diff options
Diffstat (limited to 'ld')
| -rw-r--r-- | ld/emultempl/elf32.em | 178 | ||||
| -rw-r--r-- | ld/ld.texinfo | 26 |
2 files changed, 188 insertions, 16 deletions
diff --git a/ld/emultempl/elf32.em b/ld/emultempl/elf32.em index 2a92f58..ee34e3f 100644 --- a/ld/emultempl/elf32.em +++ b/ld/emultempl/elf32.em @@ -41,6 +41,9 @@ cat >e${EMULATION_NAME}.c <<EOF #include "libiberty.h" #include "safe-ctype.h" #include "getopt.h" +#include "md5.h" +#include "sha1.h" +#include <fcntl.h> #include "bfdlink.h" @@ -859,6 +862,169 @@ EOF if test x"$LDEMUL_AFTER_OPEN" != xgld"$EMULATION_NAME"_after_open; then cat >>e${EMULATION_NAME}.c <<EOF +static bfd_size_type +gld${EMULATION_NAME}_id_note_section_size (bfd *abfd, + struct bfd_link_info *link_info) +{ + const char *style = link_info->emit_note_gnu_build_id; + bfd_size_type size; + + abfd = abfd; + + size = offsetof (Elf_External_Note, name[sizeof "GNU"]); + size = (size + 3) & -(bfd_size_type) 4; + + if (!strcmp (style, "md5") || !strcmp (style, "uuid")) + size += 128 / 8; + else if (!strcmp (style, "sha1")) + size += 160 / 8; + else if (!strncmp (style, "0x", 2)) + { + /* ID is in string form (hex). Convert to bits. */ + const char *id = style + 2; + do + { + if (ISXDIGIT (id[0]) && ISXDIGIT (id[1])) + { + ++size; + id += 2; + } + else if (*id == '-' || *id == ':') + ++id; + else + { + size = 0; + break; + } + } while (*id != '\0'); + } + else + size = 0; + + return size; +} + +static unsigned char +read_hex (const char xdigit) +{ + if (ISDIGIT (xdigit)) + return xdigit - '0'; + if (ISUPPER (xdigit)) + return xdigit - 'A' + 0xa; + if (ISLOWER (xdigit)) + return xdigit - 'a' + 0xa; + abort (); + return 0; +} + +struct build_id_info +{ + const char *style; + asection *sec; +}; + +static bfd_boolean +gld${EMULATION_NAME}_write_build_id_section (bfd *abfd) +{ + const struct elf_backend_data *bed = get_elf_backend_data (abfd); + struct build_id_info *info = + elf_tdata (abfd)->after_write_object_contents_info; + asection *asec; + Elf_Internal_Shdr *i_shdr; + unsigned char *contents, *id_bits; + bfd_size_type size; + Elf_External_Note *e_note; + + asec = info->sec; + if (asec->output_section == NULL) + { + einfo (_("%P: .note.gnu.build-id section missing")); + return FALSE; + } + i_shdr = &elf_section_data (asec->output_section)->this_hdr; + + if (i_shdr->contents == NULL) + { + ASSERT (asec->output_offset == 0); + i_shdr->contents = xcalloc (i_shdr->sh_size, 1); + if (i_shdr->contents == NULL) + return FALSE; + } + contents = i_shdr->contents + asec->output_offset; + + e_note = (void *) contents; + size = offsetof (Elf_External_Note, name[sizeof "GNU"]); + size = (size + 3) & -(bfd_size_type) 4; + id_bits = contents + size; + size = asec->size - size; + + bfd_h_put_32 (abfd, sizeof "GNU", &e_note->namesz); + bfd_h_put_32 (abfd, size, &e_note->descsz); + bfd_h_put_32 (abfd, NT_GNU_BUILD_ID, &e_note->type); + memcpy (e_note->name, "GNU", sizeof "GNU"); + + if (!strcmp (info->style, "md5")) + { + struct md5_ctx ctx; + md5_init_ctx (&ctx); + if (bed->s->checksum_contents (abfd, + (void (*) (const void *, size_t, void *)) + &md5_process_bytes, + &ctx)) + md5_finish_ctx (&ctx, id_bits); + else + return FALSE; + } + else if (!strcmp (info->style, "sha1")) + { + struct sha1_ctx ctx; + sha1_init_ctx (&ctx); + if (bed->s->checksum_contents (abfd, + (void (*) (const void *, size_t, void *)) + &sha1_process_bytes, + &ctx)) + sha1_finish_ctx (&ctx, id_bits); + else + return FALSE; + } + else if (!strcmp (info->style, "uuid")) + { + int n; + int fd = open ("/dev/urandom", O_RDONLY); + if (fd < 0) + return FALSE; + n = read (fd, id_bits, size); + close (fd); + if (n < (int) size) + return FALSE; + } + else if (!strncmp (info->style, "0x", 2)) + { + /* ID