4330 open(2) manual describes O_SYNC twice
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If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner] 13 .TH OPEN 2 "Nov 16, 2013" 14 .SH NAME 15 open, openat \- open a file 16 .SH SYNOPSIS 17 .LP 18 .nf 19 #include <sys/types.h> 20 #include <sys/stat.h> 21 #include <fcntl.h> 22 23 \fBint\fR \fBopen\fR(\fBconst char *\fR\fIpath\fR, \fBint\fR \fIoflag\fR, \fB/* mode_t\fR \fImode\fR */); 24 .fi 25 26 .LP 27 .nf 28 \fBint\fR \fBopenat\fR(\fBint\fR \fIfildes\fR, \fBconst char *\fR\fIpath\fR, \fBint\fR \fIoflag\fR, 29 \fB/* mode_t\fR \fImode\fR */); 30 .fi 31 32 .SH DESCRIPTION 33 .sp 34 .LP 35 The \fBopen()\fR function establishes the connection between a file and a file 36 descriptor. It creates an open file description that refers to a file and a 37 file descriptor that refers to that open file description. The file descriptor 38 is used by other I/O functions to refer to that file. The \fIpath\fR argument 39 points to a pathname naming the file. 40 .sp 41 .LP 42 The \fBopenat()\fR function is identical to the \fBopen()\fR function except 43 that the \fIpath\fR argument is interpreted relative to the starting point 44 implied by the \fIfildes\fR argument. If the \fIfildes\fR argument has the 45 special value \fBAT_FDCWD\fR, a relative path argument will be resolved 46 relative to the current working directory. If the \fIpath\fR argument is 47 absolute, the \fIfildes\fR argument is ignored. 48 .sp 49 .LP 50 The \fBopen()\fR function returns a file descriptor for the named file that is 51 the lowest file descriptor not currently open for that process. The open file 52 description is new, and therefore the file descriptor does not share it with 53 any other process in the system. The \fBFD_CLOEXEC\fR file descriptor flag 54 associated with the new file descriptor is cleared. 55 .sp 56 .LP 57 The file offset used to mark the current position within the file is set to the 58 beginning of the file. 59 .sp 60 .LP 61 The file status flags and file access modes of the open file description are 62 set according to the value of \fIoflag\fR. The \fImode\fR argument is used only 63 when \fBO_CREAT\fR is specified (see below.) 64 .sp 65 .LP 66 Values for \fIoflag\fR are constructed by a bitwise-inclusive-OR of flags from 67 the following list, defined in <\fBfcntl.h\fR>. Applications must specify 68 exactly one of the first three values (file access modes) below in the value of 69 \fIoflag\fR: 70 .sp 71 .ne 2 72 .na 73 \fB\fBO_RDONLY\fR\fR 74 .ad 75 .RS 12n 76 Open for reading only. 77 .RE 78 79 .sp 80 .ne 2 81 .na 82 \fB\fBO_WRONLY\fR\fR 83 .ad 84 .RS 12n 85 Open for writing only. 86 .RE 87 88 .sp 89 .ne 2 90 .na 91 \fB\fBO_RDWR\fR\fR 92 .ad 93 .RS 12n 94 Open for reading and writing. The result is undefined if this flag is applied 95 to a FIFO. 96 .RE 97 98 .sp 99 .LP 100 Any combination of the following may be used: 101 .sp 102 .ne 2 103 .na 104 \fB\fBO_APPEND\fR\fR 105 .ad 106 .sp .6 107 .RS 4n 108 If set, the file offset is set to the end of the file prior to each write. 109 .RE 110 111 .sp 112 .ne 2 113 .na 114 \fB\fBO_CREAT\fR\fR 115 .ad 116 .sp .6 117 .RS 4n 118 Create the file if it does not exist. This flag requires that the \fImode\fR 119 argument be specified. 