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 };
 209
 210 void enter_phase(uint32_t new_phase)
 211 {
 212     struct phase_hook *i;
 213
 214     if (!LIST_EMPTY(&hooks[new_phase]))
 215         Message(M_DEBUG_PHASE,"Running hooks for %s...\n", phases[new_phase]);
 216     current_phase=new_phase;
 217
 218     LIST_FOREACH(i, &hooks[new_phase], entry)
 219         i->fn(i->state, new_phase);
 220     Message(M_DEBUG_PHASE,"Now in %s\n",phases[new_phase]);
 221 }
 222
 223 void phase_hooks_init(void)
 224 {
 225     int i;
 226     for (i=0; i<NR_PHASES; i++)
 227         LIST_INIT(&hooks[i]);
 228 }
 229
 230 bool_t add_hook(uint32_t phase, hook_fn *fn, void *state)
 231 {
 232     struct phase_hook *h;
 233
 234     h=safe_malloc(sizeof(*h),"add_hook");
 235     h->fn=fn;
 236     h->state=state;
 237     LIST_INSERT_HEAD(&hooks[phase],h,entry);
 238     return True;
 239 }
 240
 241 bool_t remove_hook(uint32_t phase, hook_fn *fn, void *state)
 242 {
 243     fatal("remove_hook: not implemented");
 244
 245     return False;
 246 }
 247
 248 void vslilog(struct log_if *lf, int priority, const char *message, va_list ap)
 249 {
 250     lf->vlogfn(lf->st,priority,message,ap);
 251 }
 252
 253 void slilog(struct log_if *lf, int priority, const char *message, ...)
 254 {
 255     va_list ap;
 256
 257     va_start(ap,message);
 258     vslilog(lf,priority,message,ap);
 259     va_end(ap);
 260 }
 261
 262 struct buffer {
 263     closure_t cl;
 264     struct buffer_if ops;
 265 };
 266
 267 void buffer_assert_free(struct buffer_if *buffer, cstring_t file,
 268                         int line)
 269 {
 270     if (!buffer->free) {
 271         fprintf(stderr,"secnet: BUF_ASSERT_FREE, %s line %d, owned by %s",
 272                 file,line,buffer->owner);
 273         assert(!"buffer_assert_free failure");
 274     }
 275 }
 276
 277 void buffer_assert_used(struct buffer_if *buffer, cstring_t file,
 278                         int line)
 279 {
 280     if (buffer->free) {
 281         fprintf(stderr,"secnet: BUF_ASSERT_USED, %s line %d, last owned by %s",
 282                 file,line,buffer->owner);
 283         assert(!"buffer_assert_used failure");
 284     }
 285 }
 286
 287 void buffer_init(struct buffer_if *buffer, int32_t max_start_pad)
 288 {
 289     assert(max_start_pad<=buffer->alloclen);
 290     buffer->start=buffer->base+max_start_pad;
 291     buffer->size=0;
 292 }
 293
 294 void buffer_destroy(struct buffer_if *buf)
 295 {
 296     BUF_ASSERT_FREE(buf);
 297     free(buf->base);
 298     buf->start=buf->base=0;
 299     buf->size=buf->alloclen=0;
 300 }
 301
 302 void *buf_append(struct buffer_if *buf, int32_t amount) {
 303     void *p;
 304     assert(amount <= buf_remaining_space(buf));
 305     p=buf->start + buf->size;
 306     buf->size+=amount;
 307     return p;
 308 }
 309
 310 void *buf_prepend(struct buffer_if *buf, int32_t amount) {
 311     assert(amount <= buf->start - buf->base);
 312     buf->size+=amount;
 313     return buf->start-=amount;
 314 }
 315
 316 void *buf_unappend(struct buffer_if *buf, int32_t amount) {
 317     if (buf->size < amount) return 0;
 318     return buf->start+(buf->size-=amount);
 319 }
 320
 321 void *buf_unprepend(struct buffer_if *buf, int32_t amount) {
 322     void *p;
 323     if (buf->size < amount) return 0;
 324     p=buf->start;
 325     buf->start+=amount;
 326     buf->size-=amount;
 327     return p;
 328 }
 329
 330 /* Append a two-byte length and the string to the buffer. Length is in
 331    network byte order. */
 332 void buf_append_string(struct buffer_if *buf, cstring_t s)
 333 {
 334     size_t len;
 335
 336     len=strlen(s);
 337     /* fixme: if string is longer than 65535, result is a corrupted packet */
 338     buf_append_uint16(buf,len);
 339     BUF_ADD_BYTES(append,buf,s,len);
 340 }
 341
