xref: /illumos-gate/usr/src/cmd/sgs/libld/common/outfile.c (revision 2b4a78020b9c38d1b95e2f3fefa6d6e4be382d1f)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  *	Copyright (c) 1988 AT&T
24  *	  All Rights Reserved
25  *
26  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 
30 /*
31  * This file contains the functions responsible for opening the output file
32  * image, associating the appropriate input elf structures with the new image,
33  * and obtaining new elf structures to define the new image.
34  */
35 #include	<stdio.h>
36 #include	<sys/stat.h>
37 #include	<fcntl.h>
38 #include	<link.h>
39 #include	<errno.h>
40 #include	<string.h>
41 #include	<limits.h>
42 #include	<debug.h>
43 #include	<unistd.h>
44 #include	"msg.h"
45 #include	"_libld.h"
46 
47 /*
48  * Determine a least common multiplier.  Input sections contain an alignment
49  * requirement, which elf_update() uses to insure that the section is aligned
50  * correctly off of the base of the elf image.  We must also insure that the
51  * sections mapping is congruent with this alignment requirement.  For each
52  * input section associated with a loadable segment determine whether the
53  * segments alignment must be adjusted to compensate for a sections alignment
54  * requirements.
55  */
56 Xword
57 ld_lcm(Xword a, Xword b)
58 {
59 	Xword	_r, _a, _b;
60 
61 	if ((_a = a) == 0)
62 		return (b);
63 	if ((_b = b) == 0)
64 		return (a);
65 
66 	if (_a > _b)
67 		_a = b, _b = a;
68 	while ((_r = _b % _a) != 0)
69 		_b = _a, _a = _r;
70 	return ((a / _a) * b);
71 }
72 
73 /*
74  * Open the output file and insure the correct access modes.
75  */
76 uintptr_t
77 ld_open_outfile(Ofl_desc * ofl)
78 {
79 	mode_t		mode;
80 	struct stat	status;
81 
82 	/*
83 	 * Determine the required file mode from the type of output file we
84 	 * are creating.
85 	 */
86 	mode = (ofl->ofl_flags & (FLG_OF_EXEC | FLG_OF_SHAROBJ))
87 	    ? 0777 : 0666;
88 
89 	/* Determine if the output file already exists */
90 	if (stat(ofl->ofl_name, &status) == 0) {
91 		if ((status.st_mode & S_IFMT) != S_IFREG) {
92 			/*
93 			 * It is not a regular file, so don't delete it
94 			 * or allow it to be deleted.  This allows root
95 			 * users to specify /dev/null output file for
96 			 * verification links.
97 			 */
98 			ofl->ofl_flags1 |= FLG_OF1_NONREG;
99 		} else {
100 			/*
101 			 * It's a regular file, so unlink it. In standard
102 			 * Unix fashion, the old file will continue to
103 			 * exist until its link count drops to 0 and no
104 			 * process has the file open. In the meantime, we
105 			 * create a new file (inode) under the same name,
106 			 * available for new use.
107 			 *
108 			 * The advantage of this policy is that creating
109 			 * a new executable or sharable library does not
110 			 * corrupt existing processes using the old file.
111 			 * A possible disadvantage is that if the existing
112 			 * file has a (link_count > 1), the other names will
113 			 * continue to reference the old inode, thus
114 			 * breaking the link.
115 			 *
116 			 * A subtlety here is that POSIX says we are not
117 			 * supposed to replace a non-writable file, which
118 			 * is something that unlink() is happy to do. The
119 			 * only 100% reliable test against this is to open
120 			 * the file for non-destructive write access. If the
121 			 * open succeeds, we are clear to unlink it, and if
122 			 * not, then the error generated is the error we
123 			 * need to report.
124 			 */
125 			if ((ofl->ofl_fd = open(ofl->ofl_name, O_RDWR,
126 			    mode)) < 0) {
127 				int	err = errno;
128 
129 				if (err != ENOENT) {
130 					eprintf(ofl->ofl_lml, ERR_FATAL,
131 					    MSG_INTL(MSG_SYS_OPEN),
132 					    ofl->ofl_name, strerror(err));
133 					return (S_ERROR);
134 				}
135 			} else {
136 				(void) close(ofl->ofl_fd);
137 			}
138 
139 			if ((unlink(ofl->ofl_name) == -1) &&
140 			    (errno != ENOENT)) {
141 				int err = errno;
142 
143 				eprintf(ofl->ofl_lml, ERR_FATAL,
144 				    MSG_INTL(MSG_SYS_UNLINK),
145 				    ofl->ofl_name, strerror(err));
146 				return (S_ERROR);
147 			}
148 		}
149 	}
150 
151 	/*
152 	 * Open (or create) the output file name (ofl_fd acts as a global
153 	 * flag to ldexit() signifying whether the output file should be
154 	 * removed or not on error).
