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
  10  *    Copyright (C) 1995--2001 Stephen Early <steve@greenend.org.uk>
  11  *
  12  *  It is part of secnet, which is
  13  *    Copyright (C) 1995--2001 Stephen Early <steve@greenend.org.uk>
  14  *    Copyright (C) 1998 Ross Anderson, Eli Biham, Lars Knudsen
  15  *
  16  *  This program is free software; you can redistribute it and/or modify
  17  *  it under the terms of the GNU General Public License as published by
  18  *  the Free Software Foundation; either version 2, or (at your option)
  19  *  any later version.
  20  *
  21  *  This program is distributed in the hope that it will be useful,
  22  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  23  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  24  *  GNU General Public License for more details.
  25  *
  26  *  You should have received a copy of the GNU General Public License
  27  *  along with this program; if not, write to the Free Software Foundation,
  28  *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  29  */
  30
  31 #include "secnet.h"
  32 #include <stdio.h>
  33 #include <string.h>
  34 #include <errno.h>
  35 #include <unistd.h>
  36 #include <limits.h>
  37 #include <assert.h>
  38 #include <sys/wait.h>
  39 #include <adns.h>
  40 #include "util.h"
  41 #include "unaligned.h"
  42 #include "magic.h"
  43 #include "ipaddr.h"
  44
  45 #define MIN_BUFFER_SIZE 64
  46 #define DEFAULT_BUFFER_SIZE 4096
  47 #define MAX_BUFFER_SIZE 131072
  48
  49 static const char *hexdigits="0123456789abcdef";
  50
  51 uint32_t current_phase=0;
  52
  53 struct phase_hook {
  54     hook_fn *fn;
  55     void *state;
  56     LIST_ENTRY(phase_hook) entry;
  57 };
  58
  59 static LIST_HEAD(, phase_hook) hooks[NR_PHASES];
  60
  61 char *safe_strdup(const char *s, const char *message)
  62 {
  63     char *d;
  64     d=strdup(s);
  65     if (!d) {
  66         fatal_perror("%s",message);
  67     }
  68     return d;
  69 }
  70
  71 void *safe_malloc(size_t size, const char *message)
  72 {
  73     void *r;
  74     if (!size)
  75         return 0;
  76     r=malloc(size);
  77     if (!r) {
  78         fatal_perror("%s",message);
  79     }
  80     return r;
  81 }
  82 void *safe_realloc_ary(void *p, size_t size, size_t count,
  83                        const char *message) {
  84     if (count >= INT_MAX/size) {
  85         fatal("array allocation overflow: %s", message);
  86     }
  87     assert(size && count);
  88     p = realloc(p, size*count);
  89     if (!p)
  90         fatal_perror("%s", message);
  91     return p;
  92 }
  93
  94 void *safe_malloc_ary(size_t size, size_t count, const char *message) {
  95     if (!size || !count)
  96         return 0;
  97     return safe_realloc_ary(0,size,count,message);
  98 }
  99
 100 /* Convert a buffer into its MP_INT representation */
 101 void read_mpbin(MP_INT *a, uint8_t *bin, int binsize)
 102 {
 103     char *buff;
 104     int i;
 105
 106     buff=safe_malloc(binsize*2 + 1,"read_mpbin");
 107
 108     for (i=0; i<binsize; i++) {
 109         buff[i*2]=hexdigits[(bin[i] & 0xf0) >> 4];
 110         buff[i*2+1]=hexdigits[(bin[i] & 0xf)];
 111     }
 112     buff[binsize*2]=0;
 113
 114     mpz_set_str(a, buff, 16);
 115     free(buff);
 116 }
 117
 118 /* Convert a MP_INT into a hex string */
 119 char *write_mpstring(MP_INT *a)
 120 {
 121     char *buff;
 122
 123     buff=safe_malloc(mpz_sizeinbase(a,16)+2,"write_mpstring");
 124     mpz_get_str(buff, 16, a);
 125     return buff;
 126 }
 127
 128 static uint8_t hexval(uint8_t c)
 129 {
 130     switch (c) {
 131     case '0': return 0;
 132     case '1': return 1;
 133     case '2': return 2;
