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 <stdio.h>
  23
  24 #include <sys/stat.h>
  25 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  26 # include <string.h>
  27 #else
  28 # include <strings.h>
  29 #endif /* STDC_HEADERS || HAVE_STRING_H */
  30
  31 #include "readutmp.h"
  32
  33 char *xmalloc ();
  34 char *realloc ();
  35
  36 /* Copy UT->ut_name into storage obtained from malloc.  Then remove any
  37    trailing spaces from the copy, NUL terminate it, and return the copy.  */
  38
  39 char *
  40 extract_trimmed_name (const STRUCT_UTMP *ut)
  41 {
  42   char *p, *trimmed_name;
  43
  44   trimmed_name = xmalloc (sizeof (ut->ut_name) + 1);
  45   strncpy (trimmed_name, ut->ut_name, sizeof (ut->ut_name));
  46   /* Append a trailing space character.  Some systems pad names shorter than
  47      the maximum with spaces, others pad with NULs.  Remove any spaces.  */
  48   trimmed_name[sizeof (ut->ut_name)] = ' ';
  49   p = strchr (trimmed_name, ' ');
  50   if (p != NULL)
  51     *p = '\0';
  52   return trimmed_name;
  53 }
  54
  55 /* Read the utmp entries corresponding to file FILENAME into freshly-
  56    malloc'd storage, set *UTMP_BUF to that pointer, set *N_ENTRIES to
  57    the number of entries, and return zero.  If there is any error,
  58    return non-zero and don't modify the parameters.  */
  59
  60 #if HAVE_UTMPNAME
  61
  62 int
  63 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
  64 {
  65   int n_read;
  66   STRUCT_UTMP *u;
  67   STRUCT_UTMP *utmp = NULL;
  68
  69   /* Ignore the return value for now.
  70      Solaris' utmpname returns 1 upon success -- which is contrary
  71      to what the GNU libc version does.  In addition, older GNU libc
  72      versions are actually void.   */
  73   UTMP_NAME_FUNCTION (filename);
  74
  75   SET_UTMP_ENT ();
  76
  77   n_read = 0;
  78   while ((u = GET_UTMP_ENT ()) != NULL)
  79     {
  80       ++n_read;
  81       utmp = (STRUCT_UTMP *) realloc (utmp, n_read * sizeof (STRUCT_UTMP));
  82       if (utmp == NULL)
  83         return 1;
  84       utmp[n_read - 1] = *u;
  85     }
  86
  87   END_UTMP_ENT ();
  88
  89   *n_entries = n_read;
  90   *utmp_buf = utmp;
  91
  92   return 0;
  93 }
  94
  95 #else
  96
  97 int
  98 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
  99 {
 100   FILE *utmp;
 101   struct stat file_stats;
 102   size_t n_read;
 103   size_t size;
 104   STRUCT_UTMP *buf;
 105
 106   utmp = fopen (filename, "r");
 107   if (utmp == NULL)
 108     return 1;
 109
 110   fstat (fileno (utmp), &file_stats);
 111   size = file_stats.st_size;
 112   if (size > 0)
 113     buf = (STRUCT_UTMP *) xmalloc (size);
 114   else
 115     {
 116       fclose (utmp);
 117       return 1;
 118     }
 119
 120   /* Use < instead of != in case the utmp just grew.  */
 121   n_read = fread (buf, 1, size, utmp);
 122   if (ferror (utmp) || fclose (utmp) == EOF
 123       || n_read < size)
 124     return 1;
 125
 126   *n_entries = size / sizeof (STRUCT_UTMP);
 127   *utmp_buf = buf;
 128
 129   return 0;
 130 }
 131
 132 #endif /* HAVE_UTMPNAME */