120 .sp 121 If the file exists, this flag has no effect except as noted under \fBO_EXCL\fR 122 below. Otherwise, the file is created with the user \fBID\fR of the file set 123 to the effective user \fBID\fR of the process. The group \fBID\fR of the file 124 is set to the effective group \fBIDs\fR of the process, or if the \fBS_ISGID\fR 125 bit is set in the directory in which the file is being created, the file's 126 group \fBID\fR is set to the group \fBID\fR of its parent directory. If the 127 group \fBID\fR of the new file does not match the effective group \fBID\fR or 128 one of the supplementary groups IDs, the \fBS_ISGID\fR bit is cleared. The 129 access permission bits (see \fB<sys/stat.h>\fR) of the file mode are set to the 130 value of \fImode\fR, modified as follows (see \fBcreat\fR(2)): a bitwise-AND is 131 performed on the file-mode bits and the corresponding bits in the complement of 132 the process's file mode creation mask. Thus, all bits set in the process's file 133 mode creation mask (see \fBumask\fR(2)) are correspondingly cleared in the 134 file's permission mask. The "save text image after execution bit" of the mode 135 is cleared (see \fBchmod\fR(2)). When bits other than the file permission bits 136 are set, the effect is unspecified. The \fImode\fR argument does not affect 137 whether the file is open for reading, writing or for both. 138 .RE 139 140 .sp 141 .ne 2 142 .na 143 \fB\fBO_DSYNC\fR\fR 144 .ad 145 .sp .6 146 .RS 4n 147 Write I/O operations on the file descriptor complete as defined by synchronized 148 I/O data integrity completion. 149 .RE 150 151 .sp 152 .ne 2 153 .na 154 \fB\fBO_EXCL\fR\fR 155 .ad 156 .sp .6 157 .RS 4n 158 If \fBO_CREAT\fR and \fBO_EXCL\fR are set, \fBopen()\fR fails if the file 159 exists. The check for the existence of the file and the creation of the file if 160 it does not exist is atomic with respect to other threads executing 161 \fBopen()\fR naming the same filename in the same directory with \fBO_EXCL\fR 162 and \fBO_CREAT\fR set. If \fBO_EXCL\fR and \fBO_CREAT\fR are set, and path 163 names a symbolic link, \fBopen()\fR fails and sets \fBerrno\fR to \fBEEXIST\fR, 164 regardless of the contents of the symbolic link. If \fBO_EXCL\fR is set and 165 \fBO_CREAT\fR is not set, the result is undefined. 166 .RE 167 168 .sp 169 .ne 2 170 .na 171 \fB\fBO_LARGEFILE\fR\fR 172 .ad 173 .sp .6 174 .RS 4n 175 If set, the offset maximum in the open file description is the largest value 176 that can be represented correctly in an object of type \fBoff64_t\fR. 177 .RE 178 179 .sp 180 .ne 2 181 .na 182 \fB\fBO_NOCTTY\fR\fR 183 .ad 184 .sp .6 185 .RS 4n 186 If set and \fIpath\fR identifies a terminal device, \fBopen()\fR does not cause 187 the terminal device to become the controlling terminal for the process. 188 .RE 189 190 .sp 191 .ne 2 192 .na 193 \fB\fBO_NOFOLLOW\fR\fR 194 .ad 195 .sp .6 196 .RS 4n 197 If the path names a symbolic link, \fBopen()\fR fails and sets \fBerrno\fR to 198 \fBELOOP\fR. 199 .RE 200 201 .sp 202 .ne 2 203 .na 204 \fB\fBO_NOLINKS\fR\fR 205 .ad 206 .sp .6 207 .RS 4n 208 If the link count of the named file is greater than 1, \fBopen()\fR fails and 209 sets \fBerrno\fR to \fBEMLINK\fR. 210 .RE 211 212 .sp 213 .ne 2 214 .na 215 \fB\fBO_CLOEXEC\fR\fR 216 .ad 217 .sp .6 218 .RS 4n 219 If set, the file descriptor returned will be closed prior to any future 220 \fBexec()\fR calls. 