 134     case '3': return 3;
 135     case '4': return 4;
 136     case '5': return 5;
 137     case '6': return 6;
 138     case '7': return 7;
 139     case '8': return 8;
 140     case '9': return 9;
 141     case 'a': return 10;
 142     case 'A': return 10;
 143     case 'b': return 11;
 144     case 'B': return 11;
 145     case 'c': return 12;
 146     case 'C': return 12;
 147     case 'd': return 13;
 148     case 'D': return 13;
 149     case 'e': return 14;
 150     case 'E': return 14;
 151     case 'f': return 15;
 152     case 'F': return 15;
 153     }
 154     return -1;
 155 }
 156
 157 /* Convert a MP_INT into a buffer; return length; truncate if necessary */
 158 int32_t write_mpbin(MP_INT *a, uint8_t *buffer, int32_t buflen)
 159 {
 160     char *hb;
 161     int i,j,l;
 162
 163     if (buflen==0) return 0;
 164     hb=write_mpstring(a);
 165
 166     l=strlen(hb);
 167     i=0; j=0;
 168     if (l&1) {
 169         /* The number starts with a half-byte */
 170         buffer[i++]=hexval(hb[j++]);
 171     }
 172     for (; hb[j] && i<buflen; i++) {
 173         buffer[i]=(hexval(hb[j])<<4)|hexval(hb[j+1]);
 174         j+=2;
 175     }
 176     free(hb);
 177     return i;
 178 }
 179
 180 #define DEFINE_SETFDFLAG(fn,FL,FLAG)                                    \
 181 void fn(int fd) {                                                       \
 182     int r=fcntl(fd, F_GET##FL);                                         \
 183     if (r<0) fatal_perror("fcntl(,F_GET" #FL ") failed");               \
 184     r=fcntl(fd, F_SET##FL, r|FLAG);                                     \
 185     if (r<0) fatal_perror("fcntl(,F_SET" #FL ",|" #FLAG ") failed");    \
 186 }
 187
 188 DEFINE_SETFDFLAG(setcloexec,FD,FD_CLOEXEC);
 189 DEFINE_SETFDFLAG(setnonblock,FL,O_NONBLOCK);
 190
 191 void pipe_cloexec(int fd[2]) {
 192     int r=pipe(fd);
 193     if (r) fatal_perror("pipe");
 194     setcloexec(fd[0]);
 195     setcloexec(fd[1]);
 196 }
 197
 198 static const char *phases[NR_PHASES]={
 199     "PHASE_INIT",
 200     "PHASE_GETOPTS",
 201     "PHASE_READCONFIG",
 202     "PHASE_SETUP",
 203     "PHASE_DAEMONIZE",
 204     "PHASE_GETRESOURCES",
 205     "PHASE_DROPPRIV",
 206     "PHASE_RUN",
 207     "PHASE_SHUTDOWN",
 208     "PHASE_CHILDPERSIST"
 209 };
 210
 211 void enter_phase(uint32_t new_phase)
 212 {
 213     struct phase_hook *i;
 214
 215     if (!LIST_EMPTY(&hooks[new_phase]))
 216         Message(M_DEBUG_PHASE,"Running hooks for %s...\n", phases[new_phase]);
 217     current_phase=new_phase;
 218
 219     LIST_FOREACH(i, &hooks[new_phase], entry)
 220         i->fn(i->state, new_phase);
 221     Message(M_DEBUG_PHASE,"Now in %s\n",phases[new_phase]);
 222 }
 223
 224 void phase_hooks_init(void)
 225 {
 226     int i;
 227     for (i=0; i<NR_PHASES; i++)
 228         LIST_INIT(&hooks[i]);
 229 }
 230
 231 void clear_phase_hooks(uint32_t phase)
 232 {
 233     struct phase_hook *h, *htmp;
 234     LIST_FOREACH_SAFE(h, &hooks[phase], entry, htmp)
 235         free(h);
 236     LIST_INIT(&hooks[phase]);
 237 }
 238
 239 bool_t add_hook(uint32_t phase, hook_fn *fn, void *state)
 240 {
 241     struct phase_hook *h;
 242
 243     NEW(h);
 244     h->fn=fn;
 245     h->state=state;
 246     LIST_INSERT_HEAD(&hooks[phase],h,entry);
 247     return True;
 248 }
 249
 250 bool_t remove_hook(uint32_t phase, hook_fn *fn, void *state)
 251 {
 252     fatal("remove_hook: not implemented");
 253
 254     return False;
 255 }
 256
 257 void vslilog(struct log_if *lf, int priority, const char *message, va_list ap)
 258 {
 259     lf->vlogfn(lf->st,priority,message,ap);
 260 }
 261
 262 void slilog(struct log_if *lf, int priority, const char *message, ...)
