lib/readutmp.c

   1 /* GNU's read utmp module.
   2    Copyright (C) 1992-2001, 2003 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 #include <string.h>
  27 #include <stdlib.h>
  28
  29 #include "readutmp.h"
  30 #include "unlocked-io.h"
  31 #include "xalloc.h"
  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_USER (ut)) + 1);
  42   strncpy (trimmed_name, UT_USER (ut), sizeof (UT_USER (ut)));
  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_USER (ut))] = ' ';
  46   p = strchr (trimmed_name, ' ');
  47   if (p != NULL)
  48     *p = '\0';
  49   return trimmed_name;
  50 }
  51
  52 /* Read the utmp entries corresponding to file FILENAME into freshly-
  53    malloc'd storage, set *UTMP_BUF to that pointer, set *N_ENTRIES to
  54    the number of entries, and return zero.  If there is any error,
  55    return non-zero and don't modify the parameters.  */
  56
  57 #ifdef UTMP_NAME_FUNCTION
  58
  59 int
  60 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
  61 {
  62   int n_read;
  63   STRUCT_UTMP *u;
  64   STRUCT_UTMP *utmp = NULL;
  65
  66   /* Ignore the return value for now.
  67      Solaris' utmpname returns 1 upon success -- which is contrary
  68      to what the GNU libc version does.  In addition, older GNU libc
  69      versions are actually void.   */
  70   UTMP_NAME_FUNCTION (filename);
  71
  72   SET_UTMP_ENT ();
  73
  74   n_read = 0;
  75   while ((u = GET_UTMP_ENT ()) != NULL)
  76     {
  77       ++n_read;
  78       utmp = (STRUCT_UTMP *) realloc (utmp, n_read * sizeof (STRUCT_UTMP));
  79       if (utmp == NULL)
  80         return 1;
  81       utmp[n_read - 1] = *u;
  82     }
  83
  84   END_UTMP_ENT ();
  85
  86   *n_entries = n_read;
  87   *utmp_buf = utmp;
  88
  89   return 0;
  90 }
  91
  92 #else
  93
  94 int
  95 read_utmp (const char *filename, int *n_entries, STRUCT_UTMP **utmp_buf)
  96 {
  97   FILE *utmp;
  98   struct stat file_stats;
  99   size_t n_read;
 100   size_t size;
 101   STRUCT_UTMP *buf;
 102
 103   utmp = fopen (filename, "r");
 104   if (utmp == NULL)
 105     return 1;
 106
 107   if (fstat (fileno (utmp), &file_stats) != 0)
 108     {
 109       int e = errno;
 110       fclose (utmp);
 111       errno = e;
 112       return 1;
 113     }
 114   size = file_stats.st_size;
 115   buf = xmalloc (size);
 116   n_read = fread (buf, sizeof *buf, size / sizeof *buf, utmp);
 117   if (ferror (utmp))
 118     {
 119       int e = errno;
 120       free (buf);
 121       fclose (utmp);
 122       errno = e;
 123       return 1;
 124     }
 125   if (fclose (utmp) != 0)
 126     {
 127       int e = errno;
 128       free (buf);
 129       errno = e;
 130       return 1;
 131     }
 132
 133   *n_entries = n_read;
 134   *utmp_buf = buf;
 135
 136   return 0;
 137 }
 138
 139 #endif