libiberty/simple-object-mach-o.c

   1 /* simple-object-mach-o.c -- routines to manipulate Mach-O object files.
   2    Copyright 2010 Free Software Foundation, Inc.
   3    Written by Ian Lance Taylor, Google.
   4
   5 This program is free software; you can redistribute it and/or modify it
   6 under the terms of the GNU General Public License as published by the
   7 Free Software Foundation; either version 2, or (at your option) any
   8 later version.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License
  16 along with this program; if not, write to the Free Software
  17 Foundation, 51 Franklin Street - Fifth Floor,
  18 Boston, MA 02110-1301, USA.  */
  19
  20 #include "config.h"
  21 #include "libiberty.h"
  22 #include "simple-object.h"
  23
  24 #include <stddef.h>
  25
  26 #ifdef HAVE_STDLIB_H
  27 #include <stdlib.h>
  28 #endif
  29
  30 #ifdef HAVE_STDINT_H
  31 #include <stdint.h>
  32 #endif
  33
  34 #ifdef HAVE_STRING_H
  35 #include <string.h>
  36 #endif
  37
  38 #ifdef HAVE_INTTYPES_H
  39 #include <inttypes.h>
  40 #endif
  41
  42 #include "simple-object-common.h"
  43
  44 /* Mach-O structures and constants.  */
  45
  46 /* Mach-O header (32-bit version).  */
  47
  48 struct mach_o_header_32
  49 {
  50   unsigned char magic[4];       /* Magic number.  */
  51   unsigned char cputype[4];     /* CPU that this object is for.  */
  52   unsigned char cpusubtype[4];  /* CPU subtype.  */
  53   unsigned char filetype[4];    /* Type of file.  */
  54   unsigned char ncmds[4];       /* Number of load commands.  */
  55   unsigned char sizeofcmds[4];  /* Total size of load commands.  */
  56   unsigned char flags[4];       /* Flags for special featues.  */
  57 };
  58
  59 /* Mach-O header (64-bit version).  */
  60
  61 struct mach_o_header_64
  62 {
  63   unsigned char magic[4];       /* Magic number.  */
  64   unsigned char cputype[4];     /* CPU that this object is for.  */
  65   unsigned char cpusubtype[4];  /* CPU subtype.  */
  66   unsigned char filetype[4];    /* Type of file.  */
  67   unsigned char ncmds[4];       /* Number of load commands.  */
  68   unsigned char sizeofcmds[4];  /* Total size of load commands.  */
  69   unsigned char flags[4];       /* Flags for special featues.  */
  70   unsigned char reserved[4];    /* Reserved.  Duh.  */
  71 };
  72
  73 /* For magic field in header.  */
  74
  75 #define MACH_O_MH_MAGIC                 0xfeedface
  76 #define MACH_O_MH_MAGIC_64              0xfeedfacf
  77
  78 /* For filetype field in header.  */
  79
  80 #define MACH_O_MH_OBJECT                0x01
  81
  82 /* A Mach-O file is a list of load commands.  This is the header of a
  83    load command.  */
  84
  85 struct mach_o_load_command
  86 {
  87   unsigned char cmd[4];         /* The type of load command.  */
  88   unsigned char cmdsize[4];     /* Size in bytes of entire command.  */
  89 };
  90
  91 /* For cmd field in load command.   */
  92
  93 #define MACH_O_LC_SEGMENT               0x01
  94 #define MACH_O_LC_SEGMENT_64            0x19
  95
  96 /* LC_SEGMENT load command.  */
  97
  98 struct mach_o_segment_command_32
  99 {
 100   unsigned char cmd[4];         /* The type of load command (LC_SEGMENT).  */
 101   unsigned char cmdsize[4];     /* Size in bytes of entire command.  */
 102   unsigned char segname[16];    /* Name of this segment.  */
 103   unsigned char vmaddr[4];      /* Virtual memory address of this segment.  */
 104   unsigned char vmsize[4];      /* Size there, in bytes.  */
 105   unsigned char fileoff[4];     /* Offset in bytes of the data to be mapped.  */
 106   unsigned char filesize[4];    /* Size in bytes on disk.  */
 107   unsigned char maxprot[4];     /* Maximum permitted vmem protection.  */
 108   unsigned char initprot[4];    /* Initial vmem protection.  */
 109   unsigned char nsects[4];      /* Number of sections in this segment.  */
 110   unsigned char flags[4];       /* Flags that affect the loading.  */
 111 };
 112
 113 /* LC_SEGMENT_64 load command.  */
 114
 115 struct mach_o_segment_command_64
 116 {
 117   unsigned char cmd[4];         /* The type of load command (LC_SEGMENT_64).  */
 118   unsigned char cmdsize[4];     /* Size in bytes of entire command.  */
 119   unsigned char segname[16];    /* Name of this segment.  */
 120   unsigned char vmaddr[8];      /* Virtual memory address of this segment.  */
 121   unsigned char vmsize[8];      /* Size there, in bytes.  */
 122   unsigned char fileoff[8];     /* Offset in bytes of the data to be mapped.  */
 123   unsigned char filesize[8];    /* Size in bytes on disk.  */
 124   unsigned char maxprot[4];     /* Maximum permitted vmem protection.  */
 125   unsigned char initprot[4];    /* Initial vmem protection.  */
 126   unsigned char nsects[4];      /* Number of sections in this segment.  */