 263 {
 264     va_list ap;
 265
 266     va_start(ap,message);
 267     vslilog(lf,priority,message,ap);
 268     va_end(ap);
 269 }
 270
 271 struct buffer {
 272     closure_t cl;
 273     struct buffer_if ops;
 274 };
 275
 276 void buffer_assert_free(struct buffer_if *buffer, cstring_t file,
 277                         int line)
 278 {
 279     if (!buffer->free) {
 280         fprintf(stderr,"secnet: BUF_ASSERT_FREE, %s line %d, owned by %s",
 281                 file,line,buffer->owner);
 282         assert(!"buffer_assert_free failure");
 283     }
 284 }
 285
 286 void buffer_assert_used(struct buffer_if *buffer, cstring_t file,
 287                         int line)
 288 {
 289     if (buffer->free) {
 290         fprintf(stderr,"secnet: BUF_ASSERT_USED, %s line %d, last owned by %s",
 291                 file,line,buffer->owner);
 292         assert(!"buffer_assert_used failure");
 293     }
 294 }
 295
 296 void buffer_init(struct buffer_if *buffer, int32_t max_start_pad)
 297 {
 298     assert(max_start_pad<=buffer->alloclen);
 299     buffer->start=buffer->base+max_start_pad;
 300     buffer->size=0;
 301 }
 302
 303 void buffer_destroy(struct buffer_if *buf)
 304 {
 305     BUF_ASSERT_FREE(buf);
 306     free(buf->base);
 307     buf->start=buf->base=0;
 308     buf->size=buf->alloclen=0;
 309 }
 310
 311 void *buf_append(struct buffer_if *buf, int32_t amount) {
 312     void *p;
 313     assert(amount <= buf_remaining_space(buf));
 314     p=buf->start + buf->size;
 315     buf->size+=amount;
 316     return p;
 317 }
 318
 319 void *buf_prepend(struct buffer_if *buf, int32_t amount) {
 320     assert(amount <= buf->start - buf->base);
 321     buf->size+=amount;
 322     return buf->start-=amount;
 323 }
 324
 325 void *buf_unappend(struct buffer_if *buf, int32_t amount) {
 326     if (buf->size < amount) return 0;
 327     return buf->start+(buf->size-=amount);
 328 }
 329
 330 void *buf_unprepend(struct buffer_if *buf, int32_t amount) {
 331     void *p;
 332     if (buf->size < amount) return 0;
 333     p=buf->start;
 334     buf->start+=amount;
 335     buf->size-=amount;
 336     return p;
 337 }
 338
 339 /* Append a two-byte length and the string to the buffer. Length is in
 340    network byte order. */
 341 void buf_append_string(struct buffer_if *buf, cstring_t s)
 342 {
 343     size_t len;
 344
 345     len=strlen(s);
 346     /* fixme: if string is longer than 65535, result is a corrupted packet */
 347     buf_append_uint16(buf,len);
 348     BUF_ADD_BYTES(append,buf,s,len);
 349 }
 350
 351 void buffer_new(struct buffer_if *buf, int32_t len)
 352 {
 353     buf->free=True;
 354     buf->owner=NULL;
 355     buf->flags=0;
 356     buf->loc.file=NULL;
 357     buf->loc.line=0;
 358     buf->size=0;
 359     buf->alloclen=len;
 360     buf->start=NULL;
 361     buf->base=safe_malloc(len,"buffer_new");
 362 }
 363
 364 void buffer_readonly_view(struct buffer_if *buf, const void *data, int32_t len)
 365 {
 366     buf->free=False;
 367     buf->owner="READONLY";
 368     buf->flags=0;
 369     buf->loc.file=NULL;
 370     buf->loc.line=0;
 371     buf->size=buf->alloclen=len;
 372     buf->base=buf->start=(uint8_t*)data;
 373 }
 374
 375 void buffer_readonly_clone(struct buffer_if *out, const struct buffer_if *in)
 376 {
 377     buffer_readonly_view(out,in->start,in->size);
 378 }
 379
 380 void buffer_copy(struct buffer_if *dst, const struct buffer_if *src)
 381 {
 382     if (dst->alloclen < src->alloclen) {
 383         dst->base=realloc(dst->base,src->alloclen);
 384         if (!dst->base) fatal_perror("buffer_copy");
 385         dst->alloclen = src->alloclen;
 386     }
 387     dst->start = dst->base + (src->start - src->base);
 388     dst->size = src->size;
 389     memcpy(dst->start, src->start, dst->size);
 390 }
 391
 392 static list_t *buffer_apply(closure_t *self, struct cloc loc, dict_t *context,
 393                             list_t *args)
 394 {
 395     struct buffer *st;
 396     item_t *item;
