lib/readutmp.c

   1 /* GNU's read utmp module.
   2    Copyright (C) 1992-2001 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/types.h>
  25 #include <sys/stat.h>
  26 #if defined(STDC_HEADERS) || defined(HAVE_STRING_H)
  27 # include <string.h>
  28 #else
  29 # include <strings.h>
  30 #endif /* STDC_HEADERS || HAVE_STRING_H */
  31
  32 #include "readutmp.h"
  33 #include "unlocked-io.h"
  34
  35 char *xmalloc ();
  36 char *realloc ();
  37
  38 /* Copy UT->ut_name into storage obtained from malloc.  Then remove any
  39    trailing spaces from the copy, NUL terminate it, and return the copy.  */
  40
  41 char *
  42 extract_trimmed_name (const STRUCT_UTMP *ut)
  43 {
  44   char *p, *trimmed_name;
  45
  46   trimmed_name = xmalloc (sizeof (UT_USER (ut)) + 1);
  47   strncpy (trimmed_name, UT_USER (ut), sizeof (UT_USER (ut)));
  48   /* Append a trailing space character.  Some systems pad names shorter than
  49      the maximum with spaces, others pad with NULs.  Remove any spaces.  */
  50   trimmed_name[sizeof (UT_USER (ut))] = ' ';
  51   p = strchr (trimmed_name, ' ');
  52   if (p != NULL)
  53     *p = '\0';
  54   return trimmed_name;
  55 }
  56
  57 /* Read the utmp entries corresponding to file FILENAME into freshly-
  58    malloc'd storage, set *UTMP_BUF to that pointer, set *N_ENTRIES to
  59    the number of entries, and return zero.  If there is any error,
  60    return non-zero and don't modify the parameters.  */
  61
  62 #ifdef UTMP_NAME_FUNCTION
  63
  64 int
  65 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
  66 {
  67   int n_read;
  68   STRUCT_UTMP *u;
  69   STRUCT_UTMP *utmp = NULL;
  70
  71   /* Ignore the return value for now.
  72      Solaris' utmpname returns 1 upon success -- which is contrary
  73      to what the GNU libc version does.  In addition, older GNU libc
  74      versions are actually void.   */
  75   UTMP_NAME_FUNCTION (filename);
  76
  77   SET_UTMP_ENT ();
  78
  79   n_read = 0;
  80   while ((u = GET_UTMP_ENT ()) != NULL)
  81     {
  82       ++n_read;
  83       utmp = (STRUCT_UTMP *) realloc (utmp, n_read * sizeof (STRUCT_UTMP));
  84       if (utmp == NULL)
  85         return 1;
  86       utmp[n_read - 1] = *u;
  87     }
  88
  89   END_UTMP_ENT ();
  90
  91   *n_entries = n_read;
  92   *utmp_buf = utmp;
  93
  94   return 0;
  95 }
  96
  97 #else
  98
  99 int
 100 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
 101 {
 102   FILE *utmp;
 103   struct stat file_stats;
 104   size_t n_read;
 105   size_t size;
 106   STRUCT_UTMP *buf;
 107
 108   utmp = fopen (filename, "r");
 109   if (utmp == NULL)
 110     return 1;
 111
 112   fstat (fileno (utmp), &file_stats);
 113   size = file_stats.st_size;
 114   if (size > 0)
 115     buf = (STRUCT_UTMP *) xmalloc (size);
 116   else
 117     {
 118       fclose (utmp);
 119       return 1;
 120     }
 121
 122   /* Use < instead of != in case the utmp just grew.  */
 123   n_read = fread (buf, 1, size, utmp);
 124   if (ferror (utmp) || fclose (utmp) == EOF
 125       || n_read < size)
 126     return 1;
 127
 128   *n_entries = size / sizeof (STRUCT_UTMP);
 129   *utmp_buf = buf;
 130
 131   return 0;
 132 }
 133
 134 #endif