lib/readutmp.c

   1 /* GNU's read utmp module.
   2    Copyright (C) 1992-1999 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Written by jla; revised by djm */
  19
  20 #include <config.h>
  21
  22 #include <sys/stat.h>
  23 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  24 # include <string.h>
  25 #else
  26 # include <strings.h>
  27 #endif /* STDC_HEADERS || HAVE_STRING_H */
  28
  29 #include "readutmp.h"
  30
  31 char *xmalloc ();
  32
  33 /* Copy UT->ut_name into storage obtained from malloc.  Then remove any
  34    trailing spaces from the copy, NUL terminate it, and return the copy.  */
  35
  36 char *
  37 extract_trimmed_name (const STRUCT_UTMP *ut)
  38 {
  39   char *p, *trimmed_name;
  40
  41   trimmed_name = xmalloc (sizeof (ut->ut_name) + 1);
  42   strncpy (trimmed_name, ut->ut_name, sizeof (ut->ut_name));
  43   /* Append a trailing space character.  Some systems pad names shorter than
  44      the maximum with spaces, others pad with NULs.  Remove any spaces.  */
  45   trimmed_name[sizeof (ut->ut_name)] = ' ';
  46   p = strchr (trimmed_name, ' ');
  47   if (p != NULL)
  48     *p = '\0';
  49   return trimmed_name;
  50 }
  51
  52 /* Read the utmp file FILENAME into *UTMP_BUF, set *N_ENTRIES to the
  53    number of entries read, and return zero.  If there is any error,
  54    return non-zero and don't modify the parameters.  */
  55
  56 /* FIXME: use `#if HAVE_UTMPNAME' instead...  */
  57 #if 0
  58
  59 int
  60 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
  61 {
  62   int count_utmp = 0;
  63   int n_read;
  64   STRUCT_UTMP *u;
  65   STRUCT_UTMP *uptr;
  66   STRUCT_UTMP *utmp_contents;
  67
  68   if (utmpname (filename))
  69     {
  70       return 1;
  71     }
  72
  73   /* FIXME: going through the list twice is wasteful. */
  74
  75   /* count the entries in utmp */
  76   setutent ();
  77   while ((u = getutent ()) != NULL)
  78     ++count_utmp;
  79
  80   if (count_utmp == 0)
  81     return 0;
  82
  83   utmp_contents = (STRUCT_UTMP *) xmalloc (count_utmp * sizeof (STRUCT_UTMP));
  84
  85   /* read the entries in utmp */
  86
  87   /* FIXME: can this fail? */
  88   setutent ();
  89
  90   n_read = 0;
  91   uptr = utmp_contents;
  92   while ((u = getutent ()) != NULL)
  93     {
  94       ++n_read;
  95       if (n_read > count_utmp)
  96         {
  97           STRUCT_UTMP *old_utmp_contents = utmp_contents;
  98           ++count_utmp;
  99           utmp_contents = (STRUCT_UTMP *) xrealloc (utmp_contents,
 100                                                     (count_utmp
 101                                                      * sizeof (STRUCT_UTMP)));
 102           uptr = utmp_contents + (uptr - old_utmp_contents);
 103         }
 104       *uptr = *u;
 105       ++uptr;
 106     }
 107
 108   if (n_read != count_utmp)
 109     utmp_contents = (STRUCT_UTMP *) xrealloc (utmp_contents,
 110                                               n_read * sizeof (STRUCT_UTMP));
 111
 112   /* FIXME: can this fail? */
 113   endutent ();
 114
 115   *n_entries = n_read;
 116   *utmp_buf = utmp_contents;
 117
 118   return 0;
 119 }
 120
 121 #else
 122
 123 int
 124 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
 125 {
 126   FILE *utmp;
 127   struct stat file_stats;
 128   size_t n_read;
 129   size_t size;
 130   STRUCT_UTMP *buf;
 131
 132   utmp = fopen (filename, "r");
 133   if (utmp == NULL)
 134     return 1;
 135
 136   fstat (fileno (utmp), &file_stats);
 137   size = file_stats.st_size;
 138   if (size > 0)
 139     buf = (STRUCT_UTMP *) xmalloc (size);
 140   else
 141     {
 142       fclose (utmp);
 143       return 1;
 144     }
 145
 146   /* Use < instead of != in case the utmp just grew.  */
 147   n_read = fread (buf, 1, size, utmp);
 148   if (ferror (utmp) || fclose (utmp) == EOF
 149       || n_read < size)
 150     return 1;
 151
 152   *n_entries = size / sizeof (STRUCT_UTMP);
 153   *utmp_buf = buf;
 154
 155   return 0;
 156 }
 157
 158 #endif /* HAVE_UTMPNAME */