Re: WTMP file

From: Dan Yefimov (dan_at_D00M.integrate.com.ru)
Date: 11/06/03

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    Date: Thu, 6 Nov 2003 18:34:13 +0300 (MSK)
To: BORJA RUIZ CASTRO MORON <padre@fedro.ugr.es>

    On Wed, 5 Nov 2003, BORJA RUIZ CASTRO MORON wrote:

    > Hi! I´m coding an aplication for remove user entries in WTMP.
    > I think the code is OK,but it does not work! :P
    > Could somebody take a look please?
    >
    > Thanks a lot! :D
    >
    >
    > ----------------------------------------------
    > #include <stdio.h>
    > #include <fcntl.h>
    > #include <pwd.h>
    > #include <unistd.h>
    > #include <utmp.h>
    > #include <sys/time.h>
    >
    > #define WTMP "/var/log/wtmp"
    >
    > int main (int argc, char **argv){
    >
    > int fd;
    >
    > struct passwd *acceso;
    > struct utmp rosita;
    > setutent();
    >
    > if (argc<2) {
    > printf("Usage: %s <user>\n",argv[0]);
    > exit(-1);
    > }
    > if((fd=open(WTMP,O_WRONLY))<0) {
    > printf("\nFile not found.\n\n");
    > exit(-1);
    > }
    >
    > if ((acceso=getpwnam(argv[1]))==NULL) {
    > printf("\nUnknow user :P\n\n");
    > exit(-1);
    > }
    >
    > // Our info
    >
    > rosita.ut_type=DEAD_PROCESS;
    > memset(rosita.ut_line,0,UT_LINESIZE);
    > memset(rosita.ut_user,0,UT_NAMESIZE);
    > memset(rosita.ut_host,0,UT_HOSTSIZE);
    > rosita.ut_time=0;
    >
    > while((acceso=getpwent())!=NULL) {
    >
    > lseek(fd,sizeof(struct utmp)*acceso->pw_uid,SEEK_SET);
    > pututline(&rosita);
    > }
    >
    > endutent();
    >
    > close(fd);
    > return(0);
    > }
    >
    >
    It won't work because utmp/wtmp files aren't ordered by uid. For this program to
    work you should scan utmp file for records related to the given uid. 

    -- 
    Sincerely Your, Dan.
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