 397     dict_t *dict;
 398     bool_t lockdown=False;
 399     uint32_t len=DEFAULT_BUFFER_SIZE;
 400
 401     NEW(st);
 402     st->cl.description="buffer";
 403     st->cl.type=CL_BUFFER;
 404     st->cl.apply=NULL;
 405     st->cl.interface=&st->ops;
 406
 407     /* First argument, if present, is buffer length */
 408     item=list_elem(args,0);
 409     if (item) {
 410         if (item->type!=t_number) {
 411             cfgfatal(st->ops.loc,"buffer","first parameter must be a "
 412                      "number (buffer size)\n");
 413         }
 414         len=item->data.number;
 415         if (len<MIN_BUFFER_SIZE) {
 416             cfgfatal(st->ops.loc,"buffer","ludicrously small buffer size\n");
 417         }
 418         if (len>MAX_BUFFER_SIZE) {
 419             cfgfatal(st->ops.loc,"buffer","ludicrously large buffer size\n");
 420         }
 421     }
 422     /* Second argument, if present, is a dictionary */
 423     item=list_elem(args,1);
 424     if (item) {
 425         if (item->type!=t_dict) {
 426             cfgfatal(st->ops.loc,"buffer","second parameter must be a "
 427                      "dictionary\n");
 428         }
 429         dict=item->data.dict;
 430         lockdown=dict_read_bool(dict,"lockdown",False,"buffer",st->ops.loc,
 431                                 False);
 432     }
 433
 434     buffer_new(&st->ops,len);
 435     if (lockdown) {
 436         /* XXX mlock the buffer if possible */
 437     }
 438
 439     return new_closure(&st->cl);
 440 }
 441
 442 void send_nak(const struct comm_addr *dest, uint32_t our_index,
 443               uint32_t their_index, uint32_t msgtype,
 444               struct buffer_if *buf, const char *logwhy)
 445 {
 446     buffer_init(buf,calculate_max_start_pad());
 447     buf_append_uint32(buf,their_index);
 448     buf_append_uint32(buf,our_index);
 449     buf_append_uint32(buf,LABEL_NAK);
 450     if (logwhy)
 451         Message(M_INFO,"%s: %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
 452                 " %s; sending NAK\n",
 453                 comm_addr_to_string(dest),
 454                 our_index, their_index, msgtype, logwhy);
 455     dest->comm->sendmsg(dest->comm->st, buf, dest);
 456 }
 457
 458 int consttime_memeq(const void *s1in, const void *s2in, size_t n)
 459 {
 460     const uint8_t *s1=s1in, *s2=s2in;
 461     register volatile uint8_t accumulator=0;
 462
 463     while (n-- > 0) {
 464         accumulator |= (*s1++ ^ *s2++);
 465     }
 466     accumulator |= accumulator >> 4; /* constant-time             */
 467     accumulator |= accumulator >> 2; /*  boolean canonicalisation */
 468     accumulator |= accumulator >> 1;
 469     accumulator &= 1;
 470     accumulator ^= 1;
 471     return accumulator;
 472 }
 473
 474 void util_module(dict_t *dict)
 475 {
 476     add_closure(dict,"sysbuffer",buffer_apply);
 477 }
 478
 479 void update_max_start_pad(int32_t *our_module_global, int32_t our_instance)
 480 {
 481     if (*our_module_global < our_instance)
 482         *our_module_global=our_instance;
 483 }
 484
 485 int32_t transform_max_start_pad, comm_max_start_pad;
 486
 487 int32_t calculate_max_start_pad(void)
 488 {
 489     return
 490         site_max_start_pad +
 491         transform_max_start_pad +
 492         comm_max_start_pad;
 493 }
 494
 495 void vslilog_part(struct log_if *lf, int priority, const char *message, va_list ap)
 496 {
 497     char *buff=lf->buff;
 498     size_t bp;
 499     char *nlp;
 500
 501     bp=strlen(buff);
 502     assert(bp < LOG_MESSAGE_BUFLEN);
 503     vsnprintf(buff+bp,LOG_MESSAGE_BUFLEN-bp,message,ap);
 504     buff[LOG_MESSAGE_BUFLEN-1] = '\n';
 505     buff[LOG_MESSAGE_BUFLEN] = '\0';
 506     /* Each line is sent separately */
 507     while ((nlp=strchr(buff,'\n'))) {
 508         *nlp=0;
 509         slilog(lf,priority,"%s",buff);
 510         memmove(buff,nlp+1,strlen(nlp+1)+1);
 511     }
 512 }
 513
 514 extern void slilog_part(struct log_if *lf, int priority, const char *message, ...)
