1 /*********************************************************************** 2 * * 3 * This software is part of the ast package * 4 * Copyright (c) 1985-2009 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 30 ssize_t sfread(Sfio_t* f, Void_t* buf, size_t n) 31 #else 32 ssize_t sfread(f,buf,n) 33 Sfio_t* f; /* read from this stream. */ 34 Void_t* buf; /* buffer to read into */ 35 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 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