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util/nvmutil: move looping logic to rw_file_exact

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rw_file_once was doing what rw_file_exact should be
doing

_once does what it says: once

we were passing an offset (rc) to it that it was not
meaningfully using.

this makes the code now more robust, especially if
we later swap out or break _once - then we don't
get weird behaviour (if there is a regression).

Signed-off-by: Leah Rowe <leah@libreboot.org>
This commit is contained in:
Leah Rowe
2026-03-14 21:21:31 +00:00
parent c825d80198
commit 3b9761fbed
1 changed files with 20 additions and 15 deletions
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util/nvmutil/nvmutil.c
+19 -14
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@@ -411,7 +411,7 @@ static ssize_t rw_file_once(int fd, u8 *mem, size_t len,
static ssize_t prw(int fd, void *mem, size_t nrw, static ssize_t prw(int fd, void *mem, size_t nrw,
off_t off, int rw_type, int loop_eagain, int loop_eintr); off_t off, int rw_type, int loop_eagain, int loop_eintr);
static int check_file(int fd, struct stat *st); static int check_file(int fd, struct stat *st);
static int rw_over_nrw(ssize_t r, size_t nrw); static ssize_t rw_over_nrw(ssize_t r, size_t nrw);
static off_t lseek_loop(int fd, off_t off, static off_t lseek_loop(int fd, off_t off,
int whence, int loop_eagain, int loop_eintr); int whence, int loop_eagain, int loop_eintr);
static int try_err(int loop_err, int errval); static int try_err(int loop_err, int errval);
@@ -1874,32 +1874,37 @@ rw_file_exact(int fd, u8 *mem, size_t nrw,
int loop_eintr, size_t max_retries) int loop_eintr, size_t max_retries)
{ {
ssize_t rv = 0; ssize_t rv = 0;
size_t rc = 0; ssize_t rc = 0;
size_t retries_on_zero = 0;
for (rc = 0, rv = 0; rc < nrw; ) { while (1) {
rc += (size_t)rv; rc += rv;
if ((size_t)rc >= nrw)
break;
if ((rv = rw_file_once(fd, if ((rv = rw_file_once(fd,
mem + rc, nrw - rc, off + rc, rw_type, mem + rc, nrw - rc, off + rc, rw_type,
loop_eagain, loop_eintr, max_retries)) < 0) loop_eagain, loop_eintr, max_retries)) < 0)
return -1; return -1;
/* rw_file_once never returns /* Prevent theoretical overflow */
zero, but it's still logically if ((size_t)rv > (nrw - rc))
incorrect not to handle it here */ goto err_rw_file_exact;
if (rv == 0) { if (rv == 0) {
errno = EIO; if (retries_on_zero++ < max_retries)
return -1; continue;
goto err_rw_file_exact;
} }
/* Prevent theoretical overflow */ retries_on_zero = 0;
if ((size_t)rv > nrw - rc)
goto err_rw_file_exact;
} }
return rc; if ((size_t)rc != nrw)
goto err_rw_file_exact;
return rw_over_nrw(rc, nrw);
err_rw_file_exact: err_rw_file_exact:
errno = EIO; errno = EIO;
@@ -2113,7 +2118,7 @@ err_is_file:
* POSIX can say whatever it wants. * POSIX can say whatever it wants.
* specification != implementation * specification != implementation
*/ */
static int static ssize_t
rw_over_nrw(ssize_t r, size_t nrw) rw_over_nrw(ssize_t r, size_t nrw)
{ {
if (r == -1) if (r == -1)