1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * taken from gdb/remote.c
4 *
5 * I am only interested in the write to memory stuff - everything else
6 * has been ripped out
7 *
8 * all the copyright notices etc have been left in
9 */
10
11 /* enough so that it will compile */
12 #include <stdio.h>
13 #include <stdlib.h>
14 #include <string.h>
15 #include <errno.h>
16
17 /*nicked from gcc..*/
18
19 #ifndef alloca
20 #ifdef __GNUC__
21 #define alloca __builtin_alloca
22 #else /* not GNU C. */
23 #if (!defined (__STDC__) && defined (sparc)) || defined (__sparc__) || defined (__sparc) || defined (__sgi)
24 #include <alloca.h>
25 #else /* not sparc */
26 #if defined (MSDOS) && !defined (__TURBOC__)
27 #include <malloc.h>
28 #else /* not MSDOS, or __TURBOC__ */
29 #if defined(_AIX)
30 #include <malloc.h>
31 #pragma alloca
32 #else /* not MSDOS, __TURBOC__, or _AIX */
33 #ifdef __hpux
34 #endif /* __hpux */
35 #endif /* not _AIX */
36 #endif /* not MSDOS, or __TURBOC__ */
37 #endif /* not sparc. */
38 #endif /* not GNU C. */
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
42 void* alloca(size_t);
43 #ifdef __cplusplus
44 }
45 #endif
46 #endif /* alloca not defined. */
47
48
49 #include "serial.h"
50 #include "error.h"
51 #include "remote.h"
52 #define REGISTER_BYTES 0
53 #define fprintf_unfiltered fprintf
54 #define fprintf_filtered fprintf
55 #define fputs_unfiltered fputs
56 #define fputs_filtered fputs
57 #define fputc_unfiltered fputc
58 #define fputc_filtered fputc
59 #define printf_unfiltered printf
60 #define printf_filtered printf
61 #define puts_unfiltered puts
62 #define puts_filtered puts
63 #define putchar_unfiltered putchar
64 #define putchar_filtered putchar
65 #define fputstr_unfiltered(a,b,c) fputs((a), (c))
66 #define gdb_stdlog stderr
67 #define SERIAL_READCHAR(fd,timo) serialreadchar((fd), (timo))
68 #define SERIAL_WRITE(fd, addr, len) serialwrite((fd), (addr), (len))
69 #define error Error
70 #define perror_with_name Perror
71 #define gdb_flush fflush
72 #define max(a,b) (((a)>(b))?(a):(b))
73 #define min(a,b) (((a)<(b))?(a):(b))
74 #define target_mourn_inferior() {}
75 #define ULONGEST unsigned long
76 #define CORE_ADDR unsigned long
77
78 static int putpkt (char *);
79 static int putpkt_binary(char *, int);
80 static void getpkt (char *, int);
81
82 static int remote_debug = 0, remote_register_buf_size = 0, watchdog = 0;
83
84 int remote_desc = -1, remote_timeout = 10;
85
86 static void
fputstrn_unfiltered(char * s,int n,int x,FILE * fp)87 fputstrn_unfiltered(char *s, int n, int x, FILE *fp)
88 {
89 while (n-- > 0)
90 fputc(*s++, fp);
91 }
92
93 void
remote_reset(void)94 remote_reset(void)
95 {
96 SERIAL_WRITE(remote_desc, "+", 1);
97 }
98
99 void
remote_continue(void)100 remote_continue(void)
101 {
102 putpkt("c");
103 }
104
105 /* Remote target communications for serial-line targets in custom GDB protocol
106 Copyright 1988, 91, 92, 93, 94, 95, 96, 97, 98, 1999
107 Free Software Foundation, Inc.
108
109 This file is part of GDB.
110 */
111 /* *INDENT-OFF* */
112 /* Remote communication protocol.
113
114 A debug packet whose contents are <data>
115 is encapsulated for transmission in the form:
116
117 $ <data> # CSUM1 CSUM2
118
119 <data> must be ASCII alphanumeric and cannot include characters
120 '$' or '#'. If <data> starts with two characters followed by
121 ':', then the existing stubs interpret this as a sequence number.
