xref: /titanic_52/usr/src/cmd/sgs/libld/common/outfile.c (revision 9512fe850e98fdd448c638ca63fdd92a8a510255)
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 	/* Determine if the output file already exists */
84 	if (stat(ofl->ofl_name, &status) == 0) {
85 		if ((status.st_mode & S_IFMT) != S_IFREG) {
86 			/*
87 			 * It is not a regular file, so don't delete it
88 			 * or allow it to be deleted.  This allows root
89 			 * users to specify /dev/null output file for
90 			 * verification links.
91 			 */
92 			ofl->ofl_flags1 |= FLG_OF1_NONREG;
93 		} else {
94 			/*
95 			 * It's a regular file, so unlink it. In standard
96 			 * Unix fashion, the old file will continue to
97 			 * exist until its link count drops to 0 and no
98 			 * process has the file open. In the meantime, we
99 			 * create a new file (inode) under the same name,
100 			 * available for new use.
101 			 *
102 			 * The advantage of this policy is that creating
103 			 * a new executable or sharable library does not
104 			 * corrupt existing processes using the old file.
105 			 * A possible disadvantage is that if the existing
106 			 * file has a (link_count > 1), the other names will
107 			 * continue to reference the old inode, thus
108 			 * breaking the link.
109 			 */
110 			if ((unlink(ofl->ofl_name) == -1) &&
111 			    (errno != ENOENT)) {
112 				int err = errno;
113 
114 				eprintf(ofl->ofl_lml, ERR_FATAL,
115 					MSG_INTL(MSG_SYS_UNLINK),
116 					ofl->ofl_name, strerror(err));
117 				return (S_ERROR);
118 			}
119 		}
120 	}
121 
122 	/*
123 	 * Determine the required file mode from the type of output file we
124 	 * are creating.
125 	 */
126 	mode = (ofl->ofl_flags & (FLG_OF_EXEC | FLG_OF_SHAROBJ))
127 		? 0777 : 0666;
128 
129 	/*
130 	 * Open (or create) the output file name (ofl_fd acts as a global
131 	 * flag to ldexit() signifying whether the output file should be
132 	 * removed or not on error).
133 	 */
134 	if ((ofl->ofl_fd = open(ofl->ofl_name, O_RDWR | O_CREAT | O_TRUNC,
135 	    mode)) < 0) {
136 		int	err = errno;
137 
138 		eprintf(ofl->ofl_lml, ERR_FATAL, MSG_INTL(MSG_SYS_OPEN),
139 		    ofl->ofl_name, strerror(err));
140 		return (S_ERROR);
141 	}
142 
143 	return (1);
144 }
145 
146 
147 /*
148  * If we are creating a memory model we need to update the present memory image.
149  * First we need to call elf_update(ELF_C_NULL) which will calculate the offsets
150  * of each section and its associated data buffers.  From this information we
151  * can then determine what padding is required.
152  * Two actions are necessary to convert the present disc image into a memory
153  * image:
154  *
155  *  o	Loadable segments must be padded so that the next segments virtual
156  *	address and file offset are the same.
157  *
158  *  o	NOBITS sections must be converted into allocated, null filled sections.
159  */
160 static uintptr_t
161 pad_outfile(Ofl_desc *ofl)
162 {
163 	Listnode	*lnp;
164 	off_t		offset;
165 	Elf_Scn		*oscn = 0;
166 	Sg_desc		*sgp;
167 	Ehdr		*ehdr;
168 
169 	/*
170 	 * Update all the elf structures.  This will assign offsets to the
171 	 * section headers and data buffers as they relate to the new image.
172 	 */
173 	if (elf_update(ofl->ofl_welf, ELF_C_NULL) == -1) {
174 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_UPDATE),
175 		    ofl->ofl_name);
176 		return (S_ERROR);
177 	}
178 	if ((ehdr = elf_getehdr(ofl->ofl_welf)) == NULL) {
179 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR),
180 		    ofl->ofl_name);
181 		return (S_ERROR);
182 	}
183 
184 	/*
185 	 * Initialize the offset by skipping the Elf header and program
186 	 * headers.
