1 /* Functions to handle creation of Linux archives. 2 Copyright (C) 2007 Red Hat, Inc. 3 Written by Ulrich Drepper <drepper (at) redhat.com>, 2007. 4 5 Red Hat elfutils is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by the 7 Free Software Foundation; version 2 of the License. 8 9 Red Hat elfutils is distributed in the hope that it will be useful, but 10 WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 General Public License for more details. 13 14 You should have received a copy of the GNU General Public License along 15 with Red Hat elfutils; if not, write to the Free Software Foundation, 16 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. 17 18 Red Hat elfutils is an included package of the Open Invention Network. 19 An included package of the Open Invention Network is a package for which 20 Open Invention Network licensees cross-license their patents. No patent 21 license is granted, either expressly or impliedly, by designation as an 22 included package. Should you wish to participate in the Open Invention 23 Network licensing program, please visit www.openinventionnetwork.com 24 <http://www.openinventionnetwork.com>. */ 25 26 #ifdef HAVE_CONFIG_H 27 # include <config.h> 28 #endif 29 30 #include <assert.h> 31 #include <error.h> 32 #include <gelf.h> 33 #include <libintl.h> 34 #include <stdio.h> 35 #include <stdlib.h> 36 #include <time.h> 37 38 #include <system.h> 39 40 #include "arlib.h" 41 42 43 /* The one symbol table we hanble. */ 44 struct arlib_symtab symtab; 45 46 47 /* Initialize ARLIB_SYMTAB structure. */ 48 void 49 arlib_init (void) 50 { 51 #define obstack_chunk_alloc xmalloc 52 #define obstack_chunk_free free 53 obstack_init (&symtab.symsoffob); 54 obstack_init (&symtab.symsnameob); 55 obstack_init (&symtab.longnamesob); 56 57 /* We add the archive header here as well, that avoids allocating 58 another memory block. */ 59 struct ar_hdr ar_hdr; 60 memcpy (ar_hdr.ar_name, "/ ", sizeof (ar_hdr.ar_name)); 61 /* Using snprintf here has a problem: the call always wants to add a 62 NUL byte. We could use a trick whereby we specify the target 63 buffer size longer than it is and this would not actually fail, 64 since all the fields are consecutive and we fill them in in 65 sequence (i.e., the NUL byte gets overwritten). But 66 _FORTIFY_SOURCE=2 would not let us play these games. Therefore 67 we play it safe. */ 68 char tmpbuf[sizeof (ar_hdr.ar_date) + 1]; 69 memcpy (ar_hdr.ar_date, tmpbuf, 70 snprintf (tmpbuf, sizeof (tmpbuf), "%-*lld", 71 (int) sizeof (ar_hdr.ar_date), 72 (long long int) time (NULL))); 73 assert ((sizeof (struct ar_hdr) % sizeof (uint32_t)) == 0); 74 75 /* Note the string for the ar_uid and ar_gid cases is longer than 76 necessary. This does not matter since we copy only as much as 77 necessary but it helps the compiler to use the same string for 78 the ar_mode case. */ 79 memcpy (ar_hdr.ar_uid, "0 ", sizeof (ar_hdr.ar_uid)); 80 memcpy (ar_hdr.ar_gid, "0 ", sizeof (ar_hdr.ar_gid)); 81 memcpy (ar_hdr.ar_mode, "0 ", sizeof (ar_hdr.ar_mode)); 82 memcpy (ar_hdr.ar_fmag, ARFMAG, sizeof (ar_hdr.ar_fmag)); 83 84 /* Add the archive header to the file content. */ 85 