#include "jpeglib.h"#include "jpg.h"/* Expanded data source object for stdio input */typedef struct {  struct jpeg_source_mgr pub;	/* public fields */  FILE * infile;		/* source stream */  JOCTET * buffer;		/* start of buffer */  int buffer_length;  boolean start_of_file;	/* have we gotten any data yet? */} my_source_mgr;typedef my_source_mgr * my_src_ptr;#define INPUT_BUF_SIZE  4096	/* choose an efficiently fread'able size *//* * Initialize source --- called by jpeg_read_header * before any data is actually read. */METHODDEF(void)init_source (j_decompress_ptr cinfo){  my_src_ptr src = (my_src_ptr) cinfo->src;  /* We reset the empty-input-file flag for each image,   * but we don't clear the input buffer.   * This is correct behavior for reading a series of images from one source.   */  src->start_of_file = TRUE;}METHODDEF(boolean)fill_input_buffer (j_decompress_ptr cinfo){  my_src_ptr src = (my_src_ptr) cinfo->src;  size_t nbytes;  if (src->infile!=NULL) {      /* read from file */      nbytes = JFREAD(src->infile, src->buffer, INPUT_BUF_SIZE);      if (nbytes <= 0) {        if (src->start_of_file)	/* Treat empty input file as fatal error */          ERREXIT(cinfo, JERR_INPUT_EMPTY);        WARNMS(cinfo, JWRN_JPEG_EOF);        /* Insert a fake EOI marker */        src->buffer[0] = (JOCTET) 0xFF;        src->buffer[1] = (JOCTET) JPEG_EOI;        nbytes = 2;      }      src->pub.next_input_byte = src->buffer;      src->pub.bytes_in_buffer = nbytes;      src->start_of_file = FALSE;  }  else {      /* in fact, these code could only been called just one time */      src->pub.next_input_byte = src->buffer;      src->pub.bytes_in_buffer = src->buffer_length;      src->start_of_file = FALSE;  }  return TRUE;}METHODDEF(void)skip_input_data (j_decompress_ptr cinfo, long num_bytes){  my_src_ptr src = (my_src_ptr) cinfo->src;  /* Just a dumb implementation for now.  Could use fseek() except   * it doesn't work on pipes.  Not clear that being smart is worth   * any trouble anyway --- large skips are infrequent.   */  if (num_bytes > 0) {    while (num_bytes > (long) src->pub.bytes_in_buffer) {      num_bytes -= (long) src->pub.bytes_in_buffer;      (void) fill_input_buffer(cinfo);      /* note we assume that fill_input_buffer will never return FALSE,       * so suspension need not be handled.       */    }    src->pub.next_input_byte += (size_t) num_bytes;    src->pub.bytes_in_buffer -= (size_t) num_bytes;  }}METHODDEF(void)term_source (j_decompress_ptr cinfo){  /* no work necessary here */}/* * Prepare for input from a stdio stream. * The caller must have already opened the stream, and is responsible * for closing it after finishing decompression. */GLOBAL(void)jpeg_stdio_src (j_decompress_ptr cinfo, FILE * infile){  my_src_ptr src;  /* The source object and input buffer are made permanent so that a series   * of JPEG images can be read from the same file by calling jpeg_stdio_src   * only before the first one.  (If we discarded the buffer at the end of   * one image, we'd likely lose the start of the next one.)   * This makes it unsafe to use this manager and a different source   * manager serially with the same JPEG object.  Caveat programmer.   */  if (cinfo->src == NULL) {	/* first time for this JPEG object? */    cinfo->src = (struct jpeg_source_mgr *)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,				  SIZEOF(my_source_mgr));    src = (my_src_ptr) cinfo->src;    src->buffer = (JOCTET *)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,				  INPUT_BUF_SIZE * SIZEOF(JOCTET));  }  src = (my_src_ptr) cinfo->src;  src->pub.init_source = init_source;  src->pub.fill_input_buffer = fill_input_buffer;  src->pub.skip_input_data = skip_input_data;  src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */  src->pub.term_source = term_source;  src->infile = infile;  src->buffer_length=INPUT_BUF_SIZE;  src->pub.bytes_in_buffer = 0; /* forces fill_input_buffer on first read */  src->pub.next_input_byte = NULL; /* until buffer loaded */}/* * Prepare for input from memory stream. */GLOBAL(void)jpeg_memory_src (j_decompress_ptr cinfo, char* jpg_buffer, int jpg_buffer_length){  my_src_ptr src;  /* The source object and input buffer are made permanent so that a series   * of JPEG images can be read from the same file by calling jpeg_stdio_src   * only before the first one.  (If we discarded the buffer at the end of   * one image, we'd likely lose the start of the next one.)   * This makes it unsafe to use this manager and a different source   * manager serially with the same JPEG object.  Caveat programmer.   */  if (cinfo->src == NULL) {	/* first time for this JPEG object? */    cinfo->src = (struct jpeg_source_mgr *)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,				  SIZEOF(my_source_mgr));    src = (my_src_ptr) cinfo->src;  }  else{    src = (my_src_ptr) cinfo->src;    }      src->buffer = (JOCTET *)      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT,			      jpg_buffer_length);    memcpy(src->buffer,jpg_buffer,jpg_buffer_length);    src = (my_src_ptr) cinfo->src;    src->pub.init_source = init_source;    src->pub.fill_input_buffer = fill_input_buffer;    src->pub.skip_input_data = skip_input_data;    src->pub.resync_to_restart = jpeg_resync_to_restart; /* use default method */    src->pub.term_source = term_source;    src->infile          = NULL;    src->buffer_length   = jpg_buffer_length;    src->pub.bytes_in_buffer = 0;    src->pub.next_input_byte = NULL;}