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Diffstat (limited to 'tools/sstrip/src/sstrip.c')
| -rw-r--r-- | tools/sstrip/src/sstrip.c | 466 |
1 files changed, 0 insertions, 466 deletions
diff --git a/tools/sstrip/src/sstrip.c b/tools/sstrip/src/sstrip.c deleted file mode 100644 index 12cf12e095..0000000000 --- a/tools/sstrip/src/sstrip.c +++ /dev/null @@ -1,466 +0,0 @@ -/* http://www.muppetlabs.com/~breadbox/software/elfkickers.html */ - -/* sstrip: Copyright (C) 1999-2001 by Brian Raiter, under the GNU - * General Public License. No warranty. See COPYING for details. - * - * Aug 23, 2004 Hacked by Manuel Novoa III <mjn3@codepoet.org> to - * handle targets of different endianness and/or elf class, making - * it more useful in a cross-devel environment. - */ - -/* ============== original README =================== - * - * sstrip is a small utility that removes the contents at the end of an - * ELF file that are not part of the program's memory image. - * - * Most ELF executables are built with both a program header table and a - * section header table. However, only the former is required in order - * for the OS to load, link and execute a program. sstrip attempts to - * extract the ELF header, the program header table, and its contents, - * leaving everything else in the bit bucket. It can only remove parts of - * the file that occur at the end, after the parts to be saved. However, - * this almost always includes the section header table, and occasionally - * a few random sections that are not used when running a program. - * - * It should be noted that the GNU bfd library is (understandably) - * dependent on the section header table as an index to the file's - * contents. Thus, an executable file that has no section header table - * cannot be used with gdb, objdump, or any other program based upon the - * bfd library, at all. In fact, the program will not even recognize the - * file as a valid executable. (This limitation is noted in the source - * code comments for bfd, and is marked "FIXME", so this may change at - * some future date. However, I would imagine that it is a pretty - * low-priority item, as executables without a section header table are - * rare in the extreme.) This probably also explains why strip doesn't - * offer the option to do this. - * - * Shared library files may also have their section header table removed. - * Such a library will still function; however, it will no longer be - * possible for a compiler to link a new program against it. - * - * As an added bonus, sstrip also tries to removes trailing zero bytes - * from the end of the file. (This normally cannot be done with an - * executable that has a section header table.) - * - * sstrip is a very simplistic program. It depends upon the common - * practice of putting the parts of the file that contribute to the - * memory image at the front, and the remaining material at the end. This - * permits it to discard the latter material without affecting file - * offsets and memory addresses in what remains. Of course, the ELF - * standard permits files to be organized in almost any order, so if a - * pathological linker decided to put its section headers at the top, - * sstrip would be useless on such executables. - */ - -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <errno.h> -#include <unistd.h> -#include <fcntl.h> -#include <elf.h> -#include <byteswap.h> - -#ifndef TRUE -#define TRUE 1 -#define FALSE 0 -#endif - -/* The name of the program. - */ -static char const *progname; - -/* The name of the current file. - */ -static char const *filename; - - -/* A simple