1gelf(3ELF) ELF Library Functions gelf(3ELF)
2
6 gelf, gelf_checksum, gelf_fsize, gelf_getcap, gelf_getclass, gelf_get‐
7 dyn, gelf_getehdr, gelf_getmove, gelf_getphdr, gelf_getrel,
8 gelf_getrela, gelf_getshdr, gelf_getsym, gelf_getsyminfo, gelf_get‐
9 symshndx, gelf_newehdr, gelf_newphdr, gelf_update_cap, gelf_update_dyn,
10 gelf_update_ehdr, gelf_update_getmove, gelf_update_move,
11 gelf_update_phdr, gelf_update_rel, gelf_update_rela, gelf_update_shdr,
12 gelf_update_sym, gelf_update_symshndx, gelf_update_syminfo,
13 gelf_xlatetof, gelf_xlatetom - generic class-independent ELF interface
14
16 cc [ flag... ] file... −lelf [ library... ]
17 #include <gelf.h>
18 long gelf_checksum(Elf *elf);
20 size_t gelf_fsize(Elf *elf, Elf_Type type, size_t cnt, unsigned ver);
23 int gelf_getcap(Elf_Data *src, int ndx, GElf_Cap *dst);
26 int gelf_getclass(Elf *elf);
29 GElf_Dyn *gelf_getdyn(Elf_Data *src, int ndx, GElf_Dyn *dst);
32 GElf_Ehdr *gelf_getehdr(Elf *elf, GElf_Ehdr *dst);
35 GElf_Move *gelf_getmove(Elf_Data *src, int ndx, GElf_Move *dst);
38 GElf_Phdr *gelf_getphdr(Elf *elf, int ndx, GElf_Phdr *dst);
41 GElf_Rel *gelf_getrel(Elf_Data *src, int ndx, GElf_Rel *dst);
44 GElf_Rela *gelf_getrela(Elf_Data *src, int ndx, GElf_Rela *dst);
47 GElf_Shdr *gelf_getshdr(Elf_Scn *scn, GElf_Shdr *dst);
50 GElf_Sym *gelf_getsym(Elf_Data *src, int ndx, GElf_Sym *dst);
53 GElf_Syminfo *gelf_getsyminfo(Elf_Data *src, int ndx, GElf_Syminfo *dst);
56 GElf_Sym *gelf_getsymshndx(Elf_Data *symsrc, Elf_Data *shndxsrc,
59 int ndx, GElf_Sym *symdst, Elf32_Word *shndxdst);
60 unsigned long gelf_newehdr(Elf *elf, int class);
63 unsigned long gelf_newphdr(Elf *elf, size_t phnum);
66 int gelf_update_cap(Elf_Data *dst, int ndx, GElf_Cap *src);
69 int gelf_update_dyn(Elf_Data *dst, int ndx, GElf_Dyn *src);
72 int gelf_update_ehdr(Elf *elf, GElf_Ehdr *src);
75 int gelf_update_move(Elf_Data *dst, int ndx, GElf_Move *src);
78 int gelf_update_phdr(Elf *elf, int ndx, GElf_Phdr *src);
81 int gelf_update_rel(Elf_Data *dst, int ndx, GElf_Rel *src);
84 int gelf_update_rela(Elf_Data *dst, int ndx, GElf_Rela *src);
87 int gelf_update_shdr(Elf_Scn *dst, GElf_Shdr *src);
90 int gelf_update_sym(Elf_Data *dst, int ndx, GElf_Sym *src);
93 int gelf_update_syminfo(Elf_Data *dst, int ndx, GElf_Syminfo *src);
96 int gelf_update_symshndx(Elf_Data *symdst, Elf_Data *shndxdst, int ndx,
99 GElf_Sym *symsrc, Elf32_Word shndxsrc);
100 Elf_Data *gelf_xlatetof(Elf *elf, Elf_Data *dst, const Elf_Data *src,
103 unsigned encode);
104 Elf_Data *gelf_xlatetom(Elf *elf, Elf_Data *dst, const Elf_Data *src,
107 unsigned encode);
108
111 GElf is a generic, ELF class-independent API for manipulating ELF
112 object files. GElf provides a single, common interface for handling
113 32-bit and 64-bit ELF format object files. GElf is a translation layer
114 between the application and the class-dependent parts of the ELF
115 library. Thus, the application can use GElf, which in turn, will call
116 the corresponding elf32_ or elf64_ functions on behalf of the applica‐
117 tion. The data structures returned are all large enough to hold 32-bit
118 and 64-bit data.
119 GElf provides a simple, class-independent layer of indirection over the
122 class-dependent ELF32 and ELF64 API's. GElf is stateless, and may be
123 used along side the ELF32 and ELF64 API's.
