mdw@git.distorted.org.uk Git - secnet/blob - util.c

   1 /*
   2  * util.c
   3  * - output and logging support
   4  * - program lifetime support
   5  * - IP address and subnet munging routines
   6  * - MPI convenience functions
   7  */
   8 /*
   9  * This file is part of secnet.
  10  * See README for full list of copyright holders.
  11  *
  12  * secnet is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License as published by
  14  * the Free Software Foundation; either version d of the License, or
  15  * (at your option) any later version.
  16  *
  17  * secnet is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * version 3 along with secnet; if not, see
  24  * https://www.gnu.org/licenses/gpl.html.
  25  */
  26
  27 #include "secnet.h"
  28 #include <stdio.h>
  29 #include <string.h>
  30 #include <errno.h>
  31 #include <unistd.h>
  32 #include <limits.h>
  33 #include <assert.h>
  34 #include <sys/wait.h>
  35 #include <adns.h>
  36 #include "util.h"
  37 #include "unaligned.h"
  38 #include "magic.h"
  39 #include "ipaddr.h"
  40
  41 #define MIN_BUFFER_SIZE 64
  42 #define DEFAULT_BUFFER_SIZE 4096
  43 #define MAX_BUFFER_SIZE 131072
  44
  45 static const char *hexdigits="0123456789abcdef";
  46
  47 uint32_t current_phase=0;
  48
  49 struct phase_hook {
  50     hook_fn *fn;
  51     void *state;
  52     LIST_ENTRY(phase_hook) entry;
  53 };
  54
  55 static LIST_HEAD(, phase_hook) hooks[NR_PHASES];
  56
  57 char *safe_strdup(const char *s, const char *message)
  58 {
  59     char *d;
  60     d=strdup(s);
  61     if (!d) {
  62         fatal_perror("%s",message);
  63     }
  64     return d;
  65 }
  66
  67 void *safe_malloc(size_t size, const char *message)
  68 {
  69     void *r;
  70     if (!size)
  71         return 0;
  72     r=malloc(size);
  73     if (!r) {
  74         fatal_perror("%s",message);
  75     }
  76     return r;
  77 }
  78 void *safe_realloc_ary(void *p, size_t size, size_t count,
  79                        const char *message) {
  80     if (count >= INT_MAX/size) {
  81         fatal("array allocation overflow: %s", message);
  82     }
  83     assert(size && count);
  84     p = realloc(p, size*count);
  85     if (!p)
  86         fatal_perror("%s", message);
  87     return p;
  88 }
  89
  90 void *safe_malloc_ary(size_t size, size_t count, const char *message) {
  91     if (!size || !count)
  92         return 0;
  93     return safe_realloc_ary(0,size,count,message);
  94 }
  95
  96 /* Convert a buffer into its MP_INT representation */
  97 void read_mpbin(MP_INT *a, uint8_t *bin, int binsize)
  98 {
  99     char *buff;
 100     int i;
 101
 102     buff=safe_malloc(binsize*2 + 1,"read_mpbin");
 103
 104     for (i=0; i<binsize; i++) {
 105         buff[i*2]=hexdigits[(bin[i] & 0xf0) >> 4];
 106         buff[i*2+1]=hexdigits[(bin[i] & 0xf)];
 107     }
 108     buff[binsize*2]=0;
 109
 110     mpz_set_str(a, buff, 16);
 111     free(buff);
 112 }
 113
 114 /* Convert a MP_INT into a hex string */
 115 char *write_mpstring(MP_INT *a)
 116 {
 117     char *buff;
 118
 119     buff=safe_malloc(mpz_sizeinbase(a,16)+2,"write_mpstring");
 120     mpz_get_str(buff, 16, a);
 121     return buff;
 122 }
 123
 124 static uint8_t hexval(uint8_t c)
 125 {
 126     switch (c) {
 127     case '0': return 0;
 128     case '1': return 1;
 129     case '2': return 2;
 130     case '3': return 3;
 131     case '4': return 4;
 132     case '5': return 5;
 133     case '6': return 6;
 134     case '7': return 7;
 135     case '8': return 8;
