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util/nvmutil: stricter return in pread

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we were returning if verified is not off, but we
were not doing the check soon enough.

now it's clearer: just after either a reset,
or we found out offset doesn't match, we
return sooner.

otherwise, we read, and we verify again right
after. in the old code, we verified twice in
a row.

this is just more optimal, for error handling.

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe
2026-03-15 01:59:45 +00:00
parent b365781a4c
commit 5d95d4dfe9
1 changed files with 19 additions and 31 deletions
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50
util/nvmutil/nvmutil.c
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@@ -2077,27 +2077,28 @@ real_pread_pwrite:
* then another thread may have
* changed it. Enabled if
* off_reset is OFF_RESET.
*
* We do this *once*, on the theory
* that nothing is touching it now.
*/
if (off != verified) {
if (!off_reset)
goto err_prw;
/*
* Even if we allow to continue,
* we still need to reset the
* offset. If we can't, then
* we can't recover at all.
*
* However, we must preserve
* errno in that case, so
* just return immediately.
*/
if (lseek_loop(fd, off, SEEK_SET,
loop_eagain, loop_eintr) == (off_t)-1)
return -1;
}
if (off_reset && off != verified)
lseek_loop(fd, off, SEEK_SET,
loop_eagain, loop_eintr);
do {
if (off != verified)
return -1;
if (rw_type == IO_PREAD)
r = read(fd, mem, nrw);
else if (rw_type == IO_PWRITE)
r = write(fd, mem, nrw);
if (rw_over_nrw(r, nrw) == -1) {
errno = EIO;
break;
}
/*
* Verify again before I/O
* (even with OFF_ERR)
@@ -2118,19 +2119,6 @@ real_pread_pwrite:
verified = lseek_loop(fd, (off_t)0, SEEK_CUR,
loop_eagain, loop_eintr);
if (verified != off)
goto err_prw;
if (rw_type == IO_PREAD)
r = read(fd, mem, nrw);
else if (rw_type == IO_PWRITE)
r = write(fd, mem, nrw);
if (rw_over_nrw(r, nrw) == -1) {
errno = EIO;
break;
}
} while (r == -1 &&
(errno == try_err(loop_eintr, EINTR)
|| errno == try_err(loop_eagain, EAGAIN)));