is in string form (hex). Convert to bits. */ + const char *id = info->style + 2; + size_t n = 0; + do + { + if (ISXDIGIT (id[0]) && ISXDIGIT (id[1])) + { + id_bits[n] = read_hex (*id++) << 4; + id_bits[n++] |= read_hex (*id++); + } + else if (*id == '-' || *id == ':') + ++id; + else + abort (); /* Should have been validated earlier. */ + } while (*id != '\0'); + } + else + abort (); /* Should have been validated earlier. */ + + size = i_shdr->sh_size; + return (bfd_seek (abfd, i_shdr->sh_offset, SEEK_SET) == 0 + && bfd_bwrite (i_shdr->contents, size, abfd) == size); +} + + /* This is called after all the input files have been opened. */ static void @@ -874,7 +1040,7 @@ gld${EMULATION_NAME}_after_open (void) abfd = link_info.input_bfds; - size = _bfd_id_note_section_size (abfd, &link_info); + size = gld${EMULATION_NAME}_id_note_section_size (abfd, &link_info); if (size == 0) { einfo ("%P: warning: unrecognized --build-id style ignored.\n"); @@ -890,10 +1056,14 @@ gld${EMULATION_NAME}_after_open (void) if (s != NULL && bfd_set_section_alignment (abfd, s, 2)) { struct elf_obj_tdata *t = elf_tdata (output_bfd); - t->emit_note_gnu_build_id = link_info.emit_note_gnu_build_id; - t->note_gnu_build_id_sec = s; + struct build_id_info *b = xmalloc (sizeof *b); + b->style = link_info.emit_note_gnu_build_id; + b->sec = s; elf_section_type (s) = SHT_NOTE; s->size = size; + t->after_write_object_contents + = &gld${EMULATION_NAME}_write_build_id_section; + t->after_write_object_contents_info = b; } else { @@ -1839,7 +2009,7 @@ cat >>e${EMULATION_NAME}.c <<EOF memcpy (*longopts + nl, &xtra_long, sizeof (xtra_long)); } -#define DEFAULT_BUILD_ID_STYLE "md5" +#define DEFAULT_BUILD_ID_STYLE "sha1" static bfd_boolean gld${EMULATION_NAME}_handle_option (int optc) diff --git a/ld/ld.texinfo b/ld/ld.texinfo index 9bc1afa..aca0162 100644 --- a/ld/ld.texinfo +++ b/ld/ld.texinfo @@ -1973,18 +1973,20 @@ enable other tradeoffs in future versions of the linker. Request creation of @code{.note.gnu.build-id} ELF note section. The contents of the note are unique bits identifying this linked file. @var{style} can be @code{uuid} to use 128 random bits, -@code{md5} to use a 128-bit @sc{MD5} hash on the normative parts -of the output contents, or @code{0x@var{hexstring}} to use a -chosen bit string specified as an even number of hexadecimal -digits (@code{-} and @code{:} characters between digit pairs are -ignored). If @var{style} is omitted, @code{md5} is used. - -The @code{md5} style produces an identifier that is always the -same in an identical output file, but will be unique among all -nonidentical output files. It is not intended to be compared as -a checksum for the file's contents. A linked file may be -changed later by other tools, but the build ID bit string -identifying the original linked file does not change. +@code{sha1} to use a 160-bit @sc{SHA1} hash on the normative +parts of the output contents, @code{md5} to use a 128-bit +@sc{MD5} hash on the normative parts of the output contents, or +@code{0x@var{hexstring}} to use a chosen bit string specified as +an even number of hexadecimal digits (@code{-} and @code{:} +characters between digit pairs are ignored). If @var{style} is +omitted, @code{sha1} is used. + +The @code{md5} and @code{sha1} styles produces an identifier +that is always the same in an identical output file, but will be +unique among all nonidentical output files. It is not intended +to be compared as a checksum for the file's contents. A linked +file may be changed later by other tools, but the build ID bit +string identifying the original linked file does not change. Passing @code{none} for @var{style} disables the setting from any @code{--build-id} options earlier on the command line. |