contrib/sendmail-8.14/libsm/fopen.c

   1 /*
   2  * Copyright (c) 2000-2002, 2004 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * By using this file, you agree to the terms and conditions set
  11  * forth in the LICENSE file which can be found at the top level of
  12  * the sendmail distribution.
  13  */
  14
  15 #include <sm/gen.h>
  16 SM_RCSID("@(#)$Id: fopen.c,v 1.62 2005/06/14 23:07:20 ca Exp $")
  17 #include <errno.h>
  18 #include <setjmp.h>
  19 #include <sm/time.h>
  20 #include <sm/heap.h>
  21 #include <sm/signal.h>
  22 #include <sm/assert.h>
  23 #include <sm/io.h>
  24 #include <sm/clock.h>
  25 #include "local.h"
  26
  27 static void     openalrm __P((int));
  28 static void     reopenalrm __P((int));
  29 extern int      sm_io_fclose __P((SM_FILE_T *));
  30
  31 static jmp_buf OpenTimeOut, ReopenTimeOut;
  32
  33 /*
  34 **  OPENALRM -- handler when timeout activated for sm_io_open()
  35 **
  36 **  Returns flow of control to where setjmp(OpenTimeOut) was set.
  37 **
  38 **      Parameters:
  39 **              sig -- unused
  40 **
  41 **      Returns:
  42 **              does not return
  43 **
  44 **      Side Effects:
  45 **              returns flow of control to setjmp(OpenTimeOut).
  46 **
  47 **      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
  48 **              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
  49 **              DOING.
  50 */
  51
  52 /* ARGSUSED0 */
  53 static void
  54 openalrm(sig)
  55         int sig;
  56 {
  57         longjmp(OpenTimeOut, 1);
  58 }
  59 /*
  60 **  REOPENALRM -- handler when timeout activated for sm_io_reopen()
  61 **
  62 **  Returns flow of control to where setjmp(ReopenTimeOut) was set.
  63 **
  64 **      Parameters:
  65 **              sig -- unused
  66 **
  67 **      Returns:
  68 **              does not return
  69 **
  70 **      Side Effects:
  71 **              returns flow of control to setjmp(ReopenTimeOut).
  72 **
  73 **      NOTE:   THIS CAN BE CALLED FROM A SIGNAL HANDLER.  DO NOT ADD
  74 **              ANYTHING TO THIS ROUTINE UNLESS YOU KNOW WHAT YOU ARE
  75 **              DOING.
  76 */
  77
  78 /* ARGSUSED0 */
  79 static void
  80 reopenalrm(sig)
  81         int sig;
  82 {
  83         longjmp(ReopenTimeOut, 1);
  84 }
  85
  86 /*
  87 **  SM_IO_OPEN -- open a file of a specific type
  88 **
  89 **      Parameters:
  90 **              type -- type of file to open
  91 **              timeout -- time to complete the open
  92 **              info -- info describing what is to be opened (type dependant)
  93 **              flags -- user selected flags
  94 **              rpool -- pointer to rpool to be used for this open
  95 **
  96 **      Returns:
  97 **              Raises exception on heap exhaustion.
  98 **              Aborts if type is invalid.
  99 **              Returns NULL and sets errno
 100 **                      - when the type specific open fails
 101 **                      - when open vector errors
 102 **                      - when flags not set or invalid
 103 **              Success returns a file pointer to the opened file type.