 127   unsigned char flags[4];       /* Flags that affect the loading.  */
 128 };
 129
 130 /* 32-bit section header.  */
 131
 132 struct mach_o_section_32
 133 {
 134   unsigned char sectname[16];   /* Section name.  */
 135   unsigned char segname[16];    /* Segment that the section belongs to.  */
 136   unsigned char addr[4];        /* Address of this section in memory.  */
 137   unsigned char size[4];        /* Size in bytes of this section.  */
 138   unsigned char offset[4];      /* File offset of this section.  */
 139   unsigned char align[4];       /* log2 of this section's alignment.  */
 140   unsigned char reloff[4];      /* File offset of this section's relocs.  */
 141   unsigned char nreloc[4];      /* Number of relocs for this section.  */
 142   unsigned char flags[4];       /* Section flags/attributes.  */
 143   unsigned char reserved1[4];
 144   unsigned char reserved2[4];
 145 };
 146
 147 /* 64-bit section header.  */
 148
 149 struct mach_o_section_64
 150 {
 151   unsigned char sectname[16];   /* Section name.  */
 152   unsigned char segname[16];    /* Segment that the section belongs to.  */
 153   unsigned char addr[8];        /* Address of this section in memory.  */
 154   unsigned char size[8];        /* Size in bytes of this section.  */
 155   unsigned char offset[4];      /* File offset of this section.  */
 156   unsigned char align[4];       /* log2 of this section's alignment.  */
 157   unsigned char reloff[4];      /* File offset of this section's relocs.  */
 158   unsigned char nreloc[4];      /* Number of relocs for this section.  */
 159   unsigned char flags[4];       /* Section flags/attributes.  */
 160   unsigned char reserved1[4];
 161   unsigned char reserved2[4];
 162   unsigned char reserved3[4];
 163 };
 164
 165 /* Flags for Mach-O sections.  */
 166
 167 #define MACH_O_S_ATTR_DEBUG                     0x02000000
 168
 169 /* The length of a segment or section name.  */
 170
 171 #define MACH_O_NAME_LEN (16)
 172
 173 /* A GNU specific extension for long section names.  */
 174
 175 #define GNU_SECTION_NAMES "__section_names"
 176
 177 /* Private data for an simple_object_read.  */
 178
 179 struct simple_object_mach_o_read
 180 {
 181   /* User specified segment name.  */
 182   char *segment_name;
 183   /* Magic number.  */
 184   unsigned int magic;
 185   /* Whether this file is big-endian.  */
 186   int is_big_endian;
 187   /* CPU type from header.  */
 188   unsigned int cputype;
 189   /* CPU subtype from header.  */
 190   unsigned int cpusubtype;
 191   /* Number of commands, from header.  */
 192   unsigned int ncmds;
 193   /* Flags from header.  */
 194   unsigned int flags;
 195   /* Reserved field from header, only used on 64-bit.  */
 196   unsigned int reserved;
 197 };
 198
 199 /* Private data for an simple_object_attributes.  */
 200
 201 struct simple_object_mach_o_attributes
 202 {
 203   /* Magic number.  */
 204   unsigned int magic;
 205   /* Whether this file is big-endian.  */
 206   int is_big_endian;
 207   /* CPU type from header.  */
 208   unsigned int cputype;
 209   /* CPU subtype from header.  */
 210   unsigned int cpusubtype;
 211   /* Flags from header.  */
 212   unsigned int flags;
 213   /* Reserved field from header, only used on 64-bit.  */
 214   unsigned int reserved;
 215 };
 216
 217 /* See if we have a Mach-O file.  */
 218
 219 static void *
 220 simple_object_mach_o_match (
 221     unsigned char header[SIMPLE_OBJECT_MATCH_HEADER_LEN],
 222     int descriptor,
 223     off_t offset,
 224     const char *segment_name,
 225     const char **errmsg,
 226     int *err)
 227 {
 228   unsigned int magic;
 229   int is_big_endian;
 230   unsigned int (*fetch_32) (const unsigned char *);
 231   unsigned int filetype;
 232   struct simple_object_mach_o_read *omr;
 233   unsigned char buf[sizeof (struct mach_o_header_64)];
 234   unsigned char *b;
 235
 236   magic = simple_object_fetch_big_32 (header);
 237   if (magic == MACH_O_MH_MAGIC || magic == MACH_O_MH_MAGIC_64)
 238     is_big_endian = 1;
 239   else
 240     {
 241       magic = simple_object_fetch_little_32 (header);
 242       if (magic == MACH_O_MH_MAGIC || magic == MACH_O_MH_MAGIC_64)
 243         is_big_endian = 0;
 244       else
 245         {
 246           *errmsg = NULL;
 247           *err = 0;
 248           return NULL;
 249         }
 250     }
 251
 252 #ifndef UNSIGNED_64BIT_TYPE
 253   if (magic == MACH_O_MH_MAGIC_64)
 254     {
 255       *errmsg = "64-bit Mach-O objects not supported";
 256       *err = 0;
 257       return NULL;
 258     }
 259 #endif
 260
 261   /* We require the user to provide a segment name.  This is
 262      unfortunate but I don't see any good choices here.  */
 263
 264   if (segment_name == NULL)
 265     {
