text: /*
   * io_file.c
   *
   * Implements the file interface.
   *
   * As will all I/O modules, most functions are for local use only (called
   * via function pointers in the I/O context).
   *
   * Most functions are just 'wrappers' for standard file functions.
   *
   * Written/Modified 1999, Philip Warner.
   *
   */
  
  #ifdef HAVE_CONFIG_H
  #	include "config.h"
  #endif
  
  /* For platforms with incomplete ANSI defines. Fortunately,
   * SEEK_SET is defined to be zero by the standard. */
  
  #ifndef SEEK_SET
  #	define SEEK_SET 0
  #endif /* SEEK_SET */
  
  #include <math.h>
  #include <string.h>
  #include <stdlib.h>
  #include "gd.h"
  #include "gdhelpers.h"
  
  /* this is used for creating images in main memory */
  
  typedef struct fileIOCtx
  {
  	gdIOCtx ctx;
  	FILE *f;
  }
  fileIOCtx;
  
  gdIOCtx *newFileCtx(FILE *f);
  
  static int fileGetbuf(gdIOCtx *, void *, int);
  static int filePutbuf(gdIOCtx *, const void *, int);
  static void filePutchar(gdIOCtx *, int);
  static int fileGetchar(gdIOCtx *ctx);
  
  static int fileSeek(struct gdIOCtx *, const int);
  static long fileTell(struct gdIOCtx *);
  static void gdFreeFileCtx(gdIOCtx *ctx);
  
  /* return data as a dynamic pointer */
  BGD_DECLARE(gdIOCtx *) gdNewFileCtx(FILE *f)
  {
  	fileIOCtx *ctx;
  
  	if (f == NULL) return NULL;
  	ctx = (fileIOCtx *)gdMalloc(sizeof(fileIOCtx));
  	if(ctx == NULL) {
  		return NULL;
  	}
  
  	ctx->f = f;
  
  	ctx->ctx.getC = fileGetchar;
  	ctx->ctx.putC = filePutchar;
  
  	ctx->ctx.getBuf = fileGetbuf;
  	ctx->ctx.putBuf = filePutbuf;
  
  	ctx->ctx.tell = fileTell;
  	ctx->ctx.seek = fileSeek;
  
  	ctx->ctx.gd_free = gdFreeFileCtx;
  
  	return (gdIOCtx *)ctx;
  }
  
  static void gdFreeFileCtx(gdIOCtx *ctx)
  {
  	gdFree(ctx);
  }
  
  
  static int filePutbuf(gdIOCtx *ctx, const void *buf, int size)
  {
  	fileIOCtx *fctx;
  	fctx = (fileIOCtx *)ctx;
  
  	return fwrite(buf, 1, size, fctx->f);
  }
  
  static int fileGetbuf(gdIOCtx *ctx, void *buf, int size)
  {
  	fileIOCtx *fctx;
  	fctx = (fileIOCtx *)ctx;
  
  	return (fread(buf, 1, size, fctx->f));
  }
  
  static void filePutchar(gdIOCtx *ctx, int a)
  {
  	unsigned char b;
  	fileIOCtx *fctx;
  	fctx = (fileIOCtx *)ctx;
  
  	b = a;
  
  	putc(b, fctx->f);
  }
  
  static int fileGetchar(gdIOCtx *ctx)
  {
  	fileIOCtx *fctx;
  	fctx = (fileIOCtx *)ctx;
  
  	return getc(fctx->f);
  }
  
  static int fileSeek(struct gdIOCtx *ctx, const int pos)
  {
  	fileIOCtx *fctx;
  	fctx = (fileIOCtx *)ctx;
  	return (fseek(fctx->f, pos, SEEK_SET) == 0);
  }
  
  static long fileTell (struct gdIOCtx *ctx)
  {
  	fileIOCtx *fctx;
  	fctx = (fileIOCtx *)ctx;
  
  	return ftell(fctx->f);
  }
  