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#include <u.h>
2 
#include <libc.h>
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#include "iotrack.h"
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#include "dat.h"
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#include "fns.h"
6 
 
7 
#define	FIDMOD	127	/* prime */
8 
 
9 
static Xfs	*xhead;
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static Xfile	*xfiles[FIDMOD], *freelist;
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static MLock	xlock, xlocks[FIDMOD], freelock;
12 
 
13 
static int
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okmode(int omode, int fmode)
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{
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	if(omode == OREAD)
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		return fmode & 4;
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	/* else ORDWR */
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	return (fmode & 6) == 6;
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}
21 
 
22 
Xfs *
23 
getxfs(char *user, char *name)
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{
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	Xfs *xf, *fxf;
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	Dir *dir;
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	Qid dqid;
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	char *p, *q;
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	long offset;
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	int fd, omode;
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32 
	USED(user);
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	if(name==nil || name[0]==0)
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		name = deffile;
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	if(name == nil){
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		errno = Enofilsys;
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		return 0;
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	}
39 
 
40 
	/*
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	 * If the name passed is of the form 'name:offset' then
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	 * offset is used to prime xf->offset. This allows accessing
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	 * a FAT-based filesystem anywhere within a partition.
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	 * Typical use would be to mount a filesystem in the presence
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	 * of a boot manager programme at the beginning of the disc.
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	 */
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	offset = 0;
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	if(p = strrchr(name, ':')){
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		*p++ = 0;
50 
		offset = strtol(p, &q, 0);
51 
		chat("name %s, offset %ld\n", p, offset);
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		if(offset < 0 || p == q){
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			errno = Enofilsys;
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			return 0;
55 
		}
56 
		offset *= Sectorsize;
57 
	}
58 
 
59 
	if(readonly)
60 
		omode = OREAD;
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	else
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		omode = ORDWR;
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	fd = open(name, omode);
64 
 
65 
	if(fd < 0 && omode==ORDWR){
66 
		omode = OREAD;
67 
		fd = open(name, omode);
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	}
69 
 
70 
	if(fd < 0){
71 
		chat("can't open %s: %r\n", name);
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		errno = Eerrstr;
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		return 0;
74 
	}
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	dir = dirfstat(fd);
76 
	if(dir == nil){
77 
		errno = Eio;
78 
		close(fd);
79 
		return 0;
80 
	}
81 
 
82 
	dqid = dir->qid;
83 
	free(dir);
84 
	mlock(&xlock);
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	for(fxf=0,xf=xhead; xf; xf=xf->next){
86 
		if(xf->ref == 0){
87 
			if(fxf == 0)
88 
				fxf = xf;
89 
			continue;
90 
		}
91 
		if(!eqqid(xf->qid, dqid))
92 
			continue;
93 
		if(strcmp(xf->name, name) != 0 || xf->dev < 0)
94 
			continue;
95 
		if(devcheck(xf) < 0) /* look for media change */
96 
			continue;
97 
		if(offset && xf->offset != offset)
98 
			continue;
99 
		chat("incref \"%s\", dev=%d...", xf->name, xf->dev);
100 
		++xf->ref;
101 
		unmlock(&xlock);
102 
		close(fd);
103 
		return xf;
104 
	}
105 
	if(fxf == nil){
106 
		fxf = malloc(sizeof(Xfs));
107 
		if(fxf == nil){
108 
			unmlock(&xlock);
109 
			close(fd);
110 
			errno = Enomem;
111 
			return nil;
112 
		}
113 
		fxf->next = xhead;
114 
		xhead = fxf;
115 
	}
116 
	chat("alloc \"%s\", dev=%d...", name, fd);
117 
	fxf->name = strdup(name);
118 
	fxf->ref = 1;
119 
	fxf->qid = dqid;
120 
	fxf->dev = fd;
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	fxf->fmt = 0;
122 
	fxf->offset = offset;
123 
	fxf->ptr = nil;
124 
	fxf->isfat32 = 0;
125 
	fxf->omode = omode;
126 
	unmlock(&xlock);
127 
	return fxf;
128 
}
129 
 
