summaryrefslogtreecommitdiff
path: root/src/libbio/bseek.c
diff options
context:
space:
mode:
authorOndřej Surý <ondrej@sury.org>2011-09-13 13:13:40 +0200
committerOndřej Surý <ondrej@sury.org>2011-09-13 13:13:40 +0200
commit5ff4c17907d5b19510a62e08fd8d3b11e62b431d (patch)
treec0650497e988f47be9c6f2324fa692a52dea82e1 /src/libbio/bseek.c
parent80f18fc933cf3f3e829c5455a1023d69f7b86e52 (diff)
downloadgolang-upstream/60.tar.gz
Imported Upstream version 60upstream/60
Diffstat (limited to 'src/libbio/bseek.c')
-rw-r--r--src/libbio/bseek.c93
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;
+}