187 	 */
188 	offset = ehdr->e_phoff + (ehdr->e_phnum * ehdr->e_phentsize);
189 
190 	/*
191 	 * Traverse the segment list looking for loadable segments.
192 	 */
193 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp, sgp)) {
194 		Phdr	*phdr = &(sgp->sg_phdr);
195 		Os_desc	**ospp, *osp;
196 		Aliste	off;
197 
198 		/*
199 		 * If we've already processed a loadable segment, the `scn'
200 		 * variable will be initialized to the last section that was
201 		 * part of that segment.  Add sufficient padding to this section
202 		 * to cause the next segments virtual address and file offset to
203 		 * be the same.
204 		 */
205 		if (oscn && (phdr->p_type == PT_LOAD)) {
206 			Elf_Data *	data;
207 			size_t 		size;
208 
209 			size = (size_t)(S_ROUND(offset, phdr->p_align) -
210 			    offset);
211 
212 			if ((data = elf_newdata(oscn)) == NULL) {
213 				eprintf(ofl->ofl_lml, ERR_ELF,
214 				    MSG_INTL(MSG_ELF_NEWDATA), ofl->ofl_name);
215 				return (S_ERROR);
216 			}
217 			if ((data->d_buf = libld_calloc(size, 1)) == 0)
218 				return (S_ERROR);
219 
220 			data->d_type = ELF_T_BYTE;
221 			data->d_size = size;
222 			data->d_align = 1;
223 			data->d_version = ofl->ofl_dehdr->e_version;
224 		}
225 
226 		/*
227 		 * Traverse the output sections for this segment calculating the
228 		 * offset of each section. Retain the final section descriptor
229 		 * as this will be where any padding buffer will be added.
230 		 */
231 		for (ALIST_TRAVERSE(sgp->sg_osdescs, off, ospp)) {
232 			Shdr	*shdr;
233 
234 			osp = *ospp;
235 			shdr = osp->os_shdr;
236 
237 			offset = (off_t)S_ROUND(offset, shdr->sh_addralign);
238 			offset += shdr->sh_size;
239 
240 			/*
241 			 * If this is a NOBITS output section convert all of
242 			 * its associated input sections into real, null filled,
243 			 * data buffers, and change the section to PROGBITS.
244 			 */
245 			if (shdr->sh_type == SHT_NOBITS)
246 				shdr->sh_type = SHT_PROGBITS;
247 		}
248 
249 		/*
250 		 * If this is a loadable segment retain the last output section
251 		 * descriptor.  This acts both as a flag that a loadable
252 		 * segment has been seen, and as the segment to which a padding
253 		 * buffer will be added.
254 		 */
255 		if (phdr->p_type == PT_LOAD)
256 			oscn =	osp->os_scn;
257 	}
258 	return (1);
259 }
260 
261 /*
262  * Create an output section.  The first instance of an input section triggers
263  * the creation of a new output section.
264  */
265 static uintptr_t
266 create_outsec(Ofl_desc *ofl, Sg_desc *sgp, Os_desc *osp, Word ptype, int shidx,
267     Boolean fixalign)
268 {
269 	Elf_Scn	*scn;
270 	Shdr	*shdr;
271 
272 	/*
273 	 * Get a section descriptor for the section.
274 	 */
275 	if ((scn = elf_newscn(ofl->ofl_welf)) == NULL) {
276 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_NEWSCN),
277 		    ofl->ofl_name);
278 		return (S_ERROR);
279 	}
280 	osp->os_scn = scn;
281 
282 	/*
283 	 * Get a new section header table entry and copy the pertinent
284 	 * information from the in-core descriptor.
285 	 */
286 	if ((shdr = elf_getshdr(scn)) == NULL) {
287 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETSHDR),
288 		    ofl->ofl_name);
289 		return (S_ERROR);
290 	}
291 	*shdr = *(osp->os_shdr);
292 	osp->os_shdr = shdr;
293 
294 	/*
295 	 * If this is the first section within a loadable segment, and the
296 	 * alignment needs to be updated, record this section.