122
123 CSUM1 and CSUM2 are ascii hex representation of an 8-bit
124 checksum of <data>, the most significant nibble is sent first.
125 the hex digits 0-9,a-f are used.
126
127 Receiver responds with:
128
129 + - if CSUM is correct and ready for next packet
130 - - if CSUM is incorrect
131
132 <data> is as follows:
133 Most values are encoded in ascii hex digits. Signal numbers are according
134 to the numbering in target.h.
135
136 Request Packet
137
138 set thread Hct... Set thread for subsequent operations.
139 c = 'c' for thread used in step and
140 continue; t... can be -1 for all
141 threads.
142 c = 'g' for thread used in other
143 operations. If zero, pick a thread,
144 any thread.
145 reply OK for success
146 ENN for an error.
147
148 read registers g
149 reply XX....X Each byte of register data
150 is described by two hex digits.
151 Registers are in the internal order
152 for GDB, and the bytes in a register
153 are in the same order the machine uses.
154 or ENN for an error.
155
156 write regs GXX..XX Each byte of register data
157 is described by two hex digits.
158 reply OK for success
159 ENN for an error
160
161 write reg Pn...=r... Write register n... with value r...,
162 which contains two hex digits for each
163 byte in the register (target byte
164 order).
165 reply OK for success
166 ENN for an error
167 (not supported by all stubs).
168
169 read mem mAA..AA,LLLL AA..AA is address, LLLL is length.
170 reply XX..XX XX..XX is mem contents
171 Can be fewer bytes than requested
172 if able to read only part of the data.
173 or ENN NN is errno
174
175 write mem MAA..AA,LLLL:XX..XX
176 AA..AA is address,
177 LLLL is number of bytes,
178 XX..XX is data
179 reply OK for success
180 ENN for an error (this includes the case
181 where only part of the data was
182 written).
183
184 write mem XAA..AA,LLLL:XX..XX
185 (binary) AA..AA is address,
186 LLLL is number of bytes,
187 XX..XX is binary data
188 reply OK for success
189 ENN for an error
190
191 continue cAA..AA AA..AA is address to resume
192 If AA..AA is omitted,
193 resume at same address.
194
195 step sAA..AA AA..AA is address to resume
196 If AA..AA is omitted,
197 resume at same address.
198
199 continue with Csig;AA..AA Continue with signal sig (hex signal
200 signal number). If ;AA..AA is omitted,
201 resume at same address.
202
203 step with Ssig;AA..AA Like 'C' but step not continue.
204 signal
205
206 last signal ? Reply the current reason for stopping.
207 This is the same reply as is generated
208 for step or cont : SAA where AA is the
209 signal number.
210
211 detach D Reply OK.
212
213 There is no immediate reply to step or cont.
214 The reply comes when the machine stops.
215 It is SAA AA is the signal number.
216
217 or... TAAn...:r...;n...:r...;n...:r...;
218 AA = signal number
219 n... = register number (hex)
220 r... = register contents
221 n... = `thread'
222 r... = thread process ID. This is
223 a hex integer.
224 n... = other string not starting
225 with valid hex digit.
226 gdb should ignore this n,r pair
227 and go on to the next. This way
228 we can extend the protocol.
229 or... WAA The process exited, and AA is
230 the exit status. This is only
231 applicable for certains sorts of
232 targets.
233 or... XAA The process terminated with signal
234 AA.
235 or (obsolete) NAA;tttttttt;dddddddd;bbbbbbbb
236 AA = signal number
237 tttttttt = address of symbol "_start"
238 dddddddd = base of data section
239 bbbbbbbb = base of bss section.
240 Note: only used by Cisco Systems
241 targets. The difference between this
242 reply and the "qOffsets" query is that
243 the 'N' packet may arrive spontaneously
244 whereas the 'qOffsets' is a query
245 initiated by the host debugger.
246 or... OXX..XX XX..XX is hex encoding of ASCII data. This
247 can happen at any time while the
248 program is running and the debugger
249 should continue to wait for
250 'W', 'T', etc.
251
252 thread alive TXX Find out if the thread XX is alive.
253 reply OK thread is still alive
254 ENN thread is dead
255
256 remote restart RXX Restart the remote server
257
258 extended ops ! Use the extended remote protocol.
