common/replacements/open_memstream.c

   1 /* nbdkit
   2  * Copyright Red Hat
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are
   6  * met:
   7  *
   8  * * Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * * Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * * Neither the name of Red Hat nor the names of its contributors may be
  16  * used to endorse or promote products derived from this software without
  17  * specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
  20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
  21  * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  22  * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  24  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  25  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  26  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  27  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  28  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  29  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  */
  32
  33 /* Replacement for open_memstream for platforms which lack this function. */
  34
  35 #include <config.h>
  36
  37 #include <stdio.h>
  38
  39 #include "open_memstream.h"
  40
  41 #ifndef HAVE_OPEN_MEMSTREAM
  42
  43 #ifdef WIN32
  44
  45 /* Replacement open_memstream for Win32. */
  46
  47 #include <windows.h>
  48
  49 #include <assert.h>
  50
  51 /* This is provided by common/utils which hasn't been compiled yet.
  52  * Programs using this replacement will need to link to
  53  * libutils.la. XXX
  54  */
  55 #include "../utils/vector.h"
  56 #include "../utils/nbdkit-string.h"
  57
  58 /* Map FILE* that we return to the user buffer. */
  59 struct file_to_memstream {
  60   FILE *fp;
  61   char tmpname[MAX_PATH];
  62   char **ptr;
  63   size_t *size;
  64 };
  65 DEFINE_VECTOR_TYPE (file_vector, struct file_to_memstream);
  66 static file_vector files = empty_vector;
  67
  68 FILE *
  69 open_memstream (char **ptr, size_t *size)
  70 {
  71   struct file_to_memstream f2m;
  72   char tmppath[MAX_PATH];
  73   DWORD ret;
  74   FILE *fp;
  75
  76   ret = GetTempPath (MAX_PATH, tmppath);
  77   if (ret > MAX_PATH || ret == 0)
  78     return NULL;
  79
  80   ret = GetTempFileName (tmppath, TEXT ("nbdkit"), 0, f2m.tmpname);
  81   if (!ret)
  82     return NULL;
  83
  84   fp = fopen (f2m.tmpname, "w+");
  85   if (fp == NULL)
  86     return NULL;
  87
  88   f2m.fp = fp;
  89   f2m.ptr = ptr;
  90   f2m.size = size;
  91   if (file_vector_append (&files, f2m) == -1) {
  92     fclose (fp);
  93     return NULL;
  94   }
  95
  96   return fp;
  97 }
  98
  99 int
 100 close_memstream (FILE *fp)
 101 {
 102   size_t i;
 103   int c, r;
 104   string content = empty_vector;
 105   struct file_to_memstream *f2m;
 106
 107   for (i = 0; i < files.len; ++i) {
 108     if (files.ptr[i].fp == fp)
 109       break;
 110   }
 111   assert (i < files.len);
 112   f2m = &files.ptr[i];
 113
 114   /* Read the file back into memory. */
 115   rewind (fp);
 116   while ((c = getc (fp)) != EOF) {
 117     if (string_append (&content, c) == -1) {
 118     append_failed:
 119       fclose (fp);
 120       unlink (f2m->tmpname);
 121       free (content.ptr);
 122       file_vector_remove (&files, i);
 123       return -1;
 124     }
 125   }
 126   /* Make sure the buffer is \0-terminated but don't include this
 127    * in the buffer size returned below.
 128    */
 129   if (string_append (&content, 0) == -1) goto append_failed;
 130
 131   r = fclose (fp);
 132   unlink (f2m->tmpname);
 133   if (r == EOF) {
 134     free (content.ptr);
 135     file_vector_remove (&files, i);
 136     return -1;
 137   }
 138
 139   /* Pass the buffer to the user.  User will free it. */
 140   *(files.ptr[i].ptr) = content.ptr;
 141   *(files.ptr[i].size) = content.len - 1;
 142   file_vector_remove (&files, i);
 143   return 0;
 144 }
 145
 146 #else /* !WIN32 */
 147 #error "no replacement open_memstream is available on this platform"
 148 #endif
 149
 150 #endif /* !HAVE_OPEN_MEMSTREAM */