 515 {
 516     va_list ap;
 517     va_start(ap,message);
 518     vslilog_part(lf,priority,message,ap);
 519     va_end(ap);
 520 }
 521
 522 void string_item_to_iaddr(const item_t *item, uint16_t port, union iaddr *ia,
 523                           const char *desc)
 524 {
 525 #ifndef CONFIG_IPV6
 526
 527     ia->sin.sin_family=AF_INET;
 528     ia->sin.sin_addr.s_addr=string_item_to_ipaddr(item,desc);
 529
 530 #else /* CONFIG_IPV6 => we have adns_text2addr */
 531
 532     if (item->type!=t_string)
 533         cfgfatal(item->loc,desc,"expecting a string IP (v4 or v6) address\n");
 534     socklen_t salen=sizeof(*ia);
 535     int r=adns_text2addr(item->data.string, port,
 536                          adns_qf_addrlit_ipv4_quadonly,
 537                          &ia->sa, &salen);
 538     assert(r!=ENOSPC);
 539     if (r) cfgfatal(item->loc,desc,"invalid IP (v4 or v6) address: %s\n",
 540                     strerror(r));
 541
 542 #endif /* CONFIG_IPV6 */
 543 }
 544
 545 #define IADDR_NBUFS_SHIFT 3
 546 #define IADDR_NBUFS (1 << IADDR_NBUFS_SHIFT)
 547
 548 const char *iaddr_to_string(const union iaddr *ia)
 549 {
 550     static int b;
 551
 552     b++;
 553     b &= IADDR_NBUFS-1;
 554
 555 #ifndef CONFIG_IPV6
 556
 557     static char bufs[IADDR_NBUFS][100];
 558
 559     assert(ia->sa.sa_family == AF_INET);
 560
 561     snprintf(bufs[b], sizeof(bufs[b]), "[%s]:%d",
 562              inet_ntoa(ia->sin.sin_addr),
 563              ntohs(ia->sin.sin_port));
 564
 565 #else /* CONFIG_IPV6 => we have adns_addr2text */
 566
 567     static char bufs[IADDR_NBUFS][1+ADNS_ADDR2TEXT_BUFLEN+20];
 568
 569     int port;
 570
 571     char *addrbuf = bufs[b];
 572     *addrbuf++ = '[';
 573     int addrbuflen = ADNS_ADDR2TEXT_BUFLEN;
 574
 575     int r = adns_addr2text(&ia->sa, 0, addrbuf, &addrbuflen, &port);
 576     if (r) {
 577         const char fmt[]= "scoped IPv6 addr, error: %.*s";
 578         sprintf(addrbuf, fmt,
 579                 ADNS_ADDR2TEXT_BUFLEN - sizeof(fmt) /* underestimate */,
 580                 strerror(r));
 581     }
 582
 583     char *portbuf = addrbuf;
 584     int addrl = strlen(addrbuf);
 585     portbuf += addrl;
 586
 587     snprintf(portbuf, sizeof(bufs[b])-addrl, "]:%d", port);
 588
 589 #endif /* CONFIG_IPV6 */
 590
 591     return bufs[b];
 592 }
 593
 594 bool_t iaddr_equal(const union iaddr *ia, const union iaddr *ib,
 595                    bool_t ignoreport)
 596 {
 597     if (ia->sa.sa_family != ib->sa.sa_family)
 598         return 0;
 599     switch (ia->sa.sa_family) {
 600     case AF_INET:
 601         return ia->sin.sin_addr.s_addr == ib->sin.sin_addr.s_addr
 602            && (ignoreport ||
 603                ia->sin.sin_port        == ib->sin.sin_port);
 604 #ifdef CONFIG_IPV6
 605     case AF_INET6:
 606         return !memcmp(&ia->sin6.sin6_addr, &ib->sin6.sin6_addr, 16)
 607            &&  ia->sin6.sin6_scope_id  == ib->sin6.sin6_scope_id
 608            && (ignoreport ||
 609                ia->sin6.sin6_port      == ib->sin6.sin6_port)
 610             /* we ignore the flowinfo field */;
 611 #endif /* CONFIG_IPV6 */
 612     default:
 613         abort();
 614     }
 615 }
 616
 617 int iaddr_socklen(const union iaddr *ia)
 618 {
 619     switch (ia->sa.sa_family) {
 620     case AF_INET:  return sizeof(ia->sin);
 621 #ifdef CONFIG_IPV6
 622     case AF_INET6: return sizeof(ia->sin6);