297 	 */
298 	if ((fixalign == TRUE) && (ptype == PT_LOAD) && (shidx == 1))
299 		sgp->sg_fscn = scn;
300 
301 	/*
302 	 * Remove any SHF_ORDERED or SHF_LINK_ORDER flags.  If we are not
303 	 * building a relocatable object, remove any SHF_GROUP flag.
304 	 */
305 	osp->os_shdr->sh_flags &= ~ALL_SHF_ORDER;
306 	if ((ofl->ofl_flags & FLG_OF_RELOBJ) == 0)
307 		osp->os_shdr->sh_flags &= ~SHF_GROUP;
308 
309 	/*
310 	 * If this is a TLS section, save it so that the PT_TLS program header
311 	 * information can be established after the output image has been
312 	 * initially created.  At this point, all TLS input sections are ordered
313 	 * as they will appear in the output image.
314 	 */
315 	if ((ofl->ofl_flags & FLG_OF_TLSPHDR) &&
316 	    (osp->os_shdr->sh_flags & SHF_TLS) &&
317 	    (list_appendc(&ofl->ofl_ostlsseg, osp) == 0))
318 		return (S_ERROR);
319 
320 	return (0);
321 }
322 
323 /*
324  * Create the elf structures that allow the input data to be associated with the
325  * new image:
326  *
327  *	o	define the new elf image using elf_begin(),
328  *
329  *	o	obtain an elf header for the image,
330  *
331  *	o	traverse the input segments and create a program header array
332  *		to define the required segments,
333  *
334  *	o 	traverse the output sections for each segment assigning a new
335  *		section descriptor and section header for each,
336  *
337  *	o	traverse the input sections associated with each output section
338  *		and assign a new data descriptor to each (each output section
339  *		becomes a linked list of input data buffers).
340  */
341 uintptr_t
342 ld_create_outfile(Ofl_desc *ofl)
343 {
344 	Listnode	*lnp1;
345 	Sg_desc		*sgp;
346 	Os_desc		**ospp;
347 	Is_desc		*isp;
348 	Elf_Data	*tlsdata = 0;
349 	Aliste		off;
350 	Word		flags = ofl->ofl_flags;
351 	size_t		ndx = 0, fndx = 0;
352 	Elf_Cmd		cmd;
353 	Boolean		fixalign = FALSE;
354 	int		fd, nseg = 0, shidx = 0, dataidx = 0, ptloadidx = 0;
355 
356 	/*
357 	 * If DF_1_NOHDR was set in map_parse() or FLG_OF1_VADDR was set,
358 	 * we need to do alignment adjustment.
359 	 */
360 	if ((ofl->ofl_flags1 & FLG_OF1_VADDR) ||
361 	    (ofl->ofl_dtflags_1 & DF_1_NOHDR)) {
362 		fixalign = TRUE;
363 	}
364 
365 	if (flags & FLG_OF_MEMORY) {
366 		cmd = ELF_C_IMAGE;
367 		fd = 0;
368 	} else {
369 		fd = ofl->ofl_fd;
370 		cmd = ELF_C_WRITE;
371 	}
372 
373 	/*
374 	 * If there are any ordered section, handle them here.
375 	 */
376 	if ((ofl->ofl_ordered.head != NULL) &&
377 	    (ld_sort_ordered(ofl) == S_ERROR))
378 		return (S_ERROR);
379 
380 	/*
381 	 * Tell the access library about our new temporary file.
382 	 */
383 	if ((ofl->ofl_welf = elf_begin(fd, cmd, 0)) == NULL) {
384 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_BEGIN),
385 		    ofl->ofl_name);
386 		return (S_ERROR);
387 	}
388 
389 	/*
390 	 * Obtain a new Elf header.
