gcc/collect2-aix.c

   1 /* AIX cross support for collect2.
   2    Copyright (C) 2009-2020 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "tm.h"
  24 #include "collect2-aix.h"
  25
  26 #ifdef CROSS_AIX_SUPPORT
  27
  28 /* Read SIZE bytes starting at DATA as a big-endian value.  */
  29
  30 static inline bfd_vma
  31 read_value (char *data, unsigned int size)
  32 {
  33   bfd_vma value;
  34   unsigned int i;
  35
  36   value = 0;
  37   for (i = 0; i < size; i++)
  38     {
  39       value <<= 8;
  40       value += (unsigned char) data[i];
  41     }
  42   return value;
  43 }
  44
  45 /* FIELD is a char array.  Read the contents as a big-endian integer.  */
  46 #define READ_FIELD(FIELD) \
  47   read_value (FIELD, sizeof (FIELD))
  48
  49 /* OBJECT is a char pointer to an in-file object of type struct TYPE.
  50    Return the address of field FIELD.  */
  51 #define OBJECT_FIELD(OBJECT, TYPE, FIELD) \
  52   (OBJECT) + offsetof (struct TYPE, FIELD)
  53
  54 /* Return the size of FIELD, which is a field of struct TYPE.  */
  55 #define FIELD_SIZE(TYPE, FIELD) \
  56   sizeof (((struct TYPE *) (0))->FIELD)
  57
  58 /* OBJECT is a char pointer to an in-file object of type struct TYPE.
  59    Read the value of field FIELD as a big-endian integer.  */
  60 #define READ_OBJECT(OBJECT, TYPE, FIELD) \
  61   read_value (OBJECT_FIELD (OBJECT, TYPE, FIELD), FIELD_SIZE (TYPE, FIELD))
  62
  63 /* Copy FIELD from an external structure of type TYPE at address FROM
  64    to an internal structure pointed to by TO.  */
  65 #define COPY_FIELD(TO, FROM, TYPE, FIELD) \
  66   ((TO)->FIELD = READ_OBJECT (FROM, TYPE, FIELD))
  67
  68 /* Return true if STRING is less than SIZE bytes long.  EXTRA_TERMINATOR
  69    is another character (besides '\0') that acts as a terminator,
  70    or '\0' if none.  */
  71
  72 static bool
  73 string_within_bounds_p (const char *string, size_t size, char extra_terminator)
  74 {
  75   const char *p;
  76
  77   for (p = string; p < string + size; p++)
  78     if (*p == '\0' || *p == extra_terminator)
  79       return true;
  80   return false;
  81 }
  82
  83 /* STRING is a pointer to a char array.  Try to read its value as an
  84    ASCII-encoded integer.  On success, return true and store the result
  85    in TARGET.  */
  86 #define PARSE_INTEGER(TARGET, STRING) \
  87   (string_within_bounds_p (&(STRING)[0], sizeof (STRING), ' ') \
  88    && ((TARGET) = strtoul (STRING, NULL, 0), true))
  89
  90 /* Check that LDFILE's current object has SIZE bytes starting at OFFSET.  */
  91
  92 static inline bool
  93 within_object_p (LDFILE *ldfile, size_t offset, size_t size)
  94 {
  95   return offset <= ldfile->object_size && offset + size <= ldfile->object_size;
  96 }
  97
  98 /* Try to read the file header for an XCOFF object at OFFSET bytes into
  99    LDFILE.  The object is expected to be OBJECT_SIZE bytes in size.
 100    If the object is a member of an archive, NEXT_MEMBER is the offset
 101    of the next member, otherwise it is -1.
