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.
   *
 */
 
/* 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 */
gdIOCtx * gdNewFileCtx (FILE * f)
{
    fileIOCtx *ctx;
 
    ctx = (fileIOCtx *) gdMalloc(sizeof (fileIOCtx));
 
    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);
}