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glibc  2.9
Functions
login.c File Reference
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <utmp.h>
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Functions

static int tty_name (int fd, char **tty, size_t buf_len)
void login (const struct utmp *ut)

Function Documentation

void login ( const struct utmp ut)

Definition at line 82 of file login.c.

{
#ifdef PATH_MAX
  char _tty[PATH_MAX + UT_LINESIZE];
#else
  char _tty[512 + UT_LINESIZE];
#endif
  char *tty = _tty;
  int found_tty;
  const char *ttyp;
  struct utmp copy = *ut;

  /* Fill in those fields we supply.  */
#if _HAVE_UT_TYPE - 0
  copy.ut_type = USER_PROCESS;
#endif
#if _HAVE_UT_PID - 0
  copy.ut_pid = getpid ();
#endif

  /* Seek tty.  */
  found_tty = tty_name (STDIN_FILENO, &tty, sizeof (_tty));
  if (found_tty < 0)
    found_tty = tty_name (STDOUT_FILENO, &tty, sizeof (_tty));
  if (found_tty < 0)
    found_tty = tty_name (STDERR_FILENO, &tty, sizeof (_tty));

  if (found_tty >= 0)
    {
      /* We only want to insert the name of the tty without path.
        But take care of name like /dev/pts/3.  */
      if (strncmp (tty, "/dev/", 5) == 0)
       ttyp = tty + 5;             /* Skip the "/dev/".  */
      else
       ttyp = basename (tty);

      /* Position to record for this tty.  */
      strncpy (copy.ut_line, ttyp, UT_LINESIZE);

      /* Tell that we want to use the UTMP file.  */
      if (utmpname (_PATH_UTMP) == 0)
       {
         /* Open UTMP file.  */
         setutent ();

         /* Write the entry.  */
         pututline (&copy);

         /* Close UTMP file.  */
         endutent ();
       }

      if (tty != _tty)
       free (tty);          /* Free buffer malloced by tty_name.  */
    }
  else
    /* We provide a default value so that the output does not contain
       an random bytes in this field.  */
    strncpy (copy.ut_line, "???", UT_LINESIZE);

  /* Update the WTMP file.  Here we have to add a new entry.  */
  updwtmp (_PATH_WTMP, &copy);
}

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static int tty_name ( int  fd,
char **  tty,
size_t  buf_len 
) [static]

Definition at line 34 of file login.c.

{
  int rv;                   /* Return value.  0 = success.  */
  char *buf = *tty;         /* Buffer for ttyname, initially the user's. */

  for (;;)
    {
      char *new_buf;

      if (buf_len)
       {
         rv = ttyname_r (fd, buf, buf_len);

         if (rv != 0 || memchr (buf, '\0', buf_len))
           /* We either got an error, or we succeeded and the
              returned name fit in the buffer.  */
           break;

         /* Try again with a longer buffer.  */
         buf_len += buf_len;       /* Double it */
       }
      else
       /* No initial buffer; start out by mallocing one.  */
       buf_len = 128;              /* First time guess.  */

      if (buf != *tty)
       /* We've already malloced another buffer at least once.  */
       new_buf = realloc (buf, buf_len);
      else
       new_buf = malloc (buf_len);
      if (! new_buf)
       {
         rv = -1;
         __set_errno (ENOMEM);
         break;
       }
      buf = new_buf;
    }

  if (rv == 0)
    *tty = buf;             /* Return buffer to the user.  */
  else if (buf != *tty)
    free (buf);             /* Free what we malloced when returning an error.  */

  return rv;
}

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