/* Generic serial interface functions. Copyright (C) 1992-2020 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #include "defs.h" #include "serial.h" #include "ser-base.h" #include "gdbsupport/event-loop.h" #include "gdbsupport/gdb_select.h" #include "gdbsupport/gdb_sys_time.h" #ifdef USE_WIN32API #include <winsock2.h> #endif static timer_handler_func push_event; static handler_func fd_event; /* Event handling for ASYNC serial code. At any time the SERIAL device either: has an empty FIFO and is waiting on a FD event; or has a non-empty FIFO/error condition and is constantly scheduling timer events. ASYNC only stops pestering its client when it is de-async'ed or it is told to go away. */ /* Value of scb->async_state: */ enum { /* >= 0 (TIMER_SCHEDULED) */ /* The ID of the currently scheduled timer event. This state is rarely encountered. Timer events are one-off so as soon as the event is delivered the state is changed to NOTHING_SCHEDULED. */ FD_SCHEDULED = -1, /* The fd_event() handler is scheduled. It is called when ever the file descriptor becomes ready. */ NOTHING_SCHEDULED = -2 /* Either no task is scheduled (just going into ASYNC mode) or a timer event has just gone off and the current state has been forced into nothing scheduled. */ }; /* Identify and schedule the next ASYNC task based on scb->async_state and scb->buf* (the input FIFO). A state machine is used to avoid the need to make redundant calls into the event-loop - the next scheduled task is only changed when needed. */ static void reschedule (struct serial *scb) { if (serial_is_async_p (scb)) { int next_state; switch (scb->async_state) { case FD_SCHEDULED: if (scb->bufcnt == 0) next_state = FD_SCHEDULED; else { delete_file_handler (scb->fd); next_state = create_timer (0, push_event, scb); } break; case NOTHING_SCHEDULED: if (scb->bufcnt == 0) { add_file_handler (scb->fd, fd_event, scb); next_state = FD_SCHEDULED; } else { next_state = create_timer (0, push_event, scb); } break; default: /* TIMER SCHEDULED */ if (scb->bufcnt == 0) { delete_timer (scb->async_state); add_file_handler (scb->fd, fd_event, scb); next_state = FD_SCHEDULED; } else next_state = scb->async_state; break; } if (serial_debug_p (scb)) { switch (next_state) { case FD_SCHEDULED: if (scb->async_state != FD_SCHEDULED) fprintf_unfiltered (gdb_stdlog, "[fd%d->fd-scheduled]\n", scb->fd); break; default: /* TIMER SCHEDULED */ if (scb->async_state == FD_SCHEDULED) fprintf_unfiltered (gdb_stdlog, "[fd%d->timer-scheduled]\n", scb->fd); break; } } scb->async_state = next_state; } } /* Run the SCB's async handle, and reschedule, if the handler doesn't close SCB. */ static void run_async_handler_and_reschedule (struct serial *scb) { int is_open; /* Take a reference, so a serial_close call within the handler doesn't make SCB a dangling pointer. */ serial_ref (scb); /* Run the handler. */ scb->async_handler (scb, scb->async_context); is_open = serial_is_open (scb); serial_unref (scb); /* Get ready for more, if not already closed. */ if (is_open) reschedule (scb); } /* FD_EVENT: This is scheduled when the input FIFO is empty (and there is no pending error). As soon as data arrives, it is read into the input FIFO and the client notified. The client should then drain the FIFO using readchar(). If the FIFO isn't immediatly emptied, push_event() is used to nag the client until it is. */ static void fd_event (int error, void *context) { struct serial *scb = (struct serial *) context; if (error != 0) { scb->bufcnt = SERIAL_ERROR; } else if (scb->bufcnt == 0) { /* Prime the input FIFO. The readchar() function is used to pull characters out of the buffer. See also generic_readchar(). */ int nr; do { nr = scb->ops->read_prim (scb, BUFSIZ); } while (nr < 0 && errno == EINTR); if (nr == 0) { scb->bufcnt = SERIAL_EOF; } else if (nr > 0) { scb->bufcnt = nr; scb->bufp = scb->buf; } else { scb->bufcnt = SERIAL_ERROR; } } run_async_handler_and_reschedule (scb); } /* PUSH_EVENT: The input FIFO is non-empty (or there is a pending error). Nag the client until all the data has been read. In the case of errors, the client will need to close or de-async the device before nagging stops. */ static void push_event (void *context) { struct