221 .RE 222 223 .sp 224 .ne 2 225 .na 226 \fB\fBO_NONBLOCK\fR or \fBO_NDELAY\fR\fR 227 .ad 228 .sp .6 229 .RS 4n 230 These flags can affect subsequent reads and writes (see \fBread\fR(2) and 231 \fBwrite\fR(2)). If both \fBO_NDELAY\fR and \fBO_NONBLOCK\fR are set, 232 \fBO_NONBLOCK\fR takes precedence. 233 .sp 234 When opening a \fBFIFO\fR with \fBO_RDONLY\fR or \fBO_WRONLY\fR set: 235 .RS +4 236 .TP 237 .ie t \(bu 238 .el o 239 If \fBO_NONBLOCK\fR or \fBO_NDELAY\fR is set, an \fBopen()\fR for reading only 240 returns without delay. An \fBopen()\fR for writing only returns an error if no 241 process currently has the file open for reading. 242 .RE 243 .RS +4 244 .TP 245 .ie t \(bu 246 .el o 247 If \fBO_NONBLOCK\fR and \fBO_NDELAY\fR are clear, an \fBopen()\fR for reading 248 only blocks until a thread opens the file for writing. An \fBopen()\fR for 249 writing only blocks the calling thread until a thread opens the file for 250 reading. 251 .RE 252 After both ends of a \fBFIFO\fR have been opened, there is no guarantee that 253 further calls to \fBopen()\fR \fBO_RDONLY\fR (\fBO_WRONLY\fR) will synchronize 254 with later calls to \fBopen()\fR \fBO_WRONLY\fR (\fBO_RDONLY\fR) until both 255 ends of the \fBFIFO\fR have been closed by all readers and writers. Any data 256 written into a \fBFIFO\fR will be lost if both ends of the \fBFIFO\fR are 257 closed before the data is read. 258 .sp 259 When opening a block special or character special file that supports 260 non-blocking opens: 261 .RS +4 262 .TP 263 .ie t \(bu 264 .el o 265 If \fBO_NONBLOCK\fR or \fBO_NDELAY\fR is set, the \fBopen()\fR function returns 266 without blocking for the device to be ready or available. Subsequent behavior 267 of the device is device-specific. 268 .RE 269 .RS +4 270 .TP 271 .ie t \(bu 272 .el o 273 If \fBO_NONBLOCK\fR and \fBO_NDELAY\fR are clear, the \fBopen()\fR function 274 blocks the calling thread until the device is ready or available before 275 returning. 276 .RE 277 Otherwise, the behavior of \fBO_NONBLOCK\fR and \fBO_NDELAY\fR is unspecified. 278 .RE 279 280 .sp 281 .ne 2 282 .na 283 \fB\fBO_RSYNC\fR\fR 284 .ad 285 .sp .6 286 .RS 4n 287 Read I/O operations on the file descriptor complete at the same level of 288 integrity as specified by the \fBO_DSYNC\fR and \fBO_SYNC\fR flags. If both 289 \fBO_DSYNC\fR and \fBO_RSYNC\fR are set in \fIoflag\fR, all I/O operations on 290 the file descriptor complete as defined by synchronized I/O data integrity 291 completion. If both \fBO_SYNC\fR and \fBO_RSYNC\fR are set in \fIoflag\fR, all 292 I/O operations on the file descriptor complete as defined by synchronized I/O 293 file integrity completion. 294 .RE 295 296 .sp 297 .ne 2 298 .na 299 \fB\fBO_SYNC\fR\fR 300 .ad 301 .sp .6 302 .RS 4n 303 Write I/O operations on the file descriptor complete as defined by synchronized 304 I/O file integrity completion (see \fBfcntl.h\fR(3HEAD) definition of 305 \fBO_SYNC\fR.) 306 .RE 307 308 .sp 309 .ne 2 310 .na 311 \fB\fBO_TRUNC\fR\fR 312 .ad 313 .sp .6 314 .RS 4n 315 If the file exists and is a regular file, and the file is successfully opened 316 \fBO_RDWR\fR or \fBO_WRONLY\fR, its length is truncated to 0 and the mode and 317 owner are unchanged. It has no effect on \fBFIFO\fR special files or terminal 318 device files. Its effect on other file types is implementation-dependent. The 319 result of using \fBO_TRUNC\fR with \fBO_RDONLY\fR is undefined. 