 623 #endif /* CONFIG_IPV6 */
 624     default:       abort();
 625     }
 626 }
 627
 628 const char *pollbadbit(int revents)
 629 {
 630 #define BADBIT(b) \
 631     if ((revents & b)) return #b
 632     BADBIT(POLLERR);
 633     BADBIT(POLLHUP);
 634     /* POLLNVAL is handled by the event loop - see afterpoll_fn comment */
 635 #undef BADBIT
 636     return 0;
 637 }
 638
 639 enum async_linebuf_result
 640 async_linebuf_read(struct pollfd *pfd, struct buffer_if *buf,
 641                    const char **emsg_out)
 642 {
 643     int revents=pfd->revents;
 644
 645 #define BAD(m) do{ *emsg_out=(m); return async_linebuf_broken; }while(0)
 646
 647     const char *badbit=pollbadbit(revents);
 648     if (badbit) BAD(badbit);
 649
 650     if (!(revents & POLLIN))
 651         return async_linebuf_nothing;
 652
 653     /*
 654      * Data structure: A line which has been returned to the user is
 655      * stored in buf at base before start.  But we retain the usual
 656      * buffer meaning of size.  So:
 657      *
 658      *   | returned :    | input read,   |    unused    |
 659      *   |  to user : \0 |  awaiting     |     buffer   |
 660      *   |          :    |  processing   |      space   |
 661      *   |          :    |               |              |
 662      *   ^base           ^start          ^start+size    ^base+alloclen
 663      */
 664
 665     BUF_ASSERT_USED(buf);
 666
 667     /* firstly, eat any previous */
 668     if (buf->start != buf->base) {
 669         memmove(buf->base,buf->start,buf->size);
 670         buf->start=buf->base;
 671     }
 672
 673     uint8_t *searched=buf->base;
 674
 675     /*
 676      * During the workings here we do not use start.  We set start
 677      * when we return some actual data.  So we have this:
 678      *
 679      *   | searched     | read, might   |  unused      |
 680      *   |  for \n      |  contain \n   |   buffer     |
 681      *   |  none found  |  but not \0   |    space     |
 682      *   |              |               |              |
 683      *   ^base          ^searched       ^base+size     ^base+alloclen
 684      *  [^start]                        ^dataend
 685      *
 686      */
 687     for (;;) {
 688         uint8_t *dataend=buf->base+buf->size;
 689         char *newline=memchr(searched,'\n',dataend-searched);
 690         if (newline) {
 691             *newline=0;
 692             buf->start=newline+1;
 693             buf->size=dataend-buf->start;
 694             return async_linebuf_ok;
 695         }
 696         searched=dataend;
 697         ssize_t space=(buf->base+buf->alloclen)-dataend;
 698         if (!space) BAD("input line too long");
 699         ssize_t r=read(pfd->fd,searched,space);
 700         if (r==0) {
 701             *searched=0;
 702             *emsg_out=buf->size?"no newline at eof":0;
 703             buf->start=searched+1;
 704             buf->size=0;
 705             return async_linebuf_eof;
 706         }
 707         if (r<0) {
 708             if (errno==EINTR)
 709                 continue;
 710             if (iswouldblock(errno))
 711                 return async_linebuf_nothing;
 712             BAD(strerror(errno));
 713         }
 714         assert(r<=space);
 715         if (memchr(searched,0,r)) BAD("nul in input data");
 716         buf->size+=r;
 717     }
 718
 719 #undef BAD
 720 }