 266       *errmsg = "Mach-O file found but no segment name specified";
 267       *err = 0;
 268       return NULL;
 269     }
 270
 271   if (strlen (segment_name) > MACH_O_NAME_LEN)
 272     {
 273       *errmsg = "Mach-O segment name too long";
 274       *err = 0;
 275       return NULL;
 276     }
 277
 278   /* The 32-bit and 64-bit headers are similar enough that we can use
 279      the same code.  */
 280
 281   fetch_32 = (is_big_endian
 282               ? simple_object_fetch_big_32
 283               : simple_object_fetch_little_32);
 284
 285   if (!simple_object_internal_read (descriptor, offset, buf,
 286                                     (magic == MACH_O_MH_MAGIC
 287                                      ? sizeof (struct mach_o_header_32)
 288                                      : sizeof (struct mach_o_header_64)),
 289                                     errmsg, err))
 290     return NULL;
 291
 292   b = &buf[0];
 293
 294   filetype = (*fetch_32) (b + offsetof (struct mach_o_header_32, filetype));
 295   if (filetype != MACH_O_MH_OBJECT)
 296     {
 297       *errmsg = "Mach-O file is not object file";
 298       *err = 0;
 299       return NULL;
 300     }
 301
 302   omr = XNEW (struct simple_object_mach_o_read);
 303   omr->segment_name = xstrdup (segment_name);
 304   omr->magic = magic;
 305   omr->is_big_endian = is_big_endian;
 306   omr->cputype = (*fetch_32) (b + offsetof (struct mach_o_header_32, cputype));
 307   omr->cpusubtype = (*fetch_32) (b
 308                                  + offsetof (struct mach_o_header_32,
 309                                              cpusubtype));
 310   omr->ncmds = (*fetch_32) (b + offsetof (struct mach_o_header_32, ncmds));
 311   omr->flags = (*fetch_32) (b + offsetof (struct mach_o_header_32, flags));
 312   if (magic == MACH_O_MH_MAGIC)
 313     omr->reserved = 0;
 314   else
 315     omr->reserved = (*fetch_32) (b
 316                                  + offsetof (struct mach_o_header_64,
 317                                              reserved));
 318
 319   return (void *) omr;
 320 }
 321
 322 /* Get the file offset and size from a section header.  */
 323
 324 static void
 325 simple_object_mach_o_section_info (int is_big_endian, int is_32,
 326                                    const unsigned char *sechdr, off_t *offset,
 327                                    size_t *size)
 328 {
 329   unsigned int (*fetch_32) (const unsigned char *);
 330   ulong_type (*fetch_64) (const unsigned char *);
 331
 332   fetch_32 = (is_big_endian
 333               ? simple_object_fetch_big_32
 334               : simple_object_fetch_little_32);
 335
 336   fetch_64 = NULL;
 337 #ifdef UNSIGNED_64BIT_TYPE
 338   fetch_64 = (is_big_endian
 339               ? simple_object_fetch_big_64
 340               : simple_object_fetch_little_64);
 341 #endif
 342
 343   if (is_32)
 344     {
 345       *offset = fetch_32 (sechdr
 346                           + offsetof (struct mach_o_section_32, offset));
 347       *size = fetch_32 (sechdr
 348                         + offsetof (struct mach_o_section_32, size));
 349     }
 350   else
 351     {
 352       *offset = fetch_32 (sechdr
 353                           + offsetof (struct mach_o_section_64, offset));
 354       *size = fetch_64 (sechdr
 355                         + offsetof (struct mach_o_section_64, size));
 356     }
 357 }
 358
 359 /* Handle a segment in a Mach-O file.  Return 1 if we should continue,
 360    0 if the caller should return.  */
 361
 362 static int
 363 simple_object_mach_o_segment (simple_object_read *sobj, off_t offset,
 364                               const unsigned char *segbuf,
 365                               int (*pfn) (void *, const char *, off_t offset,
 366                                           off_t length),
 367                               void *data,
 368                               const char **errmsg, int *err)
 369 {
 370   struct simple_object_mach_o_read *omr =
 371     (struct simple_object_mach_o_read *) sobj->data;
 372   unsigned int (*fetch_32) (const unsigned char *);
 373   int is_32;
 374   size_t seghdrsize;
 375   size_t sechdrsize;
 376   size_t segname_offset;
 377   size_t sectname_offset;
 378   unsigned int nsects;
 379   unsigned char *secdata;
 380   unsigned int i;
 381   unsigned int strtab_index;
 382   char *strtab;
 383   size_t strtab_size;
 384
 385   fetch_32 = (omr->is_big_endian
 386               ? simple_object_fetch_big_32
 387               : simple_object_fetch_little_32);
 388
 389   is_32 = omr->magic == MACH_O_MH_MAGIC;
 390
 391   if (is_32)
 392     {
 393       seghdrsize = sizeof (struct mach_o_segment_command_32);
 394       sechdrsize = sizeof (struct mach_o_section_32);
 395       segname_offset = offsetof (struct mach_o_section_32, segname);