259 Sticky -- only needs to be set once.
260
261 kill request k
262
263 toggle debug d toggle debug flag (see 386 & 68k stubs)
264 reset r reset -- see sparc stub.
265 reserved <other> On other requests, the stub should
266 ignore the request and send an empty
267 response ($#<checksum>). This way
268 we can extend the protocol and GDB
269 can tell whether the stub it is
270 talking to uses the old or the new.
271 search tAA:PP,MM Search backwards starting at address
272 AA for a match with pattern PP and
273 mask MM. PP and MM are 4 bytes.
274 Not supported by all stubs.
275
276 general query qXXXX Request info about XXXX.
277 general set QXXXX=yyyy Set value of XXXX to yyyy.
278 query sect offs qOffsets Get section offsets. Reply is
279 Text=xxx;Data=yyy;Bss=zzz
280
281 Responses can be run-length encoded to save space. A '*' means that
282 the next character is an ASCII encoding giving a repeat count which
283 stands for that many repititions of the character preceding the '*'.
284 The encoding is n+29, yielding a printable character where n >=3
285 (which is where rle starts to win). Don't use an n > 126.
286
287 So
288 "0* " means the same as "0000". */
289 /* *INDENT-ON* */
290
291 /* This variable (available to the user via "set remotebinarydownload")
292 dictates whether downloads are sent in binary (via the 'X' packet).
293 We assume that the stub can, and attempt to do it. This will be cleared if
294 the stub does not understand it. This switch is still needed, though
295 in cases when the packet is supported in the stub, but the connection
296 does not allow it (i.e., 7-bit serial connection only). */
297 static int remote_binary_download = 1;
298
299 /* Have we already checked whether binary downloads work? */
300 static int remote_binary_checked;
301
302 /* Maximum number of bytes to read/write at once. The value here
303 is chosen to fill up a packet (the headers account for the 32). */
304 #define MAXBUFBYTES(N) (((N)-32)/2)
305
306 /* Having this larger than 400 causes us to be incompatible with m68k-stub.c
307 and i386-stub.c. Normally, no one would notice because it only matters
308 for writing large chunks of memory (e.g. in downloads). Also, this needs
309 to be more than 400 if required to hold the registers (see below, where
310 we round it up based on REGISTER_BYTES). */
311 /* Round up PBUFSIZ to hold all the registers, at least. */
312 #define PBUFSIZ ((REGISTER_BYTES > MAXBUFBYTES (400)) \
313 ? (REGISTER_BYTES * 2 + 32) \
314 : 400)
315
316
317 /* This variable sets the number of bytes to be written to the target
318 in a single packet. Normally PBUFSIZ is satisfactory, but some
319 targets need smaller values (perhaps because the receiving end
320 is slow). */
321
322 static int remote_write_size = 0x7fffffff;
323
324 /* This variable sets the number of bits in an address that are to be
325 sent in a memory ("M" or "m") packet. Normally, after stripping
326 leading zeros, the entire address would be sent. This variable
327 restricts the address to REMOTE_ADDRESS_SIZE bits. HISTORY: The
328 initial implementation of remote.c restricted the address sent in
329 memory packets to ``host::sizeof long'' bytes - (typically 32
330 bits). Consequently, for 64 bit targets, the upper 32 bits of an