320 .RE 321 322 .sp 323 .ne 2 324 .na 325 \fB\fBO_XATTR\fR\fR 326 .ad 327 .sp .6 328 .RS 4n 329 If set in \fBopenat()\fR, a relative path argument is interpreted as a 330 reference to an extended attribute of the file associated with the supplied 331 file descriptor. This flag therefore requires the presence of a legal 332 \fIfildes\fR argument. If set in \fBopen()\fR, the implied file descriptor is 333 that for the current working directory. Extended attributes must be referenced 334 with a relative path; providing an absolute path results in a normal file 335 reference. 336 .RE 337 338 .sp 339 .LP 340 If \fBO_CREAT\fR is set and the file did not previously exist, upon successful 341 completion, \fBopen()\fR marks for update the \fBst_atime\fR, \fBst_ctime\fR, 342 and \fBst_mtime\fR fields of the file and the \fBst_ctime\fR and \fBst_mtime\fR 343 fields of the parent directory. 344 .sp 345 .LP 346 If \fBO_TRUNC\fR is set and the file did previously exist, upon successful 347 completion, \fBopen()\fR marks for update the \fBst_ctime\fR and \fBst_mtime\fR 348 fields of the file. 349 .sp 350 .LP 351 If both the \fBO_SYNC\fR and \fBO_DSYNC\fR flags are set, the effect is as if 352 only the \fBO_SYNC\fR flag was set. 353 .sp 354 .LP 355 If \fIpath\fR refers to a \fBSTREAMS\fR file, \fIoflag\fR may be constructed 356 from \fBO_NONBLOCK\fR or \fBO_NODELAY\fR OR-ed with either \fBO_RDONLY\fR, 357 \fBO_WRONLY\fR, or \fBO_RDWR\fR. Other flag values are not applicable to 358 \fBSTREAMS\fR devices and have no effect on them. The values \fBO_NONBLOCK\fR 359 and \fBO_NODELAY\fR affect the operation of \fBSTREAMS\fR drivers and certain 360 functions (see \fBread\fR(2), \fBgetmsg\fR(2), \fBputmsg\fR(2), and 361 \fBwrite\fR(2)) applied to file descriptors associated with \fBSTREAMS\fR 362 files. For \fBSTREAMS\fR drivers, the implementation of \fBO_NONBLOCK\fR and 363 \fBO_NODELAY\fR is device-specific. 364 .sp 365 .LP 366 When \fBopen()\fR is invoked to open a named stream, and the \fBconnld\fR 367 module (see \fBconnld\fR(7M)) has been pushed on the pipe, \fBopen()\fR blocks 368 until the server process has issued an \fBI_RECVFD\fR \fBioctl()\fR (see 369 \fBstreamio\fR(7I)) to receive the file descriptor. 370 .sp 371 .LP 372 If \fIpath\fR names the master side of a pseudo-terminal device, then it is 373 unspecified whether \fBopen()\fR locks the slave side so that it cannot be 374 opened. Portable applications must call \fBunlockpt\fR(3C) before opening the 375 slave side. 376 .sp 377 .LP 378 If the file is a regular file and the local file system is mounted with the 379 \fBnbmand\fR mount option, then a mandatory share reservation is automatically 380 obtained on the file. The share reservation is obtained as if \fBfcntl\fR(2) 381 were called with \fIcmd\fR \fBF_SHARE_NBMAND\fR and the \fBfshare_t\fR values 382 set as follows: 383 .sp 384 .ne 2 385 .na 386 \fB\fBf_access\fR\fR 387 .ad 388 .RS 12n 389 Set to the type of read/write access for which the file is opened. 