dba_write.c

   1 /*      $Id: dba_write.c,v 1.2 2016/07/20 00:23:14 schwarze Exp $ */
   2 /*
   3  * Copyright (c) 2016 Ingo Schwarze <schwarze@openbsd.org>
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  16  *
  17  * Low-level functions for serializing allocation-based data to disk.
  18  * The interface is defined in "dba_write.h".
  19  */
  20 #include "config.h"
  21
  22 #include <assert.h>
  23 #include <endian.h>
  24 #if HAVE_ERR
  25 #include <err.h>
  26 #endif
  27 #include <errno.h>
  28 #include <fcntl.h>
  29 #include <stdint.h>
  30 #include <stdio.h>
  31
  32 #include "dba_write.h"
  33
  34 static FILE     *ofp;
  35
  36
  37 int
  38 dba_open(const char *fname)
  39 {
  40         ofp = fopen(fname, "w");
  41         return ofp == NULL ? -1 : 0;
  42 }
  43
  44 int
  45 dba_close(void)
  46 {
  47         return fclose(ofp) == EOF ? -1 : 0;
  48 }
  49
  50 int32_t
  51 dba_tell(void)
  52 {
  53         long             pos;
  54
  55         if ((pos = ftell(ofp)) == -1)
  56                 err(1, "ftell");
  57         if (pos >= INT32_MAX) {
  58                 errno = EOVERFLOW;
  59                 err(1, "ftell = %ld", pos);
  60         }
  61         return pos;
  62 }
  63
  64 void
  65 dba_seek(int32_t pos)
  66 {
  67         if (fseek(ofp, pos, SEEK_SET) == -1)
  68                 err(1, "fseek(%d)", pos);
  69 }
  70
  71 int32_t
  72 dba_align(void)
  73 {
  74         int32_t          pos;
  75
  76         pos = dba_tell();
  77         while (pos & 3) {
  78                 dba_char_write('\0');
  79                 pos++;
  80         }
  81         return pos;
  82 }
  83
  84 int32_t
  85 dba_skip(int32_t nmemb, int32_t sz)
  86 {
  87         const int32_t    out[5] = {0, 0, 0, 0, 0};
  88         int32_t          i, pos;
  89
  90         assert(sz >= 0);
  91         assert(nmemb > 0);
  92         assert(nmemb <= 5);
  93         pos = dba_tell();
  94         for (i = 0; i < sz; i++)
  95                 if (nmemb - fwrite(&out, sizeof(out[0]), nmemb, ofp))
  96                         err(1, "fwrite");
  97         return pos;
  98 }
  99
 100 void
 101 dba_char_write(int c)
 102 {
 103         if (putc(c, ofp) == EOF)
 104                 err(1, "fputc");
 105 }
 106
 107 void
 108 dba_str_write(const char *str)
 109 {
 110         if (fputs(str, ofp) == EOF)
 111                 err(1, "fputs");
 112         dba_char_write('\0');
 113 }
 114
 115 void
 116 dba_int_write(int32_t i)
 117 {
 118         i = htobe32(i);
 119         if (fwrite(&i, sizeof(i), 1, ofp) != 1)
 120                 err(1, "fwrite");
 121 }