refactor(dnsmasq): make signal_dhcp_process const

Make the `dhcp_bin_path` parameter to signal_dhcp_process() `const`.

Because we call `basename()` on this value, which may change the input
string, we need to first make a temporary copy of the string into a
buffer.

This fixes the segmentation fault in `test_signal_dhcp_process()`
test on FreeBSD.

.cirrus.yml

@@ -24,7 +24,7 @@ task:
  cmake --build --preset freebsd --parallel "$(($(sysctl -n hw.ncpu) + 1))"
  env:
  # list of tests that are currently failing on FreeBSD
- FAILING_TESTS: test_edgesec test_dnsmasq test_mdns_service
+ FAILING_TESTS: test_edgesec test_mdns_service
  test_script: |
  ctest --preset freebsd --output-on-failure --output-junit junit-test-results.xml \
  || true # We look at junit XML output file for failures

src/dhcp/dnsmasq.c

@@ -414,9 +414,13 @@ int signal_dhcp_process(char *dhcp_bin_path, char *dhcp_conf_path) {
  return 0;
 }
 #else
-int signal_dhcp_process(char *dhcp_bin_path) {
- os_strlcpy(dnsmasq_proc_name, basename(dhcp_bin_path), MAX_OS_PATH_LEN);
-
+int signal_dhcp_process(const char *dhcp_bin_path) {
+ {
+ char dhcp_bin_path_buffer[MAX_OS_PATH_LEN];
+ os_strlcpy(dhcp_bin_path_buffer, dhcp_bin_path, MAX_OS_PATH_LEN);
+ os_strlcpy(dnsmasq_proc_name, basename(dhcp_bin_path_buffer),
+ MAX_OS_PATH_LEN);
+ }
  // Signal any running dnsmasq process to reload the config
  if (!signal_process(dnsmasq_proc_name, SIGHUP)) {
  log_error("signal_process fail");

src/dhcp/dnsmasq.h

@@ -62,7 +62,7 @@ bool kill_dhcp_process(void);
  * @param dhcp_bin_path The DHCP server binary path
  * @return int 0 on success, -1 on failure
  */
-int signal_dhcp_process(char *dhcp_bin_path);
+int signal_dhcp_process(const char *dhcp_bin_path);
 
 /**
  * @brief Clear the DHCP lease entry for a MAC addrress