 136     case '9': return 9;
 137     case 'a': return 10;
 138     case 'A': return 10;
 139     case 'b': return 11;
 140     case 'B': return 11;
 141     case 'c': return 12;
 142     case 'C': return 12;
 143     case 'd': return 13;
 144     case 'D': return 13;
 145     case 'e': return 14;
 146     case 'E': return 14;
 147     case 'f': return 15;
 148     case 'F': return 15;
 149     }
 150     return -1;
 151 }
 152
 153 /* Convert a MP_INT into a buffer; return length; truncate if necessary */
 154 int32_t write_mpbin(MP_INT *a, uint8_t *buffer, int32_t buflen)
 155 {
 156     char *hb;
 157     int i,j,l;
 158
 159     if (buflen==0) return 0;
 160     hb=write_mpstring(a);
 161
 162     l=strlen(hb);
 163     i=0; j=0;
 164     if (l&1) {
 165         /* The number starts with a half-byte */
 166         buffer[i++]=hexval(hb[j++]);
 167     }
 168     for (; hb[j] && i<buflen; i++) {
 169         buffer[i]=(hexval(hb[j])<<4)|hexval(hb[j+1]);
 170         j+=2;
 171     }
 172     free(hb);
 173     return i;
 174 }
 175
 176 #define DEFINE_SETFDFLAG(fn,FL,FLAG)                                    \
 177 void fn(int fd) {                                                       \
 178     int r=fcntl(fd, F_GET##FL);                                         \
 179     if (r<0) fatal_perror("fcntl(,F_GET" #FL ") failed");               \
 180     r=fcntl(fd, F_SET##FL, r|FLAG);                                     \
 181     if (r<0) fatal_perror("fcntl(,F_SET" #FL ",|" #FLAG ") failed");    \
 182 }
 183
 184 DEFINE_SETFDFLAG(setcloexec,FD,FD_CLOEXEC);
 185 DEFINE_SETFDFLAG(setnonblock,FL,O_NONBLOCK);
 186
 187 void pipe_cloexec(int fd[2]) {
 188     int r=pipe(fd);
 189     if (r) fatal_perror("pipe");
 190     setcloexec(fd[0]);
 191     setcloexec(fd[1]);
 192 }
 193
 194 static const char *phases[NR_PHASES]={
 195     "PHASE_INIT",
 196     "PHASE_GETOPTS",
 197     "PHASE_READCONFIG",
 198     "PHASE_SETUP",
 199     "PHASE_DAEMONIZE",
 200     "PHASE_GETRESOURCES",
 201     "PHASE_DROPPRIV",
 202     "PHASE_RUN",
 203     "PHASE_SHUTDOWN",
 204     "PHASE_CHILDPERSIST"
 205 };
 206
 207 void enter_phase(uint32_t new_phase)
 208 {
 209     struct phase_hook *i;
 210
 211     if (!LIST_EMPTY(&hooks[new_phase]))
 212         Message(M_DEBUG_PHASE,"Running hooks for %s...\n", phases[new_phase]);
 213     current_phase=new_phase;
 214
 215     LIST_FOREACH(i, &hooks[new_phase], entry)
 216         i->fn(i->state, new_phase);
 217     Message(M_DEBUG_PHASE,"Now in %s\n",phases[new_phase]);
 218 }
 219
 220 void phase_hooks_init(void)
 221 {
 222     int i;
 223     for (i=0; i<NR_PHASES; i++)
 224         LIST_INIT(&hooks[i]);
 225 }
 226
 227 void clear_phase_hooks(uint32_t phase)
 228 {
 229     struct phase_hook *h, *htmp;
 230     LIST_FOREACH_SAFE(h, &hooks[phase], entry, htmp)
 231         free(h);
 232     LIST_INIT(&hooks[phase]);
 233 }
 234
 235 bool_t add_hook(uint32_t phase, hook_fn *fn, void *state)
 236 {
 237     struct phase_hook *h;
 238
 239     NEW(h);
 240     h->fn=fn;
 241     h->state=state;
 242     LIST_INSERT_HEAD(&hooks[phase],h,entry);
 243     return True;
 244 }
 245
 246 bool_t remove_hook(uint32_t phase, hook_fn *fn, void *state)
 247 {
 248     fatal("remove_hook: not implemented");
 249
 250     return False;
 251 }
 252
 253 void vslilog(struct log_if *lf, int priority, const char *message, va_list ap)
 254 {
 255     lf->vlogfn(lf->st,priority,message,ap);
 256 }
 257
 258 void slilog(struct log_if *lf, int priority, const char *message, ...)
