR
Frank B. Brokken (f.b.brokken@rug.nl). libbobcat1-dev_3.01.00-x.tar.gz 2005-2012 FBB::Hostname(3bobcat)
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