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gd-libgd / src / gd_io_file.c

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/*
 * 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;

	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);
}