 104 */
 105
 106 SM_FILE_T *
 107 sm_io_open(type, timeout, info, flags, rpool)
 108         const SM_FILE_T *type;
 109         int SM_NONVOLATILE timeout;     /* this is not the file type timeout */
 110         const void *info;
 111         int flags;
 112         const void *rpool;
 113 {
 114         register SM_FILE_T *fp;
 115         int ioflags;
 116         SM_EVENT *evt = NULL;
 117
 118         ioflags = sm_flags(flags);
 119
 120         if (ioflags == 0)
 121         {
 122                 /* must give some indication/intent */
 123                 errno = EINVAL;
 124                 return NULL;
 125         }
 126
 127         if (timeout == SM_TIME_DEFAULT)
 128                 timeout = SM_TIME_FOREVER;
 129         if (timeout == SM_TIME_IMMEDIATE)
 130         {
 131                 errno = EAGAIN;
 132                 return NULL;
 133         }
 134
 135         fp = sm_fp(type, ioflags, NULL);
 136
 137         /*  Okay, this is where we set the timeout.  */
 138         if (timeout != SM_TIME_FOREVER)
 139         {
 140                 if (setjmp(OpenTimeOut) != 0)
 141                 {
 142                         errno = EAGAIN;
 143                         return NULL;
 144                 }
 145                 evt = sm_seteventm(timeout, openalrm, 0);
 146         }
 147
 148         if ((*fp->f_open)(fp, info, flags, rpool) < 0)
 149         {
 150                 fp->f_flags = 0;        /* release */
 151                 fp->sm_magic = NULL;    /* release */
 152                 return NULL;
 153         }
 154
 155         /*  We're back. So undo our timeout and handler */
 156         if (evt != NULL)
 157                 sm_clrevent(evt);
 158
 159 #if SM_RPOOL
 160         if (rpool != NULL)
 161                 sm_rpool_attach_x(rpool, sm_io_fclose, fp);
 162 #endif /* SM_RPOOL */
 163
 164         return fp;
 165 }
 166 /*
 167 **  SM_IO_DUP -- duplicate a file pointer
 168 **
 169 **      Parameters:
 170 **              fp -- file pointer to duplicate
 171 **
 172 **      Returns:
 173 **              Success - the duplicated file pointer
 174 **              Failure - NULL (was an invalid file pointer or too many open)
 175 **
 176 **      Increments the duplicate counter (dup_cnt) for the open file pointer.
 177 **      The counter counts the number of duplicates. When the duplicate
 178 **      counter is 0 (zero) then the file pointer is the only one left
 179 **      (no duplicates, it is the only one).
 180 */
 181
 182 SM_FILE_T *
 183 sm_io_dup(fp)
 184         SM_FILE_T *fp;
 185 {
 186
 187         SM_REQUIRE_ISA(fp, SmFileMagic);
 188         if (fp->sm_magic != SmFileMagic)
 189         {
 190                 errno = EBADF;
 191                 return NULL;
 192         }
 193         if (fp->f_dup_cnt >= INT_MAX - 1)
 194         {
 195                 /* Can't let f_dup_cnt wrap! */
 196                 errno = EMFILE;
 197                 return NULL;
 198         }
 199         fp->f_dup_cnt++;
 200         return fp;
 201 }
 202 /*
 203 **  SM_IO_REOPEN -- open a new file using the old file pointer
 204 **
 205 **      Parameters:
 206 **              type -- file type to be opened
 207 **              timeout -- time to complete the reopen
 208 **              info -- infomation about what is to be "re-opened" (type dep.)
 209 **              flags -- user flags to map to internal flags
 210 **              rpool -- rpool file to be associated with
 211 **              fp -- the file pointer to reuse
 212 **
 213 **      Returns:
 214 **              Raises an exception on heap exhaustion.
 215 **              Aborts if type is invalid.
 216 **              Failure: returns NULL
 217 **              Success: returns "reopened" file pointer
 218 */
 219
 220 SM_FILE_T *
 221 sm_io_reopen(type, timeout, info, flags, rpool, fp)
 222         const SM_FILE_T *type;
 223         int SM_NONVOLATILE timeout;
 224         const void *info;
 225         int flags;
 226         const void *rpool;
 227         SM_FILE_T *fp;
 228 {
 229         int ioflags, ret;
 230         SM_FILE_T *fp2;
 231         SM_EVENT *evt = NULL;
 232
 233         if ((ioflags = sm_flags(flags)) == 0)
 234         {
 235                 (void) sm_io_close(fp, timeout);
 236                 return NULL;
 237         }
 238
 239         if (!Sm_IO_DidInit)
 240                 sm_init();
 241
 242         if (timeout == SM_TIME_DEFAULT)
 243                 timeout = SM_TIME_FOREVER;
 244         if (timeout == SM_TIME_IMMEDIATE)
 245         {
 246                 /*
 247                 **  Filling the buffer will take time and we are wanted to
 248                 **  return immediately. So...
 249                 */
 250
 251                 errno = EAGAIN;
 252                 return NULL;
 253         }
 254         /*  Okay, this is where we set the timeout.  */
 255         if (timeout != SM_TIME_FOREVER)
 256         {
 257                 if (setjmp(ReopenTimeOut) != 0)
 258                 {
 259                         errno = EAGAIN;
 260                         return NULL;
 261                 }
 262
 263                 evt = sm_seteventm(timeout, reopenalrm, 0);
 264         }
 265
 266         /*
 267         **  There are actually programs that depend on being able to "reopen"
 268         **  descriptors that weren't originally open.  Keep this from breaking.