155 	 */
156 	if ((ofl->ofl_fd = open(ofl->ofl_name, O_RDWR | O_CREAT | O_TRUNC,
157 	    mode)) < 0) {
158 		int	err = errno;
159 
160 		eprintf(ofl->ofl_lml, ERR_FATAL, MSG_INTL(MSG_SYS_OPEN),
161 		    ofl->ofl_name, strerror(err));
162 		return (S_ERROR);
163 	}
164 
165 	return (1);
166 }
167 
168 
169 /*
170  * If we are creating a memory model we need to update the present memory image.
171  * First we need to call elf_update(ELF_C_NULL) which will calculate the offsets
172  * of each section and its associated data buffers.  From this information we
173  * can then determine what padding is required.
174  * Two actions are necessary to convert the present disc image into a memory
175  * image:
176  *
177  *  o	Loadable segments must be padded so that the next segments virtual
178  *	address and file offset are the same.
179  *
180  *  o	NOBITS sections must be converted into allocated, null filled sections.
181  */
182 static uintptr_t
183 pad_outfile(Ofl_desc *ofl)
184 {
185 	Listnode	*lnp;
186 	off_t		offset;
187 	Elf_Scn		*oscn = 0;
188 	Sg_desc		*sgp;
189 	Ehdr		*ehdr;
190 
191 	/*
192 	 * Update all the elf structures.  This will assign offsets to the
193 	 * section headers and data buffers as they relate to the new image.
194 	 */
195 	if (elf_update(ofl->ofl_welf, ELF_C_NULL) == -1) {
196 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_UPDATE),
197 		    ofl->ofl_name);
198 		return (S_ERROR);
199 	}
200 	if ((ehdr = elf_getehdr(ofl->ofl_welf)) == NULL) {
201 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR),
202 		    ofl->ofl_name);
203 		return (S_ERROR);
204 	}
205 
206 	/*
207 	 * Initialize the offset by skipping the Elf header and program
208 	 * headers.
209 	 */
210 	offset = ehdr->e_phoff + (ehdr->e_phnum * ehdr->e_phentsize);
211 
212 	/*
213 	 * Traverse the segment list looking for loadable segments.
214 	 */
215 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp, sgp)) {
216 		Phdr	*phdr = &(sgp->sg_phdr);
217 		Os_desc	*osp;
218 		Aliste	idx;
219 
220 		/*
221 		 * If we've already processed a loadable segment, the `scn'
222 		 * variable will be initialized to the last section that was
223 		 * part of that segment.  Add sufficient padding to this section
224 		 * to cause the next segments virtual address and file offset to
225 		 * be the same.
226 		 */
227 		if (oscn && (phdr->p_type == PT_LOAD)) {
228 			Elf_Data *	data;
229 			size_t 		size;
230 
231 			size = (size_t)(S_ROUND(offset, phdr->p_align) -
232 			    offset);
233 
234 			if ((data = elf_newdata(oscn)) == NULL) {
235 				eprintf(ofl->ofl_lml, ERR_ELF,
236 				    MSG_INTL(MSG_ELF_NEWDATA), ofl->ofl_name);
237 				return (S_ERROR);
238 			}
239 			if ((data->d_buf = libld_calloc(size, 1)) == 0)
240 				return (S_ERROR);
241 
242 			data->d_type = ELF_T_BYTE;
243 			data->d_size = size;
244 			data->d_align = 1;
245 			data->d_version = ofl->ofl_dehdr->e_version;
246 		}
247 
248 		/*
249 		 * Traverse the output sections for this segment calculating the
250 		 * offset of each section. Retain the final section descriptor
251 		 * as this will be where any padding buffer will be added.
252 		 */
253 		for (APLIST_TRAVERSE(sgp->sg_osdescs, idx, osp)) {
254 			Shdr	*shdr = osp->os_shdr;
255 
256 			offset = (off_t)S_ROUND(offset, shdr->sh_addralign);
257 			offset += shdr->sh_size;
258 
259 			/*
260 			 * If this is a NOBITS output section convert all of
261 			 * its associated input sections into real, null filled,
262 			 * data buffers, and change the section to PROGBITS.
