mirror of git://sourceware.org/git/glibc.git
127 lines
3.1 KiB
C
127 lines
3.1 KiB
C
/* Update p_align of the first PT_LOAD segment.
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Copyright (C) 2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <stdbool.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <link.h>
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#include <error.h>
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#include <errno.h>
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#include <sys/stat.h>
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#include <sys/mman.h>
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const char *file_name;
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static size_t update_p_align (size_t);
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int
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main (int argc, char ** argv)
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{
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if (argc != 2)
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{
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printf ("Usage: %s: file\n", argv[0]);
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return 0;
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}
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file_name = argv[1];
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struct stat statbuf;
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int errno_saved;
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if (stat (file_name, &statbuf) < 0)
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error (1, errno, "%s: not exist", file_name);
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ElfW(Ehdr) *ehdr;
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if (statbuf.st_size < sizeof (*ehdr))
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error (1, 0, "%s: too small", file_name);
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int fd = open (file_name, O_RDWR);
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if (fd < 0)
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error (1, errno, "%s: can't open", file_name);
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/* Map in the whole file. */
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void *base = mmap (NULL, statbuf.st_size, PROT_READ | PROT_WRITE,
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MAP_SHARED, fd, 0);
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if (base == MAP_FAILED)
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{
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errno_saved = errno;
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close (fd);
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error (1, errno_saved, "%s: failed to map", file_name);
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}
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ehdr = (ElfW(Ehdr) *) base;
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if (ehdr->e_ident[EI_MAG0] != ELFMAG0
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|| ehdr->e_ident[EI_MAG1] != ELFMAG1
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|| ehdr->e_ident[EI_MAG2] != ELFMAG2
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|| ehdr->e_ident[EI_MAG3] != ELFMAG3)
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{
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close (fd);
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error (1, 0, "%s: bad ELF header", file_name);
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}
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if (ehdr->e_type != ET_DYN)
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{
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close (fd);
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error (1, 0, "%s: not shared library", file_name);
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}
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bool unsupported_class = true;
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switch (ehdr->e_ident[EI_CLASS])
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{
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default:
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break;
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case ELFCLASS32:
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unsupported_class = __ELF_NATIVE_CLASS != 32;
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break;
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case ELFCLASS64:
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unsupported_class = __ELF_NATIVE_CLASS != 64;
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break;
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}
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if (unsupported_class)
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{
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close (fd);
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error (1, 0, "%s: unsupported ELF class: %d",
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file_name, ehdr->e_ident[EI_CLASS]);
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}
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size_t phdr_size = sizeof (ElfW(Phdr)) * ehdr->e_phentsize;
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if (statbuf.st_size < (ehdr->e_phoff + phdr_size))
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{
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close (fd);
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error (1, 0, "%s: too small", file_name);
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}
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ElfW(Phdr) *phdr = (ElfW(Phdr) *) (base + ehdr->e_phoff);
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for (int i = 0; i < ehdr->e_phnum; i++, phdr++)
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if (phdr->p_type == PT_LOAD)
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{
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/* Update p_align of the first PT_LOAD segment. */
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phdr->p_align = update_p_align (phdr->p_align);
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break;
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}
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munmap (base, statbuf.st_size);
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close (fd);
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return 0;
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}
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