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*                  Common Public License, Version 1.0                  *
7*                    by AT&T Intellectual Property                     *
8*                                                                      *
9*                A copy of the License is available at                 *
10*            http://www.opensource.org/licenses/cpl1.0.txt             *
11*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
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/*	Read n bytes from a stream into a buffer
25**
26**	Written by Kiem-Phong Vo.
27*/
28
29#if __STD_C
30ssize_t sfread(Sfio_t* f, Void_t* buf, size_t n)
31#else
32ssize_t sfread(f,buf,n)
33Sfio_t*		f;	/* read from this stream. 	*/
34Void_t*		buf;	/* buffer to read into		*/
35size_t		n;	/* number of bytes to be read. 	*/
36#endif
37{
38	reg uchar	*s, *begs;
39	reg ssize_t	r;
40	reg int		local, justseek;
41	SFMTXDECL(f);
42
43	SFMTXENTER(f, (ssize_t)(-1));
44
45	GETLOCAL(f,local);
46	justseek = f->bits&SF_JUSTSEEK; f->bits &= ~SF_JUSTSEEK;
47
48	if(!buf)
49		SFMTXRETURN(f, (ssize_t)(n == 0 ? 0 : -1) );
50
51	/* release peek lock */
52	if(f->mode&SF_PEEK)
53	{	if(!(f->mode&SF_READ) )
54			SFMTXRETURN(f, (ssize_t)(-1));
55
56		if(f->mode&SF_GETR)
57		{	if(((uchar*)buf + f->val) != f->next &&
58			   (!f->rsrv || f->rsrv->data != (uchar*)buf) )
59				SFMTXRETURN(f, (ssize_t)(-1));
60			f->mode &= ~SF_PEEK;
61			SFMTXRETURN(f, 0);
62		}
63		else
64		{	if((uchar*)buf != f->next)
65				SFMTXRETURN(f, (ssize_t)(-1));
66			f->mode &= ~SF_PEEK;
67			if(f->mode&SF_PKRD)
68			{	/* actually read the data now */
69				f->mode &= ~SF_PKRD;
70				if(n > 0)
71					n = (r = sysreadf(f->file,f->data,n)) < 0 ? 0 : r;
72				f->endb = f->data+n;
73				f->here += n;
74			}
75			f->next += n;
76			f->endr = f->endb;
77			SFMTXRETURN(f, n);
78		}
79	}
80
81	s = begs = (uchar*)buf;
82	for(;; f->mode &= ~SF_LOCK)
83	{	/* check stream mode */
84		if(SFMODE(f,local) != SF_READ && _sfmode(f,SF_READ,local) < 0)
85		{	n = s > begs ? s-begs : (size_t)(-1);
86			SFMTXRETURN(f, (ssize_t)n);
87		}
88
89		SFLOCK(f,local);
90
91		if((r = f->endb - f->next) > 0) /* has buffered data */
92		{	if(r > (ssize_t)n)
93				r = (ssize_t)n;
94			if(s != f->next)
95				memcpy(s, f->next, r);
96			f->next += r;
97			s += r;
98			n -= r;
99		}
100
101		if(n <= 0)	/* all done */
102			break;
103
104		if(!(f->flags&SF_STRING) && !(f->bits&SF_MMAP) )
105		{	f->next = f->endb = f->data;
106
107			/* exact IO is desirable for these cases */
108			if(SFDIRECT(f,n) ||
109			   ((f->flags&SF_SHARE) && f->extent < 0) )
110				r = (ssize_t)n;
111			else if(justseek && n <= f->iosz && f->iosz <= f->size)
112				r = f->iosz;	/* limit buffering */
113			else	r = f->size;	/* full buffering */
114
115			/* if read almost full size, then just do it direct */
116			if(r > (ssize_t)n && (r - r/8) <= (ssize_t)n)
117				r = (ssize_t)n;
118
119			/* read directly to user's buffer */
120			if(r == (ssize_t)n && (r = SFRD(f,s,r,f->disc)) >= 0)
121			{	s += r;
122				n -= r;
123				if(r == 0 || n == 0) /* eof or eob */
124					break;
125			}
126			else	goto do_filbuf;
127		}
128		else
129		{ do_filbuf:
130			if(justseek)
131				f->bits |= SF_JUSTSEEK;
132			if(SFFILBUF(f,-1) <= 0)
133				break;
134		}
135	}
136
137	SFOPEN(f,local);
138	r = s-begs;
139	SFMTXRETURN(f, r);
140}
141