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authorIgor Pashev <pashev.igor@gmail.com>2012-06-24 22:28:35 +0000
committerIgor Pashev <pashev.igor@gmail.com>2012-06-24 22:28:35 +0000
commit3950ffe2a485479f6561c27364d3d7df5a21d124 (patch)
tree468c6e14449d1b1e279222ec32f676b0311917d2 /src/lib/libast/sfio/sfreserve.c
downloadksh-upstream.tar.gz
Imported Upstream version 93u+upstream
Diffstat (limited to 'src/lib/libast/sfio/sfreserve.c')
-rw-r--r--src/lib/libast/sfio/sfreserve.c210
1 files changed, 210 insertions, 0 deletions
diff --git a/src/lib/libast/sfio/sfreserve.c b/src/lib/libast/sfio/sfreserve.c
new file mode 100644
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--- /dev/null
+++ b/src/lib/libast/sfio/sfreserve.c
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+/***********************************************************************
+* *
+* This software is part of the ast package *
+* Copyright (c) 1985-2011 AT&T Intellectual Property *
+* and is licensed under the *
+* Eclipse Public License, Version 1.0 *
+* by AT&T Intellectual Property *
+* *
+* A copy of the License is available at *
+* http://www.eclipse.org/org/documents/epl-v10.html *
+* (with md5 checksum b35adb5213ca9657e911e9befb180842) *
+* *
+* Information and Software Systems Research *
+* AT&T Research *
+* Florham Park NJ *
+* *
+* Glenn Fowler <gsf@research.att.com> *
+* David Korn <dgk@research.att.com> *
+* Phong Vo <kpv@research.att.com> *
+* *
+***********************************************************************/
+#include "sfhdr.h"
+
+/* Reserve a segment of data or buffer.
+**
+** Written by Kiem-Phong Vo.
+*/
+
+#if __STD_C
+Void_t* sfreserve(Sfio_t* f, ssize_t size, int type)
+#else
+Void_t* sfreserve(f,size,type)
+Sfio_t* f; /* file to peek */
+ssize_t size; /* size of peek */
+int type; /* LOCKR: lock stream, LASTR: last record */
+#endif
+{
+ reg ssize_t n, now, sz, iosz;
+ reg Sfrsrv_t* rsrv;
+ reg Void_t* data;
+ reg int mode, local;
+ SFMTXDECL(f);
+
+ SFMTXENTER(f,NIL(Void_t*));
+
+ sz = size < 0 ? -size : size;
+
+ /* see if we need to bias toward SF_WRITE instead of the default SF_READ */
+ if(type < 0)
+ mode = 0;
+ else if((mode = type&SF_WRITE) )
+ type &= ~SF_WRITE;
+
+ /* return the last record */
+ if(type == SF_LASTR )
+ { if((n = f->endb - f->next) > 0 && n == f->val )
+ { data = (Void_t*)f->next;
+ f->next += n;
+ }
+ else if((rsrv = f->rsrv) && (n = -rsrv->slen) > 0)
+ { rsrv->slen = 0;
+ _Sfi = f->val = n;
+ data = (Void_t*)rsrv->data;
+ }
+ else
+ { _Sfi = f->val = -1;
+ data = NIL(Void_t*);
+ }
+
+ SFMTXRETURN(f, data);
+ }
+
+ if(type > 0)
+ { if(type == 1 ) /* upward compatibility mode */
+ type = SF_LOCKR;
+ else if(type != SF_LOCKR)
+ SFMTXRETURN(f, NIL(Void_t*));
+ }
+
+ if(size == 0 && (type < 0 || type == SF_LOCKR) )
+ { if((f->mode&SF_RDWR) != f->mode && _sfmode(f,0,0) < 0)
+ SFMTXRETURN(f, NIL(Void_t*));
+
+ SFLOCK(f,0);
+ if((n = f->endb - f->next) < 0)
+ n = 0;
+
+ goto done;
+ }
+
+ /* iterate until get to a stream that has data or buffer space */
