1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2007 AT&T Knowledge Ventures * 5 * and is licensed under the * 6 * Common Public License, Version 1.0 * 7 * by AT&T Knowledge Ventures * 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 30 ssize_t sfread(reg Sfio_t* f, Void_t* buf, reg size_t n) 31 #else 32 ssize_t sfread(f,buf,n) 33 reg Sfio_t* f; /* read from this stream. */ 34 Void_t* buf; /* buffer to read into */ 35 reg size_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 42 SFMTXSTART(f, (ssize_t)(-1)); 43 44 GETLOCAL(f,local); 45 justseek = f->bits&SF_JUSTSEEK; f->bits &= ~SF_JUSTSEEK; 46 47 if(!buf) 48 SFMTXRETURN(f, (ssize_t)(n == 0 ? 0 : -1) ); 49 50 /* release peek lock */ 51 if(f->mode&SF_PEEK) 52 { if(!(f->mode&SF_READ) ) 53 SFMTXRETURN(f, (ssize_t)(-1)); 54 55 if(f->mode&SF_GETR) 56 { if(((uchar*)buf + f->val) != f->next && 57 (!f->rsrv || f->rsrv->data != (uchar*)buf) ) 58 SFMTXRETURN(f, (ssize_t)(-1)); 59 f->mode &= ~SF_PEEK; 60 SFMTXRETURN(f, 0); 61 } 62 else 63 { if((uchar*)buf != f->next) 64 SFMTXRETURN(f, (ssize_t)(-1)); 65 f->mode &= ~SF_PEEK; 66 if(f->mode&SF_PKRD) 67 { /* actually read the data now */ 68 f->mode &= ~SF_PKRD; 69 if(n > 0) 70 n = (r = sysreadf(f->file,f->data,n)) < 0 ? 0 : r; 71 f->endb = f->data+n; 72 f->here += n; 73 } 74 f->next += n; 75 f->endr = f->endb; 76 SFMTXRETURN(f, n); 77 } 78 } 79 80 s = begs = (uchar*)buf; 81 for(;; f->mode &= ~SF_LOCK) 82 { /* check stream mode */ 83 if(SFMODE(f,local) != SF_READ && _sfmode(f,SF_READ,local) < 0) 84 { n = s > begs ? s-begs : (size_t)(-1); 85 SFMTXRETURN(f, (ssize_t)n); 86 } 87 88 SFLOCK(f,local); 89 90 if((r = f->endb - f->next) > 0) /* has buffered data */ 91 { if(r > (ssize_t)n) 92 r = (ssize_t)n; 93 if(s != f->next) 94 memcpy(s, f->next, r); 95 f->next += r; 96 s += r; 97 n -= r; 98 } 99 100 if(n <= 0) /* all done */ 101 break; 102 103 if(!(f->flags&SF_STRING) && !(f->bits&SF_MMAP) ) 104 { f->next = f->endb = f->data; 105 106 /* exact IO is desirable for these cases */ 107 if(SFDIRECT(f,n) || 108 ((f->flags&SF_SHARE) && f->extent < 0) ) 109 r = (ssize_t)n; 110 else if(justseek && n <= f->iosz && f->iosz <= f->size) 111 r = f->iosz; /* limit buffering */ 112 else r = f->size; /* full buffering */ 113 114 /* if read almost full size, then just do it direct */ 115 if(r > (ssize_t)n && (r - r/8) <= (ssize_t)n) 116 r = (ssize_t)n; 117 118 /* read directly to user's buffer */ 119 if(r == (ssize_t)n && (r = SFRD(f,s,r,f->disc)) >= 0) 120 { s += r; 121 n -= r; 122 if(r == 0 || n == 0) /* eof or eob */ 123 break; 124 } 125 else goto do_filbuf; 126 } 127 else 128 { do_filbuf: 129 if(justseek) 130 f->bits |= SF_JUSTSEEK; 131 if(SFFILBUF(f,-1) <= 0) 132 break; 133 } 134 } 135 136 SFOPEN(f,local); 137 r = s-begs; 138 SFMTXRETURN(f, r); 139 } 140