 259 {
 260     va_list ap;
 261
 262     va_start(ap,message);
 263     vslilog(lf,priority,message,ap);
 264     va_end(ap);
 265 }
 266
 267 struct buffer {
 268     closure_t cl;
 269     struct buffer_if ops;
 270 };
 271
 272 void buffer_assert_free(struct buffer_if *buffer, cstring_t file,
 273                         int line)
 274 {
 275     if (!buffer->free) {
 276         fprintf(stderr,"secnet: BUF_ASSERT_FREE, %s line %d, owned by %s",
 277                 file,line,buffer->owner);
 278         assert(!"buffer_assert_free failure");
 279     }
 280 }
 281
 282 void buffer_assert_used(struct buffer_if *buffer, cstring_t file,
 283                         int line)
 284 {
 285     if (buffer->free) {
 286         fprintf(stderr,"secnet: BUF_ASSERT_USED, %s line %d, last owned by %s",
 287                 file,line,buffer->owner);
 288         assert(!"buffer_assert_used failure");
 289     }
 290 }
 291
 292 void buffer_init(struct buffer_if *buffer, int32_t max_start_pad)
 293 {
 294     assert(max_start_pad<=buffer->alloclen);
 295     buffer->start=buffer->base+max_start_pad;
 296     buffer->size=0;
 297 }
 298
 299 void buffer_destroy(struct buffer_if *buf)
 300 {
 301     BUF_ASSERT_FREE(buf);
 302     free(buf->base);
 303     buf->start=buf->base=0;
 304     buf->size=buf->alloclen=0;
 305 }
 306
 307 void *buf_append(struct buffer_if *buf, int32_t amount) {
 308     void *p;
 309     assert(amount <= buf_remaining_space(buf));
 310     p=buf->start + buf->size;
 311     buf->size+=amount;
 312     return p;
 313 }
 314
 315 void *buf_prepend(struct buffer_if *buf, int32_t amount) {
 316     assert(amount <= buf->start - buf->base);
 317     buf->size+=amount;
 318     return buf->start-=amount;
 319 }
 320
 321 void *buf_unappend(struct buffer_if *buf, int32_t amount) {
 322     if (buf->size < amount) return 0;
 323     return buf->start+(buf->size-=amount);
 324 }
 325
 326 void *buf_unprepend(struct buffer_if *buf, int32_t amount) {
 327     void *p;
 328     if (buf->size < amount) return 0;
 329     p=buf->start;
 330     buf->start+=amount;
 331     buf->size-=amount;
 332     return p;
 333 }
 334
 335 /* Append a two-byte length and the string to the buffer. Length is in
 336    network byte order. */
 337 void buf_append_string(struct buffer_if *buf, cstring_t s)
 338 {
 339     size_t len;
 340
 341     len=strlen(s);
 342     /* fixme: if string is longer than 65535, result is a corrupted packet */
 343     buf_append_uint16(buf,len);
 344     BUF_ADD_BYTES(append,buf,s,len);
 345 }
 346
 347 void buffer_new(struct buffer_if *buf, int32_t len)
 348 {
 349     buf->free=True;
 350     buf->owner=NULL;
 351     buf->flags=0;
 352     buf->loc.file=NULL;
 353     buf->loc.line=0;
 354     buf->size=0;
 355     buf->alloclen=len;
 356     buf->start=NULL;
 357     buf->base=safe_malloc(len,"buffer_new");
 358 }
 359
 360 void buffer_readonly_view(struct buffer_if *buf, const void *data, int32_t len)
 361 {
 362     buf->free=False;
 363     buf->owner="READONLY";
 364     buf->flags=0;
 365     buf->loc.file=NULL;
 366     buf->loc.line=0;
 367     buf->size=buf->alloclen=len;
 368     buf->base=buf->start=(uint8_t*)data;
 369 }
 370
 371 void buffer_readonly_clone(struct buffer_if *out, const struct buffer_if *in)
 372 {
 373     buffer_readonly_view(out,in->start,in->size);
 374 }
 375
 376 void buffer_copy(struct buffer_if *dst, const struct buffer_if *src)
 377 {
 378     if (dst->alloclen < src->alloclen) {
 379         dst->base=realloc(dst->base,src->alloclen);
 380         if (!dst->base) fatal_perror("buffer_copy");
 381         dst->alloclen = src->alloclen;
 382     }
 383     dst->start = dst->base + (src->start - src->base);
 384     dst->size = src->size;
 385     memcpy(dst->start, src->start, dst->size);
 386 }
 387
 388 static list_t *buffer_apply(closure_t *self, struct cloc loc, dict_t *context,
 389                             list_t *args)
 390 {
 391     struct buffer *st;
 392     item_t *item;