 396       sectname_offset = offsetof (struct mach_o_section_32, sectname);
 397       nsects = (*fetch_32) (segbuf
 398                             + offsetof (struct mach_o_segment_command_32,
 399                                         nsects));
 400     }
 401   else
 402     {
 403       seghdrsize = sizeof (struct mach_o_segment_command_64);
 404       sechdrsize = sizeof (struct mach_o_section_64);
 405       segname_offset = offsetof (struct mach_o_section_64, segname);
 406       sectname_offset = offsetof (struct mach_o_section_64, sectname);
 407       nsects = (*fetch_32) (segbuf
 408                             + offsetof (struct mach_o_segment_command_64,
 409                                         nsects));
 410     }
 411
 412   secdata = XNEWVEC (unsigned char, nsects * sechdrsize);
 413   if (!simple_object_internal_read (sobj->descriptor, offset + seghdrsize,
 414                                     secdata, nsects * sechdrsize, errmsg, err))
 415     {
 416       XDELETEVEC (secdata);
 417       return 0;
 418     }
 419
 420   /* Scan for a __section_names section.  This is in effect a GNU
 421      extension that permits section names longer than 16 chars.  */
 422
 423   for (i = 0; i < nsects; ++i)
 424     {
 425       size_t nameoff;
 426
 427       nameoff = i * sechdrsize + segname_offset;
 428       if (strcmp ((char *) secdata + nameoff, omr->segment_name) != 0)
 429         continue;
 430       nameoff = i * sechdrsize + sectname_offset;
 431       if (strcmp ((char *) secdata + nameoff, GNU_SECTION_NAMES) == 0)
 432         break;
 433     }
 434
 435   strtab_index = i;
 436   if (strtab_index >= nsects)
 437     {
 438       strtab = NULL;
 439       strtab_size = 0;
 440     }
 441   else
 442     {
 443       off_t strtab_offset;
 444
 445       simple_object_mach_o_section_info (omr->is_big_endian, is_32,
 446                                          secdata + strtab_index * sechdrsize,
 447                                          &strtab_offset, &strtab_size);
 448       strtab = XNEWVEC (char, strtab_size);
 449       if (!simple_object_internal_read (sobj->descriptor,
 450                                         sobj->offset + strtab_offset,
 451                                         (unsigned char *) strtab, strtab_size,
 452                                         errmsg, err))
 453         {
 454           XDELETEVEC (strtab);
 455           XDELETEVEC (secdata);
 456           return 0;
 457         }
 458     }
 459
 460   /* Process the sections.  */
 461
 462   for (i = 0; i < nsects; ++i)
 463     {
 464       const unsigned char *sechdr;
 465       char namebuf[MACH_O_NAME_LEN + 1];
 466       char *name;
 467       off_t secoffset;
 468       size_t secsize;
 469
 470       if (i == strtab_index)
 471         continue;
 472
 473       sechdr = secdata + i * sechdrsize;
 474
 475       if (strcmp ((char *) sechdr + segname_offset, omr->segment_name) != 0)
 476         continue;
 477
 478       memcpy (namebuf, sechdr + sectname_offset, MACH_O_NAME_LEN);
 479       namebuf[MACH_O_NAME_LEN] = '\0';
 480
 481       name = &namebuf[0];
 482       if (strtab != NULL && name[0] == '_' && name[1] == '_')
 483         {
 484           unsigned long stringoffset;
 485
 486           if (sscanf (name + 2, "%08lX", &stringoffset) == 1)
 487             {
 488               if (stringoffset >= strtab_size)
 489                 {
 490                   *errmsg = "section name offset out of range";
 491                   *err = 0;
 492                   XDELETEVEC (strtab);
 493                   XDELETEVEC (secdata);
 494                   return 0;
 495                 }
 496
 497               name = strtab + stringoffset;
 498             }
 499         }
 500
 501       simple_object_mach_o_section_info (omr->is_big_endian, is_32, sechdr,
 502                                          &secoffset, &secsize);
 503
 504       if (!(*pfn) (data, name, secoffset, secsize))
 505         {
 506           *errmsg = NULL;
 507           *err = 0;
 508           XDELETEVEC (strtab);
 509           XDELETEVEC (secdata);
 510           return 0;
 511         }
 512     }
 513
 514   XDELETEVEC (strtab);
 515   XDELETEVEC (secdata);
 516
 517   return 1;
 518 }
 519
 520 /* Find all sections in a Mach-O file.  */
 521
 522 static const char *
 523 simple_object_mach_o_find_sections (simple_object_read *sobj,
 524                                     int (*pfn) (void *, const char *,
 525                                                 off_t offset, off_t length),
 526                                     void *data,
 527                                     int *err)
 528 {
 529   struct simple_object_mach_o_read *omr =
 530     (struct simple_object_mach_o_read *) sobj->data;
