github.com/roboticscm/goman@v0.0.0-20210203095141-87c07b4a0a55/src/libbio/binit.c (about)

     1  /*
     2  http://code.google.com/p/inferno-os/source/browse/libbio/binit.c
     3  
     4  	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
     5  	Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
     6  
     7  Permission is hereby granted, free of charge, to any person obtaining a copy
     8  of this software and associated documentation files (the "Software"), to deal
     9  in the Software without restriction, including without limitation the rights
    10  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    11  copies of the Software, and to permit persons to whom the Software is
    12  furnished to do so, subject to the following conditions:
    13  
    14  The above copyright notice and this permission notice shall be included in
    15  all copies or substantial portions of the Software.
    16  
    17  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    18  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    19  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
    20  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    21  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    22  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    23  THE SOFTWARE.
    24  */
    25  
    26  #include	<u.h>
    27  #include	<libc.h>
    28  #include	<bio.h>
    29  
    30  enum
    31  {
    32  	MAXBUFS	= 20
    33  };
    34  
    35  static	Biobuf*	wbufs[MAXBUFS];
    36  static	int		atexitflag;
    37  
    38  static
    39  void
    40  batexit(void)
    41  {
    42  	Biobuf *bp;
    43  	int i;
    44  
    45  	for(i=0; i<MAXBUFS; i++) {
    46  		bp = wbufs[i];
    47  		if(bp != 0) {
    48  			wbufs[i] = 0;
    49  			Bflush(bp);
    50  		}
    51  	}
    52  }
    53  
    54  static
    55  void
    56  deinstall(Biobuf *bp)
    57  {
    58  	int i;
    59  
    60  	for(i=0; i<MAXBUFS; i++)
    61  		if(wbufs[i] == bp)
    62  			wbufs[i] = 0;
    63  }
    64  
    65  static
    66  void
    67  install(Biobuf *bp)
    68  {
    69  	int i;
    70  
    71  	deinstall(bp);
    72  	for(i=0; i<MAXBUFS; i++)
    73  		if(wbufs[i] == 0) {
    74  			wbufs[i] = bp;
    75  			break;
    76  		}
    77  	if(atexitflag == 0) {
    78  		atexitflag = 1;
    79  		atexit(batexit);
    80  	}
    81  }
    82  
    83  int
    84  Binits(Biobuf *bp, int f, int mode, unsigned char *p, int size)
    85  {
    86  
    87  	p += Bungetsize;	/* make room for Bungets */
    88  	size -= Bungetsize;
    89  
    90  	switch(mode&~(ORCLOSE|OTRUNC)) {
    91  	default:
    92  		fprint(2, "Bopen: unknown mode %d\n", mode);
    93  		return Beof;
    94  
    95  	case OREAD:
    96  		bp->state = Bractive;
    97  		bp->ocount = 0;
    98  		break;
    99  
   100  	case OWRITE:
   101  		install(bp);
   102  		bp->state = Bwactive;
   103  		bp->ocount = -size;
   104  		break;
   105  	}
   106  	bp->bbuf = p;
   107  	bp->ebuf = p+size;
   108  	bp->bsize = size;
   109  	bp->icount = 0;
   110  	bp->gbuf = bp->ebuf;
   111  	bp->fid = f;
   112  	bp->flag = 0;
   113  	bp->rdline = 0;
   114  	bp->offset = 0;
   115  	bp->runesize = 0;
   116  	return 0;
   117  }
   118  
   119  
   120  int
   121  Binit(Biobuf *bp, int f, int mode)
   122  {
   123  	return Binits(bp, f, mode, bp->b, sizeof(bp->b));
   124  }
   125  
   126  Biobuf*
   127  Bfdopen(int f, int mode)
   128  {
   129  	Biobuf *bp;
   130  
   131  	bp = malloc(sizeof(Biobuf));
   132  	if(bp == 0)
   133  		return 0;
   134  	Binits(bp, f, mode, bp->b, sizeof(bp->b));
   135  	bp->flag = Bmagic;
   136  	return bp;
   137  }
   138  
   139  Biobuf*
   140  Bopen(char *name, int mode)
   141  {
   142  	Biobuf *bp;
   143  	int f;
   144  
   145  	switch(mode&~(ORCLOSE|OTRUNC)) {
   146  	default:
   147  		fprint(2, "Bopen: unknown mode %d\n", mode);
   148  		return 0;
   149  
   150  	case OREAD:
   151  		f = open(name, OREAD);
   152  		if(f < 0)
   153  			return 0;
   154  		break;
   155  
   156  	case OWRITE:
   157  		f = create(name, OWRITE|OTRUNC, 0666);
   158  		if(f < 0)
   159  			return 0;
   160  	}
   161  	bp = Bfdopen(f, mode);
   162  	if(bp == 0)
   163  		close(f);
   164  	return bp;
   165  }
   166  
   167  int
   168  Bterm(Biobuf *bp)
   169  {
   170  
   171  	deinstall(bp);
   172  	Bflush(bp);
   173  	if(bp->flag == Bmagic) {
   174  		bp->flag = 0;
   175  		close(bp->fid);
   176  		free(bp);
   177  	}
   178  	return 0;
   179  }