263 			 */
264 			if (shdr->sh_type == SHT_NOBITS)
265 				shdr->sh_type = SHT_PROGBITS;
266 		}
267 
268 		/*
269 		 * If this is a loadable segment retain the last output section
270 		 * descriptor.  This acts both as a flag that a loadable
271 		 * segment has been seen, and as the segment to which a padding
272 		 * buffer will be added.
273 		 */
274 		if (phdr->p_type == PT_LOAD)
275 			oscn = osp->os_scn;
276 	}
277 	return (1);
278 }
279 
280 /*
281  * Create an output section.  The first instance of an input section triggers
282  * the creation of a new output section.
283  */
284 static uintptr_t
285 create_outsec(Ofl_desc *ofl, Sg_desc *sgp, Os_desc *osp, Word ptype, int shidx,
286     Boolean fixalign)
287 {
288 	Elf_Scn	*scn;
289 	Shdr	*shdr;
290 
291 	/*
292 	 * Get a section descriptor for the section.
293 	 */
294 	if ((scn = elf_newscn(ofl->ofl_welf)) == NULL) {
295 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_NEWSCN),
296 		    ofl->ofl_name);
297 		return (S_ERROR);
298 	}
299 	osp->os_scn = scn;
300 
301 	/*
302 	 * Get a new section header table entry and copy the pertinent
303 	 * information from the in-core descriptor.
304 	 */
305 	if ((shdr = elf_getshdr(scn)) == NULL) {
306 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR),
307 		    ofl->ofl_name);
308 		return (S_ERROR);
309 	}
310 	*shdr = *(osp->os_shdr);
311 	osp->os_shdr = shdr;
312 
313 	/*
314 	 * If this is the first section within a loadable segment, and the
315 	 * alignment needs to be updated, record this section.
316 	 */
317 	if ((fixalign == TRUE) && (ptype == PT_LOAD) && (shidx == 1))
318 		sgp->sg_fscn = scn;
319 
320 	/*
321 	 * If not building a relocatable object, remove any of the
322 	 * following flags, as they have been acted upon and are not
323 	 * meaningful in the output:
324 	 *	SHF_ORDERED, SHF_LINK_ORDER, SHF_GROUP
325 	 * For relocatable objects, we allow them to propagate to
326 	 * the output object to be handled by the next linker that
327 	 * sees them.
328 	 */
329 	if ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0)
330 		osp->os_shdr->sh_flags &= ~(ALL_SHF_ORDER|SHF_GROUP);
331 
332 	/*
333 	 * If this is a TLS section, save it so that the PT_TLS program header
334 	 * information can be established after the output image has been
335 	 * initially created.  At this point, all TLS input sections are ordered
336 	 * as they will appear in the output image.
337 	 */
338 	if ((ofl->ofl_flags & FLG_OF_TLSPHDR) &&
339 	    (osp->os_shdr->sh_flags & SHF_TLS) &&
340 	    (list_appendc(&ofl->ofl_ostlsseg, osp) == 0))
341 		return (S_ERROR);
342 
343 	return (0);
344 }
345 
346 /*
347  * Create the elf structures that allow the input data to be associated with the
348  * new image:
349  *
350  *	o	define the new elf image using elf_begin(),
351  *
352  *	o	obtain an elf header for the image,
353  *
354  *	o	traverse the input segments and create a program header array
355  *		to define the required segments,
356  *
357  *	o 	traverse the output sections for each segment assigning a new
358  *		section descriptor and section header for each,
359  *
360  *	o	traverse the input sections associated with each output section
361  *		and assign a new data descriptor to each (each output section
362  *		becomes a linked list of input data buffers).
363  */
364 uintptr_t
365 ld_create_outfile(Ofl_desc *ofl)
366 {
367 	Listnode	*lnp1;
368 	Sg_desc		*sgp;
369 	Os_desc		*osp;
370 	Is_desc		*isp;
371 	Elf_Data	*tlsdata = 0;
372 	Aliste		idx;
373 	ofl_flag_t	flags = ofl->ofl_flags;
374 	ofl_flag_t	flags1 = ofl->ofl_flags1;
375 	size_t		ndx = 0, fndx = 0;
376 	Elf_Cmd		cmd;
377 	Boolean		fixalign = FALSE;
378 	int		fd, nseg = 0, shidx = 0, dataidx = 0, ptloadidx = 0;
379 
380 	/*
381 	 * If DF_1_NOHDR was set in map_parse() or FLG_OF1_VADDR was set,
382 	 * we need to do alignment adjustment.
