xref: /titanic_41/usr/src/cmd/sgs/libld/common/outfile.c (revision bb25c06cca41ca78e5fb87fbb8e81d55beb18c95)
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 2006 Sun Microsystems, Inc.  All rights reserved.
27  * Use is subject to license terms.
28  */
29 #pragma ident	"%Z%%M%	%I%	%E% SMI"
30 
31 /*
32  * This file contains the functions responsible for opening the output file
33  * image, associating the appropriate input elf structures with the new image,
34  * and obtaining new elf structures to define the new image.
35  */
36 #include	<stdio.h>
37 #include	<sys/stat.h>
38 #include	<fcntl.h>
39 #include	<link.h>
40 #include	<errno.h>
41 #include	<string.h>
42 #include	<limits.h>
43 #include	<debug.h>
44 #include	<unistd.h>
45 #include	"msg.h"
46 #include	"_libld.h"
47 
48 /*
49  * Determine a least common multiplier.  Input sections contain an alignment
50  * requirement, which elf_update() uses to insure that the section is aligned
51  * correctly off of the base of the elf image.  We must also insure that the
52  * sections mapping is congruent with this alignment requirement.  For each
53  * input section associated with a loadable segment determine whether the
54  * segments alignment must be adjusted to compensate for a sections alignment
55  * requirements.
56  */
57 Xword
58 ld_lcm(Xword a, Xword b)
59 {
60 	Xword	_r, _a, _b;
61 
62 	if ((_a = a) == 0)
63 		return (b);
64 	if ((_b = b) == 0)
65 		return (a);
66 
67 	if (_a > _b)
68 		_a = b, _b = a;
69 	while ((_r = _b % _a) != 0)
70 		_b = _a, _a = _r;
71 	return ((a / _a) * b);
72 }
73 
74 /*
75  * Open the output file and insure the correct access modes.
76  */
77 uintptr_t
78 ld_open_outfile(Ofl_desc * ofl)
79 {
80 	mode_t		mode;
81 	struct stat	status;
82 
83 	/*
84 	 * Determine the required file mode from the type of output file we
85 	 * are creating.
86 	 */
87 	mode = (ofl->ofl_flags & (FLG_OF_EXEC | FLG_OF_SHAROBJ))
88 		? 0777 : 0666;
89 
90 	/* Determine if the output file already exists */
91 	if (stat(ofl->ofl_name, &status) == 0) {
92 		if ((status.st_mode & S_IFMT) != S_IFREG) {
93 			/*
94 			 * It is not a regular file, so don't delete it
95 			 * or allow it to be deleted.  This allows root
96 			 * users to specify /dev/null output file for
97 			 * verification links.
98 			 */
99 			ofl->ofl_flags1 |= FLG_OF1_NONREG;
100 		} else {
101 			/*
102 			 * It's a regular file, so unlink it. In standard
103 			 * Unix fashion, the old file will continue to
104 			 * exist until its link count drops to 0 and no
105 			 * process has the file open. In the meantime, we
106 			 * create a new file (inode) under the same name,
107 			 * available for new use.
108 			 *
109 			 * The advantage of this policy is that creating
110 			 * a new executable or sharable library does not
111 			 * corrupt existing processes using the old file.
112 			 * A possible disadvantage is that if the existing
113 			 * file has a (link_count > 1), the other names will
114 			 * continue to reference the old inode, thus
115 			 * breaking the link.
116 			 *
117 			 * A subtlety here is that POSIX says we are not
118 			 * supposed to replace a non-writable file, which
119 			 * is something that unlink() is happy to do. The
120 			 * only 100% reliable test against this is to open
121 			 * the file for non-destructive write access. If the
122 			 * open succeeds, we are clear to unlink it, and if
123 			 * not, then the error generated is the error we
124 			 * need to report.
