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/*
* Copyright (C) 2020 - Vito Caputo - <vcaputo@pengaru.com>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 3 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include <fcntl.h>
#include <liburing.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <iou.h>
#include <thunk.h>
#include "bootid.h"
#include "readfile.h"
/* Implements iou-based bootid retrieval.
*
* Note there's not really any reason for doing this async vio iou, it just
* served as the initial test/use case while iou was fleshed out, so here it
* is, no harm in using it. I guess it's kind of convenient to have a little
* kicking of the tires iou/io_uring user at the start of the program anyways,
* rather than having something more complex to debug io_uring issues out of
* the hole. At least if the bootid is retrieved there's some evidence of the
* basic machinery working.
*/
#define BOOTID_PATH "/proc/sys/kernel/random/boot_id"
/* perform in-place removal of hyphens from str */
static void dehyphen(char *str)
{
char *dest;
for (dest = str; *str; str++) {
if (*str == '-')
continue;
*dest++ = *str;
}
*dest = '\0';
}
/* call user-supplied closure now that buf is populated, after some baking of the data */
THUNK_DEFINE_STATIC(have_bootid, iou_t *, iou, char *, buf, size_t *, size, char **, res_ptr, thunk_t *, closure)
{
assert(iou);
assert(closure);
/* FIXME: I'm just assuming it's a proper nl-terminated bootid for now, null terminate it */
buf[*size - 1] = '\0';
dehyphen(buf); /* replicating what systemd does with the bootid */
*res_ptr = strdup(buf);
if (!*res_ptr)
return -ENOMEM;
return thunk_dispatch(closure);
}
/* get a bootid via iou, scheduling closure once gotten */
/* returns < 0 on error, 0 on successful queueing of operation */
THUNK_DEFINE(bootid_get, iou_t *, iou, char **, res_ptr, thunk_t *, closure)
{
thunk_t *bootid_thunk;
struct {
char buf[4096];
size_t len;
} *buf;
/* we need a buffer for readfiles, it only needs to last until have_bootid,
* where it gets null terminated and strdup()d, so allocae it as part of
* the have_bootid thunk. The THUNK_ALLOC/THUNK_INIT interfaces are still
* evolving.
*/
bootid_thunk = THUNK_ALLOC(have_bootid, (void **)&buf, sizeof(*buf));
buf->len = sizeof(buf->buf);
THUNK_INIT(have_bootid(bootid_thunk, iou, buf->buf, &buf->len, res_ptr, closure));
return readfile(iou, BOOTID_PATH, buf->buf, &buf->len, bootid_thunk);
}
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