124 GElf always returns a copy of the underlying ELF32 or ELF64 structure,
127 and therefore the programming practice of using the address of an ELF
128 header as the base offset for the ELF's mapping into memory should be
129 avoided. Also, data accessed by type-casting the Elf_Data buffer to a
130 class-dependent type and treating it like an array, for example, a sym‐
131 bol table, will not work under GElf, and the gelf_get functions must be
132 used instead. See the EXAMPLE section.
133 Programs that create or modify ELF files using libelf(3LIB) need to
136 perform an extra step when using GElf. Modifications to GElf values
137 must be explicitly flushed to the underlying ELF32 or ELF64 structures
138 by way of the gelf_update_ interfaces. Use of elf_update or elf_flagelf
139 and the like remains the same.
140 The sizes of versioning structures remain the same between ELF32 and
143 ELF64. The GElf API only defines types for versioning, rather than a
144 functional API. The processing of versioning information will stay the
145 same in the GElf environment as it was in the class-dependent ELF envi‐
146 ronment.
147 List of Functions
149 gelf_checksum() An analog to elf32_checksum(3ELF) and
150 elf64_checksum(3ELF).
151 gelf_fsize() An analog to elf32_fsize(3ELF) and
154 elf64_fsize(3ELF).
155 gelf_getcap() Retrieves the Elf32_Cap or Elf64_Cap informa‐
158 tion from the capability table at the given
159 index. dst points to the location where the
160 GElf_Cap capability entry is stored.
161 gelf_getclass() Returns one of the constants ELFCLASS32, ELF‐
164 CLASS64 or ELFCLASSNONE.
165 gelf_getdyn() Retrieves the Elf32_Dyn or Elf64_Dyn informa‐
168 tion from the dynamic table at the given
169 index. dst points to the location where the
170 GElf_Dyn dynamic entry is stored.
171 gelf_getehdr() An analog to elf32_getehdr(3ELF) and
174 elf64_getehdr(3ELF). dst points to the loca‐
175 tion where the GElf_Ehdr header is stored.
176 gelf_getmove() Retrieves the Elf32_Move or Elf64_Move infor‐
179 mation from the move table at the given
180 index. dst points to the location where the
181 GElf_Move move entry is stored.
182 gelf_getphdr() An analog toelf32_getphdr(3ELF) and
185 elf64_getphdr(3ELF). dst points to the loca‐
186 tion where the GElf_Phdr program header is
187 stored.
188 gelf_getrel() Retrieves the Elf32_Rel or Elf64_Rel informa‐
191 tion from the relocation table at the given
192 index. dst points to the location where the
193 GElf_Rel relocation entry is stored.
194 gelf_getrela() Retrieves the Elf32_Rela or Elf64_Rela infor‐
197 mation from the relocation table at the given
198 index. dst points to the location where the
199 GElf_Rela relocation entry is stored.
200 gelf_getshdr() An analog to elf32_getshdr(3ELF) and
203 elf64_getshdr(3ELF). dst points to the loca‐
204 tion where the GElf_Shdr section header is
205 stored.
206 gelf_getsym() Retrieves the Elf32_Sym or Elf64_Sym informa‐
209 tion from the symbol table at the given
210 index. dst points to the location where the
211 GElf_Sym symbol entry is stored.
212 gelf_getsyminfo() Retrieves the Elf32_Syminfo or Elf64_Syminfo
215 information from the relocation table at the
216 given index. dst points to the location where
217 the GElf_Syminfo symbol information entry is
218 stored.
219 gelf_getsymshndx() Provides an extension to gelf_getsym() that
222 retrieves the Elf32_Sym or Elf64_Sym informa‐
223 tion, and the section index from the symbol
224 table at the given index ndx.
225 The symbols section index is typically
227 recorded in the st_shndx field of the symbols
228 structure. However, a file that requires ELF
229 Extended Sections may record an st_shndx of
230 SHN_XINDEX indicating that the section index
231 must be obtained from an associated
232 SHT_SYMTAB_SHNDX section entry. If xshndx and
233 shndxdata are non-null, the value recorded at
234 index ndx of the SHT_SYMTAB_SHNDX table
235 pointed to by shndxdata is returned in xsh‐
236 ndx. See USAGE.
237 gelf_newehdr() An analog to elf32_newehdr(3ELF) and
240 elf64_newehdr(3ELF).
241 gelf_newphdr() An analog to elf32_newphdr(3ELF) and
244 elf64_newphdr(3ELF).
245 gelf_update_cap() Copies the GElf_Cap information back into the
248 underlying Elf32_Cap or Elf64_Cap structure
249 at the given index.