390 .RE 391 392 .sp 393 .ne 2 394 .na 395 \fB\fBf_deny\fR\fR 396 .ad 397 .RS 12n 398 \fBF_NODNY\fR 399 .RE 400 401 .sp 402 .ne 2 403 .na 404 \fB\fBf_id\fR\fR 405 .ad 406 .RS 12n 407 The file descriptor value returned from \fBopen()\fR. 408 .RE 409 410 .sp 411 .LP 412 If \fIpath\fR is a symbolic link and \fBO_CREAT\fR and \fBO_EXCL\fR are set, 413 the link is not followed. 414 .sp 415 .LP 416 Certain flag values can be set following \fBopen()\fR as described in 417 \fBfcntl\fR(2). 418 .sp 419 .LP 420 The largest value that can be represented correctly in an object of type 421 \fBoff_t\fR is established as the offset maximum in the open file description. 422 .SH RETURN VALUES 423 .sp 424 .LP 425 Upon successful completion, the \fBopen()\fR function opens the file and return 426 a non-negative integer representing the lowest numbered unused file descriptor. 427 Otherwise, \fB\(mi1\fR is returned, \fBerrno\fR is set to indicate the error, 428 and no files are created or modified. 429 .SH ERRORS 430 .sp 431 .LP 432 The \fBopen()\fR and \fBopenat()\fR functions will fail if: 433 .sp 434 .ne 2 435 .na 436 \fB\fBEACCES\fR\fR 437 .ad 438 .RS 16n 439 Search permission is denied on a component of the path prefix. 440 .sp 441 The file exists and the permissions specified by \fIoflag\fR are denied. 442 .sp 443 The file does not exist and write permission is denied for the parent directory 444 of the file to be created. 445 .sp 446 \fBO_TRUNC\fR is specified and write permission is denied. 447 .sp 448 The {\fBPRIV_FILE_DAC_SEARCH\fR} privilege allows processes to search 449 directories regardless of permission bits. The {\fBPRIV_FILE_DAC_WRITE\fR} 450 privilege allows processes to open files for writing regardless of permission 451 bits. See \fBprivileges\fR(5) for special considerations when opening files 452 owned by UID 0 for writing. The {\fBPRIV_FILE_DAC_READ\fR} privilege allows 453 processes to open files for reading regardless of permission bits. 454 .RE 455 456 .sp 457 .ne 2 458 .na 459 \fB\fBEAGAIN\fR\fR 460 .ad 461 .RS 16n 462 A mandatory share reservation could not be obtained because the desired access 463 conflicts with an existing \fBf_deny\fR share reservation. 464 .RE 465 466 .sp 467 .ne 2 468 .na 469 \fB\fBEBADF\fR\fR 470 .ad 471 .RS 16n 472 The file descriptor provided to \fBopenat()\fR is invalid. 473 .RE 474 475 .sp 476 .ne 2 477 .na 478 \fB\fBEDQUOT\fR\fR 479 .ad 480 .RS 16n 481 The file does not exist, \fBO_CREAT\fR is specified, and either the directory 482 where the new file entry is being placed cannot be extended because the user's 483 quota of disk blocks on that file system has been exhausted, or the user's 484 quota of inodes on the file system where the file is being created has been 485 exhausted. 486 .RE 487 488 .sp 489 .ne 2 490 .na 491 \fB\fBEEXIST\fR\fR 492 .ad 493 .RS 16n 494 The \fBO_CREAT\fR and \fBO_EXCL\fR flags are set and the named file exists. 495 .RE 496 497 .sp 498 .ne 2 499 .na 500 \fB\fBEILSEQ\fR\fR 501 .ad 502 .RS 16n 503 The \fIpath\fR argument includes non-UTF8 characters and the file system 504 accepts only file names where all characters are part of the UTF-8 character 505 codeset. 