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 /* Delete all pending data in the buffer
25 **
26 ** Written by Kiem-Phong Vo.
27 */
28
29 #if __STD_C
sfpurge(Sfio_t * f)30 int sfpurge(Sfio_t* f)
31 #else
32 int sfpurge(f)
33 Sfio_t* f;
34 #endif
35 {
36 reg int mode;
37 SFMTXDECL(f);
38
39 SFMTXENTER(f,-1);
40
41 if((mode = f->mode&SF_RDWR) != (int)f->mode && _sfmode(f,mode|SF_SYNCED,0) < 0)
42 SFMTXRETURN(f, -1);
43
44 if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
45 (void)(*f->disc->exceptf)(f,SF_PURGE,(Void_t*)((int)1),f->disc);
46
47 if(f->disc == _Sfudisc)
48 (void)sfclose((*_Sfstack)(f,NIL(Sfio_t*)));
49
50 /* cannot purge read string streams */
51 if((f->flags&SF_STRING) && (f->mode&SF_READ) )
52 goto done;
53
54 SFLOCK(f,0);
55
56 /* if memory map must be a read stream, pretend data is gone */
57 #ifdef MAP_TYPE
58 if(f->bits&SF_MMAP)
59 { f->here -= f->endb - f->next;
60 if(f->data)
61 { SFMUNMAP(f,f->data,f->endb-f->data);
62 (void)SFSK(f,f->here,SEEK_SET,f->disc);
63 }
64 SFOPEN(f,0);
65 SFMTXRETURN(f, 0);
66 }
67 #endif
68
69 switch(f->mode&~SF_LOCK)
70 {
71 default :
72 SFOPEN(f,0);
73 SFMTXRETURN(f, -1);
74 case SF_WRITE :
75 f->next = f->data;
76 if(!f->proc || !(f->flags&SF_READ) || !(f->mode&SF_WRITE) )
77 break;
78
79 /* 2-way pipe, must clear read buffer */
80 (void)_sfmode(f,SF_READ,1);
81 /* fall through */
82 case SF_READ:
83 if(f->extent >= 0 && f->endb > f->next)
84 { f->here -= f->endb-f->next;
85 (void)SFSK(f,f->here,SEEK_SET,f->disc);
86 }
87 f->endb = f->next = f->data;
88 break;
89 }
90
91 SFOPEN(f,0);
92
93 done:
94 if((f->flags&SF_IOCHECK) && f->disc && f->disc->exceptf)
95 (void)(*f->disc->exceptf)(f,SF_PURGE,(Void_t*)((int)0),f->disc);
96
97 SFMTXRETURN(f, 0);
98 }
99