331 address was never sent. Since fixing this bug may cause a break in
332 some remote targets this variable is principly provided to
333 facilitate backward compatibility. */
334
335 static int remote_address_size;
336
337 /* Convert hex digit A to a number. */
338
339 static int
fromhex(int a)340 fromhex (int a)
341 {
342 if (a >= '0' && a <= '9')
343 return a - '0';
344 else if (a >= 'a' && a <= 'f')
345 return a - 'a' + 10;
346 else if (a >= 'A' && a <= 'F')
347 return a - 'A' + 10;
348 else {
349 error ("Reply contains invalid hex digit %d", a);
350 return -1;
351 }
352 }
353
354 /* Convert number NIB to a hex digit. */
355
356 static int
tohex(int nib)357 tohex (int nib)
358 {
359 if (nib < 10)
360 return '0' + nib;
361 else
362 return 'a' + nib - 10;
363 }
364
365 /* Return the number of hex digits in num. */
366
367 static int
hexnumlen(ULONGEST num)368 hexnumlen (ULONGEST num)
369 {
370 int i;
371
372 for (i = 0; num != 0; i++)
373 num >>= 4;
374
375 return max (i, 1);
376 }
377
378 /* Set BUF to the hex digits representing NUM. */
379
380 static int
hexnumstr(char * buf,ULONGEST num)381 hexnumstr (char *buf, ULONGEST num)
382 {
383 int i;
384 int len = hexnumlen (num);
385
386 buf[len] = '\0';
387
388 for (i = len - 1; i >= 0; i--)
389 {
390 buf[i] = "0123456789abcdef"[(num & 0xf)];
391 num >>= 4;
392 }
393
394 return len;
395 }
396
397 /* Mask all but the least significant REMOTE_ADDRESS_SIZE bits. */
398
399 static CORE_ADDR
remote_address_masked(CORE_ADDR addr)400 remote_address_masked (CORE_ADDR addr)
401 {
402 if (remote_address_size > 0
403 && remote_address_size < (sizeof (ULONGEST) * 8))
404 {
405 /* Only create a mask when that mask can safely be constructed
406 in a ULONGEST variable. */
407 ULONGEST mask = 1;
408 mask = (mask << remote_address_size) - 1;
409 addr &= mask;
410 }
411 return addr;
412 }
413
414 /* Determine whether the remote target supports binary downloading.
415 This is accomplished by sending a no-op memory write of zero length
416 to the target at the specified address. It does not suffice to send
417 the whole packet, since many stubs strip the eighth bit and subsequently
418 compute a wrong checksum, which causes real havoc with remote_write_bytes.
419
420 NOTE: This can still lose if the serial line is not eight-bit clean. In
421 cases like this, the user should clear "remotebinarydownload". */
422 static void
check_binary_download(CORE_ADDR addr)423 check_binary_download (CORE_ADDR addr)
424 {
425 if (remote_binary_download && !remote_binary_checked)
426 {
427 char *buf = alloca (PBUFSIZ);
428 char *p;
429 remote_binary_checked = 1;
430
431 p = buf;
432 *p++ = 'X';
433 p += hexnumstr (p, (ULONGEST) addr);
434 *p++ = ',';
435 p += hexnumstr (p, (ULONGEST) 0);
436 *p++ = ':';
437 *p = '\0';
438
439 putpkt_binary (buf, (int) (p - buf));
440 getpkt (buf, 0);
441
442 if (buf[0] == '\0')
443 remote_binary_download = 0;
444 }
445
446 if (remote_debug)
447 {
448 if (remote_binary_download)
449 fprintf_unfiltered (gdb_stdlog,
450 "binary downloading suppported by target\n");
451 else
452 fprintf_unfiltered (gdb_stdlog,
453 "binary downloading NOT suppported by target\n");
454 }
455 }
456
457 /* Write memory data directly to the remote machine.