383 	 */
384 	if ((flags1 & FLG_OF1_VADDR) ||
385 	    (ofl->ofl_dtflags_1 & DF_1_NOHDR)) {
386 		fixalign = TRUE;
387 	}
388 
389 	if (flags1 & FLG_OF1_MEMORY) {
390 		cmd = ELF_C_IMAGE;
391 		fd = 0;
392 	} else {
393 		fd = ofl->ofl_fd;
394 		cmd = ELF_C_WRITE;
395 	}
396 
397 	/*
398 	 * If there are any ordered sections, handle them here.
399 	 */
400 	if ((ofl->ofl_ordered.head != NULL) &&
401 	    (ld_sort_ordered(ofl) == S_ERROR))
402 		return (S_ERROR);
403 
404 	/*
405 	 * Tell the access library about our new temporary file.
406 	 */
407 	if ((ofl->ofl_welf = elf_begin(fd, cmd, 0)) == NULL) {
408 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_BEGIN),
409 		    ofl->ofl_name);
410 		return (S_ERROR);
411 	}
412 
413 	/*
414 	 * Obtain a new Elf header.
415 	 */
416 	if ((ofl->ofl_nehdr = elf_newehdr(ofl->ofl_welf)) == NULL) {
417 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_NEWEHDR),
418 		    ofl->ofl_name);
419 		return (S_ERROR);
420 	}
421 	ofl->ofl_nehdr->e_machine = ofl->ofl_dehdr->e_machine;
422 
423 	DBG_CALL(Dbg_util_nl(ofl->ofl_lml, DBG_NL_STD));
424 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) {
425 		int	frst = 0;
426 		Phdr	*phdr = &(sgp->sg_phdr);
427 		Word	ptype = phdr->p_type;
428 
429 		/*
430 		 * Count the number of segments that will go in the program
431 		 * header table. If a segment is empty, ignore it.
432 		 */
433 		if (!(flags & FLG_OF_RELOBJ)) {
434 			if (ptype == PT_PHDR) {
435 				/*
436 				 * If we are generating an interp section (and
437 				 * thus an associated PT_INTERP program header
438 				 * entry) also generate a PT_PHDR program header
439 				 * entry.  This allows the kernel to generate
440 				 * the appropriate aux vector entries to pass to
441 				 * the interpreter (refer to exec/elf/elf.c).
442 				 * Note that if an image was generated with an
443 				 * interp section, but no associated PT_PHDR
444 				 * program header entry, the kernel will simply
445 				 * pass the interpreter an open file descriptor
446 				 * when the image is executed).
447 				 */
448 				if (ofl->ofl_osinterp)
449 					nseg++;
450 			} else if (ptype == PT_INTERP) {
451 				if (ofl->ofl_osinterp)
452 					nseg++;
453 			} else if (ptype == PT_DYNAMIC) {
454 				if (flags & FLG_OF_DYNAMIC)
455 					nseg++;
456 			} else if (ptype == PT_TLS) {
457 				if (flags & FLG_OF_TLSPHDR)
458 					nseg++;
459 #if	defined(_ELF64)
460 			} else if ((ld_targ.t_m.m_mach == EM_AMD64) &&
461 			    (ptype == PT_SUNW_UNWIND)) {
462 				if (ofl->ofl_unwindhdr)
463 					nseg++;
464 #endif
465 			} else if (ptype == PT_SUNWBSS) {
466 				if (ofl->ofl_issunwbss)
467 					nseg++;
468 			} else if (ptype == PT_SUNWDTRACE) {
469 				if (ofl->ofl_dtracesym)
470 					nseg++;
471 			} else if (ptype == PT_SUNWCAP) {
472 				if (ofl->ofl_oscap)
473 					nseg++;
474 			} else if (sgp->sg_flags & FLG_SG_EMPTY) {
475 					nseg++;
476 			} else if (sgp->sg_osdescs != NULL) {
477 				if ((sgp->sg_flags & FLG_SG_PHREQ) == 0) {
478 					/*
479 					 * If this is a segment for which
480 					 * we are not making a program header,
481 					 * don't increment nseg
482 					 */
483 					ptype = (sgp->sg_phdr).p_type = PT_NULL;
484 				} else if (ptype != PT_NULL)
485 					nseg++;
486 			}
487 		}
488 
489 		/*
490 		 * If the first loadable segment has the ?N flag,
491 		 * then ?N will be on.
