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73f8bc754e
add memory fences because why not.
69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
#include <unistd.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <stdatomic.h>
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#include "common.h"
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static int tabfs_to_ws[2];
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static int ws_to_tabfs[2];
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void common_init() {
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if (pipe(tabfs_to_ws)) exit(1);
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if (pipe(ws_to_tabfs)) exit(1);
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}
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// We probably technically need memory fences here? especially on
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// non-x86?? Are these right? idk. See
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// https://stackoverflow.com/questions/35837539/does-the-use-of-an-anonymous-pipe-introduce-a-memory-barrier-for-interthread-com
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// https://preshing.com/20120913/acquire-and-release-semantics/
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void common_send_tabfs_to_ws(char *request_data) {
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atomic_thread_fence(memory_order_release);
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write(tabfs_to_ws[1], &request_data, sizeof(request_data));
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}
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char *common_receive_tabfs_to_ws(fd_set_filler_fn_t filler) {
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fd_set read_fds, write_fds, except_fds;
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FD_ZERO(&read_fds);
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FD_ZERO(&write_fds);
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FD_ZERO(&except_fds);
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int max_fd = filler(&read_fds, &write_fds, &except_fds);
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FD_SET(tabfs_to_ws[0], &read_fds);
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if (tabfs_to_ws[0] > max_fd) { max_fd = tabfs_to_ws[0]; }
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struct timeval timeout;
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timeout.tv_sec = 0;
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timeout.tv_usec = 200000;
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select(max_fd + 1, &read_fds, &write_fds, &except_fds, &timeout);
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if (!FD_ISSET(tabfs_to_ws[0], &read_fds)) {
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// We can't read from tabfs_to_ws right now. Could be that it
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// timed out, could be that we got a websocket event instead,
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// whatever.
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return NULL;
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}
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char *request_data;
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read(tabfs_to_ws[0], &request_data, sizeof(request_data));
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atomic_thread_fence(memory_order_acquire);
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return request_data;
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}
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void common_send_ws_to_tabfs(char *response_data) {
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atomic_thread_fence(memory_order_release);
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write(ws_to_tabfs[1], &response_data, sizeof(response_data));
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}
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char *common_receive_ws_to_tabfs() {
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char *response_data;
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read(ws_to_tabfs[0], &response_data, sizeof(response_data));
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atomic_thread_fence(memory_order_acquire);
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return response_data;
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}
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