458 This does not inform the data cache; the data cache uses this.
459 MEMADDR is the address in the remote memory space.
460 MYADDR is the address of the buffer in our space.
461 LEN is the number of bytes.
462
463 Returns number of bytes transferred, or 0 for error. */
464
465 int
remote_write_bytes(memaddr,myaddr,len)466 remote_write_bytes (memaddr, myaddr, len)
467 CORE_ADDR memaddr;
468 char *myaddr;
469 int len;
470 {
471 unsigned char *buf = alloca (PBUFSIZ);
472 int max_buf_size; /* Max size of packet output buffer */
473 int origlen;
474 extern int verbose;
475
476 /* Verify that the target can support a binary download */
477 check_binary_download (memaddr);
478
479 /* Chop the transfer down if necessary */
480
481 max_buf_size = min (remote_write_size, PBUFSIZ);
482 if (remote_register_buf_size != 0)
483 max_buf_size = min (max_buf_size, remote_register_buf_size);
484
485 /* Subtract header overhead from max payload size - $M<memaddr>,<len>:#nn */
486 max_buf_size -= 2 + hexnumlen (memaddr + len - 1) + 1 + hexnumlen (len) + 4;
487
488 origlen = len;
489 while (len > 0)
490 {
491 unsigned char *p, *plen;
492 int todo;
493 int i;
494
495 /* construct "M"<memaddr>","<len>":" */
496 /* sprintf (buf, "M%lx,%x:", (unsigned long) memaddr, todo); */
497 memaddr = remote_address_masked (memaddr);
498 p = buf;
499 if (remote_binary_download)
500 {
501 *p++ = 'X';
502 todo = min (len, max_buf_size);
503 }
504 else
505 {
506 *p++ = 'M';
507 todo = min (len, max_buf_size / 2); /* num bytes that will fit */
508 }
509
510 p += hexnumstr ((char *)p, (ULONGEST) memaddr);
511 *p++ = ',';
512
513 plen = p; /* remember where len field goes */
514 p += hexnumstr ((char *)p, (ULONGEST) todo);
515 *p++ = ':';
516 *p = '\0';
517
518 /* We send target system values byte by byte, in increasing byte
519 addresses, each byte encoded as two hex characters (or one
520 binary character). */
521 if (remote_binary_download)
522 {
523 int escaped = 0;
524 for (i = 0;
525 (i < todo) && (i + escaped) < (max_buf_size - 2);
526 i++)
527 {
528 switch (myaddr[i] & 0xff)
529 {
530 case '$':
531 case '#':
532 case 0x7d:
533 /* These must be escaped */
534 escaped++;
535 *p++ = 0x7d;
536 *p++ = (myaddr[i] & 0xff) ^ 0x20;
537 break;
538 default:
539 *p++ = myaddr[i] & 0xff;
540 break;
541 }
542 }
543
544 if (i < todo)
545 {
546 /* Escape chars have filled up the buffer prematurely,
547 and we have actually sent fewer bytes than planned.
548 Fix-up the length field of the packet. */
549
550 /* FIXME: will fail if new len is a shorter string than
551 old len. */
552
553 plen += hexnumstr ((char *)plen, (ULONGEST) i);
554 *plen++ = ':';
555 }
556 }
557 else
558 {
559 for (i = 0; i < todo; i++)
560 {
561 *p++ = tohex ((myaddr[i] >> 4) & 0xf);
562 *p++ = tohex (myaddr[i] & 0xf);
563 }
564 *p = '\0';
565 }
566
567 putpkt_binary ((char *)buf, (int) (p - buf));
568 getpkt ((char *)buf, 0);
569
570 if (buf[0] == 'E')
571 {
572 /* There is no correspondance between what the remote protocol uses
573 for errors and errno codes. We would like a cleaner way of
574 representing errors (big enough to include errno codes, bfd_error
575 codes, and others). But for now just return EIO. */
576 errno = EIO;
577 return 0;
578 }
579
580 /* Increment by i, not by todo, in case escape chars
581 caused us to send fewer bytes than we'd planned. */
582 myaddr += i;
583 memaddr += i;
584 len -= i;
585
586 if (verbose)
587 putc('.', stderr);
588 }
589 return origlen;
590 }
591
592 /* Stuff for dealing with the packets which are part of this protocol.