492 		 */
493 		if ((ptype == PT_LOAD) && (ptloadidx == 0)) {
494 			ptloadidx++;
495 			if (sgp->sg_flags & FLG_SG_NOHDR) {
496 				fixalign = TRUE;
497 				ofl->ofl_dtflags_1 |= DF_1_NOHDR;
498 			}
499 		}
500 
501 		shidx = 0;
502 		for (APLIST_TRAVERSE(sgp->sg_osdescs, idx, osp)) {
503 			Listnode	*lnp2;
504 
505 			dataidx = 0;
506 			for (LIST_TRAVERSE(&(osp->os_isdescs), lnp2, isp)) {
507 				Elf_Data *	data;
508 				Ifl_desc *	ifl = isp->is_file;
509 
510 				/*
511 				 * An input section in the list that has
512 				 * been previously marked to be discarded
513 				 * should be completely ignored.
514 				 */
515 				if (isp->is_flags & FLG_IS_DISCARD)
516 					continue;
517 
518 				/*
519 				 * At this point we know whether a section has
520 				 * been referenced.  If it hasn't, and the whole
521 				 * file hasn't been referenced (which would have
522 				 * been caught in ignore_section_processing()),
523 				 * give a diagnostic (-D unused,detail) or
524 				 * discard the section if -zignore is in effect.
525 				 */
526 				if (ifl &&
527 				    (((ifl->ifl_flags & FLG_IF_FILEREF) == 0) ||
528 				    ((ptype == PT_LOAD) &&
529 				    ((isp->is_flags & FLG_IS_SECTREF) == 0) &&
530 				    (isp->is_shdr->sh_size > 0)))) {
531 					Lm_list	*lml = ofl->ofl_lml;
532 
533 					if (ifl->ifl_flags & FLG_IF_IGNORE) {
534 						isp->is_flags |= FLG_IS_DISCARD;
535 						DBG_CALL(Dbg_unused_sec(lml,
536 						    isp));
537 						continue;
538 					} else {
539 						DBG_CALL(Dbg_unused_sec(lml,
540 						    isp));
541 					}
542 				}
543 
544 				/*
545 				 * If this section provides no data, and isn't
546 				 * referenced, then it can be discarded as well.
547 				 * Note, if this is the first input section
548 				 * associated to an output section, let it
549 				 * through, there may be a legitimate reason why
550 				 * the user wants a null section.  Discarding
551 				 * additional sections is intended to remove the
552 				 * empty clutter the compilers have a habit of
553 				 * creating.  Don't provide an unused diagnostic
554 				 * as these sections aren't typically the users
555 				 * creation.
556 				 */
557 				if (ifl && dataidx &&
558 				    ((isp->is_flags & FLG_IS_SECTREF) == 0) &&
559 				    (isp->is_shdr->sh_size == 0)) {
560 					isp->is_flags |= FLG_IS_DISCARD;
561 					continue;
562 				}
563 
564 				/*
565 				 * The first input section triggers the creation
566 				 * of the associated output section.
567 				 */
568 				if (osp->os_scn == NULL) {
569 					shidx++;
570 
571 					if (create_outsec(ofl, sgp, osp, ptype,
572 					    shidx, fixalign) == S_ERROR)
573 						return (S_ERROR);
574 				}
575 
576 				dataidx++;
577 
578 				/*
579 				 * Create a new output data buffer for each
580 				 * input data buffer, thus linking the new
581 				 * buffers to the new elf output structures.
582 				 * Simply make the new data buffers point to
583 				 * the old data.
584 				 */
585 				if ((data = elf_newdata(osp->os_scn)) == NULL) {
586 					eprintf(ofl->ofl_lml, ERR_ELF,
587 					    MSG_INTL(MSG_ELF_NEWDATA),
588 					    ofl->ofl_name);
589 					return (S_ERROR);
590 				}
591 				*data = *(isp->is_indata);
592 				isp->is_indata = data;
593 
594 				if ((fixalign == TRUE) && (ptype == PT_LOAD) &&
595 				    (shidx == 1) && (dataidx == 1))
596 					data->d_align = sgp->sg_addralign;
597 
598 				/*
599 				 * Save the first TLS data buffer, as this is
600 				 * the start of the TLS segment. Realign this
601 				 * buffer based on the alignment requirements
602 				 * of all the TLS input sections.