+ for(local = 0;; local = SF_LOCAL)
+ { _Sfi = f->val = -1;
+
+ if(!mode && !(mode = f->flags&SF_READ) )
+ mode = SF_WRITE;
+ if((int)f->mode != mode && _sfmode(f,mode,local) < 0)
+ { SFOPEN(f,0);
+ SFMTXRETURN(f, NIL(Void_t*));
+ }
+
+ SFLOCK(f,local);
+
+ if((n = now = f->endb - f->next) < 0)
+ n = 0;
+ if(n > 0 && n >= sz) /* all done */
+ break;
+
+ /* set amount to perform IO */
+ if(size == 0 || (f->mode&SF_WRITE))
+ iosz = -1;
+ else if(size < 0 && n == 0 && f->push) /* maybe stack-pop */
+ { if((iosz = f->push->endb - f->push->next) == 0)
+ iosz = f->push->size;
+ if(iosz < sz)
+ iosz = sz; /* so only get what is asked for */
+ }
+ else
+ { iosz = sz - n; /* get enough to fulfill requirement */
+ if(size < 0 && iosz < (f->size - n) )
+ iosz = f->size - n; /* get as much as possible */
+ if(iosz <= 0) /* nothing to do */
+ break;
+ }
+
+ /* do a buffer refill or flush */
+ now = n;
+ if(f->mode&SF_WRITE)
+ (void)SFFLSBUF(f, iosz);
+ else if(type == SF_LOCKR && f->extent < 0 && (f->flags&SF_SHARE) )
+ { if(n == 0) /* peek-read only if there is no buffered data */
+ { f->mode |= SF_RV;
+ (void)SFFILBUF(f, iosz );
+ }
+ if((n = f->endb - f->next) < sz)
+ { if(f->mode&SF_PKRD)
+ { f->endb = f->endr = f->next;
+ f->mode &= ~SF_PKRD;
+ }
+ break;
+ }
+ }
+ else
+ { /* sfreserve(f,0,0) == sfread(f, sfreserve(f,-1,SF_LOCKR), 0) */
+ if(size == 0 && type == 0)
+ f->mode |= SF_RV;
+
+ (void)SFFILBUF(f, iosz );
+ }
+
+ if((n = f->endb - f->next) <= 0)
+ n = 0;
+
+ if(n >= sz) /* got it */
+ break;
+
+ if(n == now || sferror(f) || sfeof(f)) /* no progress */
+ break;
+
+ /* request was only to assess data availability */
+ if(type == SF_LOCKR && size > 0 && n > 0 )
+ break;
+ }
+
+done: /* compute the buffer to be returned */
+ data = NIL(Void_t*);
+ if(size == 0 || n == 0)
+ { if(n > 0) /* got data */
+ data = (Void_t*)f->next;
+ else if(type == SF_LOCKR && size == 0 && (rsrv = _sfrsrv(f,0)) )
+ data = (Void_t*)rsrv->data;
+ }
+ else if(n >= sz) /* got data */
+ data = (Void_t*)f->next;
+ else if(f->flags&SF_STRING) /* try extending string buffer */
+ { if((f->mode&SF_WRITE) && (f->flags&SF_MALLOC) )
+ { (void)SFWR(f,f->next,sz,f->disc);
+ if((n = f->endb - f->next) >= sz )
+ data = (Void_t*)f->next;
+ }
+ }
+ else if(f->mode&SF_WRITE) /* allocate side buffer */
+ { if(type == SF_LOCKR && (rsrv = _sfrsrv(f, sz)) )
+ data = (Void_t*)rsrv->data;
+ }
+ else if(type != SF_LOCKR && sz > f->size && (rsrv = _sfrsrv(f,sz)) )
+ { if((n = SFREAD(f,(Void_t*)rsrv->data,sz)) >= sz) /* read side buffer */
+ data = (Void_t*)rsrv->data;
+ else rsrv->slen = -n;
+ }
+
+ SFOPEN(f,0);
+
+ if(data)
+ { if(type == SF_LOCKR)
+ { f->mode |= SF_PEEK;
+ if((f->mode & SF_READ) && size == 0 && data != f->next)
+ f->mode |= SF_GETR; /* so sfread() will unlock */
+ f->endr = f->endw = f->data;
+ }
+ else
+ { if(data == (Void_t*)f->next)
+ f->next += (size >= 0 ? size : n);
+ }
+ }
+
+ _Sfi = f->val = n; /* return true buffer size */
+
+ SFMTXRETURN(f, data);
+}