506 .RE 507 508 .sp 509 .ne 2 510 .na 511 \fB\fBEINTR\fR\fR 512 .ad 513 .RS 16n 514 A signal was caught during \fBopen()\fR. 515 .RE 516 517 .sp 518 .ne 2 519 .na 520 \fB\fBEFAULT\fR\fR 521 .ad 522 .RS 16n 523 The \fIpath\fR argument points to an illegal address. 524 .RE 525 526 .sp 527 .ne 2 528 .na 529 \fB\fBEINVAL\fR\fR 530 .ad 531 .RS 16n 532 The system does not support synchronized I/O for this file, or the 533 \fBO_XATTR\fR flag was supplied and the underlying file system does not support 534 extended file attributes. 535 .RE 536 537 .sp 538 .ne 2 539 .na 540 \fB\fBEIO\fR\fR 541 .ad 542 .RS 16n 543 The \fIpath\fR argument names a \fBSTREAMS\fR file and a hangup or error 544 occurred during the \fBopen()\fR. 545 .RE 546 547 .sp 548 .ne 2 549 .na 550 \fB\fBEISDIR\fR\fR 551 .ad 552 .RS 16n 553 The named file is a directory and \fIoflag\fR includes \fBO_WRONLY\fR or 554 \fBO_RDWR\fR. 555 .RE 556 557 .sp 558 .ne 2 559 .na 560 \fB\fBELOOP\fR\fR 561 .ad 562 .RS 16n 563 Too many symbolic links were encountered in resolving \fIpath\fR. 564 .sp 565 A loop exists in symbolic links encountered during resolution of the \fIpath\fR 566 argument. 567 .sp 568 The \fBO_NOFOLLOW\fR flag is set and the final component of path is a symbolic 569 link. 570 .RE 571 572 .sp 573 .ne 2 574 .na 575 \fB\fBEMFILE\fR\fR 576 .ad 577 .RS 16n 578 There are currently {\fBOPEN_MAX\fR} file descriptors open in the calling 579 process. 580 .RE 581 582 .sp 583 .ne 2 584 .na 585 \fB\fBEMLINK\fR\fR 586 .ad 587 .RS 16n 588 The \fBO_NOLINKS\fR flag is set and the named file has a link count greater 589 than 1. 590 .RE 591 592 .sp 593 .ne 2 594 .na 595 \fB\fBEMULTIHOP\fR\fR 596 .ad 597 .RS 16n 598 Components of \fIpath\fR require hopping to multiple remote machines and the 599 file system does not allow it. 600 .RE 601 602 .sp 603 .ne 2 604 .na 605 \fB\fBENAMETOOLONG\fR\fR 606 .ad 607 .RS 16n 608 The length of the \fIpath\fR argument exceeds {\fBPATH_MAX\fR} or a pathname 609 component is longer than {\fBNAME_MAX\fR}. 610 .RE 611 612 .sp 613 .ne 2 614 .na 615 \fB\fBENFILE\fR\fR 616 .ad 617 .RS 16n 618 The maximum allowable number of files is currently open in the system. 619 .RE 620 621 .sp 622 .ne 2 623 .na 624 \fB\fBENOENT\fR\fR 625 .ad 626 .RS 16n 627 The \fBO_CREAT\fR flag is not set and the named file does not exist; or the 628 \fBO_CREAT\fR flag is set and either the path prefix does not exist or the 629 \fIpath\fR argument points to an empty string. 630 .RE 631 632 .sp 633 .ne 2 634 .na 635 \fB\fBENOLINK\fR\fR 636 .ad 637 .RS 16n 638 The \fIpath\fR argument points to a remote machine, and the link to that 639 machine is no longer active. 640 .RE 641 642 .sp 643 .ne 2 644 .na 645 \fB\fBENOSR\fR\fR 646 .ad 647 .RS 16n 648 The \fIpath\fR argument names a STREAMS-based file and the system is unable to 649 allocate a STREAM. 650 .RE 651 652 .sp 653 .ne 2 654 .na 655 \fB\fBENOSPC\fR\fR 656 .ad 657 .RS 16n 658 The directory or file system that would contain the new file cannot be 659 expanded, the file does not exist, and \fBO_CREAT\fR is specified. 660 .RE 661 662 .sp 663 .ne 2 664 .na 665 \fB\fBENOSYS\fR\fR 666 .ad 667 .RS 16n 668 The device specified by \fIpath\fR does not support the open operation. 