603 				 */
604 				if ((flags & FLG_OF_TLSPHDR) &&
605 				    (isp->is_shdr->sh_flags & SHF_TLS)) {
606 					if (tlsdata == 0)
607 						tlsdata = data;
608 					tlsdata->d_align =
609 					    ld_lcm(tlsdata->d_align,
610 					    isp->is_shdr->sh_addralign);
611 				}
612 
613 #if	defined(_ELF64) && defined(_ILP32)
614 				/*
615 				 * 4106312, the 32-bit ELF64 version of ld
616 				 * needs to be able to create large .bss
617 				 * sections.  The d_size member of Elf_Data
618 				 * only allows 32-bits in _ILP32, so we build
619 				 * multiple data-items that each fit into 32-
620 				 * bits.  libelf (4106398) can summ these up
621 				 * into a 64-bit quantity.  This only works
622 				 * for NOBITS sections which don't have any
623 				 * real data to maintain and don't require
624 				 * large file support.
625 				 */
626 				if (isp->is_shdr->sh_type == SHT_NOBITS) {
627 					Xword sz = isp->is_shdr->sh_size;
628 
629 					while (sz >> 32) {
630 						data->d_size = SIZE_MAX;
631 						sz -= (Xword)SIZE_MAX;
632 
633 						data = elf_newdata(osp->os_scn);
634 						if (data == NULL)
635 							return (S_ERROR);
636 					}
637 					data->d_size = (size_t)sz;
638 				}
639 #endif
640 
641 				/*
642 				 * If this segment requires rounding realign the
643 				 * first data buffer associated with the first
644 				 * section.
645 				 */
646 				if ((frst++ == 0) &&
647 				    (sgp->sg_flags & FLG_SG_ROUND)) {
648 					Xword    align;
649 
650 					if (data->d_align)
651 						align = (Xword)
652 						    S_ROUND(data->d_align,
653 						    sgp->sg_round);
654 					else
655 						align = sgp->sg_round;
656 
657 					data->d_align = (size_t)align;
658 				}
659 			}
660 
661 			/*
662 			 * Clear the szoutrels counter so that it can be used
663 			 * again in the building of relocs.  See machrel.c.
664 			 */
665 			osp->os_szoutrels = 0;
666 		}
667 	}
668 
669 	/*
670 	 * Build an empty PHDR.
671 	 */
672 	if (nseg) {
673 		if ((ofl->ofl_phdr = elf_newphdr(ofl->ofl_welf,
674 		    nseg)) == NULL) {
675 			eprintf(ofl->ofl_lml, ERR_ELF,
676 			    MSG_INTL(MSG_ELF_NEWPHDR), ofl->ofl_name);
677 			return (S_ERROR);
678 		}
679 	}
680 
681 	/*
682 	 * If we need to generate a memory model, pad the image.
683 	 */
684 	if (flags1 & FLG_OF1_MEMORY) {
685 		if (pad_outfile(ofl) == S_ERROR)
686 			return (S_ERROR);
687 	}
688 
689 	/*
690 	 * After all the basic input file processing, all data pointers are
691 	 * referencing two types of memory:
692 	 *
693 	 *	o	allocated memory, ie. elf structures, internal link
694 	 *		editor structures, and any new sections that have been
695 	 *		created.
696 	 *
697 	 *	o	original input file mmap'ed memory, ie. the actual data
698 	 *		sections of the input file images.
699 	 *
700 	 * Up until now, the only memory modifications have been carried out on
701 	 * the allocated memory.  Before carrying out any relocations, write the
702 	 * new output file image and reassign any necessary data pointers to the
703 	 * output files memory image.  This insures that any relocation
704 	 * modifications are made to the output file image and not to the input
705 	 * file image, thus preventing the creation of dirty pages and reducing
706 	 * the overall swap space requirement.
707 	 *
708 	 * Write out the elf structure so as to create the new file image.
