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Factor out an offtab_compute_window_position routine.

This commit is contained in:
riastradh 2014-01-25 16:26:17 +00:00
parent 0853010545
commit 482c113d44
1 changed files with 41 additions and 33 deletions
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74
usr.bin/vndcompress/offtab.c
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@ -1,4 +1,4 @@
/* $NetBSD: offtab.c,v 1.11 2014/01/25 15:31:06 riastradh Exp $ */
/* $NetBSD: offtab.c,v 1.12 2014/01/25 16:26:17 riastradh Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
__RCSID("$NetBSD: offtab.c,v 1.11 2014/01/25 15:31:06 riastradh Exp $");
__RCSID("$NetBSD: offtab.c,v 1.12 2014/01/25 16:26:17 riastradh Exp $");
#include <sys/types.h>
#include <sys/endian.h>
@ -88,47 +88,60 @@ offtab_current_window_end(struct offtab *offtab)
return (offtab->ot_window_start + offtab_current_window_size(offtab));
}
static void
offtab_compute_window_position(struct offtab *offtab, uint32_t window_start,
size_t *bytes, off_t *pos)
{
const uint32_t window_size = offtab_compute_window_size(offtab,
window_start);
__CTASSERT(MAX_WINDOW_SIZE <= (OFF_MAX / sizeof(uint64_t)));
*bytes = (window_size * sizeof(uint64_t));
assert(window_start <= offtab->ot_n_offsets);
__CTASSERT(MAX_N_OFFSETS <= (SIZE_MAX / sizeof(uint64_t)));
const off_t window_offset = ((off_t)window_start *
(off_t)sizeof(uint64_t));
/* XXX This assertion is not justified. */
assert(offtab->ot_fdpos <= (OFF_MAX - window_offset));
*pos = (offtab->ot_fdpos + window_offset);
}
#define OFFTAB_READ_SEEK 0x01
#define OFFTAB_READ_NOSEEK 0x00
static bool
offtab_read_window(struct offtab *offtab, uint32_t blkno, int read_flags)
{
const uint32_t window_start = rounddown(blkno, offtab->ot_window_size);
size_t window_bytes;
off_t window_pos;
assert(offtab->ot_mode == OFFTAB_MODE_READ);
const uint32_t window_start = rounddown(blkno, offtab->ot_window_size);
const uint32_t window_size = offtab_compute_window_size(offtab,
window_start);
__CTASSERT(MAX_WINDOW_SIZE <= (SIZE_MAX / sizeof(uint64_t)));
__CTASSERT(MAX_N_OFFSETS <= (OFF_MAX / sizeof(uint64_t)));
assert(window_start < offtab->ot_n_offsets);
const off_t window_offset = ((off_t)window_start *
(off_t)sizeof(uint64_t));
assert(offtab->ot_fdpos <= (OFF_MAX - window_offset));
const off_t window_pos = (offtab->ot_fdpos + window_offset);
assert(ISSET(read_flags, OFFTAB_READ_SEEK) ||
(lseek(offtab->ot_fd, 0, SEEK_CUR) == offtab->ot_fdpos) ||
((lseek(offtab->ot_fd, 0, SEEK_CUR) == -1) && (errno == ESPIPE)));
const size_t n_req = (window_size * sizeof(uint64_t));
offtab_compute_window_position(offtab, window_start,
&window_bytes, &window_pos);
const ssize_t n_read = (ISSET(read_flags, OFFTAB_READ_SEEK)
? pread_block(offtab->ot_fd, offtab->ot_window, n_req, window_pos)
: read_block(offtab->ot_fd, offtab->ot_window, n_req));
? pread_block(offtab->ot_fd, offtab->ot_window, window_bytes,
window_pos)
: read_block(offtab->ot_fd, offtab->ot_window, window_bytes));
if (n_read == -1) {
(*offtab->ot_report)("read offset table at %"PRIuMAX,
(uintmax_t)window_pos);
return false;
}
assert(n_read >= 0);
if ((size_t)n_read != (window_size * sizeof(uint64_t))) {
if ((size_t)n_read != window_bytes) {
(*offtab->ot_reportx)("partial read of offset table"
" at %"PRIuMAX": %zu != %zu",
(uintmax_t)window_pos,
(size_t)n_read,
(size_t)(window_size * sizeof(uint64_t)));
(uintmax_t)window_pos, (size_t)n_read, window_bytes);
return false;
}
offtab->ot_window_start = window_start;
return true;
@ -152,27 +165,22 @@ offtab_maybe_read_window(struct offtab *offtab, uint32_t blkno, int read_flags)
static void
offtab_write_window(struct offtab *offtab)
{
size_t window_bytes;
off_t window_pos;
assert(offtab->ot_mode == OFFTAB_MODE_WRITE);
const uint32_t window_size = offtab_current_window_size(offtab);
__CTASSERT(MAX_WINDOW_SIZE <= (SIZE_MAX / sizeof(uint64_t)));
__CTASSERT(MAX_N_OFFSETS <= (OFF_MAX / sizeof(uint64_t)));
assert(offtab->ot_window_start < offtab->ot_n_offsets);
const off_t window_offset = ((off_t)offtab->ot_window_start *
(off_t)sizeof(uint64_t));
assert(offtab->ot_fdpos <= (OFF_MAX - window_offset));
const off_t window_pos = (offtab->ot_fdpos + window_offset);
offtab_compute_window_position(offtab, offtab->ot_window_start,
&window_bytes, &window_pos);
const ssize_t n_written = pwrite(offtab->ot_fd, offtab->ot_window,
(window_size * sizeof(uint64_t)),
window_pos);
window_bytes, window_pos);
if (n_written == -1)
err_ss(1, "write initial offset table");
assert(n_written >= 0);
if ((size_t)n_written != (window_size * sizeof(uint64_t)))
if ((size_t)n_written != window_bytes)
errx_ss(1, "partial write of initial offset bytes: %zu <= %zu",
(size_t)n_written,
(size_t)(window_size * sizeof(uint64_t)));
window_bytes);
}
static void