 393     dict_t *dict;
 394     bool_t lockdown=False;
 395     uint32_t len=DEFAULT_BUFFER_SIZE;
 396
 397     NEW(st);
 398     st->cl.description="buffer";
 399     st->cl.type=CL_BUFFER;
 400     st->cl.apply=NULL;
 401     st->cl.interface=&st->ops;
 402
 403     /* First argument, if present, is buffer length */
 404     item=list_elem(args,0);
 405     if (item) {
 406         if (item->type!=t_number) {
 407             cfgfatal(st->ops.loc,"buffer","first parameter must be a "
 408                      "number (buffer size)\n");
 409         }
 410         len=item->data.number;
 411         if (len<MIN_BUFFER_SIZE) {
 412             cfgfatal(st->ops.loc,"buffer","ludicrously small buffer size\n");
 413         }
 414         if (len>MAX_BUFFER_SIZE) {
 415             cfgfatal(st->ops.loc,"buffer","ludicrously large buffer size\n");
 416         }
 417     }
 418     /* Second argument, if present, is a dictionary */
 419     item=list_elem(args,1);
 420     if (item) {
 421         if (item->type!=t_dict) {
 422             cfgfatal(st->ops.loc,"buffer","second parameter must be a "
 423                      "dictionary\n");
 424         }
 425         dict=item->data.dict;
 426         lockdown=dict_read_bool(dict,"lockdown",False,"buffer",st->ops.loc,
 427                                 False);
 428     }
 429
 430     buffer_new(&st->ops,len);
 431     if (lockdown) {
 432         /* XXX mlock the buffer if possible */
 433     }
 434
 435     return new_closure(&st->cl);
 436 }
 437
 438 void send_nak(const struct comm_addr *dest, uint32_t our_index,
 439               uint32_t their_index, uint32_t msgtype,
 440               struct buffer_if *buf, const char *logwhy)
 441 {
 442     buffer_init(buf,calculate_max_start_pad());
 443     buf_append_uint32(buf,their_index);
 444     buf_append_uint32(buf,our_index);
 445     buf_append_uint32(buf,LABEL_NAK);
 446     if (logwhy)
 447         Message(M_INFO,"%s: %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
 448                 " %s; sending NAK\n",
 449                 comm_addr_to_string(dest),
 450                 our_index, their_index, msgtype, logwhy);
 451     dest->comm->sendmsg(dest->comm->st, buf, dest, 0);
 452 }
 453
 454 int consttime_memeq(const void *s1in, const void *s2in, size_t n)
 455 {
 456     const uint8_t *s1=s1in, *s2=s2in;
 457     register volatile uint8_t accumulator=0;
 458
 459     while (n-- > 0) {
 460         accumulator |= (*s1++ ^ *s2++);
 461     }
 462     accumulator |= accumulator >> 4; /* constant-time             */
 463     accumulator |= accumulator >> 2; /*  boolean canonicalisation */
 464     accumulator |= accumulator >> 1;
 465     accumulator &= 1;
 466     accumulator ^= 1;
 467     return accumulator;
 468 }
 469
 470 void util_module(dict_t *dict)
 471 {
 472     add_closure(dict,"sysbuffer",buffer_apply);
 473 }
 474
 475 void update_max_start_pad(int32_t *our_module_global, int32_t our_instance)
 476 {
 477     if (*our_module_global < our_instance)
 478         *our_module_global=our_instance;
 479 }
 480
 481 int32_t transform_max_start_pad, comm_max_start_pad;
 482
 483 int32_t calculate_max_start_pad(void)
 484 {
 485     return
 486         site_max_start_pad +
 487         transform_max_start_pad +
 488         comm_max_start_pad;
 489 }
 490
 491 void vslilog_part(struct log_if *lf, int priority, const char *message, va_list ap)
 492 {
 493     char *buff=lf->buff;
 494     size_t bp;
 495     char *nlp;
 496
 497     bp=strlen(buff);
 498     assert(bp < LOG_MESSAGE_BUFLEN);
 499     vsnprintf(buff+bp,LOG_MESSAGE_BUFLEN-bp,message,ap);
 500     buff[LOG_MESSAGE_BUFLEN-1] = '\n';
 501     buff[LOG_MESSAGE_BUFLEN] = '\0';
 502     /* Each line is sent separately */
 503     while ((nlp=strchr(buff,'\n'))) {
 504         *nlp=0;
 505         slilog(lf,priority,"%s",buff);
 506         memmove(buff,nlp+1,strlen(nlp+1)+1);
 507     }
 508 }
 509
 510 extern void slilog_part(struct log_if *lf, int priority, const char *message, ...)
