tools/sgen/sgen-entry-stream.c

   1 /*
   2  * sgen-entry-stream.c: EntryStream implementation
   3  *
   4  * Copyright (C) 2016 Xamarin Inc
   5  *
   6  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   7  */
   8
   9 #include <stdlib.h>
  10 #include <unistd.h>
  11 #include <glib.h>
  12 #include "sgen-entry-stream.h"
  13
  14 #define BUFFER_SIZE (1 << 20)
  15
  16 void
  17 init_stream (EntryStream *stream, int file)
  18 {
  19         stream->file = file;
  20         stream->buffer = g_malloc0 (BUFFER_SIZE);
  21         stream->end = stream->buffer + BUFFER_SIZE;
  22         stream->pos = stream->end;
  23 }
  24
  25 void
  26 reset_stream (EntryStream *stream)
  27 {
  28         stream->end = stream->buffer + BUFFER_SIZE;
  29         stream->pos = stream->end;
  30         lseek (stream->file, 0, SEEK_SET);
  31 }
  32
  33 void
  34 close_stream (EntryStream *stream)
  35 {
  36         g_free (stream->buffer);
  37 }
  38
  39 gboolean
  40 refill_stream (EntryStream *in, size_t size)
  41 {
  42         size_t remainder = in->end - in->pos;
  43         ssize_t refilled;
  44         g_assert (size > 0);
  45         g_assert (in->pos >= in->buffer);
  46         if (in->pos + size <= in->end)
  47                 return TRUE;
  48         memmove (in->buffer, in->pos, remainder);
  49         in->pos = in->buffer;
  50         refilled = read (in->file, in->buffer + remainder, BUFFER_SIZE - remainder);
  51         if (refilled < 0)
  52                 return FALSE;
  53         g_assert (refilled + remainder <= BUFFER_SIZE);
  54         in->end = in->buffer + refilled + remainder;
  55         return in->end - in->buffer >= size;
  56 }
  57
  58 ssize_t
  59 read_stream (EntryStream *stream, void *out, size_t size)
  60 {
  61         if (refill_stream (stream, size)) {
  62                 memcpy (out, stream->pos, size);
  63                 stream->pos += size;
  64                 return size;
  65         }
  66         return 0;
  67 }