 531   off_t offset;
 532   size_t seghdrsize;
 533   unsigned int (*fetch_32) (const unsigned char *);
 534   const char *errmsg;
 535   unsigned int i;
 536
 537   if (omr->magic == MACH_O_MH_MAGIC)
 538     {
 539       offset = sizeof (struct mach_o_header_32);
 540       seghdrsize = sizeof (struct mach_o_segment_command_32);
 541     }
 542   else
 543     {
 544       offset = sizeof (struct mach_o_header_64);
 545       seghdrsize = sizeof (struct mach_o_segment_command_64);
 546     }
 547
 548   fetch_32 = (omr->is_big_endian
 549               ? simple_object_fetch_big_32
 550               : simple_object_fetch_little_32);
 551
 552   for (i = 0; i < omr->ncmds; ++i)
 553     {
 554       unsigned char loadbuf[sizeof (struct mach_o_load_command)];
 555       unsigned int cmd;
 556       unsigned int cmdsize;
 557
 558       if (!simple_object_internal_read (sobj->descriptor,
 559                                         sobj->offset + offset,
 560                                         loadbuf,
 561                                         sizeof (struct mach_o_load_command),
 562                                         &errmsg, err))
 563         return errmsg;
 564
 565       cmd = (*fetch_32) (loadbuf + offsetof (struct mach_o_load_command, cmd));
 566       cmdsize = (*fetch_32) (loadbuf
 567                              + offsetof (struct mach_o_load_command, cmdsize));
 568
 569       if (cmd == MACH_O_LC_SEGMENT || cmd == MACH_O_LC_SEGMENT_64)
 570         {
 571           unsigned char segbuf[sizeof (struct mach_o_segment_command_64)];
 572           int r;
 573
 574           if (!simple_object_internal_read (sobj->descriptor,
 575                                             sobj->offset + offset,
 576                                             segbuf, seghdrsize, &errmsg, err))
 577             return errmsg;
 578
 579           r = simple_object_mach_o_segment (sobj, offset, segbuf, pfn,
 580                                             data, &errmsg, err);
 581           if (!r)
 582             return errmsg;
 583         }
 584
 585       offset += cmdsize;
 586     }
 587
 588   return NULL;
 589 }
 590
 591 /* Fetch the attributes for an simple_object_read.  */
 592
 593 static void *
 594 simple_object_mach_o_fetch_attributes (simple_object_read *sobj,
 595                                        const char **errmsg ATTRIBUTE_UNUSED,
 596                                        int *err ATTRIBUTE_UNUSED)
 597 {
 598   struct simple_object_mach_o_read *omr =
 599     (struct simple_object_mach_o_read *) sobj->data;
 600   struct simple_object_mach_o_attributes *ret;
 601
 602   ret = XNEW (struct simple_object_mach_o_attributes);
 603   ret->magic = omr->magic;
 604   ret->is_big_endian = omr->is_big_endian;
 605   ret->cputype = omr->cputype;
 606   ret->cpusubtype = omr->cpusubtype;
 607   ret->flags = omr->flags;
 608   ret->reserved = omr->reserved;
 609   return ret;
 610 }
 611
 612 /* Release the private data for an simple_object_read.  */
 613
 614 static void
 615 simple_object_mach_o_release_read (void *data)
 616 {
 617   struct simple_object_mach_o_read *omr =
 618     (struct simple_object_mach_o_read *) data;
 619
 620   free (omr->segment_name);
 621   XDELETE (omr);
 622 }
 623
 624 /* Compare two attributes structures.  */
 625
 626 static const char *
 627 simple_object_mach_o_attributes_merge (void *todata, void *fromdata, int *err)
 628 {
 629   struct simple_object_mach_o_attributes *to =
 630     (struct simple_object_mach_o_attributes *) todata;
 631   struct simple_object_mach_o_attributes *from =
 632     (struct simple_object_mach_o_attributes *) fromdata;
 633
 634   if (to->magic != from->magic
 635       || to->is_big_endian != from->is_big_endian
 636       || to->cputype != from->cputype)
 637     {
 638       *err = 0;
 639       return "Mach-O object format mismatch";
 640     }
 641   return NULL;
 642 }
 643
 644 /* Release the private data for an attributes structure.  */
 645
 646 static void
 647 simple_object_mach_o_release_attributes (void *data)
 648 {
 649   XDELETE (data);
 650 }
 651
 652 /* Prepare to write out a file.  */
 653
 654 static void *
 655 simple_object_mach_o_start_write (void *attributes_data,
 656                                   const char **errmsg ATTRIBUTE_UNUSED,
 657                                   int *err ATTRIBUTE_UNUSED)
 658 {
 659   struct simple_object_mach_o_attributes *attrs =
 660     (struct simple_object_mach_o_attributes *) attributes_data;
 661   struct simple_object_mach_o_attributes *ret;
 662
 663   /* We're just going to record the attributes, but we need to make a
 664      copy because the user may delete them.  */
 665   ret = XNEW (struct simple_object_mach_o_attributes);
 666   *ret = *attrs;
 667   return ret;
 668 }
 669
