xref: /illumos-gate/usr/src/contrib/ast/src/lib/libast/sfio/sfwr.c (revision b30d193948be5a7794d7ae3ba0ed9c2f72c88e0f)
1 /***********************************************************************
2 *                                                                      *
3 *               This software is part of the ast package               *
4 *          Copyright (c) 1985-2011 AT&T Intellectual Property          *
5 *                      and is licensed under the                       *
6 *                 Eclipse Public License, Version 1.0                  *
7 *                    by AT&T Intellectual Property                     *
8 *                                                                      *
9 *                A copy of the License is available at                 *
10 *          http://www.eclipse.org/org/documents/epl-v10.html           *
11 *         (with md5 checksum b35adb5213ca9657e911e9befb180842)         *
12 *                                                                      *
13 *              Information and Software Systems Research               *
14 *                            AT&T Research                             *
15 *                           Florham Park NJ                            *
16 *                                                                      *
17 *                 Glenn Fowler <gsf@research.att.com>                  *
18 *                  David Korn <dgk@research.att.com>                   *
19 *                   Phong Vo <kpv@research.att.com>                    *
20 *                                                                      *
21 ***********************************************************************/
22 #include	"sfhdr.h"
23 
24 /*	Write data with discipline.
25 **	In the case of a string stream, this is used mainly to extend
26 **	the buffer. However, this is done here so that exception handling
27 **	is done uniformly across all stream types.
28 **
29 **	Written by Kiem-Phong Vo.
30 */
31 
32 /* hole preserving writes */
33 #if __STD_C
sfoutput(Sfio_t * f,char * buf,size_t n)34 static ssize_t sfoutput(Sfio_t* f, char* buf, size_t n)
35 #else
36 static ssize_t sfoutput(f,buf,n)
37 Sfio_t*		f;
38 char*		buf;
39 size_t		n;
40 #endif
41 {	reg char	*sp, *wbuf, *endbuf;
42 	reg ssize_t	s, w, wr;
43 
44 	s = w = 0;
45 	wbuf = buf;
46 	endbuf = buf+n;
47 	while(n > 0)
48 	{	if((ssize_t)n < _Sfpage) /* no hole possible */
49 		{	buf += n;
50 			s = n = 0;
51 		}
52 		else while((ssize_t)n >= _Sfpage)
53 		{	/* see if a hole of 0's starts here */
54 			sp = buf+1;
55 			if(buf[0] == 0 && buf[_Sfpage-1] == 0)
56 			{	/* check byte at a time until int-aligned */
57 				while(((ulong)sp)%sizeof(int))
58 				{	if(*sp != 0)
59 						goto chk_hole;
60 					sp += 1;
61 				}
62 
63 				/* check using int to speed up */
64 				while(sp < endbuf)
65 				{	if(*((int*)sp) != 0)
66 						goto chk_hole;
67 					sp += sizeof(int);
68 				}
69 
70 				/* check the remaining bytes */
71 				if(sp > endbuf)
72 				{	sp -= sizeof(int);
73 					while(sp < endbuf)
74 					{	if(*sp != 0)
75 							goto chk_hole;
76 						sp += 1;
77 					}
78 				}
79 			}
80 
81 		chk_hole:
82 			if((s = sp-buf) >= _Sfpage) /* found a hole */
83 				break;
84 
85 			/* skip a dirty page */
86 			n -= _Sfpage;
87 			buf += _Sfpage;
88 		}
89 
90 		/* write out current dirty pages */
91 		if(buf > wbuf)
92 		{	if((ssize_t)n < _Sfpage)
93 			{	buf = endbuf;
94 				n = s = 0;
95 			}
96 			if((wr = syswritef(f->file,wbuf,buf-wbuf)) > 0)
97 			{	w += wr;
98 				f->bits &= ~SF_HOLE;
99 			}
100 			if(wr != (buf-wbuf))
101 				break;
102 			wbuf = buf;
103 		}
104 
105 		/* seek to a rounded boundary within the hole */
106 		if(s >= _Sfpage)
