315 lines
7.4 KiB
C
315 lines
7.4 KiB
C
/* Copyright 2013-2020 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <stdarg.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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typedef struct
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{
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unsigned char e_ident[16];
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uint16_t e_type;
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uint16_t e_machine;
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uint32_t e_version;
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uint32_t e_entry;
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uint32_t e_phoff;
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uint32_t e_shoff;
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uint32_t e_flags;
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uint16_t e_ehsize;
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uint16_t e_phentsize;
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uint16_t e_phnum;
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uint16_t e_shentsize;
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uint16_t e_shnum;
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uint16_t e_shstrndx;
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} Elf32_Ehdr;
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typedef struct
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{
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unsigned char e_ident[16];
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uint16_t e_type;
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uint16_t e_machine;
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uint32_t e_version;
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uint64_t e_entry;
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uint64_t e_phoff;
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uint64_t e_shoff;
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uint32_t e_flags;
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uint16_t e_ehsize;
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uint16_t e_phentsize;
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uint16_t e_phnum;
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uint16_t e_shentsize;
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uint16_t e_shnum;
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uint16_t e_shstrndx;
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} Elf64_Ehdr;
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typedef struct
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{
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uint32_t p_type;
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uint32_t p_offset;
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uint32_t p_vaddr;
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uint32_t p_paddr;
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uint32_t p_filesz;
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uint32_t p_memsz;
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uint32_t p_flags;
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uint32_t p_align;
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} Elf32_Phdr;
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typedef struct
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{
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uint32_t p_type;
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uint32_t p_flags;
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uint64_t p_offset;
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uint64_t p_vaddr;
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uint64_t p_paddr;
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uint64_t p_filesz;
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uint64_t p_memsz;
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uint64_t p_align;
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} Elf64_Phdr;
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struct elfbuf
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{
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const char *path;
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unsigned char *buf;
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size_t len;
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enum { ELFCLASS32 = 1,
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ELFCLASS64 = 2 } ei_class;
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};
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#define ELFBUF_EHDR_LEN(elf) \
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((elf)->ei_class == ELFCLASS32 ? sizeof (Elf32_Ehdr) : \
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sizeof (Elf64_Ehdr))
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#define ELFBUF_EHDR(elf, memb) \
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((elf)->ei_class == ELFCLASS32 ? \
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((Elf32_Ehdr *) (elf)->buf)->memb \
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: ((Elf64_Ehdr *) (elf)->buf)->memb)
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#define ELFBUF_PHDR_LEN(elf) \
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((elf)->ei_class == ELFCLASS32 ? sizeof (Elf32_Phdr) : \
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sizeof (Elf64_Phdr))
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#define ELFBUF_PHDR(elf, idx, memb) \
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((elf)->ei_class == ELFCLASS32 ? \
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((Elf32_Phdr *) &(elf)->buf[((Elf32_Ehdr *)(elf)->buf) \
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->e_phoff])[idx].memb \
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: ((Elf64_Phdr *) &(elf)->buf[((Elf64_Ehdr *)(elf)->buf) \
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->e_phoff])[idx].memb)
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static void
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exit_with_msg(const char *fmt, ...)
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{
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va_list ap;
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fflush (stdout);
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va_start (ap, fmt);
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vfprintf (stderr, fmt, ap);
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va_end (ap);
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if (errno)
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{
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fputs (": ", stderr);
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perror (NULL);
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}
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else
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fputc ('\n', stderr);
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exit (1);
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}
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static void
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read_file (unsigned char **buf_ptr, size_t *len_ptr, FILE *fp)
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{
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size_t len = 0;
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size_t size = 1024;
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size_t chunk;
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unsigned char *buf = malloc (size);
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while ((chunk = fread (buf + len, 1, size - len, fp)) == size - len)
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{
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len = size;
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size *= 2;
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buf = realloc (buf, size);
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}
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len += chunk;
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*buf_ptr = buf;
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*len_ptr = len;
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}
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static void
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write_file (unsigned char *buf, size_t len, FILE *fp)
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{
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fwrite (buf, 1, len, fp);
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}
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static void
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elfbuf_init_from_file (struct elfbuf *elf, const char *path)
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{
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FILE *fp = fopen (path, "rb");
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unsigned char *buf;
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size_t len;
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if (fp == NULL)
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exit_with_msg ("%s", path);
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read_file (&buf, &len, fp);
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fclose (fp);
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/* Validate ELF identification. */
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if (len < 16
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|| buf[0] != 0x7f || buf[1] != 0x45 || buf[2] != 0x4c || buf[3] != 0x46
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|| buf[4] < 1 || buf[4] > 2 || buf[5] < 1 || buf[5] > 2)
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exit_with_msg ("%s: unsupported or invalid ELF file", path);
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elf->path = path;
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elf->buf = buf;
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elf->len = len;
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elf->ei_class = buf[4];
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if (ELFBUF_EHDR_LEN (elf) > len
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|| ELFBUF_EHDR (elf, e_phoff) > len
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|| ELFBUF_EHDR (elf, e_phnum) > ((len - ELFBUF_EHDR (elf, e_phoff))
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/ ELFBUF_PHDR_LEN (elf)) )
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exit_with_msg ("%s: unexpected end of data", path);
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if (ELFBUF_EHDR (elf, e_phentsize) != ELFBUF_PHDR_LEN (elf))
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exit_with_msg ("%s: inconsistent ELF header", path);
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}
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static void
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elfbuf_write_to_file (struct elfbuf *elf, const char *path)
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{
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FILE *fp = fopen (path, "wb");
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if (fp == NULL)
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exit_with_msg ("%s", path);
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write_file (elf->buf, elf->len, fp);
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fclose (fp);
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}
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/* In the auxv note starting at OFFSET with size LEN, mask the hwcap
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field using the HWCAP_MASK. */
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static void
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elfbuf_handle_auxv (struct elfbuf *elf, size_t offset, size_t len,
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unsigned long hwcap_mask)
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{
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size_t i;
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uint32_t *auxv32 = (uint32_t *) (elf->buf + offset);
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uint64_t *auxv64 = (uint64_t *) auxv32;
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size_t entry_size = elf->ei_class == ELFCLASS32 ?