 670 /* Write out the header of a Mach-O file.  */
 671
 672 static int
 673 simple_object_mach_o_write_header (simple_object_write *sobj, int descriptor,
 674                                    size_t nsects, const char **errmsg,
 675                                    int *err)
 676 {
 677   struct simple_object_mach_o_attributes *attrs =
 678     (struct simple_object_mach_o_attributes *) sobj->data;
 679   void (*set_32) (unsigned char *, unsigned int);
 680   unsigned char hdrbuf[sizeof (struct mach_o_header_64)];
 681   unsigned char *hdr;
 682   size_t wrsize;
 683
 684   set_32 = (attrs->is_big_endian
 685             ? simple_object_set_big_32
 686             : simple_object_set_little_32);
 687
 688   memset (hdrbuf, 0, sizeof hdrbuf);
 689
 690   /* The 32-bit and 64-bit headers start out the same.  */
 691
 692   hdr = &hdrbuf[0];
 693   set_32 (hdr + offsetof (struct mach_o_header_32, magic), attrs->magic);
 694   set_32 (hdr + offsetof (struct mach_o_header_32, cputype), attrs->cputype);
 695   set_32 (hdr + offsetof (struct mach_o_header_32, cpusubtype),
 696           attrs->cpusubtype);
 697   set_32 (hdr + offsetof (struct mach_o_header_32, filetype), MACH_O_MH_OBJECT);
 698   set_32 (hdr + offsetof (struct mach_o_header_32, ncmds), 1);
 699   set_32 (hdr + offsetof (struct mach_o_header_32, flags), attrs->flags);
 700   if (attrs->magic == MACH_O_MH_MAGIC)
 701     {
 702       wrsize = sizeof (struct mach_o_header_32);
 703       set_32 (hdr + offsetof (struct mach_o_header_32, sizeofcmds),
 704               (sizeof (struct mach_o_segment_command_32)
 705                + nsects * sizeof (struct mach_o_section_32)));
 706     }
 707   else
 708     {
 709       set_32 (hdr + offsetof (struct mach_o_header_64, sizeofcmds),
 710               (sizeof (struct mach_o_segment_command_64)
 711                + nsects * sizeof (struct mach_o_section_64)));
 712       set_32 (hdr + offsetof (struct mach_o_header_64, reserved),
 713               attrs->reserved);
 714       wrsize = sizeof (struct mach_o_header_64);
 715     }
 716
 717   return simple_object_internal_write (descriptor, 0, hdrbuf, wrsize,
 718                                        errmsg, err);
 719 }
 720
 721 /* Write a Mach-O section header.  */
 722
 723 static int
 724 simple_object_mach_o_write_section_header (simple_object_write *sobj,
 725                                            int descriptor,
 726                                            size_t sechdr_offset,
 727                                            const char *name, size_t secaddr,
 728                                            size_t secsize, size_t offset,
 729                                            unsigned int align,
 730                                            const char **errmsg, int *err)
 731 {
 732   struct simple_object_mach_o_attributes *attrs =
 733     (struct simple_object_mach_o_attributes *) sobj->data;
 734   void (*set_32) (unsigned char *, unsigned int);
 735   unsigned char hdrbuf[sizeof (struct mach_o_section_64)];
 736   unsigned char *hdr;
 737   size_t sechdrsize;
 738
 739   set_32 = (attrs->is_big_endian
 740             ? simple_object_set_big_32
 741             : simple_object_set_little_32);
 742
 743   memset (hdrbuf, 0, sizeof hdrbuf);
 744
 745   hdr = &hdrbuf[0];
 746   if (attrs->magic == MACH_O_MH_MAGIC)
 747     {
 748       strncpy ((char *) hdr + offsetof (struct mach_o_section_32, sectname),
 749                name, MACH_O_NAME_LEN);
 750       strncpy ((char *) hdr + offsetof (struct mach_o_section_32, segname),
 751                sobj->segment_name, MACH_O_NAME_LEN);
 752       set_32 (hdr + offsetof (struct mach_o_section_32, addr), secaddr);
 753       set_32 (hdr + offsetof (struct mach_o_section_32, size), secsize);
 754       set_32 (hdr + offsetof (struct mach_o_section_32, offset), offset);
 755       set_32 (hdr + offsetof (struct mach_o_section_32, align), align);
 756       /* reloff left as zero.  */
 757       /* nreloc left as zero.  */
 758       set_32 (hdr + offsetof (struct mach_o_section_32, flags),
 759               MACH_O_S_ATTR_DEBUG);
 760       /* reserved1 left as zero.  */
 761       /* reserved2 left as zero.  */
 762       sechdrsize = sizeof (struct mach_o_section_32);
 763     }
 764   else
 765     {
 766 #ifdef UNSIGNED_64BIT_TYPE
 767       void (*set_64) (unsigned char *, ulong_type);
 768
 769       set_64 = (attrs->is_big_endian
 770                 ? simple_object_set_big_64
 771                 : simple_object_set_little_64);
 772
 773       strncpy ((char *) hdr + offsetof (struct mach_o_section_64, sectname),
 774                name, MACH_O_NAME_LEN);
 775       strncpy ((char *) hdr + offsetof (struct mach_o_section_64, segname),
 776                sobj->segment_name, MACH_O_NAME_LEN);
