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      1 /*
      2  * jdatadst-tj.c
      3  *
      4  * This file was part of the Independent JPEG Group's software:
      5  * Copyright (C) 1994-1996, Thomas G. Lane.
      6  * Modified 2009-2012 by Guido Vollbeding.
      7  * libjpeg-turbo Modifications:
      8  * Copyright (C) 2011, 2014 D. R. Commander.
      9  * For conditions of distribution and use, see the accompanying README file.
     10  *
     11  * This file contains compression data destination routines for the case of
     12  * emitting JPEG data to memory or to a file (or any stdio stream).
     13  * While these routines are sufficient for most applications,
     14  * some will want to use a different destination manager.
     15  * IMPORTANT: we assume that fwrite() will correctly transcribe an array of
     16  * JOCTETs into 8-bit-wide elements on external storage.  If char is wider
     17  * than 8 bits on your machine, you may need to do some tweaking.
     18  */
     19 
     20 /* this is not a core library module, so it doesn't define JPEG_INTERNALS */
     21 #include "jinclude.h"
     22 #include "jpeglib.h"
     23 #include "jerror.h"
     24 
     25 #ifndef HAVE_STDLIB_H           /* <stdlib.h> should declare malloc(),free() */
     26 extern void * malloc (size_t size);
     27 extern void free (void *ptr);
     28 #endif
     29 
     30 
     31 #define OUTPUT_BUF_SIZE  4096   /* choose an efficiently fwrite'able size */
     32 
     33 
     34 /* Expanded data destination object for memory output */
     35 
     36 typedef struct {
     37   struct jpeg_destination_mgr pub; /* public fields */
     38 
     39   unsigned char ** outbuffer;   /* target buffer */
     40   unsigned long * outsize;
     41   unsigned char * newbuffer;    /* newly allocated buffer */
     42   JOCTET * buffer;              /* start of buffer */
     43   size_t bufsize;
     44   boolean alloc;
     45 } my_mem_destination_mgr;
     46 
     47 typedef my_mem_destination_mgr * my_mem_dest_ptr;
     48 
     49 
     50 /*
     51  * Initialize destination --- called by jpeg_start_compress
     52  * before any data is actually written.
     53  */
     54 
     55 METHODDEF(void)
     56 init_mem_destination (j_compress_ptr cinfo)
     57 {
     58   /* no work necessary here */
     59 }
     60 
     61 
     62 /*
     63  * Empty the output buffer --- called whenever buffer fills up.
     64  *
     65  * In typical applications, this should write the entire output buffer
     66  * (ignoring the current state of next_output_byte & free_in_buffer),
     67  * reset the pointer & count to the start of the buffer, and return TRUE
     68  * indicating that the buffer has been dumped.
     69  *
     70  * In applications that need to be able to suspend compression due to output
     71  * overrun, a FALSE return indicates that the buffer cannot be emptied now.
     72  * In this situation, the compressor will return to its caller (possibly with
     73  * an indication that it has not accepted all the supplied scanlines).  The
     74  * application should resume compression after it has made more room in the
     75  * output buffer.  Note that there are substantial restrictions on the use of
     76  * suspension --- see the documentation.
     77  *
     78  * When suspending, the compressor will back up to a convenient restart point
     79  * (typically the start of the current MCU). next_output_byte & free_in_buffer
     80  * indicate where the restart point will be if the current call returns FALSE.
     81  * Data beyond this point will be regenerated after resumption, so do not
     82  * write it out when emptying the buffer externally.
