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|
/* $OpenBSD: elf2aout.c,v 1.5 2004/03/16 01:11:09 tedu Exp $ */
/*
* Copyright (c) 1995
* Ted Lemon (hereinafter referred to as the author)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <elf_abi.h>
#include <machine/elf_abi.h>
#include <stdio.h>
#include <a.out.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#define SHN_MIPS_ACOMMON 0xfff0
extern char *__progname;
struct sect {
unsigned long vaddr;
unsigned long len;
};
int phcmp();
char *saveRead(int file, off_t offset, off_t len, char *name);
int copy(int, int, off_t, off_t);
int translate_syms(int, int, off_t, off_t, off_t, off_t);
int *symTypeTable;
/* Symbol table entry... */
struct sym {
unsigned long name; /* Index into strtab of symbol name. */
unsigned long value; /* Section offset, virt addr or common align. */
unsigned long size; /* Size of object referenced. */
unsigned type:4; /* Symbol type (e.g., function, data)... */
unsigned binding:4; /* Symbol binding (e.g., global,
* local)... */
unsigned char other; /* Unused. */
unsigned short shndx; /* Section containing symbol. */
};
struct phdr {
unsigned long type; /* Segment type... */
unsigned long offset; /* File offset... */
unsigned long vaddr; /* Virtual address... */
unsigned long paddr; /* Physical address... */
unsigned long filesz; /* Size of segment in file... */
unsigned long memsz; /* Size of segment in memory... */
unsigned long flags; /* Segment flags... */
unsigned long align; /* Alighment, file and memory... */
};
int
main(int argc, char *argv[])
{
Elf32_Ehdr ex;
Elf32_Phdr *ph;
Elf32_Shdr *sh;
struct sym *symtab;
char *shstrtab;
int strtabix, symtabix;
int i;
struct sect text, data, bss;
struct exec aex;
int infile, outfile;
unsigned long cur_vma = ULONG_MAX;
int symflag = 0;
text.len = data.len = bss.len = 0;
text.vaddr = data.vaddr = bss.vaddr = 0;
/* Check args... */
if (argc < 3 || argc > 4) {
usage:
fprintf(stderr,
"usage: %s elf a.out\n", __progname);
exit(1);
}
/* Try the input file... */
if ((infile = open(argv[1], O_RDONLY)) < 0) {
fprintf(stderr, "Can't open %s for read: %s\n",
argv[1], strerror(errno));
exit(1);
}
/* Read the header, which is at the beginning of the file... */
i = read(infile, &ex, sizeof ex);
if (i != sizeof ex) {
fprintf(stderr, "ex: %s: %s.\n",
argv[1], i ? strerror(errno) : "End of file reached");
exit(1);
}
/* Read the program headers... */
ph = (Elf32_Phdr *) saveRead(infile, ex.e_phoff,
ex.e_phnum * sizeof(Elf32_Phdr), "ph");
/* Read the section headers... */
sh = (Elf32_Shdr *) saveRead(infile, ex.e_shoff,
ex.e_shnum * sizeof(Elf32_Shdr), "sh");
/* Read in the section string table. */
shstrtab = saveRead(infile, sh[ex.e_shstrndx].sh_offset,
sh[ex.e_shstrndx].sh_size, "shstrtab");
/*
* Find space for a table matching ELF section indices to a.out
* symbol types.