125 			 */
126 			if ((ofl->ofl_fd = open(ofl->ofl_name, O_RDWR,
127 			    mode)) < 0) {
128 				int	err = errno;
129 
130 				if (err != ENOENT) {
131 					eprintf(ofl->ofl_lml, ERR_FATAL,
132 					    MSG_INTL(MSG_SYS_OPEN),
133 					    ofl->ofl_name, strerror(err));
134 					return (S_ERROR);
135 				}
136 			} else {
137 				(void) close(ofl->ofl_fd);
138 			}
139 
140 			if ((unlink(ofl->ofl_name) == -1) &&
141 			    (errno != ENOENT)) {
142 				int err = errno;
143 
144 				eprintf(ofl->ofl_lml, ERR_FATAL,
145 					MSG_INTL(MSG_SYS_UNLINK),
146 					ofl->ofl_name, strerror(err));
147 				return (S_ERROR);
148 			}
149 		}
150 	}
151 
152 	/*
153 	 * Open (or create) the output file name (ofl_fd acts as a global
154 	 * flag to ldexit() signifying whether the output file should be
155 	 * removed or not on error).
156 	 */
157 	if ((ofl->ofl_fd = open(ofl->ofl_name, O_RDWR | O_CREAT | O_TRUNC,
158 	    mode)) < 0) {
159 		int	err = errno;
160 
161 		eprintf(ofl->ofl_lml, ERR_FATAL, MSG_INTL(MSG_SYS_OPEN),
162 		    ofl->ofl_name, strerror(err));
163 		return (S_ERROR);
164 	}
165 
166 	return (1);
167 }
168 
169 
170 /*
171  * If we are creating a memory model we need to update the present memory image.
172  * First we need to call elf_update(ELF_C_NULL) which will calculate the offsets
173  * of each section and its associated data buffers.  From this information we
174  * can then determine what padding is required.
175  * Two actions are necessary to convert the present disc image into a memory
176  * image:
177  *
178  *  o	Loadable segments must be padded so that the next segments virtual
179  *	address and file offset are the same.
180  *
181  *  o	NOBITS sections must be converted into allocated, null filled sections.
182  */
183 static uintptr_t
184 pad_outfile(Ofl_desc *ofl)
185 {
186 	Listnode	*lnp;
187 	off_t		offset;
188 	Elf_Scn		*oscn = 0;
189 	Sg_desc		*sgp;
190 	Ehdr		*ehdr;
191 
192 	/*
193 	 * Update all the elf structures.  This will assign offsets to the
194 	 * section headers and data buffers as they relate to the new image.
195 	 */
196 	if (elf_update(ofl->ofl_welf, ELF_C_NULL) == -1) {
197 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_UPDATE),
198 		    ofl->ofl_name);
199 		return (S_ERROR);
200 	}
201 	if ((ehdr = elf_getehdr(ofl->ofl_welf)) == NULL) {
202 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR),
203 		    ofl->ofl_name);
204 		return (S_ERROR);
205 	}
206 
207 	/*
208 	 * Initialize the offset by skipping the Elf header and program
209 	 * headers.
210 	 */
211 	offset = ehdr->e_phoff + (ehdr->e_phnum * ehdr->e_phentsize);
212 
213 	/*
214 	 * Traverse the segment list looking for loadable segments.
215 	 */
216 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp, sgp)) {
217 		Phdr	*phdr = &(sgp->sg_phdr);
218 		Os_desc	**ospp, *osp;
219 		Aliste	off;
220 
221 		/*
222 		 * If we've already processed a loadable segment, the `scn'
223 		 * variable will be initialized to the last section that was
224 		 * part of that segment.  Add sufficient padding to this section
225 		 * to cause the next segments virtual address and file offset to
226 		 * be the same.
227 		 */
228 		if (oscn && (phdr->p_type == PT_LOAD)) {
229 			Elf_Data *	data;
230 			size_t 		size;
231 
232 			size = (size_t)(S_ROUND(offset, phdr->p_align) -
233 			    offset);
234 
235 			if ((data = elf_newdata(oscn)) == NULL) {
236 				eprintf(ofl->ofl_lml, ERR_ELF,
237 				    MSG_INTL(MSG_ELF_NEWDATA), ofl->ofl_name);
238 				return (S_ERROR);
239 			}
240 			if ((data->d_buf = libld_calloc(size, 1)) == 0)
241 				return (S_ERROR);
242 
243 			data->d_type = ELF_T_BYTE;
244 			data->d_size = size;
245 			data->d_align = 1;
246 			data->d_version = ofl->ofl_dehdr->e_version;
247 		}
248 
249 		/*
250 		 * Traverse the output sections for this segment calculating the
251 		 * offset of each section. Retain the final section descriptor
252 		 * as this will be where any padding buffer will be added.
