HTTP/3: proper uni stream closure detection. Previously, closure detection for server-initiated uni streams was not properly implemented. Instead, HTTP/3 code relied on QUIC code posting the read event and setting rev->error when it needed to close the stream. Then, regular uni stream read handler called c->recv() and received error, which closed the stream. This was an ad-hoc solution. If, for whatever reason, the read handler was called earlier, c->recv() would return 0, which would also close the stream. Now server-initiated uni streams have a separate read event handler for tracking stream closure. The handler calls c->recv(), which normally returns 0, but may return error in case of closure.

/* XPM */
static char * nginx_xpm[] = {
"16 16 2 2",
/* colors */
"   c none",
"GG c #009900",
/* pixels */
"                                ",
"        GGGGGGGGGGGGGGGG        ",
"        GGGGGGGGGGGGGGGG        ",
"      GGGGGGGGGGGGGGGGGGGG      ",
"      GGGGGG        GGGGGG      ",
"    GGGGGG            GGGGGG    ",
"    GGGGGG                      ",
"  GGGGGG      GGGGGGGGGGGGGGGG  ",
"  GGGGGG    GGGGGGGGGGGGGGGGGG  ",
"    GGGGGG    GGGGGGGGGGGGGG    ",
"    GGGGGG            GGGGGG    ",
"      GGGGGG        GGGGGG      ",
"      GGGGGGGGGGGGGGGGGGGG      ",
"        GGGGGGGGGGGGGGGG        ",
"        GGGGGGGGGGGGGGGG        ",
"                                "
};