1 /* Create new section in output file. 2 Copyright (C) 2002-2011 Red Hat, Inc. 3 This file is part of elfutils. 4 Written by Ulrich Drepper <drepper (at) redhat.com>, 2002. 5 6 This file is free software; you can redistribute it and/or modify 7 it under the terms of either 8 9 * the GNU Lesser General Public License as published by the Free 10 Software Foundation; either version 3 of the License, or (at 11 your option) any later version 12 13 or 14 15 * the GNU General Public License as published by the Free 16 Software Foundation; either version 2 of the License, or (at 17 your option) any later version 18 19 or both in parallel, as here. 20 21 elfutils is distributed in the hope that it will be useful, but 22 WITHOUT ANY WARRANTY; without even the implied warranty of 23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 24 General Public License for more details. 25 26 You should have received copies of the GNU General Public License and 27 the GNU Lesser General Public License along with this program. If 28 not, see <http://www.gnu.org/licenses/>. */ 29 30 #ifdef HAVE_CONFIG_H 31 # include <config.h> 32 #endif 33 34 #include <assert.h> 35 #include <error.h> 36 #include <libintl.h> 37 #include <stdlib.h> 38 #include <string.h> 39 40 #include <libasmP.h> 41 #include <libelf.h> 42 #include <system.h> 43 44 45 /* Memory for the default pattern. The type uses a flexible array 46 which does work well with a static initializer. So we play some 47 dirty tricks here. */ 48 static const struct 49 { 50 struct FillPattern pattern; 51 char zero; 52 } xdefault_pattern = 53 { 54 .pattern = 55 { 56 .len = 1 57 }, 58 .zero = '\0' 59 }; 60 const struct FillPattern *__libasm_default_pattern = &xdefault_pattern.pattern; 61 62 63 static AsmScn_t * 64 text_newscn (AsmScn_t *result, GElf_Word type, GElf_Xword flags) 65 { 66 /* Buffer where we construct the flag string. */ 67 char flagstr[sizeof (GElf_Xword) * 8 + 5]; 68 char *wp = flagstr; 69 const char *typestr = ""; 70 71 /* Only write out the flag string if this is the first time the 72 section is selected. Some assemblers cannot cope with the 73 .section pseudo-op otherwise. */ 74 wp = stpcpy (wp, ", \""); 75 76 if (flags & SHF_WRITE) 77 *wp++ = 'w'; 78 if (flags & SHF_ALLOC) 79 *wp++ = 'a'; 80 if (flags & SHF_EXECINSTR) 81 *wp++ = 'x'; 82 if (flags & SHF_MERGE) 83 *wp++ = 'M'; 84 if (flags & SHF_STRINGS) 85 *wp++ = 'S'; 86 if (flags & SHF_LINK_ORDER) 87 *wp++ = 'L'; 88 89 *wp++ = '"'; 90 91 if (type == SHT_PROGBITS) 92 typestr = ",@progbits"; 93 else if (type == SHT_NOBITS) 94 typestr = ",@nobits"; 95 96 /* Terminate the string. */ 97 *wp = '\0'; 98 99 fprintf (result->ctx->out.file, "\t.section \"%s\"%s%s\n", 100 result->name, flagstr, typestr); 101 102 return result; 103 } 104 105 106 static AsmScn_t * 107 binary_newscn (AsmScn_t *result, GElf_Word type, GElf_Xword flags, 108 size_t scnname_len) 109 { 110 GElf_Shdr shdr_mem; 111 GElf_Shdr *shdr; 112 Elf_Scn *scn; 113 114 /* The initial subsection has the number zero. */ 115 result->subsection_id = 0; 116 117 /* We start at offset zero. */ 118 result->offset = 0; 119 /* And generic alignment. */ 120 result->max_align = 1; 121 122 /* No output yet. */ 123 result->content = NULL; 124 125 /* Put the default fill pattern in place. */ 126 result->pattern = (struct FillPattern *) __libasm_default_pattern; 127 128 /* There are no subsections so far. */ 129 result->subnext = NULL; 130 131 /* Add the name to the section header string table. */ 132 result->data.main.strent = ebl_strtabadd (result->ctx->section_strtab, 133 result->name, scnname_len); 134 assert (result->data.main.strent != NULL); 135 136 /* Create the new ELF section. */ 137 result->data.main.scn = scn = elf_newscn (result->ctx->out.elf); 138 if (scn == NULL) 139 { 140 free (result); 141 __libasm_seterrno (ASM_E_LIBELF); 142 return NULL; 143 } 144 145 /* Not part of a section group (yet). */ 146 result->data.main.next_in_group = NULL; 147 148 /* Remember the flags. */ 149 shdr = gelf_getshdr (scn, &shdr_mem); 150 151 shdr->sh_flags = flags; 152 result->type = shdr->sh_type = type; 153 154 (void) gelf_update_shdr (scn, shdr); 155 156 return result; 157 } 158 159 160 AsmScn_t * 161 asm_newscn (AsmCtx_t *ctx, const char *scnname, GElf_Word type, 162 GElf_Xword flags) 163 { 164 size_t scnname_len = strlen (scnname) + 1; 165 AsmScn_t *result; 166 167 /* If no context is given there might be an earlier error. */ 168 if (ctx == NULL) 169 return NULL; 170 171 /* Check whether only flags are set which areselectable by the user. */ 172 if (unlikely ((flags & ~(SHF_WRITE | SHF_ALLOC | SHF_EXECINSTR | SHF_MERGE 173 | SHF_STRINGS | SHF_LINK_ORDER)) != 0) 174 /* We allow only two section types: data and data without file 175 representation. */ 176 || (type != SHT_PROGBITS && unlikely (type != SHT_NOBITS))) 177 { 178 __libasm_seterrno (ASM_E_INVALID); 179 return NULL; 180 } 181 182 rwlock_wrlock (ctx->lock); 183 184 /* This is a new section. */ 185 result = (AsmScn_t *) malloc (sizeof (AsmScn_t) + scnname_len); 186 if (result != NULL) 187 { 188 /* Add the name. */ 189 memcpy (result->name, scnname, scnname_len); 190 191 /* Add the reference to the context. */ 192 result->ctx = ctx; 193 194 /* Perform operations according to output mode. */ 195 result = (unlikely (ctx->textp) 196 ? text_newscn (result, type, flags) 197 : binary_newscn (result, type, flags, scnname_len)); 198 199 /* If everything went well finally add the new section to the hash 200 table. */ 201 if (result != NULL) 202 { 203 result->allnext = ctx->section_list; 204 ctx->section_list = result; 205 } 206 } 207 208 rwlock_unlock (ctx->lock); 209 210 return result; 211 } 212 INTDEF(asm_newscn) 213