253 		 */
254 		for (ALIST_TRAVERSE(sgp->sg_osdescs, off, ospp)) {
255 			Shdr	*shdr;
256 
257 			osp = *ospp;
258 			shdr = osp->os_shdr;
259 
260 			offset = (off_t)S_ROUND(offset, shdr->sh_addralign);
261 			offset += shdr->sh_size;
262 
263 			/*
264 			 * If this is a NOBITS output section convert all of
265 			 * its associated input sections into real, null filled,
266 			 * data buffers, and change the section to PROGBITS.
267 			 */
268 			if (shdr->sh_type == SHT_NOBITS)
269 				shdr->sh_type = SHT_PROGBITS;
270 		}
271 
272 		/*
273 		 * If this is a loadable segment retain the last output section
274 		 * descriptor.  This acts both as a flag that a loadable
275 		 * segment has been seen, and as the segment to which a padding
276 		 * buffer will be added.
277 		 */
278 		if (phdr->p_type == PT_LOAD)
279 			oscn = osp->os_scn;
280 	}
281 	return (1);
282 }
283 
284 /*
285  * Create an output section.  The first instance of an input section triggers
286  * the creation of a new output section.
287  */
288 static uintptr_t
289 create_outsec(Ofl_desc *ofl, Sg_desc *sgp, Os_desc *osp, Word ptype, int shidx,
290     Boolean fixalign)
291 {
292 	Elf_Scn	*scn;
293 	Shdr	*shdr;
294 
295 	/*
296 	 * Get a section descriptor for the section.
297 	 */
298 	if ((scn = elf_newscn(ofl->ofl_welf)) == NULL) {
299 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_NEWSCN),
300 		    ofl->ofl_name);
301 		return (S_ERROR);
302 	}
303 	osp->os_scn = scn;
304 
305 	/*
306 	 * Get a new section header table entry and copy the pertinent
307 	 * information from the in-core descriptor.
308 	 */
309 	if ((shdr = elf_getshdr(scn)) == NULL) {
310 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR),
311 		    ofl->ofl_name);
312 		return (S_ERROR);
313 	}
314 	*shdr = *(osp->os_shdr);
315 	osp->os_shdr = shdr;
316 
317 	/*
318 	 * If this is the first section within a loadable segment, and the
319 	 * alignment needs to be updated, record this section.
320 	 */
321 	if ((fixalign == TRUE) && (ptype == PT_LOAD) && (shidx == 1))
322 		sgp->sg_fscn = scn;
323 
324 	/*
325 	 * Remove any SHF_ORDERED or SHF_LINK_ORDER flags.  If we are not
326 	 * building a relocatable object, remove any SHF_GROUP flag.
327 	 */
328 	osp->os_shdr->sh_flags &= ~ALL_SHF_ORDER;
329 	if ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0)
330 		osp->os_shdr->sh_flags &= ~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		**ospp;
370 	Is_desc		*isp;
371 	Elf_Data	*tlsdata = 0;
372 	Aliste		off;
373 	Word		flags = ofl->ofl_flags;
374 	Word		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(__i386) || defined(__amd64)) && defined(_ELF64)
460 			} else if (ptype == PT_SUNW_UNWIND) {
461 				if (ofl->ofl_unwindhdr)
462 					nseg++;
463 #endif
464 			} else if (ptype == PT_SUNWBSS) {
465 				if (ofl->ofl_issunwbss)
466 					nseg++;
467 			} else if (ptype == PT_SUNWSTACK) {
468 					nseg++;
469 			} else if (ptype == PT_SUNWDTRACE) {
470 				if (ofl->ofl_dtracesym)
471 					nseg++;
472 			} else if (ptype == PT_SUNWCAP) {
473 				if (ofl->ofl_oscap)
474 					nseg++;
475 			} else if ((sgp->sg_osdescs != NULL) ||
476 			    (sgp->sg_flags & FLG_SG_EMPTY)) {
477 				if (((sgp->sg_flags & FLG_SG_EMPTY) == 0) &&
478 				    ((sgp->sg_flags & FLG_SG_PHREQ) == 0)) {
479 					/*
480 					 * If this is a segment for which
481 					 * we are not making a program header,
482 					 * don't increment nseg
483 					 */
484 					ptype = (sgp->sg_phdr).p_type = PT_NULL;
485 				} else if (ptype != PT_NULL)
486 					nseg++;
487 			}
488 		}
489 
490 		/*
491 		 * If the first loadable segment has the ?N flag,
492 		 * then ?N will be on.