 342 void buffer_new(struct buffer_if *buf, int32_t len)
 343 {
 344     buf->free=True;
 345     buf->owner=NULL;
 346     buf->flags=0;
 347     buf->loc.file=NULL;
 348     buf->loc.line=0;
 349     buf->size=0;
 350     buf->alloclen=len;
 351     buf->start=NULL;
 352     buf->base=safe_malloc(len,"buffer_new");
 353 }
 354
 355 void buffer_readonly_view(struct buffer_if *buf, const void *data, int32_t len)
 356 {
 357     buf->free=False;
 358     buf->owner="READONLY";
 359     buf->flags=0;
 360     buf->loc.file=NULL;
 361     buf->loc.line=0;
 362     buf->size=buf->alloclen=len;
 363     buf->base=buf->start=(uint8_t*)data;
 364 }
 365
 366 void buffer_readonly_clone(struct buffer_if *out, const struct buffer_if *in)
 367 {
 368     buffer_readonly_view(out,in->start,in->size);
 369 }
 370
 371 void buffer_copy(struct buffer_if *dst, const struct buffer_if *src)
 372 {
 373     if (dst->alloclen < src->alloclen) {
 374         dst->base=realloc(dst->base,src->alloclen);
 375         if (!dst->base) fatal_perror("buffer_copy");
 376         dst->alloclen = src->alloclen;
 377     }
 378     dst->start = dst->base + (src->start - src->base);
 379     dst->size = src->size;
 380     memcpy(dst->start, src->start, dst->size);
 381 }
 382
 383 static list_t *buffer_apply(closure_t *self, struct cloc loc, dict_t *context,
 384                             list_t *args)
 385 {
 386     struct buffer *st;
 387     item_t *item;
 388     dict_t *dict;
 389     bool_t lockdown=False;
 390     uint32_t len=DEFAULT_BUFFER_SIZE;
 391
 392     st=safe_malloc(sizeof(*st),"buffer_apply");
 393     st->cl.description="buffer";
 394     st->cl.type=CL_BUFFER;
 395     st->cl.apply=NULL;
 396     st->cl.interface=&st->ops;
 397
 398     /* First argument, if present, is buffer length */
 399     item=list_elem(args,0);
 400     if (item) {
 401         if (item->type!=t_number) {
 402             cfgfatal(st->ops.loc,"buffer","first parameter must be a "
 403                      "number (buffer size)\n");
 404         }
 405         len=item->data.number;
 406         if (len<MIN_BUFFER_SIZE) {
 407             cfgfatal(st->ops.loc,"buffer","ludicrously small buffer size\n");
 408         }
 409         if (len>MAX_BUFFER_SIZE) {
 410             cfgfatal(st->ops.loc,"buffer","ludicrously large buffer size\n");
 411         }
 412     }
 413     /* Second argument, if present, is a dictionary */
 414     item=list_elem(args,1);
 415     if (item) {
 416         if (item->type!=t_dict) {
 417             cfgfatal(st->ops.loc,"buffer","second parameter must be a "
 418                      "dictionary\n");
 419         }
 420         dict=item->data.dict;
 421         lockdown=dict_read_bool(dict,"lockdown",False,"buffer",st->ops.loc,
 422                                 False);
 423     }
 424
 425     buffer_new(&st->ops,len);
 426     if (lockdown) {
 427         /* XXX mlock the buffer if possible */
 428     }
 429
 430     return new_closure(&st->cl);
 431 }
 432
 433 void send_nak(const struct comm_addr *dest, uint32_t our_index,
 434               uint32_t their_index, uint32_t msgtype,
 435               struct buffer_if *buf, const char *logwhy)
 436 {
 437     buffer_init(buf,calculate_max_start_pad());
 438     buf_append_uint32(buf,their_index);
 439     buf_append_uint32(buf,our_index);
 440     buf_append_uint32(buf,LABEL_NAK);
 441     if (logwhy)
 442         Message(M_INFO,"%s: %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
 443                 " %s; sending NAK\n",
 444                 comm_addr_to_string(dest),
 445                 our_index, their_index, msgtype, logwhy);
 446     dest->comm->sendmsg(dest->comm->st, buf, dest);
 447 }
 448
 449 int consttime_memeq(const void *s1in, const void *s2in, size_t n)
 450 {
 451     const uint8_t *s1=s1in, *s2=s2in;
 452     register volatile uint8_t accumulator=0;
 453