391 	 */
392 	if ((ofl->ofl_nehdr = elf_newehdr(ofl->ofl_welf)) == NULL) {
393 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_NEWEHDR),
394 		    ofl->ofl_name);
395 		return (S_ERROR);
396 	}
397 	ofl->ofl_nehdr->e_machine = ofl->ofl_dehdr->e_machine;
398 
399 	DBG_CALL(Dbg_util_nl(ofl->ofl_lml, DBG_NL_STD));
400 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) {
401 		int	frst = 0;
402 		Phdr	*phdr = &(sgp->sg_phdr);
403 		Word	ptype = phdr->p_type;
404 
405 		/*
406 		 * Count the number of segments that will go in the program
407 		 * header table. If a segment is empty, ignore it.
408 		 */
409 		if (!(flags & FLG_OF_RELOBJ)) {
410 			if (ptype == PT_PHDR) {
411 				/*
412 				 * If we are generating an interp section (and
413 				 * thus an associated PT_INTERP program header
414 				 * entry) also generate a PT_PHDR program header
415 				 * entry.  This allows the kernel to generate
416 				 * the appropriate aux vector entries to pass to
417 				 * the interpreter (refer to exec/elf/elf.c).
418 				 * Note that if an image was generated with an
419 				 * interp section, but no associated PT_PHDR
420 				 * program header entry, the kernel will simply
421 				 * pass the interpreter an open file descriptor
422 				 * when the image is executed).
423 				 */
424 				if (ofl->ofl_osinterp)
425 					nseg++;
426 			} else if (ptype == PT_INTERP) {
427 				if (ofl->ofl_osinterp)
428 					nseg++;
429 			} else if (ptype == PT_DYNAMIC) {
430 				if (flags & FLG_OF_DYNAMIC)
431 					nseg++;
432 			} else if (ptype == PT_TLS) {
433 				if (flags & FLG_OF_TLSPHDR)
434 					nseg++;
435 #if	(defined(__i386) || defined(__amd64)) && defined(_ELF64)
436 			} else if (ptype == PT_SUNW_UNWIND) {
437 				if (ofl->ofl_unwindhdr)
438 					nseg++;
439 #endif
440 			} else if (ptype == PT_SUNWBSS) {
441 				if (ofl->ofl_issunwbss)
442 					nseg++;
443 			} else if (ptype == PT_SUNWSTACK) {
444 					nseg++;
445 			} else if (ptype == PT_SUNWDTRACE) {
446 				if (ofl->ofl_dtracesym)
447 					nseg++;
448 			} else if (ptype == PT_SUNWCAP) {
449 				if (ofl->ofl_oscap)
450 					nseg++;
451 			} else if ((sgp->sg_osdescs != NULL) ||
452 			    (sgp->sg_flags & FLG_SG_EMPTY)) {
453 				if (((sgp->sg_flags & FLG_SG_EMPTY) == 0) &&
454 				    ((sgp->sg_flags & FLG_SG_PHREQ) == 0)) {
455 					/*
456 					 * If this is a segment for which
457 					 * we are not making a program header,
458 					 * don't increment nseg
459 					 */
460 					ptype = (sgp->sg_phdr).p_type = PT_NULL;
461 				} else if (ptype != PT_NULL)
462 					nseg++;
463 			}
464 		}
465 
466 		/*
467 		 * If the first loadable segment has the ?N flag,
468 		 * then ?N will be on.
469 		 */
470 		if ((ptype == PT_LOAD) && (ptloadidx == 0)) {
471 			ptloadidx++;
472 			if (sgp->sg_flags & FLG_SG_NOHDR) {
473 				fixalign = TRUE;
474 				ofl->ofl_dtflags_1 |= DF_1_NOHDR;
475 			}
476 		}
477 
478 		shidx = 0;
479 		for (ALIST_TRAVERSE(sgp->sg_osdescs, off, ospp)) {
480 			Listnode	*lnp2;
481 			Os_desc		*osp = *ospp;
482 
483 			dataidx = 0;
484 			for (LIST_TRAVERSE(&(osp->os_isdescs), lnp2, isp)) {
485 				Elf_Data *	data;
486 				Ifl_desc *	ifl = isp->is_file;
487 
488 				/*
489 				 * At this point we know whether a section has
490 				 * been referenced.  If it hasn't, and the whole
491 				 * file hasn't been referenced (which would have
492 				 * been caught in ignore_section_processing()),
493 				 * give a diagnostic (-D unused,detail) or
494 				 * discard the section if -zignore is in effect.