 102
 103    Return true on success, recording the object information in LDFILE.  */
 104
 105 static bool
 106 read_xcoff_object (LDFILE *ldfile, size_t offset, size_t object_size,
 107                    off_t next_member)
 108 {
 109   struct internal_filehdr *internal;
 110   char *external;
 111   void *map;
 112   size_t page_size;
 113
 114   /* First try to map the file into memory.  */
 115   page_size = getpagesize ();
 116   ldfile->page_offset = offset & (page_size - 1);
 117   map = mmap (NULL, object_size + ldfile->page_offset, PROT_READ,
 118               MAP_SHARED, ldfile->fd, offset - ldfile->page_offset);
 119   if (map == MAP_FAILED)
 120     return false;
 121
 122   /* Record the success.  */
 123   ldfile->object = (char *) map + ldfile->page_offset;
 124   ldfile->object_size = object_size;
 125   ldfile->next_member = next_member;
 126
 127   /* Read the magic value to determine the type of file.  */
 128   if (!within_object_p (ldfile, 0, F_MAGIC_SIZE))
 129     return false;
 130
 131   internal = &ldfile->filehdr;
 132   external = ldfile->object;
 133   internal->f_magic = read_value (external, F_MAGIC_SIZE);
 134   if (internal->f_magic == U802TOCMAGIC)
 135     {
 136       if (!within_object_p (ldfile, 0, sizeof (struct external_filehdr_32)))
 137         return false;
 138
 139       COPY_FIELD (internal, external, external_filehdr_32, f_nscns);
 140       COPY_FIELD (internal, external, external_filehdr_32, f_timdat);
 141       COPY_FIELD (internal, external, external_filehdr_32, f_symptr);
 142       COPY_FIELD (internal, external, external_filehdr_32, f_nsyms);
 143       COPY_FIELD (internal, external, external_filehdr_32, f_opthdr);
 144       COPY_FIELD (internal, external, external_filehdr_32, f_flags);
 145       return true;
 146     }
 147   else if (internal->f_magic == U803XTOCMAGIC
 148            || internal->f_magic == U64_TOCMAGIC)
 149     {
 150       if (!within_object_p (ldfile, 0, sizeof (struct external_filehdr_64)))
 151         return false;
 152
 153       COPY_FIELD (internal, external, external_filehdr_64, f_nscns);
 154       COPY_FIELD (internal, external, external_filehdr_64, f_timdat);
 155       COPY_FIELD (internal, external, external_filehdr_64, f_symptr);
 156       COPY_FIELD (internal, external, external_filehdr_64, f_nsyms);
 157       COPY_FIELD (internal, external, external_filehdr_64, f_opthdr);
 158       COPY_FIELD (internal, external, external_filehdr_64, f_flags);
 159       return true;
 160     }
 161   return false;
 162 }
 163
 164 /* Try to read an archive member at OFFSET bytes into LDFILE.
 165    Return true on success, recording the member and object
 166    information in LDFILE.  */
 167
 168 static bool
 169 read_archive_member (LDFILE *ldfile, size_t offset)
 170 {
 171   struct external_big_ar_member member;
 172   size_t namlen;
 173   size_t size;
 174   off_t next_member;
 175
 176   if (lseek (ldfile->fd, offset, SEEK_SET) >= 0
 177       && read (ldfile->fd, &member, sizeof (member)) == sizeof (member)
 178       && PARSE_INTEGER (namlen, member.ar_namlen)
 179       /* Stop once we reach the member table entry, which has a name
 180          of length 0.  */
 181       && namlen > 0
 182       && PARSE_INTEGER (size, member.ar_size)
 183       && PARSE_INTEGER (next_member, member.ar_nextoff))
 184     {
 185       /* The archive is followed by an even-padded name, then by
 186          a magic string of length SXCOFFARFMAG.  The object itself
 187          starts after that. */
 188       offset += sizeof (member) + namlen + SXCOFFARFMAG;
 189       offset += offset & 1;
 190       return read_xcoff_object (ldfile, offset, size, next_member);
 191     }
 192   return false;
 193 }
 194
 195 /* Try to treat LDFILE as a non-empty big archive.  Return true
 196    on success, storing the member and object information for
 197    the first member in LDFILE.  */
 198
 199 static bool
 200 read_big_archive (LDFILE *ldfile)
 201 {
 202   struct external_big_ar_filehdr filehdr;
 203   size_t offset;
 204
 205   return (lseek (ldfile->fd, 0L, SEEK_SET) == 0
 206           && read (ldfile->fd, &filehdr, sizeof (filehdr)) == sizeof (filehdr)
 207           && memcmp (filehdr.fl_magic, FL_MAGIC_BIG_AR, FL_MAGIC_SIZE) == 0
 208           && PARSE_INTEGER (offset, filehdr.fl_firstmemoff)
 209           && read_archive_member (ldfile, offset));
 210 }
 211
 212 /* LDFILE is a zero-initialized structure.  Try to open FILENAME,
 213    returning true on success.  */
 214
 215 static bool
 216 open_file (LDFILE *ldfile, const char *filename)
 217 {
 218   struct stat st;
 219
 220   ldfile->fd = open (filename, O_RDONLY);
 221   if (ldfile->fd < 0)
 222     return false;
 223
 224   if (read_big_archive (ldfile))