 511 {
 512     va_list ap;
 513     va_start(ap,message);
 514     vslilog_part(lf,priority,message,ap);
 515     va_end(ap);
 516 }
 517
 518 void string_item_to_iaddr(const item_t *item, uint16_t port, union iaddr *ia,
 519                           const char *desc)
 520 {
 521 #ifndef CONFIG_IPV6
 522
 523     ia->sin.sin_family=AF_INET;
 524     ia->sin.sin_addr.s_addr=string_item_to_ipaddr(item,desc);
 525     ia->sin.sin_port=htons(port);
 526
 527 #else /* CONFIG_IPV6 => we have adns_text2addr */
 528
 529     if (item->type!=t_string)
 530         cfgfatal(item->loc,desc,"expecting a string IP (v4 or v6) address\n");
 531     socklen_t salen=sizeof(*ia);
 532     int r=adns_text2addr(item->data.string, port,
 533                          adns_qf_addrlit_ipv4_quadonly,
 534                          &ia->sa, &salen);
 535     assert(r!=ENOSPC);
 536     if (r) cfgfatal(item->loc,desc,"invalid IP (v4 or v6) address: %s\n",
 537                     strerror(r));
 538
 539 #endif /* CONFIG_IPV6 */
 540 }
 541
 542 #define IADDR_NBUFS 8
 543
 544 const char *iaddr_to_string(const union iaddr *ia)
 545 {
 546 #ifndef CONFIG_IPV6
 547
 548     SBUF_DEFINE(IADDR_NBUFS, 100);
 549
 550     assert(ia->sa.sa_family == AF_INET);
 551
 552     snprintf(SBUF, sizeof(SBUF), "[%s]:%d",
 553              inet_ntoa(ia->sin.sin_addr),
 554              ntohs(ia->sin.sin_port));
 555
 556 #else /* CONFIG_IPV6 => we have adns_addr2text */
 557
 558     SBUF_DEFINE(IADDR_NBUFS, 1+ADNS_ADDR2TEXT_BUFLEN+20);
 559
 560     int port;
 561
 562     char *addrbuf = SBUF;
 563     *addrbuf++ = '[';
 564     int addrbuflen = ADNS_ADDR2TEXT_BUFLEN;
 565
 566     int r = adns_addr2text(&ia->sa, 0, addrbuf, &addrbuflen, &port);
 567     if (r) {
 568         const char fmt[]= "scoped IPv6 addr, error: %.*s";
 569         sprintf(addrbuf, fmt,
 570                 (int)(ADNS_ADDR2TEXT_BUFLEN - sizeof(fmt)) /* underestimate */,
 571                 strerror(r));
 572     }
 573
 574     char *portbuf = addrbuf;
 575     int addrl = strlen(addrbuf);
 576     portbuf += addrl;
 577
 578     snprintf(portbuf, sizeof(SBUF)-addrl, "]:%d", port);
 579
 580 #endif /* CONFIG_IPV6 */
 581
 582     return SBUF;
 583 }
 584
 585 bool_t iaddr_equal(const union iaddr *ia, const union iaddr *ib,
 586                    bool_t ignoreport)
 587 {
 588     if (ia->sa.sa_family != ib->sa.sa_family)
 589         return 0;
 590     switch (ia->sa.sa_family) {
 591     case AF_INET:
 592         return ia->sin.sin_addr.s_addr == ib->sin.sin_addr.s_addr
 593            && (ignoreport ||
 594                ia->sin.sin_port        == ib->sin.sin_port);
 595 #ifdef CONFIG_IPV6
 596     case AF_INET6:
 597         return !memcmp(&ia->sin6.sin6_addr, &ib->sin6.sin6_addr, 16)
 598            &&  ia->sin6.sin6_scope_id  == ib->sin6.sin6_scope_id
 599            && (ignoreport ||
 600                ia->sin6.sin6_port      == ib->sin6.sin6_port)
 601             /* we ignore the flowinfo field */;
 602 #endif /* CONFIG_IPV6 */
 603     default:
 604         abort();
 605     }
 606 }
 607
 608 int iaddr_socklen(const union iaddr *ia)
 609 {
 610     switch (ia->sa.sa_family) {
 611     case AF_INET:  return sizeof(ia->sin);
 612 #ifdef CONFIG_IPV6
 613     case AF_INET6: return sizeof(ia->sin6);
 614 #endif /* CONFIG_IPV6 */