 454     while (n-- > 0) {
 455         accumulator |= (*s1++ ^ *s2++);
 456     }
 457     accumulator |= accumulator >> 4; /* constant-time             */
 458     accumulator |= accumulator >> 2; /*  boolean canonicalisation */
 459     accumulator |= accumulator >> 1;
 460     accumulator &= 1;
 461     accumulator ^= 1;
 462     return accumulator;
 463 }
 464
 465 void util_module(dict_t *dict)
 466 {
 467     add_closure(dict,"sysbuffer",buffer_apply);
 468 }
 469
 470 void update_max_start_pad(int32_t *our_module_global, int32_t our_instance)
 471 {
 472     if (*our_module_global < our_instance)
 473         *our_module_global=our_instance;
 474 }
 475
 476 int32_t transform_max_start_pad, comm_max_start_pad;
 477
 478 int32_t calculate_max_start_pad(void)
 479 {
 480     return
 481         site_max_start_pad +
 482         transform_max_start_pad +
 483         comm_max_start_pad;
 484 }
 485
 486 void vslilog_part(struct log_if *lf, int priority, const char *message, va_list ap)
 487 {
 488     char *buff=lf->buff;
 489     size_t bp;
 490     char *nlp;
 491
 492     bp=strlen(buff);
 493     assert(bp < LOG_MESSAGE_BUFLEN);
 494     vsnprintf(buff+bp,LOG_MESSAGE_BUFLEN-bp,message,ap);
 495     buff[LOG_MESSAGE_BUFLEN-1] = '\n';
 496     buff[LOG_MESSAGE_BUFLEN] = '\0';
 497     /* Each line is sent separately */
 498     while ((nlp=strchr(buff,'\n'))) {
 499         *nlp=0;
 500         slilog(lf,priority,"%s",buff);
 501         memmove(buff,nlp+1,strlen(nlp+1)+1);
 502     }
 503 }
 504
 505 extern void slilog_part(struct log_if *lf, int priority, const char *message, ...)
 506 {
 507     va_list ap;
 508     va_start(ap,message);
 509     vslilog_part(lf,priority,message,ap);
 510     va_end(ap);
 511 }
 512
 513 void string_item_to_iaddr(const item_t *item, uint16_t port, union iaddr *ia,
 514                           const char *desc)
 515 {
 516 #ifndef CONFIG_IPV6
 517
 518     ia->sin.sin_family=AF_INET;
 519     ia->sin.sin_addr.s_addr=string_item_to_ipaddr(item,desc);
 520
 521 #else /* CONFIG_IPV6 => we have adns_text2addr */
 522
 523     if (item->type!=t_string)
 524         cfgfatal(item->loc,desc,"expecting a string IP (v4 or v6) address\n");
 525     socklen_t salen=sizeof(*ia);
 526     int r=adns_text2addr(item->data.string, port,
 527                          adns_qf_addrlit_ipv4_quadonly,
 528                          &ia->sa, &salen);
 529     assert(r!=ENOSPC);
 530     if (r) cfgfatal(item->loc,desc,"invalid IP (v4 or v6) address: %s\n",
 531                     strerror(r));
 532
 533 #endif /* CONFIG_IPV6 */
 534 }
 535
 536 #define IADDR_NBUFS_SHIFT 3
 537 #define IADDR_NBUFS (1 << IADDR_NBUFS_SHIFT)
 538
 539 const char *iaddr_to_string(const union iaddr *ia)
 540 {
 541     static int b;
 542
 543     b++;
 544     b &= IADDR_NBUFS-1;
 545
 546 #ifndef CONFIG_IPV6
 547
 548     static char bufs[IADDR_NBUFS][100];
 549
 550     assert(ia->sa.sa_family == AF_INET);
 551
 552     snprintf(bufs[b], sizeof(bufs[b]), "[%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     static char bufs[IADDR_NBUFS][1+ADNS_ADDR2TEXT_BUFLEN+20];
 559
 560     int port;
 561
 562     char *addrbuf = bufs[b];
 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                 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(bufs[b])-addrl, "]:%d", port);
 579
 580 #endif /* CONFIG_IPV6 */
 581
 582     return bufs[b];
 583 }
 584
 585 bool_t iaddr_equal(const union iaddr *ia, const union iaddr *ib)
 586 {
 587     if (ia->sa.sa_family != ib->sa.sa_family)
 588         return 0;
 589     switch (ia->sa.sa_family) {
 590     case AF_INET:
 591         return ia->sin.sin_addr.s_addr == ib->sin.sin_addr.s_addr
 592             && ia->sin.sin_port        == ib->sin.sin_port;
 593 #ifdef CONFIG_IPV6
 594     case AF_INET6:
 595         return !memcmp(&ia->sin6.sin6_addr, &ib->sin6.sin6_addr, 16)