493 		 */
494 		if ((ptype == PT_LOAD) && (ptloadidx == 0)) {
495 			ptloadidx++;
496 			if (sgp->sg_flags & FLG_SG_NOHDR) {
497 				fixalign = TRUE;
498 				ofl->ofl_dtflags_1 |= DF_1_NOHDR;
499 			}
500 		}
501 
502 		shidx = 0;
503 		for (ALIST_TRAVERSE(sgp->sg_osdescs, off, ospp)) {
504 			Listnode	*lnp2;
505 			Os_desc		*osp = *ospp;
506 
507 			dataidx = 0;
508 			for (LIST_TRAVERSE(&(osp->os_isdescs), lnp2, isp)) {
509 				Elf_Data *	data;
510 				Ifl_desc *	ifl = isp->is_file;
511 
512 				/*
513 				 * An input section in the list that has
514 				 * been previously marked to be discarded
515 				 * should be completely ignored.
516 				 */
517 				if (isp->is_flags & FLG_IS_DISCARD)
518 					continue;
519 
520 				/*
521 				 * At this point we know whether a section has
522 				 * been referenced.  If it hasn't, and the whole
523 				 * file hasn't been referenced (which would have
524 				 * been caught in ignore_section_processing()),
525 				 * give a diagnostic (-D unused,detail) or
526 				 * discard the section if -zignore is in effect.
527 				 */
528 				if (ifl &&
529 				    (((ifl->ifl_flags & FLG_IF_FILEREF) == 0) ||
530 				    ((ptype == PT_LOAD) &&
531 				    ((isp->is_flags & FLG_IS_SECTREF) == 0) &&
532 				    (isp->is_shdr->sh_size > 0)))) {
533 					Lm_list	*lml = ofl->ofl_lml;
534 
535 					if (ifl->ifl_flags & FLG_IF_IGNORE) {
536 					    isp->is_flags |= FLG_IS_DISCARD;
537 					    DBG_CALL(Dbg_unused_sec(lml, isp));
538 					    continue;
539 					} else
540 					    DBG_CALL(Dbg_unused_sec(lml, isp));
541 				}
542 
543 				/*
544 				 * If this section provides no data, and isn't
545 				 * referenced, then it can be discarded as well.
546 				 * Note, if this is the first input section
547 				 * associated to an output section, let it
548 				 * through, there may be a legitimate reason why
549 				 * the user wants a null section.  Discarding
550 				 * additional sections is intended to remove the
551 				 * empty clutter the compilers have a habit of
552 				 * creating.  Don't provide an unused diagnostic
553 				 * as these sections aren't typically the users
554 				 * creation.
555 				 */
556 				if (ifl && dataidx &&
557 				    ((isp->is_flags & FLG_IS_SECTREF) == 0) &&
558 				    (isp->is_shdr->sh_size == 0)) {
559 					isp->is_flags |= FLG_IS_DISCARD;
560 					continue;
561 				}
562 
563 				/*
564 				 * The first input section triggers the creation
565 				 * of the associated output section.
566 				 */
567 				if (osp->os_scn == NULL) {
568 					shidx++;
569 
570 					if (create_outsec(ofl, sgp, osp, ptype,
571 					    shidx, fixalign) == S_ERROR)
572 						return (S_ERROR);
573 				}
574 
575 				dataidx++;
576 
577 				/*
578 				 * Create a new output data buffer for each
579 				 * input data buffer, thus linking the new
580 				 * buffers to the new elf output structures.
581 				 * Simply make the new data buffers point to
582 				 * the old data.
583 				 */
584 				if ((data = elf_newdata(osp->os_scn)) == NULL) {
585 					eprintf(ofl->ofl_lml, ERR_ELF,
586 					    MSG_INTL(MSG_ELF_NEWDATA),
587 					    ofl->ofl_name);
588 					return (S_ERROR);
589 				}
590 				*data = *(isp->is_indata);
591 				isp->is_indata = data;
592 
593 				if ((fixalign == TRUE) && (ptype == PT_LOAD) &&
594 				    (shidx == 1) && (dataidx == 1))
595 					data->d_align = sgp->sg_addralign;
596 
597 				/*
598 				 * Save the first TLS data buffer, as this is
599 				 * the start of the TLS segment. Realign this
600 				 * buffer based on the alignment requirements
601 				 * of all the TLS input sections.
