select: add functionality to check socket state
osmo_fd_register() is used to register socket file descriptors,
after registering a socket, there is no way to test if the socket
is still registered or actually registered at all.
This commit adds a new function osmo_fd_register_check() that can
be used to check in advance, if the socket fd is registered,
before performing further operations.
Change-Id: I48ec7098d6bba586c81bf0d5c9088108e2c081c6
diff --git a/src/select.c b/src/select.c
index da27368..ab0734e 100644
--- a/src/select.c
+++ b/src/select.c
@@ -23,6 +23,7 @@
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
+#include <stdbool.h>
#include <sys/select.h>
#include <osmocom/core/select.h>
@@ -45,6 +46,23 @@
static LLIST_HEAD(osmo_fds);
static int unregistered_count;
+
+/*! \brief Check if a file descriptor is already registered
+ * \param[in] fd osmocom file descriptor to be checked
+ * \returns true if registered; otherwise false
+ */
+bool osmo_fd_is_registered(struct osmo_fd *fd)
+{
+ struct osmo_fd *entry;
+ llist_for_each_entry(entry, &osmo_fds, list) {
+ if (entry == fd) {
+ return true;
+ }
+ }
+
+ return false;
+}
+
/*! \brief Register a new file descriptor with select loop abstraction
* \param[in] fd osmocom file descriptor to be registered
* \returns 0 on success; negative in case of error
@@ -76,12 +94,9 @@
maxfd = fd->fd;
#ifdef BSC_FD_CHECK
- struct osmo_fd *entry;
- llist_for_each_entry(entry, &osmo_fds, list) {
- if (entry == fd) {
- fprintf(stderr, "Adding a osmo_fd that is already in the list.\n");
- return 0;
- }
+ if (osmo_fd_is_registered(fd)) {
+ fprintf(stderr, "Adding a osmo_fd that is already in the list.\n");
+ return 0;
}
#endif
@@ -95,6 +110,9 @@
*/
void osmo_fd_unregister(struct osmo_fd *fd)
{
+ /* Note: when fd is inside the osmo_fds list (not registered before)
+ * this function will crash! If in doubt, check file descriptor with
+ * osmo_fd_is_registered() */
unregistered_count++;
llist_del(&fd->list);
}