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Diffstat (limited to 'src/lib/libast/disc/sfdcunion.c')
| -rw-r--r-- | src/lib/libast/disc/sfdcunion.c | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/src/lib/libast/disc/sfdcunion.c b/src/lib/libast/disc/sfdcunion.c new file mode 100644 index 0000000..1f45909 --- /dev/null +++ b/src/lib/libast/disc/sfdcunion.c @@ -0,0 +1,203 @@ +/*********************************************************************** +* * +* 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 "sfdchdr.h" + + +/* Make a sequence of streams act like a single stream. +** This is for reading only. +** +** Written by Kiem-Phong Vo, kpv@research.att.com, 03/18/1998. +*/ + +#define UNSEEKABLE 1 + +typedef struct _file_s +{ Sfio_t* f; /* the stream */ + Sfoff_t lower; /* its lowest end */ +} File_t; + +typedef struct _union_s +{ + Sfdisc_t disc; /* discipline structure */ + short type; /* type of streams */ + short c; /* current stream */ + short n; /* number of streams */ + Sfoff_t here; /* current location */ + File_t f[1]; /* array of streams */ +} Union_t; + +#if __STD_C +static ssize_t unwrite(Sfio_t* f, const Void_t* buf, size_t n, Sfdisc_t* disc) +#else +static ssize_t unwrite(f, buf, n, disc) +Sfio_t* f; /* stream involved */ +Void_t* buf; /* buffer to read into */ +size_t n; /* number of bytes to read */ +Sfdisc_t* disc; /* discipline */ +#endif +{ + return -1; +} + +#if __STD_C +static ssize_t unread(Sfio_t* f, Void_t* buf, size_t n, Sfdisc_t* disc) +#else +static ssize_t unread(f, buf, n, disc) +Sfio_t* f; /* stream involved */ +Void_t* buf; /* buffer to read into */ +size_t n; /* number of bytes to read */ +Sfdisc_t* disc; /* discipline */ +#endif +{ + reg Union_t* un; + reg ssize_t r, m; + + un = (Union_t*)disc; + m = n; + f = un->f[un->c].f; + while(1) + { if((r = sfread(f,buf,m)) < 0 || (r == 0 && un->c == un->n-1) ) + break; + + m -= r; + un->here += r; + + if(m == 0) + break; + + buf = (char*)buf + r; + if(sfeof(f) && un->c < un->n-1) + f = un->f[un->c += 1].f; + } + return n-m; +} + +#if __STD_C +static Sfoff_t unseek(Sfio_t* f, Sfoff_t addr, int type, Sfdisc_t* disc) +#else +static Sfoff_t unseek(f, addr, type, disc) +Sfio_t* f; +Sfoff_t addr; +int type; +Sfdisc_t* disc; +#endif +{ + reg Union_t* un; + reg int i; + reg Sfoff_t extent, s; + + un = (Union_t*)disc; + if(un->type&UNSEEKABLE) + return -1L; + + if(type == 2) + { extent = 0; + for(i = 0; i < un->n; ++i) + extent += (sfsize(un->f[i].f) - un->f[i].lower); + addr += extent; + } + else if(type == 1) + addr += un->here; + + if(addr < 0) + return -1; + + /* find the stream where the addr could be in */ + extent = 0; + for(i = 0; i < un->n-1; ++i) + { s = sfsize(un->f[i].f) - un->f[i].lower; + if(addr < extent + s) + break; + extent += s; + } + + s = (addr-extent) + un->f[i].lower; + if(sfseek(un->f[i].f,s,0) != s) + return -1; + + un->c = i; + un->here = addr; + + for(i += 1; i < un->n; ++i) + sfseek(un->f[i].f,un->f[i].lower,0); + + return addr; +} + +/* on close, remove the discipline */ +#if __STD_C +static int unexcept(Sfio_t* f, int type, Void_t* data, Sfdisc_t* disc) +#else +static int unexcept(f,type,data,disc) +Sfio_t* f; +int type; +Void_t* data; +Sfdisc_t* disc; +#endif +{ + if(type == SF_FINAL || type == SF_DPOP) + free(disc); + + return 0; +} + +#if __STD_C +int sfdcunion(Sfio_t* f, Sfio_t** array, int n) +#else +int sfdcunion(f, array, n) +Sfio_t* f; +Sfio_t** array; +int n; +#endif +{ + reg Union_t* un; + reg int i; + + if(n <= 0) + return -1; + + if(!(un = (Union_t*)malloc(sizeof(Union_t)+(n-1)*sizeof(File_t))) ) + return -1; + memset(un, 0, sizeof(*un)); + + un->disc.readf = unread; + un->disc.writef = unwrite; + un->disc.seekf = unseek; + un->disc.exceptf = unexcept; + un->n = n; + + for(i = 0; i < n; ++i) + { un->f[i].f = array[i]; + if(!(un->type&UNSEEKABLE)) + { un->f[i].lower = sfseek(array[i],(Sfoff_t)0,1); + if(un->f[i].lower < 0) + un->type |= UNSEEKABLE; + } + } + + if(sfdisc(f,(Sfdisc_t*)un) != (Sfdisc_t*)un) + { free(un); + return -1; + } + + return 0; +} |