602 				 */
603 				if ((ofl->ofl_flags & FLG_OF_TLSPHDR) &&
604 				    (isp->is_shdr->sh_flags & SHF_TLS)) {
605 					if (tlsdata == 0)
606 						tlsdata = data;
607 					tlsdata->d_align =
608 					    ld_lcm(tlsdata->d_align,
609 					    isp->is_shdr->sh_addralign);
610 				}
611 
612 #if	defined(_ELF64) && defined(_ILP32)
613 				/*
614 				 * 4106312, the 32-bit ELF64 version of ld
615 				 * needs to be able to create large .bss
616 				 * sections.  The d_size member of Elf_Data
617 				 * only allows 32-bits in _ILP32, so we build
618 				 * multiple data-items that each fit into 32-
619 				 * bits.  libelf (4106398) can summ these up
620 				 * into a 64-bit quantity.  This only works
621 				 * for NOBITS sections which don't have any
622 				 * real data to maintain and don't require
623 				 * large file support.
624 				 */
625 				if (isp->is_shdr->sh_type == SHT_NOBITS) {
626 					Xword sz = isp->is_shdr->sh_size;
627 
628 					while (sz >> 32) {
629 						data->d_size = SIZE_MAX;
630 						sz -= (Xword)SIZE_MAX;
631 
632 						data = elf_newdata(osp->os_scn);
633 						if (data == NULL)
634 							return (S_ERROR);
635 					}
636 					data->d_size = (size_t)sz;
637 				}
638 #endif
639 
640 				/*
641 				 * If this segment requires rounding realign the
642 				 * first data buffer associated with the first
643 				 * section.
644 				 */
645 				if ((frst++ == 0) &&
646 				    (sgp->sg_flags & FLG_SG_ROUND)) {
647 					Xword    align;
648 
649 					if (data->d_align)
650 						align = (Xword)
651 						    S_ROUND(data->d_align,
652 						    sgp->sg_round);
653 					else
654 						align = sgp->sg_round;
655 
656 					data->d_align = (size_t)align;
657 				}
658 			}
659 
660 			/*
661 			 * Clear the szoutrels counter so that it can be used
662 			 * again in the building of relocs.  See machrel.c.
663 			 */
664 			osp->os_szoutrels = 0;
665 		}
666 	}
667 
668 	/*
669 	 * Build an empty PHDR.
670 	 */
671 	if (nseg) {
672 		if ((ofl->ofl_phdr = elf_newphdr(ofl->ofl_welf,
673 		    nseg)) == NULL) {
674 			eprintf(ofl->ofl_lml, ERR_ELF,
675 			    MSG_INTL(MSG_ELF_NEWPHDR), ofl->ofl_name);
676 			return (S_ERROR);
677 		}
678 	}
679 
680 	/*
681 	 * If we need to generate a memory model, pad the image.
682 	 */
683 	if (flags1 & FLG_OF1_MEMORY) {
684 		if (pad_outfile(ofl) == S_ERROR)
685 			return (S_ERROR);
686 	}
687 
688 	/*
689 	 * After all the basic input file processing, all data pointers are
690 	 * referencing two types of memory:
691 	 *
692 	 *	o	allocated memory, ie. elf structures, internal link
693 	 *		editor structures, and any new sections that have been
694 	 *		created.
695 	 *
696 	 *	o	original input file mmap'ed memory, ie. the actual data
697 	 *		sections of the input file images.
698 	 *
699 	 * Up until now, the only memory modifications have been carried out on
700 	 * the allocated memory.  Before carrying out any relocations, write the
701 	 * new output file image and reassign any necessary data pointers to the
702 	 * output files memory image.  This insures that any relocation
703 	 * modifications are made to the output file image and not to the input
704 	 * file image, thus preventing the creation of dirty pages and reducing
705 	 * the overall swap space requirement.
706 	 *
707 	 * Write out the elf structure so as to create the new file image.