 225     return true;
 226
 227   if (fstat (ldfile->fd, &st) < 0)
 228     return false;
 229
 230   return read_xcoff_object (ldfile, 0, st.st_size, -1);
 231 }
 232
 233 /* Release the memory associated with the current object, if one has
 234    been mapped.  */
 235
 236 static void
 237 free_object (LDFILE *ldfile)
 238 {
 239   if (ldfile->object)
 240     munmap (ldfile->object - ldfile->page_offset,
 241             ldfile->object_size + ldfile->page_offset);
 242 }
 243
 244 /* Free LDFILE and all resources associated with it.  */
 245
 246 static void
 247 free_ldfile (LDFILE *ldfile)
 248 {
 249   if (ldfile->fd >= 0)
 250     close (ldfile->fd);
 251   XDELETE (ldfile);
 252 }
 253
 254 /* Implement the API-defined ldopen function.  */
 255
 256 LDFILE *
 257 ldopen (char *filename, LDFILE *ldfile)
 258 {
 259   if (ldfile == NULL)
 260     {
 261       ldfile = XCNEW (LDFILE);
 262       if (!open_file (ldfile, filename))
 263         {
 264           free_object (ldfile);
 265           free_ldfile (ldfile);
 266           return NULL;
 267         }
 268     }
 269   return ldfile;
 270 }
 271
 272 /* Implement the API-defined ldtbread function.  */
 273
 274 int
 275 ldtbread (LDFILE *ldfile, long index, SYMENT *internal)
 276 {
 277   size_t offset, name_length;
 278   char *external;
 279
 280   /* Make sure that the symbol index is valid.  */
 281   if (index < 0 || index >= HEADER (ldfile).f_nsyms)
 282     return FAILURE;
 283
 284   /* Work out the offset of the symbol table entry.  */
 285   offset = HEADER (ldfile).f_symptr + index * sizeof (struct external_syment);
 286   if (!within_object_p (ldfile, offset, sizeof (struct external_syment)))
 287     return FAILURE;
 288
 289   /* Read all the fields.  The format differs between 32-bit and
 290      64-bit files.  */
 291   external = ldfile->object + offset;
 292   if (HEADER (ldfile).f_magic == U802TOCMAGIC)
 293     {
 294       /* Copy the n_zeroes/n_offset interpretation.  */
 295       internal->n_zeroes = READ_OBJECT (external, external_syment,
 296                                         u.xcoff32.u.u.n_zeroes);
 297       internal->n_offset = READ_OBJECT (external, external_syment,
 298                                         u.xcoff32.u.u.n_offset);
 299
 300       /* Copy the n_name interpretation.  The internal version has room
 301          for a null terminator.  */
 302       name_length = FIELD_SIZE (external_syment, u.xcoff32.u.n_name);
 303       memcpy (internal->n_name,
 304               external + offsetof (struct external_syment, u.xcoff32.u.n_name),
 305               name_length);
 306       internal->n_name[name_length] = 0;
 307
 308       internal->n_value = READ_OBJECT (external, external_syment,
 309                                        u.xcoff32.n_value);
 310     }
 311   else
 312     {
 313       internal->n_zeroes = 0;
 314       internal->n_offset = READ_OBJECT (external, external_syment,
 315                                         u.xcoff64.n_offset);
 316       internal->n_value = READ_OBJECT (external, external_syment,
 317                                        u.xcoff64.n_value);
 318     }
 319   COPY_FIELD (internal, external, external_syment, n_scnum);
 320   COPY_FIELD (internal, external, external_syment, n_type);
 321   COPY_FIELD (internal, external, external_syment, n_sclass);
 322   COPY_FIELD (internal, external, external_syment, n_numaux);
 323   return SUCCESS;
 324 }
 325
 326 /* Implement the API-defined ldgetname function.  */
 327
 328 char *
 329 ldgetname (LDFILE *ldfile, SYMENT *symbol)
 330 {
 331   char *name;
 332   size_t offset;
 333
 334   /* If the zeroes field is nonzero, the name is in the symbol table
 335      entry itself.  */
 336   if (symbol->n_zeroes != 0)
 337     return symbol->n_name;
 338
 339   /* Otherwise, the symbol table entry contains an offset into the
 340      string table, which starts after the end of the symbol table.  */
 341   offset = (HEADER (ldfile).f_symptr
 342             + HEADER (ldfile).f_nsyms * sizeof (struct external_syment)
 343             + symbol->n_offset);
 344   if (offset >= ldfile->object_size)
 345     return NULL;
 346
 347   /* Make sure that the name is entirely contained within the object.  */
 348   name = ldfile->object + offset;
 349   if (!string_within_bounds_p (name, ldfile->object_size - offset, '\0'))
 350     return NULL;
 351
 352   return name;
 353 }
 354
 355 /* Implement the API-defined ldclose function.  */
 356
 357 int
 358 ldclose (LDFILE *ldfile)
 359 {
 360   free_object (ldfile);
 361   if (ldfile->next_member >= 0
 362       && read_archive_member (ldfile, ldfile->next_member))
 363     return FAILURE;
 364
 365   free_ldfile (ldfile);
 366   return SUCCESS;
 367 }
 368
 369 #endif