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authorMiles Bader <miles@gnu.org>1995-10-14 23:17:49 +0000
committerMiles Bader <miles@gnu.org>1995-10-14 23:17:49 +0000
commit7dc780ddc4344c6667ab0d09b0208b5e00a4f79f (patch)
tree867eb6fd11fab04a8842354131f0020f66618f78 /libstore
parenta0ddb9168f0be19884b8245282c62eb92efd9015 (diff)
Formerly rdwr.c.~2~
Diffstat (limited to 'libstore')
-rw-r--r--libstore/rdwr.c56
1 files changed, 55 insertions, 1 deletions
diff --git a/libstore/rdwr.c b/libstore/rdwr.c
index b4139a4e..e14601e3 100644
--- a/libstore/rdwr.c
+++ b/libstore/rdwr.c
@@ -20,11 +20,65 @@
with this program; if not, write to the Free Software Foundation, Inc.,
675 Mass Ave, Cambridge, MA 02139, USA. */
+/* Write LEN bytes from BUF to STORE at ADDR. Returns the amount written in
+ AMOUNT. ADDR is in BLOCKS (as defined by store->block_size). */
error_t
store_write (struct store *store,
off_t addr, char *buf, size_t len, size_t *amount);
{
-
+ error_t err = 0;
+ size_t request_len = len;
+ off_t *runs = store->runs;
+ unsigned runs_len = store->runs_len;
+ store_write_meth_t write = store->meths->write;
+ int block_shift = store->log2_block_size;
+
+ /* XXX: this isn't going to be very efficient if RUNS is very complex...
+ But it should do dandy if it's short. For long run lists, we could do a
+ binary search or something to find the starting run. */
+ while (runs_len)
+ {
+ off_t run_offs = runs[0];
+ off_t run_len = runs[1];
+
+ if (run_len <= addr)
+ /* Not to the right place yet, move on... */
+ addr -= run_len;
+ else if (run_offs < 0)
+ /* A hole! Can't write here. Must stop. */
+ break;
+ else
+ /* Ok, we can write in this run, at least a bit. */
+ {
+ size_t written, blocks_written;
+ off_t end = addr + len;
+ off_t seg_len = end > run_len ? run_len - addr : len;
+
+ /* Write to the actual object at the correct address. */
+ err = (*write)(store, run_offs + addr, buf, seg_len, &written);
+ if (err)
+ /* Ack */
+ break;
+
+ buf += written;
+ len -= written;
+
+ blocks_written = written >> block_shift;
+ if ((blocks_written << block_shift) != seg_amount)
+ /* A non-block multiple amount was written!? What do we do? */
+ break;
+
+ addr += blocks_written;
+ }
+
+ runs += 2;
+ runs_len -= 2;
+ }
+
+ if (!err)
+ *amount = request_len - len;
+
+ return err;
}
error_t