593 See comment at top of file for details. */
594
595 /* Read a single character from the remote end, masking it down to 7 bits. */
596
597 static int
readchar(int timeout)598 readchar (int timeout)
599 {
600 int ch;
601
602 ch = SERIAL_READCHAR (remote_desc, timeout);
603
604 switch (ch)
605 {
606 case SERIAL_EOF:
607 error ("Remote connection closed");
608 case SERIAL_ERROR:
609 perror_with_name ("Remote communication error");
610 case SERIAL_TIMEOUT:
611 return ch;
612 default:
613 return ch & 0x7f;
614 }
615 }
616
617 static int
putpkt(buf)618 putpkt (buf)
619 char *buf;
620 {
621 return putpkt_binary (buf, strlen (buf));
622 }
623
624 /* Send a packet to the remote machine, with error checking. The data
625 of the packet is in BUF. The string in BUF can be at most PBUFSIZ - 5
626 to account for the $, # and checksum, and for a possible /0 if we are
627 debugging (remote_debug) and want to print the sent packet as a string */
628
629 static int
putpkt_binary(buf,cnt)630 putpkt_binary (buf, cnt)
631 char *buf;
632 int cnt;
633 {
634 int i;
635 unsigned char csum = 0;
636 char *buf2 = alloca (PBUFSIZ);
637 char *junkbuf = alloca (PBUFSIZ);
638
639 int ch;
640 int tcount = 0;
641 char *p;
642
643 /* Copy the packet into buffer BUF2, encapsulating it
644 and giving it a checksum. */
645
646 if (cnt > BUFSIZ - 5) /* Prosanity check */
647 abort ();
648
649 p = buf2;
650 *p++ = '$';
651
652 for (i = 0; i < cnt; i++)
653 {
654 csum += buf[i];
655 *p++ = buf[i];
656 }
657 *p++ = '#';
658 *p++ = tohex ((csum >> 4) & 0xf);
659 *p++ = tohex (csum & 0xf);
660
661 /* Send it over and over until we get a positive ack. */
662
663 while (1)
664 {
665 int started_error_output = 0;
666
667 if (remote_debug)
668 {
669 *p = '\0';
670 fprintf_unfiltered (gdb_stdlog, "Sending packet: ");
671 fputstrn_unfiltered (buf2, p - buf2, 0, gdb_stdlog);
672 fprintf_unfiltered (gdb_stdlog, "...");
673 gdb_flush (gdb_stdlog);
674 }
675 if (SERIAL_WRITE (remote_desc, buf2, p - buf2))
676 perror_with_name ("putpkt: write failed");
677
678 /* read until either a timeout occurs (-2) or '+' is read */
679 while (1)
680 {
681 ch = readchar (remote_timeout);
682
683 if (remote_debug)
684 {
685 switch (ch)
686 {
687 case '+':
688 case SERIAL_TIMEOUT:
689 case '$':
690 if (started_error_output)
691 {
692 putchar_unfiltered ('\n');
693 started_error_output = 0;
694 }
695 }
696 }
697
698 switch (ch)
699 {
700 case '+':
701 if (remote_debug)
702 fprintf_unfiltered (gdb_stdlog, "Ack\n");
703 return 1;
704 case SERIAL_TIMEOUT:
705 tcount++;
706 if (tcount > 3)
707 return 0;
708 break; /* Retransmit buffer */
709 case '$':
710 {
711 /* It's probably an old response, and we're out of sync.
712 Just gobble up the packet and ignore it. */
713 getpkt (junkbuf, 0);
714 continue; /* Now, go look for + */
715 }
716 default:
717 if (remote_debug)
718 {
719 if (!started_error_output)
720 {
721 started_error_output = 1;
722 fprintf_unfiltered (gdb_stdlog, "putpkt: Junk: ");
723 }
724 fputc_unfiltered (ch & 0177, gdb_stdlog);
725 }
726 continue;
727 }
728 break; /* Here to retransmit */
729 }
730
731 #if 0
732 /* This is wrong. If doing a long backtrace, the user should be
733 able to get out next time we call QUIT, without anything as
734 violent as interrupt_query. If we want to provide a way out of
735 here without getting to the next QUIT, it should be based on
736 hitting ^C twice as in remote_wait. */
737 if (quit_flag)
738 {
739 quit_flag = 0;
740 interrupt_query ();
741 }
742 #endif
743 }
744 }
745
746 /* Come here after finding the start of the frame. Collect the rest
747 into BUF, verifying the checksum, length, and handling run-length
748 compression. Returns 0 on any error, 1 on success. */
749
750 static int
