/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <String.h>#include "ftpfs.h" enum{	Chunk=		1024,		/* chunk size for buffered data */	Nfile=		128,		/* maximum number of cached files */}; /* a file (with cached data) */struct File{	char	*mem;		/* part of file cached in memory */	ulong	len;		/* length of cached data */	long	off;		/* current offset into tpath */	short	fd;		/* fd to cache file */	char	inuse;	char	dirty;	ulong	atime;		/* time of last access */	Node	*node;	char 	*template;}; static File	files[Nfile];static ulong	now;static int	ntmp; /* *  lookup a file, create one if not found.  if there are no *  free files, free the last oldest clean one. */static File*fileget(Node *node){	File *fp;	File *oldest; 	fp = node->fp;	if(fp)		return fp; 	oldest = 0;	for(fp = files; fp < &files[Nfile]; fp++){		if(fp->inuse == 0)			break;		if(fp->dirty == 0 && (oldest == 0 || oldest->atime > fp->atime))			oldest = fp;	} 	if(fp == &files[Nfile]){		uncache(oldest->node);		fp = oldest;	}	node->fp = fp;	fp->node = node;	fp->atime = now++;	fp->inuse = 1;	fp->fd = -1;	if(fp->mem){		free(fp->mem);		fp->mem = nil;	}	return fp;} /* *  free a cached file */voidfilefree(Node *node){	File *fp; 	fp = node->fp;	if(fp == 0)		return; 	if(fp->fd > 0){		ntmp--;		close(fp->fd);		remove(fp->template);		free(fp->template);		fp->template = 0;	}	fp->fd = -1;	if(fp->mem){		free(fp->mem);		fp->mem = nil;	}	fp->len = 0;	fp->inuse = 0;	fp->dirty = 0; 	node->fp = 0;} /* *  satisfy read first from in memory chunk and then from temporary *  file.  It's up to the caller to make sure that the file is valid. */intfileread(Node *node, char *a, long off, int n){	int sofar;	int i;	File *fp; 	fp = node->fp;	if(fp == 0)		fatal("fileread"); 	if(off + n > fp->len)		n = fp->len - off; 	for(sofar = 0; sofar < n; sofar += i, off += i, a += i){		if(off >= fp->len)			return sofar;		if(off < Chunk){			i = n;			if(off + i > Chunk)				i = Chunk - off;			memmove(a, fp->mem + off, i);			continue;		}		if(fp->off != off)			if(seek(fp->fd, off, 0) < 0){				fp->off = -1;				return -1;			}		i = read(fp->fd, a, n-sofar);		if(i < 0){			fp->off = -1;			return -1;		}		if(i == 0)			break;		fp->off = off + i;	}	return sofar;} voiduncachedir(Node *parent, Node *child){	Node *sp; 	if(parent == 0 || parent == child)		return;	for(sp = parent->children; sp; sp = sp->sibs)		if(sp->opens == 0)		if(sp != child)		if(sp->fp != nil)		if(sp->fp->dirty == 0)		if(sp->fp->fd >= 0){			filefree(sp);			UNCACHED(sp);		}} static intcreatetmp(File *fp){	char template[32]; 	strcpy(template, "/tmp/ftpXXXXXXXXXXX");	mktemp(template);	if(strcmp(template, "/") == 0){		fprint(2, "ftpfs can't create tmp file %s: %r\n", template);		return -1;	}	if(ntmp >= 16)		uncachedir(fp->node->parent, fp->node); 	fp->fd = create(template, ORDWR|ORCLOSE, 0600);	fp->template = strdup(template);	fp->off = 0;	ntmp++;	return fp->fd;} /* *  write cached data (first Chunk bytes stay in memory) */intfilewrite(Node *node, char *a, long off, int n){	int i, sofar;	File *fp; 	fp = fileget(node); 	if(fp->mem == nil){		fp->mem = malloc(Chunk);		if(fp->mem == nil)			return seterr("out of memory");	} 	for(sofar = 0; sofar < n; sofar += i, off += i, a += i){		if(off < Chunk){			i = n;			if(off + i > Chunk)				i = Chunk - off;			memmove(fp->mem + off, a, i);			continue;		}		if(fp->fd < 0)			if(createtmp(fp) < 0)				return seterr("can't create temp file");		if(fp->off != off)			if(seek(fp->fd, off, 0) < 0){				fp->off = -1;				return seterr("can't seek temp file");			}		i = write(fp->fd, a, n-sofar);		if(i <= 0){			fp->off = -1;			return seterr("can't write temp file");		}		fp->off = off + i;	} 	if(off > fp->len)		fp->len = off;	if(off > node->d->length)		node->d->length = off;	return sofar;} /* *  mark a file as dirty */voidfiledirty(Node *node){	File *fp; 	fp = fileget(node);	fp->dirty = 1;} /* *  mark a file as clean */voidfileclean(Node *node){	if(node->fp)		node->fp->dirty = 0;} intfileisdirty(Node *node){	return node->fp && node->fp->dirty;}