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sizeof (auxv32[0]) : sizeof (auxv64[0]);
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for (i = 0; i < len / entry_size; i++)
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{
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uint64_t auxv_type = elf->ei_class == ELFCLASS32 ?
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auxv32[2 * i] : auxv64[2 * i];
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if (auxv_type == 0)
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break;
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if (auxv_type != 16)
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continue;
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if (elf->ei_class == ELFCLASS32)
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auxv32[2 * i + 1] &= (uint32_t) hwcap_mask;
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else
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auxv64[2 * i + 1] &= (uint64_t) hwcap_mask;
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}
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}
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/* In the note segment starting at OFFSET with size LEN, make notes
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with type NOTE_TYPE unrecognizable by GDB. Also, mask the hwcap
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field of any auxv notes using the HWCAP_MASK. */
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static void
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elfbuf_handle_note_segment (struct elfbuf *elf, size_t offset, size_t len,
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unsigned note_type, unsigned long hwcap_mask)
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{
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size_t pos = 0;
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while (pos + 12 < len)
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{
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uint32_t *note = (uint32_t *) (elf->buf + offset + pos);
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size_t desc_pos = pos + 12 + ((note[0] + 3) & ~3);
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size_t next_pos = desc_pos + ((note[1] + 3) & ~3);
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if (desc_pos > len || next_pos > len)
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exit_with_msg ("%s: corrupt notes data", elf->path);
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if (note[2] == note_type)
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note[2] |= 0xff000000;
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else if (note[2] == 6 && hwcap_mask != 0)
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elfbuf_handle_auxv (elf, offset + desc_pos, note[1],
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hwcap_mask);
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pos = next_pos;
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}
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}
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static void
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elfbuf_handle_core_notes (struct elfbuf *elf, unsigned note_type,
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unsigned long hwcap_mask)
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{
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unsigned ph_idx;
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if (ELFBUF_EHDR (elf, e_type) != 4)
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exit_with_msg ("%s: not a core file", elf->path);
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/* Iterate over program headers. */
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for (ph_idx = 0; ph_idx != ELFBUF_EHDR (elf, e_phnum); ph_idx++)
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{
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size_t offset = ELFBUF_PHDR (elf, ph_idx, p_offset);
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size_t filesz = ELFBUF_PHDR (elf, ph_idx, p_filesz);
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if (offset > elf->len || filesz > elf->len - offset)
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exit_with_msg ("%s: unexpected end of data", elf->path);
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/* Deal with NOTE segments only. */
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if (ELFBUF_PHDR (elf, ph_idx, p_type) != 4)
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continue;
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elfbuf_handle_note_segment (elf, offset, filesz, note_type,
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hwcap_mask);
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}
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}
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int
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main (int argc, char *argv[])
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{
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unsigned note_type;
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unsigned long hwcap_mask = 0;
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struct elfbuf elf;
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if (argc < 4)
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{
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abort ();
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}
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if (sscanf (argv[3], "%u", ¬e_type) != 1)
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exit_with_msg ("%s: bad command line arguments\n", argv[0]);
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if (argc >= 5)
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{
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if (sscanf (argv[4], "%lu", &hwcap_mask) != 1)
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exit_with_msg ("%s: bad command line arguments\n", argv[0]);
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}
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elfbuf_init_from_file (&elf, argv[1]);
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elfbuf_handle_core_notes (&elf, note_type, hwcap_mask);
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elfbuf_write_to_file (&elf, argv[2]);
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return 0;
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}
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