250 gelf_update_dyn() Copies the GElf_Dyn information back into the
253 underlying Elf32_Dyn or Elf64_Dyn structure
254 at the given index.
255 gelf_update_ehdr() Copies the contents of the GElf_Ehdr ELF
258 header to the underlying Elf32_Ehdr or
259 Elf64_Ehdr structure.
260 gelf_update_move() Copies the GElf_Move information back into
263 the underlying Elf32_Move or Elf64_Move
264 structure at the given index.
265 gelf_update_phdr() Copies of the contents of GElf_Phdr program
268 header to underlying the Elf32_Phdr or
269 Elf64_Phdr structure.
270 gelf_update_rel() Copies the GElf_Rel information back into the
273 underlying Elf32_Rel or Elf64_Rel structure
274 at the given index.
275 gelf_update_rela() Copies the GElf_Rela information back into
278 the underlying Elf32_Rela or Elf64_Rela
279 structure at the given index.
280 gelf_update_shdr() Copies of the contents of GElf_Shdr section
283 header to underlying the Elf32_Shdr or
284 Elf64_Shdr structure.
285 gelf_update_sym() Copies the GElf_Sym information back into the
288 underlying Elf32_Sym or Elf64_Sym structure
289 at the given index.
290 gelf_update_syminfo() Copies the GElf_Syminfo information back into
293 the underlying Elf32_Syminfo or Elf64_Syminfo
294 structure at the given index.
295 gelf_update_symshndx() Provides an extension to gelf_update_sym()
298 that copies the GElf_Sym information back
299 into the Elf32_Sym or Elf64_Sym structure at
300 the given index ndx, and copies the extended
301 xshndx section index into the Elf32_Word at
302 the given index ndx in the buffer described
303 by shndxdata. See USAGE.
304 gelf_xlatetof() An analog to elf32_xlatetof(3ELF) and
307 elf64_xlatetof(3ELF)
308 gelf_xlatetom() An analog to elf32_xlatetom(3ELF) and
311 elf64_xlatetom(3ELF)
312
315 Upon failure, all GElf functions return 0 and set elf_errno. See
316 elf_errno(3ELF)
317
319 Example 1 Printing the ELF Symbol Table
320 #include <stdio.h>
322 #include <sys/types.h>
323 #include <sys/stat.h>
324 #include <fcntl.h>
325 #include <libelf.h>
326 #include <gelf.h>
327 void
329 main(int argc, char **argv)
330 {
331 Elf *elf;
332 Elf_Scn *scn = NULL;
333 GElf_Shdr shdr;
334 Elf_Data *data;
335 int fd, ii, count;
336 elf_version(EV_CURRENT);
338 fd = open(argv[1], O_RDONLY);
340 elf = elf_begin(fd, ELF_C_READ, NULL);
341 while ((scn = elf_nextscn(elf, scn)) != NULL) {
343 gelf_getshdr(scn, &shdr);
344 if (shdr.sh_type == SHT_SYMTAB) {
345 /* found a symbol table, go print it. */
346 break;
347 }
348 }
349 data = elf_getdata(scn, NULL);
351 count = shdr.sh_size / shdr.sh_entsize;
352 /* print the symbol names */
354 for (ii = 0; ii < count; ++ii) {
355 GElf_Sym sym;
356 gelf_getsym(data, ii, &sym);
357 printf("%s\n", elf_strptr(elf, shdr.sh_link, sym.st_name));
358 }
359 elf_end(elf);
360 close(fd);
361 }
362
365 ELF Extended Sections are employed to allow an ELF file to contain more
366 than 0xff00 (SHN_LORESERVE) section. See the Linker and Libraries Guide
367 for more information.
368
370 /lib/libelf.so.1 shared object
371 /lib/64/libelf.so.1 64-bit shared object
374
377 See attributes(5) for descriptions of the following attributes:
378 ┌─────────────────────────────┬─────────────────────────────┐
383 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
384 ├─────────────────────────────┼─────────────────────────────┤
385 │Interface Stability │Stable │
386 ├─────────────────────────────┼─────────────────────────────┤
387 │MT Level │MT-Safe │
388 └─────────────────────────────┴─────────────────────────────┘
389
391 elf(3ELF), elf32_checksum(3ELF), elf32_fsize(3ELF), elf32_gete‐
392 hdr(3ELF), elf32_newehdr(3ELF), elf32_getphdr(3ELF), elf32_new‐
393 phdr(3ELF), elf32_getshdr(3ELF), elf32_xlatetof(3ELF), elf32_xlate‐
394 tom(3ELF), elf_errno(3ELF), libelf(3LIB), attributes(5)
395 Linker and Libraries Guide
398SunOS 5.11 8 June 2004 gelf(3ELF)