serial *scb = (struct serial *) context; scb->async_state = NOTHING_SCHEDULED; /* Timers are one-off */ run_async_handler_and_reschedule (scb); } /* Wait for input on scb, with timeout seconds. Returns 0 on success, otherwise SERIAL_TIMEOUT or SERIAL_ERROR. */ /* NOTE: Some of the code below is dead. The only possible values of the TIMEOUT parameter are ONE and ZERO. OTOH, we should probably get rid of the deprecated_ui_loop_hook call in do_ser_base_readchar instead and support infinite time outs here. */ static int ser_base_wait_for (struct serial *scb, int timeout) { while (1) { int numfds; struct timeval tv; fd_set readfds, exceptfds; int nfds; /* NOTE: Some OS's can scramble the READFDS when the select() call fails (ex the kernel with Red Hat 5.2). Initialize all arguments before each call. */ tv.tv_sec = timeout; tv.tv_usec = 0; FD_ZERO (&readfds); FD_ZERO (&exceptfds); FD_SET (scb->fd, &readfds); FD_SET (scb->fd, &exceptfds); QUIT; nfds = scb->fd + 1; if (timeout >= 0) numfds = interruptible_select (nfds, &readfds, 0, &exceptfds, &tv); else numfds = interruptible_select (nfds, &readfds, 0, &exceptfds, 0); if (numfds <= 0) { if (numfds == 0) return SERIAL_TIMEOUT; else if (errno == EINTR) continue; else return SERIAL_ERROR; /* Got an error from select or poll. */ } return 0; } } /* Read any error output we might have. */ static void ser_base_read_error_fd (struct serial *scb, int close_fd) { if (scb->error_fd != -1) { ssize_t s; char buf[GDB_MI_MSG_WIDTH + 1]; for (;;) { char *current; char *newline; int to_read = GDB_MI_MSG_WIDTH; int num_bytes = -1; if (scb->ops->avail) num_bytes = (scb->ops->avail)(scb, scb->error_fd); if (num_bytes != -1) to_read = (num_bytes < to_read) ? num_bytes : to_read; if (to_read == 0) break; s = read (scb->error_fd, &buf, to_read); if ((s == -1) || (s == 0 && !close_fd)) break; if (s == 0 && close_fd) { /* End of file. */ if (serial_is_async_p (scb)) delete_file_handler (scb->error_fd); close (scb->error_fd); scb->error_fd = -1; break; } /* In theory, embedded newlines are not a problem. But for MI, we want each output line to have just one newline for legibility. So output things in newline chunks. */ gdb_assert (s > 0 && s <= GDB_MI_MSG_WIDTH); buf[s] = '\0'; current = buf; while ((newline = strstr (current, "\n")) != NULL) { *newline = '\0'; fputs_unfiltered (current, gdb_stderr); fputs_unfiltered ("\n", gdb_stderr); current = newline + 1; } fputs_unfiltered (current, gdb_stderr); } } } /* Event-loop callback for a serial's error_fd. Flushes any error output we might have. */ static void handle_error_fd (int error, gdb_client_data client_data) { serial *scb = (serial *) client_data; ser_base_read_error_fd (scb, 0); } /* Read a character with user-specified timeout. TIMEOUT is number of seconds to wait, or -1 to wait forever. Use timeout of 0 to effect a poll. Returns char if successful. Returns SERIAL_TIMEOUT if timeout expired, SERIAL_EOF if line dropped dead, or SERIAL_ERROR for any other error (see errno in that case). */ static int do_ser_base_readchar (struct serial *scb, int timeout) { int status; int delta; /* We have to be able to keep the GUI alive here, so we break the original timeout into steps of 1 second, running the "keep the GUI alive" hook each time through the loop. Also, timeout = 0 means to poll, so we just set the delta to 0, so we will only go through the loop once. */ delta = (timeout == 0 ? 0 : 1); while (1) { /* N.B. The UI may destroy our world (for instance by calling remote_stop,) in which case we want to get out of here as quickly as possible. It is not safe to touch scb, since someone else might have freed it. The deprecated_ui_loop_hook signals that we should exit by returning 1. */ if (deprecated_ui_loop_hook) { if (deprecated_ui_loop_hook (0)) return SERIAL_TIMEOUT; } status = ser_base_wait_for (scb, delta); if (timeout > 0) timeout -= delta; /* If we got a character or an error back from wait_for, then we can break from the loop before the timeout is completed. */ if (status != SERIAL_TIMEOUT) break; /* If we have exhausted the original timeout, then generate a SERIAL_TIMEOUT, and pass it out of the loop. */ else if (timeout == 0) { status = SERIAL_TIMEOUT; break; } /* We also need to check and consume the stderr because it could come before the stdout for some stubs. If we just sit and wait for stdout, we would hit a deadlock for that case. */ ser_base_read_error_fd (scb, 0); } if (status < 0) return status; do { status = scb->ops->read_prim (scb, BUFSIZ); } while (status < 0 && errno == EINTR); if (status <= 0) { if (status == 0) return SERIAL_EOF; else /* Got an error from read. */ return SERIAL_ERROR; } scb->bufcnt = status; scb->bufcnt--; scb->bufp = scb->buf; return *scb->bufp++; } /* Perform operations common to both old and new readchar. */ /* Return the next character from the input FIFO. If the FIFO is empty, call the SERIAL specific routine to try and read in more characters. Initially data from the input FIFO is returned (fd_event() pre-reads the input into that FIFO. Once that has been emptied, further data is obtained by polling the input FD using the device specific readchar() function. Note: reschedule() is called after every read. This is because there is no guarentee that the lower level fd_event() poll_event() code (which also calls reschedule()) will be called. */ int generic_readchar (struct serial *scb, int timeout, int (do_readchar) (struct serial *scb, int timeout)) { int ch; if (scb->bufcnt > 0) { ch = *scb->bufp; scb->bufcnt--; scb->bufp++; } else if (scb->bufcnt < 0) { /* Some errors/eof are are sticky. */ ch = scb->bufcnt; } else { ch = do_readchar (scb, timeout); if (ch < 0) { switch ((enum serial_rc) ch) { case SERIAL_EOF: case SERIAL_ERROR: /* Make the error/eof stick. */ scb->bufcnt = ch; break; case SERIAL_TIMEOUT: scb->bufcnt = 0; break; } } } /* Read any error output we might have. */ ser_base_read_error_fd (scb, 1); reschedule (scb); return ch; } int ser_base_readchar (struct serial *scb, int timeout) { return generic_readchar (scb, timeout, do_ser_base_readchar); } int ser_base_write (struct serial *scb, const void *buf, size_t count) { const char *str = (const char *) buf; int cc; while (count > 0) { QUIT; cc = scb->ops->write_prim (scb, str, count); if (cc < 0) { if (errno == EINTR) continue; return 1; } count -= cc; str += cc; } return 0; } int ser_base_flush_output (struct serial *scb) { return 0; } int ser_base_flush_input (struct serial *scb) { if (scb->bufcnt >= 0) { scb->bufcnt = 0; scb->bufp = scb->buf; return 0; } else return SERIAL_ERROR; } int ser_base_send_break (struct serial *scb) { return 0; } int ser_base_drain_output (struct serial *scb) { return 0; } void ser_base_raw (struct serial *scb) { return; /* Always in raw mode. */ } serial_ttystate ser_base_get_tty_state (struct serial *scb) { /* Allocate a dummy. */ return (serial_ttystate) XNEW (int); } serial_ttystate ser_base_copy_tty_state (struct serial *scb, serial_ttystate ttystate) { /* Allocate another dummy. */ return (serial_ttystate) XNEW (int); } int ser_base_set_tty_state (struct serial *scb, serial_ttystate ttystate) { return 0; } void ser_base_print_tty_state (struct serial *scb, serial_ttystate ttystate, struct ui_file *stream) { /* Nothing to print. */ return; } int ser_base_setbaudrate (struct serial *scb, int rate) { return 0; /* Never fails! */ } int ser_base_setstopbits (struct serial *scb, int num) { return 0; /* Never fails! */ } /* Implement the "setparity" serial_ops callback. */ int ser_base_setparity (struct serial *scb, int parity) { return 0; /* Never fails! */ } /* Put the SERIAL device into/out-of ASYNC mode. */ void ser_base_async (struct serial *scb, int async_p) { if (async_p) { /* Force a re-schedule. */ scb->async_state = NOTHING_SCHEDULED; if (serial_debug_p (scb)) fprintf_unfiltered (gdb_stdlog, "[fd%d->asynchronous]\n", scb->fd); reschedule (scb); if (scb->error_fd != -1) add_file_handler (scb->error_fd, handle_error_fd, scb); } else { if (serial_debug_p (scb)) fprintf_unfiltered (gdb_stdlog, "[fd%d->synchronous]\n", scb->fd); /* De-schedule whatever tasks are currently scheduled. */ switch (scb->async_state) { case FD_SCHEDULED: delete_file_handler (scb->fd); break; case NOTHING_SCHEDULED: break; default: /* TIMER SCHEDULED */ delete_timer (scb->async_state); break; } if (scb->error_fd != -1) delete_file_handler (scb->error_fd); } }