read_frame(char * buf)751 read_frame (char *buf)
752 {
753 unsigned char csum;
754 char *bp;
755 int c;
756
757 csum = 0;
758 bp = buf;
759
760 while (1)
761 {
762 c = readchar (remote_timeout);
763
764 switch (c)
765 {
766 case SERIAL_TIMEOUT:
767 if (remote_debug)
768 fputs_filtered ("Timeout in mid-packet, retrying\n", gdb_stdlog);
769 return 0;
770 case '$':
771 if (remote_debug)
772 fputs_filtered ("Saw new packet start in middle of old one\n",
773 gdb_stdlog);
774 return 0; /* Start a new packet, count retries */
775 case '#':
776 {
777 unsigned char pktcsum;
778
779 *bp = '\000';
780
781 pktcsum = fromhex (readchar (remote_timeout)) << 4;
782 pktcsum |= fromhex (readchar (remote_timeout));
783
784 if (csum == pktcsum)
785 {
786 return 1;
787 }
788
789 if (remote_debug)
790 {
791 fprintf_filtered (gdb_stdlog,
792 "Bad checksum, sentsum=0x%x, csum=0x%x, buf=",
793 pktcsum, csum);
794 fputs_filtered (buf, gdb_stdlog);
795 fputs_filtered ("\n", gdb_stdlog);
796 }
797 return 0;
798 }
799 case '*': /* Run length encoding */
800 csum += c;
801 c = readchar (remote_timeout);
802 csum += c;
803 c = c - ' ' + 3; /* Compute repeat count */
804
805 if (c > 0 && c < 255 && bp + c - 1 < buf + PBUFSIZ - 1)
806 {
807 memset (bp, *(bp - 1), c);
808 bp += c;
809 continue;
810 }
811
812 *bp = '\0';
813 printf_filtered ("Repeat count %d too large for buffer: ", c);
814 puts_filtered (buf);
815 puts_filtered ("\n");
816 return 0;
817 default:
818 if (bp < buf + PBUFSIZ - 1)
819 {
820 *bp++ = c;
821 csum += c;
822 continue;
823 }
824
825 *bp = '\0';
826 puts_filtered ("Remote packet too long: ");
827 puts_filtered (buf);
828 puts_filtered ("\n");
829
830 return 0;
831 }
832 }
833 }
834
835 /* Read a packet from the remote machine, with error checking, and
836 store it in BUF. BUF is expected to be of size PBUFSIZ. If
837 FOREVER, wait forever rather than timing out; this is used while
838 the target is executing user code. */
839
840 static void
getpkt(buf,forever)841 getpkt (buf, forever)
842 char *buf;
843 int forever;
844 {
845 int c;
846 int tries;
847 int timeout;
848 int val;
849
850 strcpy (buf, "timeout");
851
852 if (forever)
853 {
854 timeout = watchdog > 0 ? watchdog : -1;
855 }
856
857 else
858 timeout = remote_timeout;
859
860 #define MAX_TRIES 3
861
862 for (tries = 1; tries <= MAX_TRIES; tries++)
863 {
864 /* This can loop forever if the remote side sends us characters
865 continuously, but if it pauses, we'll get a zero from readchar
866 because of timeout. Then we'll count that as a retry. */
867
868 /* Note that we will only wait forever prior to the start of a packet.
869 After that, we expect characters to arrive at a brisk pace. They
870 should show up within remote_timeout intervals. */
871
872 do
873 {
874 c = readchar (timeout);
875
876 if (c == SERIAL_TIMEOUT)
877 {
878 if (forever) /* Watchdog went off. Kill the target. */
879 {
880 target_mourn_inferior ();
881 error ("Watchdog has expired. Target detached.\n");
882 }
883 if (remote_debug)
884 fputs_filtered ("Timed out.\n", gdb_stdlog);
885 goto retry;
886 }
887 }
888 while (c != '$');
889
890 /* We've found the start of a packet, now collect the data. */
891
892 val = read_frame (buf);
893
894 if (val == 1)
895 {
896 if (remote_debug)
897 {
898 fprintf_unfiltered (gdb_stdlog, "Packet received: ");
899 fputstr_unfiltered (buf, 0, gdb_stdlog);
900 fprintf_unfiltered (gdb_stdlog, "\n");
901 }
902 SERIAL_WRITE (remote_desc, "+", 1);
903 return;
904 }
905
906 /* Try the whole thing again. */
907 retry:
908 SERIAL_WRITE (remote_desc, "-", 1);
909 }
910
911 /* We have tried hard enough, and just can't receive the packet. Give up. */
912
913 printf_unfiltered ("Ignoring packet error, continuing...\n");
914 SERIAL_WRITE (remote_desc, "+", 1);
915 }
916