 269         **  Remember whether the stream was open to begin with, and which file
 270         **  descriptor (if any) was associated with it.  If it was attached to
 271         **  a descriptor, defer closing it; reopen("/dev/stdin", "r", stdin)
 272         **  should work.  This is unnecessary if it was not a Unix file.
 273         */
 274
 275         if (fp != NULL)
 276         {
 277                 if (fp->sm_magic != SmFileMagic)
 278                         fp->f_flags = SMFEOF;   /* hold on to it */
 279                 else
 280                 {
 281                         /* flush the stream; ANSI doesn't require this. */
 282                         (void) sm_io_flush(fp, SM_TIME_FOREVER);
 283                         (void) sm_io_close(fp, SM_TIME_FOREVER);
 284                 }
 285         }
 286
 287         fp2 = sm_fp(type, ioflags, fp);
 288         ret = (*fp2->f_open)(fp2, info, flags, rpool);
 289
 290         /*  We're back. So undo our timeout and handler */
 291         if (evt != NULL)
 292                 sm_clrevent(evt);
 293
 294         if (ret < 0)
 295         {
 296                 fp2->f_flags = 0;       /* release */
 297                 fp2->sm_magic = NULL;   /* release */
 298                 return NULL;
 299         }
 300
 301         /*
 302         **  We're not preserving this logic (below) for sm_io because it is now
 303         **  abstracted at least one "layer" away. By closing and reopening
 304         **  the 1st fd used should be the just released one (when Unix
 305         **  behavior followed). Old comment::
 306         **  If reopening something that was open before on a real file, try
 307         **  to maintain the descriptor.  Various C library routines (perror)
 308         **  assume stderr is always fd STDERR_FILENO, even if being reopen'd.
 309         */
 310
 311 #if SM_RPOOL
 312         if (rpool != NULL)
 313                 sm_rpool_attach_x(rpool, sm_io_close, fp2);
 314 #endif /* SM_RPOOL */
 315
 316         return fp2;
 317 }
 318 /*
 319 **  SM_IO_AUTOFLUSH -- link another file to this for auto-flushing
 320 **
 321 **      When a read occurs on fp, fp2 will be flushed iff there is no
 322 **      data waiting on fp.
 323 **
 324 **      Parameters:
 325 **              fp -- the file opened for reading.
 326 **              fp2 -- the file opened for writing.
 327 **
 328 **      Returns:
 329 **              The old flush file pointer.
 330 */
 331
 332 SM_FILE_T *
 333 sm_io_autoflush(fp, fp2)
 334         SM_FILE_T *fp;
 335         SM_FILE_T *fp2;
 336 {
 337         SM_FILE_T *savefp;
 338
 339         SM_REQUIRE_ISA(fp, SmFileMagic);
 340         if (fp2 != NULL)
 341                 SM_REQUIRE_ISA(fp2, SmFileMagic);
 342
 343         savefp = fp->f_flushfp;
 344         fp->f_flushfp = fp2;
 345         return savefp;
 346 }
 347 /*
 348 **  SM_IO_AUTOMODE -- link another file to this for auto-moding
 349 **
 350 **      When the mode (blocking or non-blocking) changes for fp1 then
 351 **      update fp2's mode at the same time. This is to be used when
 352 **      a system dup() has generated a second file descriptor for
 353 **      another sm_io_open() by file descriptor. The modes have been
 354 **      linked in the system and this formalizes it for sm_io internally.
 355 **
 356 **      Parameters:
 357 **              fp1 -- the first file
 358 **              fp2 -- the second file
 359 **
 360 **      Returns:
 361 **              nothing
 362 */
 363
 364 void
 365 sm_io_automode(fp1, fp2)
 366         SM_FILE_T *fp1;
 367         SM_FILE_T *fp2;
 368 {
 369         SM_REQUIRE_ISA(fp1, SmFileMagic);
 370         SM_REQUIRE_ISA(fp2, SmFileMagic);
 371
 372         fp1->f_modefp = fp2;
 373         fp2->f_modefp = fp1;
 374 }