1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2008 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 /* Delete all pending data in the buffer 25 ** 26 ** Written by Kiem-Phong Vo. 27 */ 28 29 #if __STD_C 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 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 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