495 				 */
496 				if (ifl &&
497 				    (((ifl->ifl_flags & FLG_IF_FILEREF) == 0) ||
498 				    ((ptype == PT_LOAD) &&
499 				    ((isp->is_flags & FLG_IS_SECTREF) == 0) &&
500 				    (isp->is_shdr->sh_size > 0)))) {
501 					Lm_list	*lml = ofl->ofl_lml;
502 
503 					if (ifl->ifl_flags & FLG_IF_IGNORE) {
504 					    isp->is_flags |= FLG_IS_DISCARD;
505 					    DBG_CALL(Dbg_unused_sec(lml, isp));
506 					    continue;
507 					} else
508 					    DBG_CALL(Dbg_unused_sec(lml, isp));
509 				}
510 
511 				/*
512 				 * If this section provides no data, and isn't
513 				 * referenced, then it can be discarded as well.
514 				 * Note, if this is the first input section
515 				 * associated to an output section, let it
516 				 * through, there may be a legitimate reason why
517 				 * the user wants a null section.  Discarding
518 				 * additional sections is intended to remove the
519 				 * empty clutter the compilers have a habit of
520 				 * creating.  Don't provide an unused diagnostic
521 				 * as these sections aren't typically the users
522 				 * creation.
523 				 */
524 				if (ifl && dataidx &&
525 				    ((isp->is_flags & FLG_IS_SECTREF) == 0) &&
526 				    (isp->is_shdr->sh_size == 0)) {
527 					isp->is_flags |= FLG_IS_DISCARD;
528 					continue;
529 				}
530 
531 				/*
532 				 * The first input section triggers the creation
533 				 * of the associated output section.
534 				 */
535 				if (osp->os_scn == NULL) {
536 					shidx++;
537 
538 					if (create_outsec(ofl, sgp, osp, ptype,
539 					    shidx, fixalign) == S_ERROR)
540 						return (S_ERROR);
541 				}
542 
543 				dataidx++;
544 
545 				/*
546 				 * Create a new output data buffer for each
547 				 * input data buffer, thus linking the new
548 				 * buffers to the new elf output structures.
549 				 * Simply make the new data buffers point to
550 				 * the old data.
551 				 */
552 				if ((data = elf_newdata(osp->os_scn)) == NULL) {
553 					eprintf(ofl->ofl_lml, ERR_ELF,
554 					    MSG_INTL(MSG_ELF_NEWDATA),
555 					    ofl->ofl_name);
556 					return (S_ERROR);
557 				}
558 				*data = *(isp->is_indata);
559 				isp->is_indata = data;
560 
561 				if ((fixalign == TRUE) && (ptype == PT_LOAD) &&
562 				    (shidx == 1) && (dataidx == 1))
563 					data->d_align = sgp->sg_addralign;
564 
565 				/*
566 				 * Save the first TLS data buffer, as this is
567 				 * the start of the TLS segment. Realign this
568 				 * buffer based on the alignment requirements
569 				 * of all the TLS input sections.
570 				 */
571 				if ((ofl->ofl_flags & FLG_OF_TLSPHDR) &&
572 				    (isp->is_shdr->sh_flags & SHF_TLS)) {
573 					if (tlsdata == 0)
574 						tlsdata = data;
575 					tlsdata->d_align =
576 					    ld_lcm(tlsdata->d_align,
577 					    isp->is_shdr->sh_addralign);
578 				}
579 
580 #if	defined(_ELF64) && defined(_ILP32)
581 				/*
582 				 * 4106312, the 32-bit ELF64 version of ld
583 				 * needs to be able to create large .bss
584 				 * sections.  The d_size member of Elf_Data
585 				 * only allows 32-bits in _ILP32, so we build
586 				 * multiple data-items that each fit into 32-
587 				 * bits.  libelf (4106398) can summ these up
588 				 * into a 64-bit quantity.  This only works
589 				 * for NOBITS sections which don't have any
590 				 * real data to maintain and don't require
591 				 * large file support.