 777       set_64 (hdr + offsetof (struct mach_o_section_64, addr), secaddr);
 778       set_64 (hdr + offsetof (struct mach_o_section_64, size), secsize);
 779       set_32 (hdr + offsetof (struct mach_o_section_64, offset), offset);
 780       set_32 (hdr + offsetof (struct mach_o_section_64, align), align);
 781       /* reloff left as zero.  */
 782       /* nreloc left as zero.  */
 783       set_32 (hdr + offsetof (struct mach_o_section_64, flags),
 784               MACH_O_S_ATTR_DEBUG);
 785       /* reserved1 left as zero.  */
 786       /* reserved2 left as zero.  */
 787       /* reserved3 left as zero.  */
 788 #endif
 789       sechdrsize = sizeof (struct mach_o_section_64);
 790     }
 791
 792   return simple_object_internal_write (descriptor, sechdr_offset, hdr,
 793                                        sechdrsize, errmsg, err);
 794 }
 795
 796 /* Write out the single segment and the sections of a Mach-O file.  */
 797
 798 static int
 799 simple_object_mach_o_write_segment (simple_object_write *sobj, int descriptor,
 800                                     size_t nsects, const char **errmsg,
 801                                     int *err)
 802 {
 803   struct simple_object_mach_o_attributes *attrs =
 804     (struct simple_object_mach_o_attributes *) sobj->data;
 805   void (*set_32) (unsigned char *, unsigned int);
 806   size_t hdrsize;
 807   size_t seghdrsize;
 808   size_t sechdrsize;
 809   size_t cmdsize;
 810   size_t offset;
 811   size_t sechdr_offset;
 812   size_t secaddr;
 813   unsigned int name_offset;
 814   simple_object_write_section *section;
 815   unsigned char hdrbuf[sizeof (struct mach_o_segment_command_64)];
 816   unsigned char *hdr;
 817
 818   set_32 = (attrs->is_big_endian
 819             ? simple_object_set_big_32
 820             : simple_object_set_little_32);
 821
 822   /* Write out the sections first.  */
 823
 824   if (attrs->magic == MACH_O_MH_MAGIC)
 825     {
 826       hdrsize = sizeof (struct mach_o_header_32);
 827       seghdrsize = sizeof (struct mach_o_segment_command_32);
 828       sechdrsize = sizeof (struct mach_o_section_32);
 829     }
 830   else
 831     {
 832       hdrsize = sizeof (struct mach_o_header_64);
 833       seghdrsize = sizeof (struct mach_o_segment_command_64);
 834       sechdrsize = sizeof (struct mach_o_section_64);
 835     }
 836
 837   sechdr_offset = hdrsize + seghdrsize;
 838   cmdsize = seghdrsize + nsects * sechdrsize;
 839   offset = hdrsize + cmdsize;
 840   name_offset = 0;
 841   secaddr = 0;
 842
 843   for (section = sobj->sections; section != NULL; section = section->next)
 844     {
 845       size_t mask;
 846       size_t new_offset;
 847       size_t secsize;
 848       struct simple_object_write_section_buffer *buffer;
 849       char namebuf[MACH_O_NAME_LEN + 1];
 850
 851       mask = (1U << section->align) - 1;
 852       new_offset = offset + mask;
 853       new_offset &= ~ mask;
 854       while (new_offset > offset)
 855         {
 856           unsigned char zeroes[16];
 857           size_t write;
 858
 859           memset (zeroes, 0, sizeof zeroes);
 860           write = new_offset - offset;
 861           if (write > sizeof zeroes)
 862             write = sizeof zeroes;
 863           if (!simple_object_internal_write (descriptor, offset, zeroes, write,
 864                                              errmsg, err))
 865             return 0;
 866           offset += write;
 867         }
 868
 869       secsize = 0;
 870       for (buffer = section->buffers; buffer != NULL; buffer = buffer->next)
 871         {
 872           if (!simple_object_internal_write (descriptor, offset + secsize,
 873                                              ((const unsigned char *)
 874                                               buffer->buffer),
 875                                              buffer->size, errmsg, err))
 876             return 0;
 877           secsize += buffer->size;
 878         }
 879
 880       snprintf (namebuf, sizeof namebuf, "__%08X", name_offset);
 881       if (!simple_object_mach_o_write_section_header (sobj, descriptor,
 882                                                       sechdr_offset, namebuf,
 883                                                       secaddr, secsize, offset,
 884                                                       section->align,
 885                                                       errmsg, err))
 886         return 0;
 887
 888       sechdr_offset += sechdrsize;
 889       offset += secsize;
 890       name_offset += strlen (section->name) + 1;
 891       secaddr += secsize;
 892     }
 893
 894   /* Write out the section names.  */
 895
 896   if (!simple_object_mach_o_write_section_header (sobj, descriptor,
 897                                                   sechdr_offset,
