/* file.c */

#include	<stdio.h>		/* FILE, fprintf, perror */
#include	<stdlib.h>		/* exit */
#include	<sys/stat.h>	/* stat */
#include	<string.h>		/* strlen, strcpy */
#include	<malloc.h>		/* malloc, free */

#include	"gendefs.h"		/* general use defs */
#include	"file.h"		/* file handling */


/*
 * file handling functions
 */

/* stat the File */
File *stat_file(const char *filename)
{
	File *file;					/* ptr to File structure */


	/* create a new File structure */
	file = (File *) malloc(sizeof(File));

	/* allocate space & copy filename */
	file->filename = (char *) malloc(strlen(filename) + 1);
	strcpy(file->filename, filename);

	/* initialize fp to null */
	file->fp = NULL;

	/* stat the file */
	if (stat(file->filename, &(file->buf)) == FAILURE)
		/* file does not yet exist; it will be new */
		file->newfile = TRUE;
	else
	{
		/* check file size */
		if (file->buf.st_size == 0)
			/* file is 0 bytes; good enough to be new */
			file->newfile = TRUE;
		else
			/* filesize is not 0, therefore it is not new */
			file->newfile = FALSE;
	}

	return file;
}

/* opens a File */
void open_file(File *file)
{
	char read_mode[READ_MODE_SZ+1];		/* file read mode (r+ or w+) */


	/* set read mode */
	if (file->newfile)
		strcpy(read_mode, OVERWRITE_MODE);
	else /* ! file.newfile */
		strcpy(read_mode, APPEND_MODE);

	/* open the file */
	if ((file->fp = fopen(file->filename, read_mode)) == NULL)
		file_error(file, "Could not open file");

	return;
}

/* closes a File */
void close_file(File *file)
{
	/* make sure we have actually opened it */
	if (file->fp != NULL)
	{
		/* close the file */
		if (fclose(file->fp) != SUCCESS)
			file_error(file, "Cannot close file");
	}

	/* free space used by filename */
	free(file->filename);

	/* free space used by file */
	free(file);

	return;
}

/* error handling function */
void file_error(const File *file, const char *text)
{
	/* write to stderr */
	fprintf(stderr, "%s: %s\n", file->filename, text);

	/* do a perror */
	perror(file->filename);

	/* exit */
	exit(FAILURE);
}