fdm: use the FDM's poll loop

fdm.c

@@ -0,0 +1,124 @@
+#include "fdm.h"
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <assert.h>
+#include <sys/epoll.h>
+
+#define LOG_MODULE "fdm"
+#define LOG_ENABLE_DBG 0
+#include "log.h"
+#include "tllist.h"
+
+struct fd {
+    int fd;
+    void *data;
+    fdm_handler_t handler;
+};
+
+struct fdm {
+    int epoll_fd;
+    tll(struct fd) fds;
+};
+
+struct fdm *
+fdm_init(void)
+{
+    int epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+    if (epoll_fd == -1) {
+        LOG_ERRNO("failed to create epoll FD");
+        return NULL;
+    }
+
+    struct fdm *fdm = malloc(sizeof(*fdm));
+    *fdm = (struct fdm){
+        .epoll_fd = epoll_fd,
+        .fds = tll_init(),
+    };
+    return fdm;
+}
+
+void
+fdm_destroy(struct fdm *fdm)
+{
+    if (fdm == NULL)
+        return;
+
+    if (tll_length(fdm->fds) > 0)
+        LOG_WARN("FD list not empty");
+
+    assert(tll_length(fdm->fds) == 0);
+
+    tll_free(fdm->fds);
+    close(fdm->epoll_fd);
+    free(fdm);
+}
+
+bool
+fdm_add(struct fdm *fdm, int fd, int events, fdm_handler_t handler, void *data)
+{
+#if defined(_DEBUG)
+    tll_foreach(fdm->fds, it) {
+        if (it->item.fd == fd) {
+            LOG_ERR("FD=%d already registered", fd);
+            return false;
+        }
+    }
+#endif
+
+    tll_push_back(
+        fdm->fds, ((struct fd){.fd = fd, .data = data, .handler = handler}));
+
+    struct epoll_event ev = {
+        .events = events,
+        .data = {.ptr = &tll_back(fdm->fds)},
+    };
+
+    if (epoll_ctl(fdm->epoll_fd, EPOLL_CTL_ADD, fd, &ev) < 0) {
+        LOG_ERRNO("failed to register FD with epoll");
+        tll_pop_back(fdm->fds);
+        return false;
+    }
+
+    return true;
+}
+
+bool
+fdm_del(struct fdm *fdm, int fd)
+{
+    tll_foreach(fdm->fds, it) {
+        if (it->item.fd == fd) {
+            if (epoll_ctl(fdm->epoll_fd, EPOLL_CTL_DEL, fd, NULL) < 0)
+                LOG_ERRNO("failed to unregister FD=%d from epoll", fd);
+
+            tll_remove(fdm->fds, it);
+            return true;
+        }
+    }
+
+    LOG_ERR("no such FD: %d", fd);
+    return false;
+}
+
+bool
+fdm_poll(struct fdm *fdm)
+{
+    struct epoll_event events[tll_length(fdm->fds)];
+    int ret = epoll_wait(fdm->epoll_fd, events, tll_length(fdm->fds), -1);
+    if (ret == -1) {
+        if (errno == EINTR)
+            return true;
+
+        LOG_ERRNO("failed to epoll");
+        return false;
+    }
+
+    for (int i = 0; i < ret; i++) {
+        struct fd *fd = events[i].data.ptr;
+        if (!fd->handler(fdm, fd->fd, events[i].events, fd->data))
+            return false;
+    }
+
+    return true;
+}