compat_memstream.h

   1 /*
   2  * Copyright (C) 2012-2020 all contributors <cmogstored-public@yhbt.net>
   3  * License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
   4  */
   5 #ifdef HAVE_OPEN_MEMSTREAM
   6 # define my_memstream_close(fp,dst,bytes) fclose((fp))
   7 # define my_memstream_errclose(fp) ((void)fclose((fp)))
   8 #else
   9 static FILE * my_open_memstream(char **ptr, size_t *sizeloc)
  10 {
  11         FILE *fp;
  12
  13         do {
  14                 errno = 0;
  15                 fp = tmpfile();
  16                 if (fp != NULL)
  17                         return fp;
  18         } while (errno == EINTR);
  19
  20         return NULL;
  21 }
  22
  23 #define open_memstream(ptr,sizeloc) my_open_memstream((ptr),(sizeloc))
  24
  25 /* EBADF is fatal in MT applications like ours */
  26 static void my_memstream_errclose(FILE *fp)
  27 {
  28         errno = 0;
  29         if (fclose(fp) != 0)
  30                 assert(errno != EBADF
  31                        && "EBADF in stdio/fclose(memstream) replacement");
  32 }
  33
  34 static int my_memstream_close(FILE *fp, char **dst, size_t *bytes)
  35 {
  36         long pos;
  37
  38         errno = 0;
  39         pos = ftell(fp);
  40
  41         if (pos >= 0) {
  42                 rewind(fp);
  43                 *bytes = (size_t)pos;
  44                 *dst = xmalloc(*bytes);
  45                 if (fread(*dst, 1, *bytes, fp) == *bytes)
  46                         goto out;
  47         } else {
  48                 assert(errno != EBADF
  49                        && "EBADF in stdio/open_memstream replacement");
  50         }
  51
  52         *bytes = 0;
  53         syslog(LOG_ERR, "stdio/open_memstream replacement failed: %m");
  54
  55 out:
  56         /*
  57          * if ftell() fails, fclose() may fail due to an I/O error,
  58          * too, but at least hope we release memory..
  59          */
  60         my_memstream_errclose(fp);
  61
  62         return 0;
  63 }
  64 #endif /* !HAVE_OPEN_MEMSTREAM */