 615     default:       abort();
 616     }
 617 }
 618
 619 const char *pollbadbit(int revents)
 620 {
 621 #define BADBIT(b) \
 622     if ((revents & b)) return #b
 623     BADBIT(POLLERR);
 624     BADBIT(POLLHUP);
 625     /* POLLNVAL is handled by the event loop - see afterpoll_fn comment */
 626 #undef BADBIT
 627     return 0;
 628 }
 629
 630 enum async_linebuf_result
 631 async_linebuf_read(struct pollfd *pfd, struct buffer_if *buf,
 632                    const char **emsg_out)
 633 {
 634     int revents=pfd->revents;
 635
 636 #define BAD(m) do{ *emsg_out=(m); return async_linebuf_broken; }while(0)
 637
 638     const char *badbit=pollbadbit(revents);
 639     if (badbit) BAD(badbit);
 640
 641     if (!(revents & POLLIN))
 642         return async_linebuf_nothing;
 643
 644     /*
 645      * Data structure: A line which has been returned to the user is
 646      * stored in buf at base before start.  But we retain the usual
 647      * buffer meaning of size.  So:
 648      *
 649      *   | returned :    | input read,   |    unused    |
 650      *   |  to user : \0 |  awaiting     |     buffer   |
 651      *   |          :    |  processing   |      space   |
 652      *   |          :    |               |              |
 653      *   ^base           ^start          ^start+size    ^base+alloclen
 654      */
 655
 656     BUF_ASSERT_USED(buf);
 657
 658     /* firstly, eat any previous */
 659     if (buf->start != buf->base) {
 660         memmove(buf->base,buf->start,buf->size);
 661         buf->start=buf->base;
 662     }
 663
 664     uint8_t *searched=buf->base;
 665
 666     /*
 667      * During the workings here we do not use start.  We set start
 668      * when we return some actual data.  So we have this:
 669      *
 670      *   | searched     | read, might   |  unused      |
 671      *   |  for \n      |  contain \n   |   buffer     |
 672      *   |  none found  |  but not \0   |    space     |
 673      *   |              |               |              |
 674      *   ^base          ^searched       ^base+size     ^base+alloclen
 675      *  [^start]                        ^dataend
 676      *
 677      */
 678     for (;;) {
 679         uint8_t *dataend=buf->base+buf->size;
 680         char *newline=memchr(searched,'\n',dataend-searched);
 681         if (newline) {
 682             *newline=0;
 683             buf->start=newline+1;
 684             buf->size=dataend-buf->start;
 685             return async_linebuf_ok;
 686         }
 687         searched=dataend;
 688         ssize_t space=(buf->base+buf->alloclen)-dataend;
 689         if (!space) BAD("input line too long");
 690         ssize_t r=read(pfd->fd,searched,space);
 691         if (r==0) {
 692             *searched=0;
 693             *emsg_out=buf->size?"no newline at eof":0;
 694             buf->start=searched+1;
 695             buf->size=0;
 696             return async_linebuf_eof;
 697         }
 698         if (r<0) {
 699             if (errno==EINTR)
 700                 continue;
 701             if (iswouldblock(errno))
 702                 return async_linebuf_nothing;
 703             BAD(strerror(errno));
 704         }
 705         assert(r<=space);
 706         if (memchr(searched,0,r)) BAD("nul in input data");
 707         buf->size+=r;
 708     }
 709
 710 #undef BAD
 711 }