obstack_grow (&symtab.symsoffob, &ar_hdr, sizeof (ar_hdr)); 86 87 /* The first word in the offset table specifies the size. Create 88 such an entry now. The real value will be filled-in later. For 89 all supported platforms the following is true. */ 90 assert (sizeof (uint32_t) == sizeof (int)); 91 obstack_int_grow (&symtab.symsoffob, 0); 92 93 /* The long name obstack also gets its archive header. As above, 94 some of the input strings are longer than required but we only 95 copy the necessary part. */ 96 memcpy (ar_hdr.ar_name, "// ", sizeof (ar_hdr.ar_name)); 97 memcpy (ar_hdr.ar_date, " ", sizeof (ar_hdr.ar_date)); 98 memcpy (ar_hdr.ar_uid, " ", sizeof (ar_hdr.ar_uid)); 99 memcpy (ar_hdr.ar_gid, " ", sizeof (ar_hdr.ar_gid)); 100 memcpy (ar_hdr.ar_mode, " ", sizeof (ar_hdr.ar_mode)); 101 /* The ar_size field will be filled in later and ar_fmag is already OK. */ 102 obstack_grow (&symtab.longnamesob, &ar_hdr, sizeof (ar_hdr)); 103 104 /* All other members are zero. */ 105 symtab.symsofflen = 0; 106 symtab.symsoff = NULL; 107 symtab.symsnamelen = 0; 108 symtab.symsname = NULL; 109 } 110 111 112 /* Finalize ARLIB_SYMTAB content. */ 113 void 114 arlib_finalize (void) 115 { 116 char tmpbuf[sizeof (((struct ar_hdr *) NULL)->ar_size) + 1]; 117 118 symtab.longnameslen = obstack_object_size (&symtab.longnamesob); 119 if (symtab.longnameslen != sizeof (struct ar_hdr)) 120 { 121 if ((symtab.longnameslen & 1) != 0) 122 { 123 /* Add one more byte to make length even. */ 124 obstack_grow (&symtab.longnamesob, "\n", 1); 125 ++symtab.longnameslen; 126 } 127 128 symtab.longnames = obstack_finish (&symtab.longnamesob); 129 130 memcpy (&((struct ar_hdr *) symtab.longnames)->ar_size, tmpbuf, 131 snprintf (tmpbuf, sizeof (tmpbuf), "%-*zu", 132 (int) sizeof (((struct ar_hdr *) NULL)->ar_size), 133 symtab.longnameslen - sizeof (struct ar_hdr))); 134 } 135 136 symtab.symsofflen = obstack_object_size (&symtab.symsoffob); 137 assert (symtab.symsofflen % sizeof (uint32_t) == 0); 138 if (symtab.symsofflen != 0) 139 { 140 symtab.symsoff = (uint32_t *) obstack_finish (&symtab.symsoffob); 141 142 /* Fill in the number of offsets now. */ 143 symtab.symsoff[AR_HDR_WORDS] = le_bswap_32 ((symtab.symsofflen 144 - sizeof (struct ar_hdr)) 145 / sizeof (uint32_t) - 1); 146 } 147 148 symtab.symsnamelen = obstack_object_size (&symtab.symsnameob); 149 if ((symtab.symsnamelen & 1) != 0) 150 { 151 /* Add one more NUL byte to make length even. */ 152 obstack_grow (&symtab.symsnameob, "", 1); 153 ++symtab.symsnamelen; 154 } 155 symtab.symsname = obstack_finish (&symtab.symsnameob); 156 157 /* Determine correction for the offsets in the symbol table. */ 158 off_t disp = 0; 159 if (symtab.symsnamelen > 0) 160 disp = symtab.symsofflen + symtab.symsnamelen; 161 if (symtab.longnameslen > sizeof (struct ar_hdr)) 162 disp += symtab.longnameslen; 163 164 if (disp != 0 && symtab.symsoff != NULL) 165 { 166 uint32_t nsyms = le_bswap_32 (symtab.symsoff[AR_HDR_WORDS]); 167 168 for (uint32_t cnt = 1; cnt <= nsyms; ++cnt) 169 { 170 uint32_t val = le_bswap_32 (symtab.symsoff[AR_HDR_WORDS + cnt]); 171 val += disp; 172 symtab.symsoff[AR_HDR_WORDS + cnt] = le_bswap_32 (val); 173 } 174 } 175 176 /* See comment for ar_date above. */ 177 memcpy (&((struct ar_hdr *) symtab.symsoff)->ar_size, tmpbuf, 178 snprintf (tmpbuf, sizeof (tmpbuf), "%-*zu", 179 (int) sizeof (((struct ar_hdr *) NULL)->ar_size), 180 symtab.symsofflen + symtab.symsnamelen 181 - sizeof (struct ar_hdr))); 182 } 183 184 185 /* Free resources for ARLIB_SYMTAB. */ 186 void 187 arlib_fini (void) 188 { 189 obstack_free (&symtab.symsoffob, NULL); 190 obstack_free (&symtab.symsnameob, NULL); 191 obstack_free (&symtab.longnamesob, NULL); 192 } 193 194 195 /* Add name a file offset of a symbol. */ 196 void 197 arlib_add_symref (const char *symname, off_t symoff) 198 { 199 /* For all supported platforms the following is true. */ 200 assert (sizeof (uint32_t) == sizeof (int)); 201 obstack_int_grow (&symtab.symsoffob, (int) le_bswap_32 (symoff)); 202 203 size_t symname_len = strlen (symname) + 1; 204 obstack_grow (&symtab.symsnameob, symname, symname_len); 205 } 206 207 208 /* Add symbols from ELF with value OFFSET to the symbol table SYMTAB. */ 209 void 210 arlib_add_symbols (Elf *elf, const char *arfname, const char *membername, 211 off_t off) 212 { 213 if (sizeof (off) > sizeof (uint32_t) && off > ~((uint32_t) 0)) 214 /* The archive is too big. */ 215 error (EXIT_FAILURE, 0, gettext ("the archive '%s' is too large"), 216 arfname); 217 218 /* We only add symbol tables for ELF files. It makes not much sense 219 to add symbols from executables but we do so for compatibility. 220 For DSOs and executables we use the dynamic symbol table, for 221 relocatable files all the DT_SYMTAB tables. */ 222 if (elf_kind (elf) != ELF_K_ELF) 223 return; 224 225 GElf_Ehdr ehdr_mem; 226 GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem); 227 if (ehdr == NULL) 228 error (EXIT_FAILURE, 0, gettext ("cannot read ELF header of %s(%s): %s"), 229 arfname, membername, elf_errmsg (-1)); 230 231 GElf_Word symtype; 232 if (ehdr->e_type == ET_REL) 233 symtype = SHT_SYMTAB; 234 else if (ehdr->e_type == ET_EXEC || ehdr->e_type == ET_DYN) 235 symtype = SHT_DYNSYM; 236 else 237 /* We do not handle that type. */ 238 return; 239 240 /* Iterate over all sections. */ 241 Elf_Scn *scn = NULL; 242 while ((scn = elf_nextscn (elf, scn)) != NULL) 243 { 244 /* Get the section header. */ 245 GElf_Shdr shdr_mem; 246 GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); 247 if (shdr == NULL) 248 continue; 249 250 if (shdr->sh_type != symtype) 251 continue; 252 253 Elf_Data *data = elf_getdata (scn, NULL); 254 if (data == NULL) 255 continue; 256 257 int nsyms = shdr->sh_size / shdr->sh_entsize; 258 for (int ndx = shdr->sh_info; ndx < nsyms; ++ndx) 259 { 260 GElf_Sym sym_mem; 261 GElf_Sym *sym = gelf_getsym (data, ndx, &sym_mem); 262 if (sym == NULL) 263 continue; 264 265 /* Ignore undefined symbols. */ 266 if (sym->st_shndx == SHN_UNDEF) 267 continue; 268 269 /* Use this symbol. */ 270 const char *symname = elf_strptr (elf, shdr->sh_link, sym->st_name); 271 if (symname != NULL) 272 arlib_add_symref (symname, off); 273 } 274 275 /* Only relocatable files can have more than one symbol table. */ 276 if (ehdr->e_type != ET_REL) 277 break; 278 } 279 } 280