669 .RE 670 671 .sp 672 .ne 2 673 .na 674 \fB\fBENOTDIR\fR\fR 675 .ad 676 .RS 16n 677 A component of the path prefix is not a directory or a relative path was 678 supplied to \fBopenat()\fR, the \fBO_XATTR\fR flag was not supplied, and the 679 file descriptor does not refer to a directory. 680 .RE 681 682 .sp 683 .ne 2 684 .na 685 \fB\fBENXIO\fR\fR 686 .ad 687 .RS 16n 688 The \fBO_NONBLOCK\fR flag is set, the named file is a FIFO, the \fBO_WRONLY\fR 689 flag is set, and no process has the file open for reading; or the named file is 690 a character special or block special file and the device associated with this 691 special file does not exist or has been retired by the fault management 692 framework . 693 .RE 694 695 .sp 696 .ne 2 697 .na 698 \fB\fBEOPNOTSUPP\fR\fR 699 .ad 700 .RS 16n 701 An attempt was made to open a path that corresponds to a \fBAF_UNIX\fR socket. 702 .RE 703 704 .sp 705 .ne 2 706 .na 707 \fB\fBEOVERFLOW\fR\fR 708 .ad 709 .RS 16n 710 The named file is a regular file and either \fBO_LARGEFILE\fR is not set and 711 the size of the file cannot be represented correctly in an object of type 712 \fBoff_t\fR or \fBO_LARGEFILE\fR is set and the size of the file cannot be 713 represented correctly in an object of type \fBoff64_t\fR. 714 .RE 715 716 .sp 717 .ne 2 718 .na 719 \fB\fBEROFS\fR\fR 720 .ad 721 .RS 16n 722 The named file resides on a read-only file system and either \fBO_WRONLY\fR, 723 \fBO_RDWR\fR, \fBO_CREAT\fR (if file does not exist), or \fBO_TRUNC\fR is set 724 in the \fIoflag\fR argument. 725 .RE 726 727 .sp 728 .LP 729 The \fBopenat()\fR function will fail if: 730 .sp 731 .ne 2 732 .na 733 \fB\fBEBADF\fR\fR 734 .ad 735 .RS 9n 736 The \fIfildes\fR argument is not a valid open file descriptor or is not 737 \fBAT_FTCWD\fR. 738 .RE 739 740 .sp 741 .LP 742 The \fBopen()\fR function may fail if: 743 .sp 744 .ne 2 745 .na 746 \fB\fBEAGAIN\fR\fR 747 .ad 748 .RS 16n 749 The \fIpath\fR argument names the slave side of a pseudo-terminal device that 750 is locked. 751 .RE 752 753 .sp 754 .ne 2 755 .na 756 \fB\fBEINVAL\fR\fR 757 .ad 758 .RS 16n 759 The value of the \fIoflag\fR argument is not valid. 760 .RE 761 762 .sp 763 .ne 2 764 .na 765 \fB\fBENAMETOOLONG\fR\fR 766 .ad 767 .RS 16n 768 Pathname resolution of a symbolic link produced an intermediate result whose 769 length exceeds {\fBPATH_MAX\fR}. 770 .RE 771 772 .sp 773 .ne 2 774 .na 775 \fB\fBENOMEM\fR\fR 776 .ad 777 .RS 16n 778 The \fIpath\fR argument names a \fBSTREAMS\fR file and the system is unable to 779 allocate resources. 780 .RE 781 782 .sp 783 .ne 2 784 .na 785 \fB\fBETXTBSY\fR\fR 786 .ad 787 .RS 16n 788 The file is a pure procedure (shared text) file that is being executed and 789 \fIoflag\fR is \fBO_WRONLY\fR or \fBO_RDWR\fR. 790 .RE 791 792 .SH EXAMPLES 793 .LP 794 \fBExample 1 \fROpen a file for writing by the owner. 795 .sp 796 .LP 797 The following example opens the file \fB/tmp/file\fR, either by creating it if 798 it does not already exist, or by truncating its length to 0 if it does exist. 799 If the call creates a new file, the access permission bits in the file mode of 800 the file are set to permit reading and writing by the owner, and to permit 801 reading only by group members and others. 