709 	 */
710 	if ((ofl->ofl_size = (size_t)elf_update(ofl->ofl_welf,
711 	    ELF_C_WRIMAGE)) == (size_t)-1) {
712 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_UPDATE),
713 		    ofl->ofl_name);
714 		return (S_ERROR);
715 	}
716 
717 	/*
718 	 * Initialize the true `ofl' information with the memory images address
719 	 * and size.  This will be used to write() out the image once any
720 	 * relocation processing has been completed.  We also use this image
721 	 * information to setup a new Elf descriptor, which is used to obtain
722 	 * all the necessary elf pointers within the new output image.
723 	 */
724 	if ((ofl->ofl_elf = elf_begin(0, ELF_C_IMAGE,
725 	    ofl->ofl_welf)) == NULL) {
726 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_BEGIN),
727 		    ofl->ofl_name);
728 		return (S_ERROR);
729 	}
730 	if ((ofl->ofl_nehdr = elf_getehdr(ofl->ofl_elf)) == NULL) {
731 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR),
732 		    ofl->ofl_name);
733 		return (S_ERROR);
734 	}
735 	if (!(flags & FLG_OF_RELOBJ))
736 		if ((ofl->ofl_phdr = elf_getphdr(ofl->ofl_elf)) == NULL) {
737 			eprintf(ofl->ofl_lml, ERR_ELF,
738 			    MSG_INTL(MSG_ELF_GETPHDR), ofl->ofl_name);
739 			return (S_ERROR);
740 		}
741 
742 	/*
743 	 * Reinitialize the section descriptors, section headers and obtain new
744 	 * output data buffer pointers (these will be used to perform any
745 	 * relocations).
746 	 */
747 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) {
748 		Phdr	*_phdr = &(sgp->sg_phdr);
749 		Os_desc	*osp;
750 		Aliste	idx;
751 		Boolean	recorded = FALSE;
752 
753 		for (APLIST_TRAVERSE(sgp->sg_osdescs, idx, osp)) {
754 			/*
755 			 * Make sure that an output section was originally
756 			 * created.  Input sections that had been marked as
757 			 * discarded may have made an output section
758 			 * unnecessary.  Remove this alist entry so that
759 			 * future output section descriptor processing doesn't
760 			 * have to compensate for this empty section.
761 			 */
762 			if (osp->os_scn == NULL) {
763 				aplist_delete(sgp->sg_osdescs, &idx);
764 				continue;
765 			}
766 
767 			if ((osp->os_scn = elf_getscn(ofl->ofl_elf, ++ndx)) ==
768 			    NULL) {
769 				eprintf(ofl->ofl_lml, ERR_ELF,
770 				    MSG_INTL(MSG_ELF_GETSCN), ofl->ofl_name,
771 				    ndx);
772 				return (S_ERROR);
773 			}
774 			if ((osp->os_shdr = elf_getshdr(osp->os_scn)) ==
775 			    NULL) {
776 				eprintf(ofl->ofl_lml, ERR_ELF,
777 				    MSG_INTL(MSG_ELF_GETSHDR), ofl->ofl_name);
778 				return (S_ERROR);
779 			}
780 			if ((fixalign == TRUE) && (sgp->sg_fscn != 0) &&
781 			    (recorded == FALSE)) {
782 				Elf_Scn *scn;
783 
784 				scn = sgp->sg_fscn;
785 				if ((fndx = elf_ndxscn(scn)) == SHN_UNDEF) {
786 					eprintf(ofl->ofl_lml, ERR_ELF,
787 					    MSG_INTL(MSG_ELF_NDXSCN),
788 					    ofl->ofl_name);
789 					return (S_ERROR);
790 				}
791 				if (ndx == fndx) {
792 					sgp->sg_fscn = osp->os_scn;
793 					recorded = TRUE;
794 				}
795 			}
796 
797 			if ((osp->os_outdata =
798 			    elf_getdata(osp->os_scn, NULL)) == NULL) {
799 				eprintf(ofl->ofl_lml, ERR_ELF,
800 				    MSG_INTL(MSG_ELF_GETDATA), ofl->ofl_name);
801 				return (S_ERROR);
802 			}
803 
804 			/*
805 			 * If this section is part of a loadable segment insure
806 			 * that the segments alignment is appropriate.
807 			 */
808 			if (_phdr->p_type == PT_LOAD) {
809 				_phdr->p_align = ld_lcm(_phdr->p_align,
810 				    osp->os_shdr->sh_addralign);
811 			}
812 		}
813 	}
814 	return (1);
815 }
816