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/*
* Exclusive lock on owned COM ports only (flock + optional setserial uart none).
* Pass real IRQ — refuse mismatch. See vault IRQ/lock contract.
*/
#define _GNU_SOURCE
#include "bcpr/bcpr_lock.h"
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
static void tty_basename(const char *serial, char *out, size_t out_sz)
{
const char *p = strrchr(serial, '/');
p = p ? p + 1 : serial;
snprintf(out, out_sz, "%s", p);
}
int bcpr_lock_verify_irq(const char *serial, unsigned expect_irq,
unsigned *got_irq, unsigned *got_io)
{
char name[64];
char path[128];
char buf[64];
FILE *f;
unsigned irq = 0;
unsigned io = 0;
if (!serial || !serial[0]) {
return -1;
}
tty_basename(serial, name, sizeof(name));
snprintf(path, sizeof(path), "/sys/class/tty/%s/irq", name);
f = fopen(path, "r");
if (f) {
if (fgets(buf, sizeof(buf), f)) {
irq = (unsigned)strtoul(buf, NULL, 0);
}
fclose(f);
} else {
/* Fallback: setserial -g (best-effort). */
char cmd[256];
FILE *p;
snprintf(cmd, sizeof(cmd), "setserial -g %s 2>/dev/null", serial);
p = popen(cmd, "r");
if (!p) {
return -1;
}
if (fgets(buf, sizeof(buf), p)) {
char *ip = strstr(buf, "IRQ: ");
char *pp = strstr(buf, "Port: ");
if (ip) {
irq = (unsigned)strtoul(ip + 5, NULL, 0);
}
if (pp) {
io = (unsigned)strtoul(pp + 6, NULL, 0);
}
}
pclose(p);
}
snprintf(path, sizeof(path), "/sys/class/tty/%s/iomem_base", name);
f = fopen(path, "r");
if (f) {
if (fgets(buf, sizeof(buf), f)) {
io = (unsigned)strtoul(buf, NULL, 0);
}
fclose(f);
}
if (got_irq) {
*got_irq = irq;
}
if (got_io) {
*got_io = io;
}
if (expect_irq == 0) {
return -1; /* never invent; refuse zero when required */
}
if (irq == 0 || irq != expect_irq) {
return -1;
}
return 0;
}
static int make_lock_path(const bcpr_dev_config_t *dev, char *out, size_t sz)
{
char name[64];
const char *dir = "/var/run/max25-bcpr";
tty_basename(dev->serial, name, sizeof(name));
if (name[0] == '\0') {
return -1;
}
snprintf(out, sz, "%s/lock-%s", dir, name);
return 0;
}
int bcpr_lock_acquire(bcpr_port_lock_t *lk, const bcpr_dev_config_t *dev,
int dry_run)
{
char lockpath[192];
unsigned got_irq = 0, got_io = 0;
if (!lk || !dev) {
return -1;
}
memset(lk, 0, sizeof(*lk));
snprintf(lk->serial, sizeof(lk->serial), "%s", dev->serial);
lk->iobase = dev->iobase;
lk->irq = dev->irq;
lk->lock_fd = -1;
lk->dry_run = dry_run ? 1 : 0;
if (dry_run) {
return 0;
}
if (!dev->serial[0] || dev->irq == 0 || dev->iobase == 0) {
return -1;
}
if (bcpr_lock_verify_irq(dev->serial, dev->irq, &got_irq, &got_io) != 0) {
#if defined(__FreeBSD__)
/*
* No Linux sysfs/setserial — operator INI is SSoT for iobase/irq
* (see vault ExSys AM1 map). Skip hard fail when probe unavailable.
*/
got_irq = dev->irq;
got_io = dev->iobase;
#else
fprintf(stderr,
"bcpr: IRQ mismatch or unreadable for %s (expect %u got %u)\n",
dev->serial, dev->irq, got_irq);
return -1;
#endif
}
if (got_io && got_io != dev->iobase) {
fprintf(stderr,
"bcpr: iobase mismatch for %s (expect 0x%x got 0x%x)\n",
dev->serial, dev->iobase, got_io);
return -1;
}
if (make_lock_path(dev, lockpath, sizeof(lockpath)) != 0) {
return -1;
}
(void)mkdir("/var/run/max25-bcpr", 0755);
lk->lock_fd = open(lockpath, O_RDWR | O_CREAT | O_CLOEXEC, 0644);
if (lk->lock_fd < 0) {
perror("bcpr lock open");
return -1;
}
if (flock(lk->lock_fd, LOCK_EX | LOCK_NB) != 0) {
fprintf(stderr, "bcpr: port %s already locked\n", dev->serial);
close(lk->lock_fd);
lk->lock_fd = -1;
return -1;
}
/* Release 8250 claim on this COM only so userspace can bit-bang. */
{
char cmd[256];
snprintf(cmd, sizeof(cmd), "setserial %s uart none 2>/dev/null",
dev->serial);
if (system(cmd) == 0) {
lk->uart_released = 1;
}
}
return 0;
}
void bcpr_lock_release(bcpr_port_lock_t *lk)
{
if (!lk) {
return;
}
if (lk->dry_run) {
memset(lk, 0, sizeof(*lk));
lk->lock_fd = -1;
return;
}
if (lk->uart_released && lk->serial[0]) {
char cmd[256];
/* Restore 16550A claim — best effort. */
snprintf(cmd, sizeof(cmd),
"setserial %s uart 16550A port 0x%x irq %u 2>/dev/null",
lk->serial, lk->iobase, lk->irq);
(void)system(cmd);
lk->uart_released = 0;
}
if (lk->lock_fd >= 0) {
flock(lk->lock_fd, LOCK_UN);
close(lk->lock_fd);
lk->lock_fd = -1;
}
memset(lk, 0, sizeof(*lk));
lk->lock_fd = -1;
}
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