592 				 */
593 				if (isp->is_shdr->sh_type == SHT_NOBITS) {
594 					Xword sz = isp->is_shdr->sh_size;
595 
596 					while (sz >> 32) {
597 						data->d_size = SIZE_MAX;
598 						sz -= (Xword)SIZE_MAX;
599 
600 						data = elf_newdata(osp->os_scn);
601 						if (data == NULL)
602 							return (S_ERROR);
603 					}
604 					data->d_size = (size_t)sz;
605 				}
606 #endif
607 
608 				/*
609 				 * If this segment requires rounding realign the
610 				 * first data buffer associated with the first
611 				 * section.
612 				 */
613 				if ((frst++ == 0) &&
614 				    (sgp->sg_flags & FLG_SG_ROUND)) {
615 					Xword    align;
616 
617 					if (data->d_align)
618 						align = (Xword)
619 						    S_ROUND(data->d_align,
620 						    sgp->sg_round);
621 					else
622 						align = sgp->sg_round;
623 
624 					data->d_align = (size_t)align;
625 				}
626 			}
627 
628 			/*
629 			 * Clear the szoutrels counter so that it can be used
630 			 * again in the building of relocs.  See machrel.c.
631 			 */
632 			osp->os_szoutrels = 0;
633 		}
634 	}
635 
636 	/*
637 	 * Build an empty PHDR.
638 	 */
639 	if (nseg) {
640 		if ((ofl->ofl_phdr = elf_newphdr(ofl->ofl_welf,
641 		    nseg)) == NULL) {
642 			eprintf(ofl->ofl_lml, ERR_ELF,
643 			    MSG_INTL(MSG_ELF_NEWPHDR), ofl->ofl_name);
644 			return (S_ERROR);
645 		}
646 	}
647 
648 	/*
649 	 * If we need to generate a memory model, pad the image.
650 	 */
651 	if (flags & FLG_OF_MEMORY) {
652 		if (pad_outfile(ofl) == S_ERROR)
653 			return (S_ERROR);
654 	}
655 
656 	/*
657 	 * After all the basic input file processing, all data pointers are
658 	 * referencing two types of memory:
659 	 *
660 	 *	o	allocated memory, ie. elf structures, internal link
661 	 *		editor structures, and any new sections that have been
662 	 *		created.
663 	 *
664 	 *	o	original input file mmap'ed memory, ie. the actual data
665 	 *		sections of the input file images.
666 	 *
667 	 * Up until now, the only memory modifications have been carried out on
668 	 * the allocated memory.  Before carrying out any relocations, write the
669 	 * new output file image and reassign any necessary data pointers to the
670 	 * output files memory image.  This insures that any relocation
671 	 * modifications are made to the output file image and not to the input
672 	 * file image, thus preventing the creation of dirty pages and reducing
673 	 * the overall swap space requirement.
674 	 *
675 	 * Write out the elf structure so as to create the new file image.
676 	 */
677 	if ((ofl->ofl_size = (size_t)elf_update(ofl->ofl_welf,
678 	    ELF_C_WRIMAGE)) == (size_t)-1) {
679 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_UPDATE),
680 		    ofl->ofl_name);
681 		return (S_ERROR);
682 	}
683 
684 	/*
685 	 * Initialize the true `ofl' information with the memory images address
686 	 * and size.  This will be used to write() out the image once any
687 	 * relocation processing has been completed.  We also use this image
688 	 * information to setup a new Elf descriptor, which is used to obtain
689 	 * all the necessary elf pointers within the new output image.