107 		{	s = (s/_Sfpage)*_Sfpage;
108 			if(SFSK(f,(Sfoff_t)s,SEEK_CUR,NIL(Sfdisc_t*)) < 0)
109 				break;
110 			w += s;
111 			n -= s;
112 			wbuf = (buf += s);
113 			f->bits |= SF_HOLE;
114 
115 			if(n > 0)
116 			{	/* next page must be dirty */
117 				s = (ssize_t)n <= _Sfpage ? 1 : _Sfpage;
118 				buf += s;
119 				n -= s;
120 			}
121 		}
122 	}
123 
124 	return w > 0 ? w : -1;
125 }
126 
127 #if __STD_C
sfwr(Sfio_t * f,const Void_t * buf,size_t n,Sfdisc_t * disc)128 ssize_t sfwr(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc)
129 #else
130 ssize_t sfwr(f,buf,n,disc)
131 Sfio_t*		f;
132 Void_t*		buf;
133 size_t		n;
134 Sfdisc_t*	disc;
135 #endif
136 {
137 	reg ssize_t	w;
138 	reg Sfdisc_t*	dc;
139 	reg int		local, oerrno;
140 	SFMTXDECL(f);
141 
142 	SFMTXENTER(f,(ssize_t)(-1));
143 
144 	GETLOCAL(f,local);
145 	if(!local && !(f->bits&SF_DCDOWN)) /* an external user's call */
146 	{	if(f->mode != SF_WRITE && _sfmode(f,SF_WRITE,0) < 0 )
147 			SFMTXRETURN(f, (ssize_t)(-1));
148 		if(f->next > f->data && SFSYNC(f) < 0 )
149 			SFMTXRETURN(f, (ssize_t)(-1));
150 	}
151 
152 	for(;;)
153 	{	/* stream locked by sfsetfd() */
154 		if(!(f->flags&SF_STRING) && f->file < 0)
155 			SFMTXRETURN(f,(ssize_t)0);
156 
157 		/* clear current error states */
158 		f->flags &= ~(SF_EOF|SF_ERROR);
159 
160 		dc = disc;
161 		if(f->flags&SF_STRING)	/* just asking to extend buffer */
162 			w = n + (f->next - f->data);
163 		else
164 		{	/* warn that a write is about to happen */
165 			SFDISC(f,dc,writef);
166 			if(dc && dc->exceptf && (f->flags&SF_IOCHECK) )
167 			{	reg int	rv;
168 				if(local)
169 					SETLOCAL(f);
170 				if((rv = _sfexcept(f,SF_WRITE,n,dc)) > 0)
171 					n = rv;
172 				else if(rv < 0)
173 				{	f->flags |= SF_ERROR;
174 					SFMTXRETURN(f, rv);
175 				}
176 			}
177 
178 			if(f->extent >= 0)
179 			{	/* make sure we are at the right place to write */
180 				if(f->flags&SF_APPENDWR)
181 				{	if(f->here != f->extent || (f->flags&SF_SHARE))
182 					{	f->here = SFSK(f,(Sfoff_t)0,SEEK_END,dc);
183 						f->extent = f->here;
184 					}
185 				}
186 				else if((f->flags&SF_SHARE) && !(f->flags&SF_PUBLIC))
187 					f->here = SFSK(f,f->here,SEEK_SET,dc);
188 			}
189 
190 			oerrno = errno;
191 			errno = 0;
192 
193 			if(dc && dc->writef)
194 			{	SFDCWR(f,buf,n,dc,w);
195 			}
196 			else if(SFISNULL(f))
197 				w = n;
198 			else if(f->flags&SF_WHOLE)
199 				goto do_write;
200 			else if((ssize_t)n >= _Sfpage &&
201 				!(f->flags&(SF_SHARE|SF_APPENDWR)) &&
202 				f->here == f->extent && (f->here%_Sfpage) == 0)
203 			{	if((w = sfoutput(f,(char*)buf,n)) <= 0)
204 					goto do_write;
205 			}
206 			else
207 			{
208 			do_write:
209 				if((w = syswritef(f->file,buf,n)) > 0)
210 					f->bits &= ~SF_HOLE;
211 			}
212 
213 			if(errno == 0)
214 				errno = oerrno;
215 
216 			if(w > 0)
217 			{	if(!(f->bits&SF_DCDOWN) )
218 				{	if((f->flags&(SF_APPENDWR|SF_PUBLIC)) && f->extent >= 0 )
219 						f->here = SFSK(f,(Sfoff_t)0,SEEK_CUR,dc);
220 					else	f->here += w;
221 					if(f->extent >= 0 && f->here > f->extent)
222 						f->extent = f->here;
223 				}
224 
225 				SFMTXRETURN(f, (ssize_t)w);
226 			}
227 		}
228 
229 		if(local)
230 			SETLOCAL(f);
231 		switch(_sfexcept(f,SF_WRITE,w,dc))
232 		{
233 		case SF_ECONT :
234 			goto do_continue;
235 		case SF_EDONE :
236 			w = local ? 0 : w;
237 			SFMTXRETURN(f, (ssize_t)w);
238 		case SF_EDISC :
239 			if(!local && !(f->flags&SF_STRING))
240 				goto do_continue;
241 			/* else fall thru */
242 		case SF_ESTACK :
243 			SFMTXRETURN(f, (ssize_t)(-1));
244 		}
245 
246 	do_continue:
247 		for(dc = f->disc; dc; dc = dc->disc)
248 			if(dc == disc)
249 				break;
250 		disc = dc;
251 	}
252 }
253