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author | Ondřej Surý <ondrej@sury.org> | 2011-09-13 13:13:40 +0200 |
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committer | Ondřej Surý <ondrej@sury.org> | 2011-09-13 13:13:40 +0200 |
commit | 5ff4c17907d5b19510a62e08fd8d3b11e62b431d (patch) | |
tree | c0650497e988f47be9c6f2324fa692a52dea82e1 /src/libbio/bseek.c | |
parent | 80f18fc933cf3f3e829c5455a1023d69f7b86e52 (diff) | |
download | golang-upstream/60.tar.gz |
Imported Upstream version 60upstream/60
Diffstat (limited to 'src/libbio/bseek.c')
-rw-r--r-- | src/libbio/bseek.c | 93 |
1 files changed, 93 insertions, 0 deletions
diff --git a/src/libbio/bseek.c b/src/libbio/bseek.c new file mode 100644 index 000000000..291498108 --- /dev/null +++ b/src/libbio/bseek.c @@ -0,0 +1,93 @@ +/* +http://code.google.com/p/inferno-os/source/browse/libbio/bseek.c + + Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved. + Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved. + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in +all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +THE SOFTWARE. +*/ + +#include <u.h> +#include <libc.h> +#include <bio.h> + +vlong +Bseek(Biobuf *bp, vlong offset, int base) +{ + vlong n, d; + int bufsz; + +#ifndef _WIN32 + if(sizeof(offset) != sizeof(off_t)) { + fprint(2, "Bseek: libbio compiled with %d-byte offset\n", sizeof(off_t)); + abort(); + } +#endif + + switch(bp->state) { + default: + fprint(2, "Bseek: unknown state %d\n", bp->state); + return Beof; + + case Bracteof: + bp->state = Bractive; + bp->icount = 0; + bp->gbuf = bp->ebuf; + + case Bractive: + n = offset; + if(base == 1) { + n += Boffset(bp); + base = 0; + } + + /* + * try to seek within buffer + */ + if(base == 0) { + d = n - Boffset(bp); + bufsz = bp->ebuf - bp->gbuf; + if(-bufsz <= d && d <= bufsz){ + bp->icount += d; + if(d >= 0) { + if(bp->icount <= 0) + return n; + } else { + if(bp->ebuf - bp->gbuf >= -bp->icount) + return n; + } + } + } + + /* + * reset the buffer + */ + n = lseek(bp->fid, n, base); + bp->icount = 0; + bp->gbuf = bp->ebuf; + break; + + case Bwactive: + Bflush(bp); + n = lseek(bp->fid, offset, base); + break; + } + bp->offset = n; + return n; +} |