130 
void
131 
refxfs(Xfs *xf, int delta)
132 
{
133 
	mlock(&xlock);
134 
	xf->ref += delta;
135 
	if(xf->ref == 0){
136 
		chat("free \"%s\", dev=%d...", xf->name, xf->dev);
137 
		free(xf->name);
138 
		free(xf->ptr);
139 
		purgebuf(xf);
140 
		if(xf->dev >= 0){
141 
			close(xf->dev);
142 
			xf->dev = -1;
143 
		}
144 
	}
145 
	unmlock(&xlock);
146 
}
147 
 
148 
Xfile *
149 
xfile(int fid, int flag)
150 
{
151 
	Xfile **hp, *f, *pf;
152 
	int k;
153 
 
154 
	k = ((ulong)fid) % FIDMOD;
155 
	hp = &xfiles[k];
156 
	mlock(&xlocks[k]);
157 
	pf = nil;
158 
	for(f=*hp; f; f=f->next){
159 
		if(f->fid == fid)
160 
			break;
161 
		pf = f;
162 
	}
163 
	if(f && pf){
164 
		pf->next = f->next;
165 
		f->next = *hp;
166 
		*hp = f;
167 
	}
168 
	switch(flag){
169 
	default:
170 
		panic("xfile");
171 
	case Asis:
172 
		unmlock(&xlocks[k]);
173 
		return (f && f->xf && f->xf->dev < 0) ? nil : f;
174 
	case Clean:
175 
		break;
176 
	case Clunk:
177 
		if(f){
178 
			*hp = f->next;
179 
			unmlock(&xlocks[k]);
180 
			clean(f);
181 
			mlock(&freelock);
182 
			f->next = freelist;
183 
			freelist = f;
184 
			unmlock(&freelock);
185 
		} else
186 
			unmlock(&xlocks[k]);
187 
		return nil;
188 
	}
189 
	unmlock(&xlocks[k]);
190 
	if(f)
191 
		return clean(f);
192 
	mlock(&freelock);
193 
	if(f = freelist){	/* assign = */
194 
		freelist = f->next;
195 
		unmlock(&freelock);
196 
	} else {
197 
		unmlock(&freelock);
198 
		f = malloc(sizeof(Xfile));
199 
		if(f == nil){
200 
			errno = Enomem;
201 
			return nil;
202 
		}
203 
	}
204 
	mlock(&xlocks[k]);
205 
	f->next = *hp;
206 
	*hp = f;
207 
	unmlock(&xlocks[k]);
208 
	f->fid = fid;
209 
	f->flags = 0;
210 
	f->qid = (Qid){0,0,0};
211 
	f->xf = nil;
212 
	f->ptr = nil;
213 
	return f;
214 
}
215 
 
216 
Xfile *
217 
clean(Xfile *f)
218 
{
219 
	if(f->ptr){
220 
		free(f->ptr);
221 
		f->ptr = nil;
222 
	}
223 
	if(f->xf){
224 
		refxfs(f->xf, -1);
225 
		f->xf = nil;
226 
	}
227 
	f->flags = 0;
228 
	f->qid = (Qid){0,0,0};
229 
	return f;
230 
}
231 
 
232 
/*
233 
 * the file at <addr, offset> has moved
234 
 * relocate the dos entries of all fids in the same file
235 
 */
236 
void
237 
dosptrreloc(Xfile *f, Dosptr *dp, ulong addr, ulong offset)
238 
{
239 
	int i;
240 
	Xfile *p;
241 
	Dosptr *xdp;
242 
 
243 
	for(i=0; i < FIDMOD; i++){
244 
		for(p = xfiles[i]; p != nil; p = p->next){
245 
			xdp = p->ptr;
246 
			if(p != f && p->xf == f->xf
247 
			&& xdp != nil && xdp->addr == addr && xdp->offset == offset){
248 
				memmove(xdp, dp, sizeof(Dosptr));
249 
				xdp->p = nil;
250 
				xdp->d = nil;
251 
				p->qid.path = QIDPATH(xdp);
252 
			}
253 
		}
254 
	}
255 
}