More file scaffolding.

adsbus/file.c

@@ -1,23 +1,104 @@
-#include <stdlib.h>
-#include <sys/types.h>
-#include <sys/stat.h>
+#include <assert.h>
 #include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 #include "flow.h"
+#include "list.h"
+#include "peer.h"
 #include "receive.h"
 #include "send.h"
+#include "uuid.h"
 
 #include "file.h"
 
-static void file_open_new(char *path, struct flow *flow, void *passthrough, int flags) {
-	int fd = open(path, flags | O_CLOEXEC, S_IRUSR | S_IWUSR);
+struct file {
+	struct peer peer;
+	uint8_t id[UUID_LEN];
+	char *path;
+	int flags;
+	struct flow *flow;
+	void *passthrough;
+	bool retry;
+	struct list_head file_list;
+};
+
+static struct list_head file_head = LIST_HEAD_INIT(file_head);
+
+static bool file_should_retry(int fd, struct file *file) {
+	// We want to retry most files, except if we're reading from a regular file
+	if (!file->flags & O_RDONLY) {
+		return true;
+	}
+
+	// Questionable heuristic time. We're going to test if the kernel driver for
+	// this fd supports polling. If it does, we assume that we have a character
+	// device, named pipe, or something else that is likely to give us different
+	// data if we read it again.
+	int epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	assert(epoll_fd >= 0);
+	struct epoll_event ev = {
+		.events = 0,
+		.data = {
+			.ptr = NULL,
+		},
+	};
+	int res = epoll_ctl(epoll_fd, EPOLL_CTL_ADD, fd, &ev);
+	assert(!close(epoll_fd));
+	return (res == 0);
+}
+
+static void file_del(struct file *file) {
+	(*file->flow->ref_count)--;
+	list_del(&file->file_list);
+	free(file->path);
+	free(file);
+}
+
+static void file_handle_close(struct peer *peer) {
+	struct file *file = (struct file *) peer;
+
+	file_del(file);
+}
+
+static void file_open(struct file *file) {
+	int fd = open(file->path, file->flags | O_CLOEXEC, S_IRUSR | S_IWUSR);
 	if (fd == -1) {
 		// TODO: log error; retry?
 		return;
 	}
-	file_fd_new(fd, flow, passthrough);
+
+	file->retry = file_should_retry(fd, file);
+	file->peer.event_handler = file_handle_close;
+	file->flow->new(fd, file->passthrough, (struct peer *) file);
+	// TODO: log error; retry?
+	flow_hello(fd, file->flow, file->passthrough);
 }
 
+static void file_new(char *path, int flags, struct flow *flow, void *passthrough) {
+	(*flow->ref_count)++;
+
+	struct file *file = malloc(sizeof(*file));
+	assert(file);
+	file->peer.fd = -1;
+	uuid_gen(file->id);
+	file->path = strdup(path);
+	assert(file->path);
+	file->flags = flags;
+	file->flow = flow;
+	file->passthrough = passthrough;
+
+	list_add(&file->file_list, &file_head);
+
+	file_open(file);
+}
+
+// TODO: this code probably belongs elsewhere
 void file_fd_new(int fd, struct flow *flow, void *passthrough) {
 	flow->new(fd, passthrough, NULL);
 	// TODO: log error; retry?
@@ -25,13 +106,13 @@ void file_fd_new(int fd, struct flow *flow, void *passthrough) {
 }
 
 void file_read_new(char *path, struct flow *flow, void *passthrough) {
-	file_open_new(path, flow, passthrough, O_RDONLY);
+	file_new(path, O_RDONLY, flow, passthrough);
 }
 
 void file_write_new(char *path, struct flow *flow, void *passthrough) {
-	file_open_new(path, flow, passthrough, O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC);
+	file_new(path, O_WRONLY | O_CREAT | O_NOFOLLOW | O_TRUNC, flow, passthrough);
 }
 
 void file_append_new(char *path, struct flow *flow, void *passthrough) {
-	file_open_new(path, flow, passthrough, O_WRONLY | O_CREAT | O_NOFOLLOW);
+	file_new(path, O_WRONLY | O_CREAT | O_NOFOLLOW, flow, passthrough);
 }