802 803 .sp 804 .LP 805 If the call to \fBopen()\fR is successful, the file is opened for writing. 806 807 .sp 808 .in +2 809 .nf 810 #include <fcntl.h> 811 \&... 812 int fd; 813 mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH; 814 char *filename = "/tmp/file"; 815 \&... 816 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, mode); 817 \&... 818 .fi 819 .in -2 820 821 .LP 822 \fBExample 2 \fROpen a file using an existence check. 823 .sp 824 .LP 825 The following example uses the \fBopen()\fR function to try to create the 826 \fBLOCKFILE\fR file and open it for writing. Since the \fBopen()\fR function 827 specifies the \fBO_EXCL\fR flag, the call fails if the file already exists. In 828 that case, the application assumes that someone else is updating the password 829 file and exits. 830 831 .sp 832 .in +2 833 .nf 834 #include <fcntl.h> 835 #include <stdio.h> 836 #include <stdlib.h> 837 #define LOCKFILE "/etc/ptmp" 838 \&... 839 int pfd; /* Integer for file descriptor returned by open() call. */ 840 \&... 841 if ((pfd = open(LOCKFILE, O_WRONLY | O_CREAT | O_EXCL, 842 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1) 843 { 844 fprintf(stderr, "Cannot open /etc/ptmp. Try again later.\en"); 845 exit(1); 846 } 847 \&... 848 .fi 849 .in -2 850 851 .LP 852 \fBExample 3 \fROpen a file for writing. 853 .sp 854 .LP 855 The following example opens a file for writing, creating the file if it does 856 not already exist. If the file does exist, the system truncates the file to 857 zero bytes. 858 859 .sp 860 .in +2 861 .nf 862 #include <fcntl.h> 863 #include <stdio.h> 864 #include <stdlib.h> 865 #define LOCKFILE "/etc/ptmp" 866 \&... 867 int pfd; 868 char filename[PATH_MAX+1]; 869 \&... 870 if ((pfd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 871 S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)) == -1) 872 { 873 perror("Cannot open output file\en"); exit(1); 874 } 875 \&... 876 .fi 877 .in -2 878 879 .SH USAGE 880 .sp 881 .LP 882 The \fBopen()\fR function has a transitional interface for 64-bit file offsets. 883 See \fBlf64\fR(5). Note that using \fBopen64()\fR is equivalent to using 884 \fBopen()\fR with \fBO_LARGEFILE\fR set in \fIoflag\fR. 885 .SH ATTRIBUTES 886 .sp 887 .LP 888 See \fBattributes\fR(5) for descriptions of the following attributes: 889 .sp 890 891 .sp 892 .TS 893 box; 894 c | c 895 l | l . 896 ATTRIBUTE TYPE ATTRIBUTE VALUE 897 _ 898 Interface Stability Committed 899 _ 900 MT-Level Async-Signal-Safe 901 _ 902 Standard For \fBopen()\fR, see \fBstandards\fR(5). 903 .TE 904 905 .SH SEE ALSO 906 .sp 907 .LP 908 \fBIntro\fR(2), \fBchmod\fR(2), \fBclose\fR(2), \fBcreat\fR(2), \fBdup\fR(2), 909 \fBexec\fR(2), \fBfcntl\fR(2), \fBgetmsg\fR(2), \fBgetrlimit\fR(2), 910 \fBlseek\fR(2), \fBputmsg\fR(2), \fBread\fR(2), \fBstat\fR(2), \fBumask\fR(2), 911 \fBwrite\fR(2), \fBattropen\fR(3C), \fBfcntl.h\fR(3HEAD), \fBstat.h\fR(3HEAD), 912 \fBunlockpt\fR(3C), \fBattributes\fR(5), \fBlf64\fR(5), \fBprivileges\fR(5), 913 \fBstandards\fR(5), \fBconnld\fR(7M), \fBstreamio\fR(7I) 914 .SH NOTES 915 .sp 916 .LP 917 Hierarchical Storage Management (HSM) file systems can sometimes cause long 918 delays when opening a file, since HSM files must be recalled from secondary 919 storage. --- EOF ---