690 	 */
691 	if ((ofl->ofl_elf = elf_begin(0, ELF_C_IMAGE,
692 	    ofl->ofl_welf)) == NULL) {
693 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_BEGIN),
694 		    ofl->ofl_name);
695 		return (S_ERROR);
696 	}
697 	if ((ofl->ofl_nehdr = elf_getehdr(ofl->ofl_elf)) == NULL) {
698 		eprintf(ofl->ofl_lml, ERR_ELF, MSG_INTL(MSG_ELF_GETEHDR),
699 		    ofl->ofl_name);
700 		return (S_ERROR);
701 	}
702 	if (!(flags & FLG_OF_RELOBJ))
703 		if ((ofl->ofl_phdr = elf_getphdr(ofl->ofl_elf)) == NULL) {
704 			eprintf(ofl->ofl_lml, ERR_ELF,
705 			    MSG_INTL(MSG_ELF_GETPHDR), ofl->ofl_name);
706 			return (S_ERROR);
707 		}
708 
709 	/*
710 	 * Reinitialize the section descriptors, section headers and obtain new
711 	 * output data buffer pointers (these will be used to perform any
712 	 * relocations).
713 	 */
714 	for (LIST_TRAVERSE(&ofl->ofl_segs, lnp1, sgp)) {
715 		Phdr	*_phdr = &(sgp->sg_phdr);
716 		Os_desc	**ospp;
717 		Aliste	off;
718 		Boolean	recorded = FALSE;
719 
720 		for (ALIST_TRAVERSE(sgp->sg_osdescs, off, ospp)) {
721 			Os_desc	*osp = *ospp;
722 
723 			/*
724 			 * Make sure that an output section was originally
725 			 * created.  Input sections that had been marked as
726 			 * discarded may have made an output section
727 			 * unnecessary.
728 			 */
729 			if (osp->os_scn == NULL)
730 				continue;
731 
732 			if ((osp->os_scn = elf_getscn(ofl->ofl_elf, ++ndx)) ==
733 			    NULL) {
734 				eprintf(ofl->ofl_lml, ERR_ELF,
735 				    MSG_INTL(MSG_ELF_GETSCN), ofl->ofl_name,
736 				    ndx);
737 				return (S_ERROR);
738 			}
739 			if ((osp->os_shdr = elf_getshdr(osp->os_scn)) ==
740 			    NULL) {
741 				eprintf(ofl->ofl_lml, ERR_ELF,
742 				    MSG_INTL(MSG_ELF_GETSHDR), ofl->ofl_name);
743 				return (S_ERROR);
744 			}
745 			if ((fixalign == TRUE) && (sgp->sg_fscn != 0) &&
746 			    (recorded == FALSE)) {
747 				Elf_Scn *scn;
748 
749 				scn = sgp->sg_fscn;
750 				if ((fndx = elf_ndxscn(scn)) == SHN_UNDEF) {
751 					eprintf(ofl->ofl_lml, ERR_ELF,
752 					    MSG_INTL(MSG_ELF_NDXSCN),
753 					    ofl->ofl_name);
754 					return (S_ERROR);
755 				}
756 				if (ndx == fndx) {
757 					sgp->sg_fscn = osp->os_scn;
758 					recorded = TRUE;
759 				}
760 			}
761 
762 			if ((osp->os_outdata =
763 			    elf_getdata(osp->os_scn, NULL)) == NULL) {
764 				eprintf(ofl->ofl_lml, ERR_ELF,
765 				    MSG_INTL(MSG_ELF_GETDATA), ofl->ofl_name);
766 				return (S_ERROR);
767 			}
768 
769 			/*
770 			 * If this section is part of a loadable segment insure
771 			 * that the segments alignment is appropriate.
772 			 */
773 			if (_phdr->p_type == PT_LOAD) {
774 				_phdr->p_align = ld_lcm(_phdr->p_align,
775 				    osp->os_shdr->sh_addralign);
776 			}
777 		}
778 	}
779 	return (1);
780 }
781