error-handling function. FALSE is always returned for the - * convenience of the caller. - */ -static int err(char const *errmsg) -{ - fprintf(stderr, "%s: %s: %s\n", progname, filename, errmsg); - return FALSE; -} - -/* A flag to signal the need for endian reversal. - */ -static int do_reverse_endian; - -/* Get a value from the elf header, compensating for endianness. - */ -#define EGET(X) \ - (__extension__ ({ \ - uint64_t __res; \ - if (!do_reverse_endian) { \ - __res = (X); \ - } else if (sizeof(X) == 1) { \ - __res = (X); \ - } else if (sizeof(X) == 2) { \ - __res = bswap_16((X)); \ - } else if (sizeof(X) == 4) { \ - __res = bswap_32((X)); \ - } else if (sizeof(X) == 8) { \ - __res = bswap_64((X)); \ - } else { \ - fprintf(stderr, "%s: %s: EGET failed for size %zu\n", \ - progname, filename, sizeof(X)); \ - exit(EXIT_FAILURE); \ - } \ - __res; \ - })) - -/* Set a value 'Y' in the elf header to 'X', compensating for endianness. - */ -#define ESET(Y,X) \ - do if (!do_reverse_endian) { \ - Y = (X); \ - } else if (sizeof(Y) == 1) { \ - Y = (X); \ - } else if (sizeof(Y) == 2) { \ - Y = bswap_16((uint16_t)(X)); \ - } else if (sizeof(Y) == 4) { \ - Y = bswap_32((uint32_t)(X)); \ - } else if (sizeof(Y) == 8) { \ - Y = bswap_64((uint64_t)(X)); \ - } else { \ - fprintf(stderr, "%s: %s: ESET failed for size %zu\n", \ - progname, filename, sizeof(Y)); \ - exit(EXIT_FAILURE); \ - } while (0) - - -/* A macro for I/O errors: The given error message is used only when - * errno is not set. - */ -#define ferr(msg) (err(errno ? strerror(errno) : (msg))) - - - -#define HEADER_FUNCTIONS(CLASS) \ - \ -/* readelfheader() reads the ELF header into our global variable, and \ - * checks to make sure that this is in fact a file that we should be \ - * munging. \ - */ \ -static int readelfheader ## CLASS (int fd, Elf ## CLASS ## _Ehdr *ehdr) \ -{ \ - if (read(fd, ((char *)ehdr)+EI_NIDENT, sizeof(*ehdr) - EI_NIDENT) \ - != sizeof(*ehdr) - EI_NIDENT) \ - return ferr("missing or incomplete ELF header."); \ - \ - /* Verify the sizes of the ELF header and the program segment \ - * header table entries. \ - */ \ - if (EGET(ehdr->e_ehsize) != sizeof(Elf ## CLASS ## _Ehdr)) \ - return err("unrecognized ELF header size."); \ - if (EGET(ehdr->e_phentsize) != sizeof(Elf ## CLASS ## _Phdr)) \ - return err("unrecognized program segment header size."); \ - \ - /* Finally, check the file type. \ - */ \ - if (EGET(ehdr->e_type) != ET_EXEC && EGET(ehdr->e_type) != ET_DYN) \ - return err("not an executable or shared-object library."); \ - \ - return TRUE; \ -} \ - \ -/* readphdrtable() loads the program segment header table into memory. \ - */ \ -static int readphdrtable ## CLASS (int fd, Elf ## CLASS ## _Ehdr const *ehdr, \ - Elf ## CLASS ## _Phdr **phdrs) \ -{ \ - size_t size; \ - \ - if (!EGET(ehdr->e_phoff) || !EGET(ehdr->e_phnum) \ -) return err("ELF file has no program header table."); \ - \ - size = EGET(ehdr->e_phnum) * sizeof **phdrs; \ - if (!(*phdrs = malloc(size))) \ - return err("Out of memory!"); \ - \ - errno = 0; \ - if (read(fd, *phdrs, size) != (ssize_t)size) \ - return ferr("missing or incomplete program segment header table."); \ - \ - return TRUE; \ -} \ - \ -/* getmemorysize() determines the offset of the last byte of the file \ - * that is referenced by an entry in the program segment header table. \ - * (Anything in the file after that point is not used when the program \ - * is executing, and thus can be safely discarded.) \ - */ \ -static int getmemorysize ## CLASS (Elf ## CLASS ## _Ehdr const *ehdr, \ - Elf ## CLASS ## _Phdr const *phdrs, \ - unsigned long *newsize) \ -{ \ - Elf ## CLASS ## _Phdr const *phdr; \ - unsigned long size, n; \ - size_t i; \ - \ - /* Start by setting the size to include the ELF header and the \ - * complete program segment header table. \ - */ \ - size = EGET(ehdr->e_phoff) + EGET(ehdr->e_phnum) * sizeof *phdrs; \ - if (size < sizeof *ehdr) \ - size = sizeof *ehdr; \ - \ - /* Then keep extending the size to include whatever data the \ - * program segment header table references. \ - */ \ - for (i = 0, phdr = phdrs ; i < EGET(ehdr->e_phnum) ; ++i, ++phdr) { \ - if (EGET(phdr->p_type) != PT_NULL) { \ - n = EGET(phdr->p_offset) + EGET(phdr->p_filesz); \ - if (n > size) \ - size = n; \ - } \ - } \ - \ - *newsize = size; \ - return TRUE; \ -} \ - \ -/* modifyheaders() removes references to the section header table if \ - * it was stripped, and reduces program header table entries that \ - * included truncated bytes at the end of the file. \ - */ \ -static int modifyheaders ## CLASS (Elf ## CLASS ## _Ehdr *ehdr, \ - Elf ## CLASS ## _Phdr *phdrs, \ - unsigned long newsize) \ -{ \ - Elf ## CLASS ## _Phdr *phdr; \ - size_t i; \ - \ - /* If the section header table is gone, then remove all references \ - * to it in the ELF header. \ - */ \ - if (EGET(ehdr->e_shoff) >= newsize) { \ - ESET(ehdr->e_shoff,0); \ - ESET(ehdr->e_shnum,0); \ - ESET(ehdr->e_shentsize,0); \ - ESET(ehdr->e_shstrndx,0); \ - } \ - \ - /* The program adjusts the file size of any segment that was \ - * truncated. The case of a segment being completely stripped out \ - * is handled separately. \ - */ \ - for (i = 0, phdr = phdrs ; i < EGET(ehdr->e_phnum) ; ++i, ++phdr) { \ - if (EGET(phdr->p_offset) >= newsize) { \ - ESET(phdr->p_offset,newsize); \ - ESET(phdr->p_filesz,0); \ - } else if (EGET(phdr->p_offset) + EGET(phdr->p_filesz) > newsize) { \ - ESET(phdr->p_filesz, newsize - EGET(phdr->p_offset)); \ - } \ - } \ - \ - return TRUE; \ -} \ - \ -/* commitchanges() writes the new headers back to the original file \ - * and sets the file to its new size. \ - */ \ -static int commitchanges ## CLASS (int fd, Elf ## CLASS ## _Ehdr const *ehdr, \ - Elf ## CLASS ## _Phdr *phdrs, \ - unsigned long newsize) \ -{ \ - size_t n; \ - \ - /* Save the changes to the ELF header, if any. \ - */ \ - if (lseek(fd, 0, SEEK_SET)) \ - return ferr("could not rewind file"); \ - errno = 0; \ - if (write(fd, ehdr, sizeof *ehdr) != sizeof *ehdr) \ - return err("could not modify file"); \ - \ - /* Save the changes to the program segment header table, if any. \ - */ \ - if (lseek(fd, EGET(ehdr->e_phoff), SEEK_SET) == (off_t)-1) { \ - err("could not seek in file."); \ - goto warning; \ - } \ - n = EGET(ehdr->e_phnum) * sizeof *phdrs; \ - if (write(fd, phdrs, n) != (ssize_t)n) { \ - err("could not write to file"); \ - goto warning; \ - } \ - \ - /* Eleventh-hour sanity check: don't truncate before the end of \ - * the program segment header table. \ - */ \ - if (newsize < EGET(ehdr->e_phoff) + n) \ - newsize = EGET(ehdr->e_phoff) + n; \ - \ - /* Chop off the end of the file. \ - */ \ - if (ftruncate(fd, newsize)) { \ - err("could not resize file"); \ - goto warning; \ - } \ - \ - return TRUE; \ - \ - warning: \ - return err("ELF file may have been corrupted!"); \ -} - - -/* First elements of Elf32_Ehdr and Elf64_Ehdr are common. - */ -static int readelfheaderident(int fd, Elf32_Ehdr *ehdr) -{ - errno = 0; - if (read(fd, ehdr, EI_NIDENT) != EI_NIDENT) - return ferr("missing or incomplete ELF header."); - - /* Check the ELF signature. - */ - if (!