708 	 */
709 	if ((ofl->ofl_size = (size_t)elf_update(ofl->ofl_welf,
710 	    ELF_C_WRIMAGE)) == (size_t)-1) {
711 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_UPDATE),
712 		    ofl->ofl_name);
713 		return (S_ERROR);
714 	}
715 
716 	/*
717 	 * Initialize the true `ofl' information with the memory images address
718 	 * and size.  This will be used to write() out the image once any
719 	 * relocation processing has been completed.  We also use this image
720 	 * information to setup a new Elf descriptor, which is used to obtain
721 	 * all the necessary elf pointers within the new output image.
722 	 */
723 	if ((ofl->ofl_elf = elf_begin(0, ELF_C_IMAGE,
724 	    ofl->ofl_welf)) == NULL) {
725 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_BEGIN),
726 		    ofl->ofl_name);
727 		return (S_ERROR);
728 	}
729 	if ((ofl->ofl_nehdr = elf_getehdr(ofl->ofl_elf)) == NULL) {
730 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR),
731 		    ofl->ofl_name);
732 		return (S_ERROR);
733 	}
734 	if (!(flags & FLG_OF_RELOBJ))
735 		if ((ofl->ofl_phdr = elf_getphdr(ofl->ofl_elf)) == NULL) {
736 			eprintf(ofl->ofl_lml, ERR_ELF,
737 			    MSG_INTL(MSG_ELF_GETPHDR), ofl->ofl_name);
738 			return (S_ERROR);
739 		}
740 
741 	/*
742 	 * Reinitialize the section descriptors, section headers and obtain new
743 	 * output data buffer pointers (these will be used to perform any
744 	 * relocations).
745 	 */
746 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) {
747 		Phdr	*_phdr = &(sgp->sg_phdr);
748 		Os_desc	**ospp;
749 		Aliste	off;
750 		Boolean	recorded = FALSE;
751 
752 		for (ALIST_TRAVERSE(sgp->sg_osdescs, off, ospp)) {
753 			Os_desc	*osp = *ospp;
754 
755 			/*
756 			 * Make sure that an output section was originally
757 			 * created.  Input sections that had been marked as
758 			 * discarded may have made an output section
759 			 * unnecessary.  Remove this alist entry so that
760 			 * future output section descriptor processing doesn't
761 			 * have to compensate for this empty section.
762 			 */
763 			if (osp->os_scn == NULL) {
764 				(void) alist_delete(sgp->sg_osdescs, 0, &off);
765 				continue;
766 			}
767 
768 			if ((osp->os_scn = elf_getscn(ofl->ofl_elf, ++ndx)) ==
769 			    NULL) {
770 				eprintf(ofl->ofl_lml, ERR_ELF,
771 				    MSG_INTL(MSG_ELF_GETSCN), ofl->ofl_name,
772 				    ndx);
773 				return (S_ERROR);
774 			}
775 			if ((osp->os_shdr = elf_getshdr(osp->os_scn)) ==
776 			    NULL) {
777 				eprintf(ofl->ofl_lml, ERR_ELF,
778 				    MSG_INTL(MSG_ELF_GETSHDR), ofl->ofl_name);
779 				return (S_ERROR);
780 			}
781 			if ((fixalign == TRUE) && (sgp->sg_fscn != 0) &&
782 			    (recorded == FALSE)) {
783 				Elf_Scn *scn;
784 
785 				scn = sgp->sg_fscn;
786 				if ((fndx = elf_ndxscn(scn)) == SHN_UNDEF) {
787 					eprintf(ofl->ofl_lml, ERR_ELF,
788 					    MSG_INTL(MSG_ELF_NDXSCN),
789 					    ofl->ofl_name);
790 					return (S_ERROR);
791 				}
792 				if (ndx == fndx) {
793 					sgp->sg_fscn = osp->os_scn;
794 					recorded = TRUE;
795 				}
796 			}
797 
798 			if ((osp->os_outdata =
799 			    elf_getdata(osp->os_scn, NULL)) == NULL) {
800 				eprintf(ofl->ofl_lml, ERR_ELF,
801 				    MSG_INTL(MSG_ELF_GETDATA), ofl->ofl_name);
802 				return (S_ERROR);
803 			}
804 
805 			/*
806 			 * If this section is part of a loadable segment insure
807 			 * that the segments alignment is appropriate.
808 			 */
809 			if (_phdr->p_type == PT_LOAD) {
810 				_phdr->p_align = ld_lcm(_phdr->p_align,
811 				    osp->os_shdr->sh_addralign);
812 			}
813 		}
814 	}
815 	return (1);
816 }
817