     83  */
     84 
     85 METHODDEF(boolean)
     86 empty_mem_output_buffer (j_compress_ptr cinfo)
     87 {
     88   size_t nextsize;
     89   JOCTET * nextbuffer;
     90   my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
     91 
     92   if (!dest->alloc) ERREXIT(cinfo, JERR_BUFFER_SIZE);
     93 
     94   /* Try to allocate new buffer with double size */
     95   nextsize = dest->bufsize * 2;
     96   nextbuffer = (JOCTET *) malloc(nextsize);
     97 
     98   if (nextbuffer == NULL)
     99     ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
    100 
    101   MEMCOPY(nextbuffer, dest->buffer, dest->bufsize);
    102 
    103   if (dest->newbuffer != NULL)
    104     free(dest->newbuffer);
    105 
    106   dest->newbuffer = nextbuffer;
    107 
    108   dest->pub.next_output_byte = nextbuffer + dest->bufsize;
    109   dest->pub.free_in_buffer = dest->bufsize;
    110 
    111   dest->buffer = nextbuffer;
    112   dest->bufsize = nextsize;
    113 
    114   return TRUE;
    115 }
    116 
    117 
    118 /*
    119  * Terminate destination --- called by jpeg_finish_compress
    120  * after all data has been written.  Usually needs to flush buffer.
    121  *
    122  * NB: *not* called by jpeg_abort or jpeg_destroy; surrounding
    123  * application must deal with any cleanup that should happen even
    124  * for error exit.
    125  */
    126 
    127 METHODDEF(void)
    128 term_mem_destination (j_compress_ptr cinfo)
    129 {
    130   my_mem_dest_ptr dest = (my_mem_dest_ptr) cinfo->dest;
    131 
    132   if(dest->alloc) *dest->outbuffer = dest->buffer;
    133   *dest->outsize = (unsigned long)(dest->bufsize - dest->pub.free_in_buffer);
    134 }
    135 
    136 
    137 /*
    138  * Prepare for output to a memory buffer.
    139  * The caller may supply an own initial buffer with appropriate size.
    140  * Otherwise, or when the actual data output exceeds the given size,
    141  * the library adapts the buffer size as necessary.
    142  * The standard library functions malloc/free are used for allocating
    143  * larger memory, so the buffer is available to the application after
    144  * finishing compression, and then the application is responsible for
    145  * freeing the requested memory.
    146  */
    147 
    148 GLOBAL(void)
    149 jpeg_mem_dest_tj (j_compress_ptr cinfo,
    150                unsigned char ** outbuffer, unsigned long * outsize,
    151                boolean alloc)
    152 {
    153   boolean reused = FALSE;
    154   my_mem_dest_ptr dest;
    155 
    156   if (outbuffer == NULL || outsize == NULL)     /* sanity check */
    157     ERREXIT(cinfo, JERR_BUFFER_SIZE);
    158 
    159   /* The destination object is made permanent so that multiple JPEG images
    160    * can be written to the same buffer without re-executing jpeg_mem_dest.
    161    */
    162   if (cinfo->dest == NULL) {    /* first time for this JPEG object? */
    163     cinfo->dest = (struct jpeg_destination_mgr *)
    164       (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,
    165                                   sizeof(my_mem_destination_mgr));
    166     dest = (my_mem_dest_ptr) cinfo->dest;
    167     dest->newbuffer = NULL;
    168     dest->buffer = NULL;
    169   }
    170 
    171   dest = (my_mem_dest_ptr) cinfo->dest;
    172   dest->pub.init_destination = init_mem_destination;
    173   dest->pub.empty_output_buffer = empty_mem_output_buffer;
    174   dest->pub.term_destination = term_mem_destination;
    175   if (dest->buffer == *outbuffer && *outbuffer != NULL && alloc)
    176     reused = TRUE;
    177   dest->outbuffer = outbuffer;
    178   dest->outsize = outsize;
    179   dest->alloc = alloc;
    180 
    181   if (*outbuffer == NULL || *outsize == 0) {
    182     if (alloc) {
    183       /* Allocate initial buffer */
    184       dest->newbuffer = *outbuffer = (unsigned char *) malloc(OUTPUT_BUF_SIZE);
    185       if (dest->newbuffer == NULL)
    186         ERREXIT1(cinfo, JERR_OUT_OF_MEMORY, 10);
    187       *outsize = OUTPUT_BUF_SIZE;
    188     }
    189     else ERREXIT(cinfo, JERR_BUFFER_SIZE);
    190   }
    191 
    192   dest->pub.next_output_byte = dest->buffer = *outbuffer;
    193   if (!reused)
    194     dest->bufsize = *outsize;
    195   dest->pub.free_in_buffer = dest->bufsize;
    196 }
    197