(ehdr->e_ident[EI_MAG0] == ELFMAG0 && - ehdr->e_ident[EI_MAG1] == ELFMAG1 && - ehdr->e_ident[EI_MAG2] == ELFMAG2 && - ehdr->e_ident[EI_MAG3] == ELFMAG3)) - { - err("missing ELF signature."); - return -1; - } - - /* Compare the file's class and endianness with the program's. - */ -#if __BYTE_ORDER == __LITTLE_ENDIAN - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB) { - do_reverse_endian = 0; - } else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) { -/* fprintf(stderr, "ELF file has different endianness.\n"); */ - do_reverse_endian = 1; - } -#elif __BYTE_ORDER == __BIG_ENDIAN - if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB) { -/* fprintf(stderr, "ELF file has different endianness.\n"); */ - do_reverse_endian = 1; - } else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB) { - do_reverse_endian = 0; - } -#else -#error unkown endianness -#endif - else { - err("Unsupported endianness"); - return -1; - } - - /* Check the target architecture. - */ -/* if (EGET(ehdr->e_machine) != ELF_ARCH) { */ -/* /\* return err("ELF file created for different architecture."); *\/ */ -/* fprintf(stderr, "ELF file created for different architecture.\n"); */ -/* } */ - return ehdr->e_ident[EI_CLASS]; -} - - -HEADER_FUNCTIONS(32) - -HEADER_FUNCTIONS(64) - -/* truncatezeros() examines the bytes at the end of the file's - * size-to-be, and reduces the size to exclude any trailing zero - * bytes. - */ -static int truncatezeros(int fd, unsigned long *newsize) -{ - unsigned char contents[1024]; - unsigned long size, n; - - size = *newsize; - do { - n = sizeof contents; - if (n > size) - n = size; - if (lseek(fd, size - n, SEEK_SET) == (off_t)-1) - return ferr("cannot seek in file."); - if (read(fd, contents, n) != (ssize_t)n) - return ferr("cannot read file contents"); - while (n && !contents[--n]) - --size; - } while (size && !n); - - /* Sanity check. - */ - if (!size) - return err("ELF file is completely blank!"); - - *newsize = size; - return TRUE; -} - -/* main() loops over the cmdline arguments, leaving all the real work - * to the other functions. - */ -int main(int argc, char *argv[]) -{ - int fd; - union { - Elf32_Ehdr ehdr32; - Elf64_Ehdr ehdr64; - } e; - union { - Elf32_Phdr *phdrs32; - Elf64_Phdr *phdrs64; - } p; - unsigned long newsize; - char **arg; - int failures = 0; - - if (argc < 2 || argv[1][0] == '-') { - printf("Usage: sstrip FILE...\n" - "sstrip discards all nonessential bytes from an executable.\n\n" - "Version 2.0-X Copyright (C) 2000,2001 Brian Raiter.\n" - "Cross-devel hacks Copyright (C) 2004 Manuel Novoa III.\n" - "This program is free software, licensed under the GNU\n" - "General Public License. There is absolutely no warranty.\n"); - return EXIT_SUCCESS; - } - - progname = argv[0]; - - for (arg = argv + 1 ; *arg != NULL ; ++arg) { - filename = *arg; - - fd = open(*arg, O_RDWR); - if (fd < 0) { - ferr("can't open"); - ++failures; - continue; - } - - switch (readelfheaderident(fd, &e.ehdr32)) { - case ELFCLASS32: - if (!(readelfheader32(fd, &e.ehdr32) && - readphdrtable32(fd, &e.ehdr32, &p.phdrs32) && - getmemorysize32(&e.ehdr32, p.phdrs32, &newsize) && - truncatezeros(fd, &newsize) && - modifyheaders32(&e.ehdr32, p.phdrs32, newsize) && - commitchanges32(fd, &e.ehdr32, p.phdrs32, newsize))) - ++failures; - break; - case ELFCLASS64: - if (!(readelfheader64(fd, &e.ehdr64) && - readphdrtable64(fd, &e.ehdr64, &p.phdrs64) && - getmemorysize64(&e.ehdr64, p.phdrs64, &newsize) && - truncatezeros(fd, &newsize) && - modifyheaders64(&e.ehdr64, p.phdrs64, newsize) && - commitchanges64(fd, &e.ehdr64, p.phdrs64, newsize))) - ++failures; - break; - default: - ++failures; - break; - } - close(fd); - } - - return failures ? EXIT_FAILURE : EXIT_SUCCESS; -} |