locate/word_io.c

   1 /* word_io.c -- word oriented I/O
   2    Copyright (C) 2007 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
  16    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  17    USA.
  18 */
  19
  20 #include <config.h>
  21 #include <errno.h>
  22
  23 #include "quote.h"
  24 #include "quotearg.h"
  25 #include "locatedb.h"
  26
  27 #if ENABLE_NLS
  28 # include <libintl.h>
  29 # define _(Text) gettext (Text)
  30 #else
  31 # define _(Text) Text
  32 #define textdomain(Domain)
  33 #define bindtextdomain(Package, Directory)
  34 #endif
  35 #ifdef gettext_noop
  36 # define N_(String) gettext_noop (String)
  37 #else
  38 /* We used to use (String) instead of just String, but apparently ISO C
  39  * doesn't allow this (at least, that's what HP said when someone reported
  40  * this as a compiler bug).  This is HP case number 1205608192.  See
  41  * also http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11250 (which references
  42  * ANSI 3.5.7p14-15).  The Intel icc compiler also rejects constructs
  43  * like: static const char buf[] = ("string");
  44  */
  45 # define N_(String) String
  46 #endif
  47
  48
  49 /* Swap bytes in 32 bit value.  This code is taken from glibc-2.3.3. */
  50 #define bswap_32(x) \
  51      ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) | \
  52       (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
  53
  54 static int
  55 decode_value(const unsigned char data[],
  56              int limit,
  57              int *endian_state_flag,
  58              const char *filename)
  59 {
  60   int val;
  61
  62   if (*endian_state_flag = GetwordEndianStateInitial)
  63     {
  64       int testflag = GetwordEndianStateNative;
  65
  66       val = decode_value(data, limit, &testflag, filename);
  67       if (val <= limit)
  68         {
  69           return val;
  70         }
  71       else
  72         {
  73           testflag = GetwordEndianStateSwab;
  74           val = decode_value(data, limit, &testflag, filename);
  75           if (val <= limit)
  76             {
  77               /* Aha, now we know we have to byte-swap. */
  78               error(0, 0,
  79                     _("Warning: locate database %s was built with a different byte order"),
  80                     quotearg_n_style(0, locale_quoting_style, filename));
  81               *endian_state_flag = testflag;
  82               return val;
  83             }
  84           else
  85             {
  86               return val;
  87             }
  88         }
  89     }
  90   else
  91     {
  92       val = *(int*)data;
  93       if (*endian_state_flag == GetwordEndianStateSwab)
  94         return bswap_32(val);
  95       else
  96         return val;
  97     }
  98 }
  99
 100
 101
 102 int
 103 getword (FILE *fp,
 104          const char *filename,
 105          size_t minvalue,
 106          size_t maxvalue,
 107          int *endian_state_flag)
 108 {
 109   enum { WORDBYTES=4 };
 110   unsigned char data[4];
 111   size_t bytes_read;
 112
 113   clearerr(fp);
 114   bytes_read = fread(data, WORDBYTES, 1, fp);
 115   if (bytes_read != 1)
 116     {
 117       const char * quoted_name = quotearg_n_style(0, locale_quoting_style,
 118                                                   filename);
 119       /* Distinguish between a truncated database and an I/O error.
 120        * Either condition is fatal.
 121        */
 122       if (feof(fp))
 123         error(1, 0, _("Unexpected EOF in %s"), quoted_name);
 124       else
 125         error(1, errno, "error reading a word from %s", quoted_name);
 126     }
 127   else
 128     {
 129       return decode_value(data, maxvalue, endian_state_flag, filename);
 130     }
 131 }
 132