 898                                                   GNU_SECTION_NAMES, secaddr,
 899                                                   name_offset, offset, 0,
 900                                                   errmsg, err))
 901     return 0;
 902
 903   for (section = sobj->sections; section != NULL; section = section->next)
 904     {
 905       size_t namelen;
 906
 907       namelen = strlen (section->name) + 1;
 908       if (!simple_object_internal_write (descriptor, offset,
 909                                          (const unsigned char *) section->name,
 910                                          namelen, errmsg, err))
 911         return 0;
 912       offset += namelen;
 913     }
 914
 915   /* Write out the segment header.  */
 916
 917   memset (hdrbuf, 0, sizeof hdrbuf);
 918
 919   hdr = &hdrbuf[0];
 920   if (attrs->magic == MACH_O_MH_MAGIC)
 921     {
 922       set_32 (hdr + offsetof (struct mach_o_segment_command_32, cmd),
 923               MACH_O_LC_SEGMENT);
 924       set_32 (hdr + offsetof (struct mach_o_segment_command_32, cmdsize),
 925               cmdsize);
 926       strncpy (((char *) hdr
 927                 + offsetof (struct mach_o_segment_command_32, segname)),
 928                sobj->segment_name, MACH_O_NAME_LEN);
 929       /* vmaddr left as zero.  */
 930       /* vmsize left as zero.  */
 931       set_32 (hdr + offsetof (struct mach_o_segment_command_32, fileoff),
 932               hdrsize + cmdsize);
 933       set_32 (hdr + offsetof (struct mach_o_segment_command_32, filesize),
 934               offset - (hdrsize + cmdsize));
 935       /* maxprot left as zero.  */
 936       /* initprot left as zero.  */
 937       set_32 (hdr + offsetof (struct mach_o_segment_command_32, nsects),
 938               nsects);
 939       /* flags left as zero.  */
 940     }
 941   else
 942     {
 943 #ifdef UNSIGNED_64BIT_TYPE
 944       void (*set_64) (unsigned char *, ulong_type);
 945
 946       set_64 = (attrs->is_big_endian
 947                 ? simple_object_set_big_64
 948                 : simple_object_set_little_64);
 949
 950       set_32 (hdr + offsetof (struct mach_o_segment_command_64, cmd),
 951               MACH_O_LC_SEGMENT);
 952       set_32 (hdr + offsetof (struct mach_o_segment_command_64, cmdsize),
 953               cmdsize);
 954       strncpy (((char *) hdr
 955                 + offsetof (struct mach_o_segment_command_64, segname)),
 956                sobj->segment_name, MACH_O_NAME_LEN);
 957       /* vmaddr left as zero.  */
 958       /* vmsize left as zero.  */
 959       set_64 (hdr + offsetof (struct mach_o_segment_command_64, fileoff),
 960               hdrsize + cmdsize);
 961       set_64 (hdr + offsetof (struct mach_o_segment_command_64, filesize),
 962               offset - (hdrsize + cmdsize));
 963       /* maxprot left as zero.  */
 964       /* initprot left as zero.  */
 965       set_32 (hdr + offsetof (struct mach_o_segment_command_64, nsects),
 966               nsects);
 967       /* flags left as zero.  */
 968 #endif
 969     }
 970
 971   return simple_object_internal_write (descriptor, hdrsize, hdr, seghdrsize,
 972                                        errmsg, err);
 973 }
 974
 975 /* Write out a complete Mach-O file.  */
 976
 977 static const char *
 978 simple_object_mach_o_write_to_file (simple_object_write *sobj, int descriptor,
 979                                     int *err)
 980 {
 981   size_t nsects;
 982   simple_object_write_section *section;
 983   const char *errmsg;
 984
 985   /* Start at 1 for symbol_names section.  */
 986   nsects = 1;
 987   for (section = sobj->sections; section != NULL; section = section->next)
 988     ++nsects;
 989
 990   if (!simple_object_mach_o_write_header (sobj, descriptor, nsects,
 991                                           &errmsg, err))
 992     return errmsg;
 993
 994   if (!simple_object_mach_o_write_segment (sobj, descriptor, nsects,
 995                                            &errmsg, err))
 996     return errmsg;
 997
 998   return NULL;
 999 }
1000
1001 /* Release the private data for an simple_object_write structure.  */
1002
1003 static void
1004 simple_object_mach_o_release_write (void *data)
1005 {
1006   XDELETE (data);
1007 }
1008
1009 /* The Mach-O functions.  */
1010
1011 const struct simple_object_functions simple_object_mach_o_functions =
1012 {
1013   simple_object_mach_o_match,
1014   simple_object_mach_o_find_sections,
1015   simple_object_mach_o_fetch_attributes,
1016   simple_object_mach_o_release_read,
1017   simple_object_mach_o_attributes_merge,
1018   simple_object_mach_o_release_attributes,
1019   simple_object_mach_o_start_write,
1020   simple_object_mach_o_write_to_file,
1021   simple_object_mach_o_release_write
1022 };