 596             && ia->sin6.sin6_scope_id  == ib->sin6.sin6_scope_id
 597             && ia->sin6.sin6_port      == ib->sin6.sin6_port
 598             /* we ignore the flowinfo field */;
 599 #endif /* CONFIG_IPV6 */
 600     default:
 601         abort();
 602     }
 603 }
 604
 605 int iaddr_socklen(const union iaddr *ia)
 606 {
 607     switch (ia->sa.sa_family) {
 608     case AF_INET:  return sizeof(ia->sin);
 609 #ifdef CONFIG_IPV6
 610     case AF_INET6: return sizeof(ia->sin6);
 611 #endif /* CONFIG_IPV6 */
 612     default:       abort();
 613     }
 614 }
 615
 616 const char *pollbadbit(int revents)
 617 {
 618 #define BADBIT(b) \
 619     if ((revents & b)) return #b
 620     BADBIT(POLLERR);
 621     BADBIT(POLLHUP);
 622     /* POLLNVAL is handled by the event loop - see afterpoll_fn comment */
 623 #undef BADBIT
 624     return 0;
 625 }
 626
 627 enum async_linebuf_result
 628 async_linebuf_read(struct pollfd *pfd, struct buffer_if *buf,
 629                    const char **emsg_out)
 630 {
 631     int revents=pfd->revents;
 632
 633 #define BAD(m) do{ *emsg_out=(m); return async_linebuf_broken; }while(0)
 634
 635     const char *badbit=pollbadbit(revents);
 636     if (badbit) BAD(badbit);
 637
 638     if (!(revents & POLLIN))
 639         return async_linebuf_nothing;
 640
 641     /*
 642      * Data structure: A line which has been returned to the user is
 643      * stored in buf at base before start.  But we retain the usual
 644      * buffer meaning of size.  So:
 645      *
 646      *   | returned :    | input read,   |    unused    |
 647      *   |  to user : \0 |  awaiting     |     buffer   |
 648      *   |          :    |  processing   |      space   |
 649      *   |          :    |               |              |
 650      *   ^base           ^start          ^start+size    ^base+alloclen
 651      */
 652
 653     BUF_ASSERT_USED(buf);
 654
 655     /* firstly, eat any previous */
 656     if (buf->start != buf->base) {
 657         memmove(buf->base,buf->start,buf->size);
 658         buf->start=buf->base;
 659     }
 660
 661     uint8_t *searched=buf->base;
 662
 663     /*
 664      * During the workings here we do not use start.  We set start
 665      * when we return some actual data.  So we have this:
 666      *
 667      *   | searched     | read, might   |  unused      |
 668      *   |  for \n      |  contain \n   |   buffer     |
 669      *   |  none found  |  but not \0   |    space     |
 670      *   |              |               |              |
 671      *   ^base          ^searched       ^base+size     ^base+alloclen
 672      *  [^start]                        ^dataend
 673      *
 674      */
 675     for (;;) {
 676         uint8_t *dataend=buf->base+buf->size;
 677         char *newline=memchr(searched,'\n',dataend-searched);
 678         if (newline) {
 679             *newline=0;
 680             buf->start=newline+1;
 681             buf->size=dataend-buf->start;
 682             return async_linebuf_ok;
 683         }
 684         searched=dataend;
 685         ssize_t space=(buf->base+buf->alloclen)-dataend;
 686         if (!space) BAD("input line too long");
 687         ssize_t r=read(pfd->fd,searched,space);
 688         if (r==0) {
 689             *searched=0;
 690             *emsg_out=buf->size?"no newline at eof":0;
 691             buf->start=searched+1;
 692             buf->size=0;
 693             return async_linebuf_eof;
 694         }
 695         if (r<0) {
 696             if (errno==EINTR)
 697                 continue;
 698             if (iswouldblock(errno))
 699                 return async_linebuf_nothing;
 700             BAD(strerror(errno));
 701         }
 702         assert(r<=space);
 703         if (memchr(searched,0,r)) BAD("nul in input data");
 704         buf->size+=r;
 705     }
 706
 707 #undef BAD
 708 }