*/
symTypeTable = (int *) malloc(ex.e_shnum * sizeof(int));
if (!symTypeTable) {
fprintf(stderr, "symTypeTable: can't allocate.\n");
exit(1);
}
memset(symTypeTable, 0, ex.e_shnum * sizeof(int));
/*
* Look for the symbol table and string table... Also map section
* indices to symbol types for a.out
*/
for (i = 0; i < ex.e_shnum; i++) {
char *name = shstrtab + sh[i].sh_name;
if (!strcmp(name, ".symtab"))
symtabix = i;
else if (!strcmp(name, ".strtab"))
strtabix = i;
else if (!strcmp(name, ".text") || !strcmp(name, ".rodata"))
symTypeTable[i] = N_TEXT;
else if (!strcmp(name, ".data") || !strcmp(name, ".sdata") ||
!strcmp(name, ".lit4") || !strcmp(name, ".lit8"))
symTypeTable[i] = N_DATA;
else if (!strcmp(name, ".bss") || !strcmp(name, ".sbss"))
symTypeTable[i] = N_BSS;
}
/*
* Figure out if we can cram the program header into an a.out
* header... Basically, we can't handle anything but loadable
* segments, but we can ignore some kinds of segments. We can't
* handle holes in the address space, and we handle start addresses
* other than 0x1000 by hoping that the loader will know where to
* load - a.out doesn't have an explicit load address. Segments may
* be out of order, so we sort them first.
*/
qsort(ph, ex.e_phnum, sizeof(Elf32_Phdr), phcmp);
for (i = 0; i < ex.e_phnum; i++) {
/* Section types we can ignore... */
if (ph[i].p_type == PT_NULL || ph[i].p_type == PT_NOTE ||
ph[i].p_type == PT_PHDR || ph[i].p_type == PT_MIPS_REGINFO)
continue;
/* Section types we can't handle... */
else if (ph[i].p_type != PT_LOAD) {
fprintf(stderr,
"Program header %d type %d can't be converted.\n",
i, ph[i].p_type);
exit(1);
}
/* Writable (data) segment? */
if (ph[i].p_flags & PF_W) {
struct sect ndata, nbss;
ndata.vaddr = ph[i].p_vaddr;
ndata.len = ph[i].p_filesz;
nbss.vaddr = ph[i].p_vaddr + ph[i].p_filesz;
nbss.len = ph[i].p_memsz - ph[i].p_filesz;
combine(&data, &ndata, 0);
combine(&bss, &nbss, 1);
} else {
struct sect ntxt;
ntxt.vaddr = ph[i].p_vaddr;
ntxt.len = ph[i].p_filesz;
combine(&text, &ntxt);
}
/* Remember the lowest segment start address. */
if (ph[i].p_vaddr < cur_vma)
cur_vma = ph[i].p_vaddr;
}
/* Sections must be in order to be converted... */
if (text.vaddr > data.vaddr || data.vaddr > bss.vaddr ||
text.vaddr + text.len > data.vaddr || data.vaddr + data.len > bss.vaddr) {
fprintf(stderr, "Sections ordering prevents a.out conversion.\n");
exit(1);
}
/*
* If there's a data section but no text section, then the loader
* combined everything into one section. That needs to be the text
* section, so just make the data section zero length following text.
*/
if (data.len && !text.len) {
text = data;
data.vaddr = text.vaddr + text.len;
data.len = 0;
}
/*
* If there is a gap between text and data, we'll fill it when we
* copy the data, so update the length of the text segment as
* represented in a.out to reflect that, since a.out doesn't allow
* gaps in the program address space.
*/
if (text.vaddr + text.len < data.vaddr)
text.len = data.vaddr - text.vaddr;
/* We now have enough information to cons up an a.out header... */
aex.a_midmag = htonl((symflag << 26) | (MID_PMAX << 16) | OMAGIC);
aex.a_text = text.len;
aex.a_data = data.len;
aex.a_bss = bss.len;
aex.a_entry = ex.e_entry;
aex.a_syms = (sizeof(struct nlist) *
(symtabix != -1
? sh[symtabix].sh_size / sizeof(struct sym) : 0));
aex.a_trsize = 0;
aex.a_drsize = 0;
/* Make the output file... */
if ((outfile = open(argv[2], O_WRONLY | O_CREAT, 0777)) < 0) {
fprintf(stderr, "Unable to create %s: %s\n", argv[2], strerror(errno));
exit(1);
}
/* Write the header... */
i = write(outfile, &aex, sizeof aex);
if (i != sizeof aex) {
perror("aex: write");
exit(1);
}
/*
* Copy the loadable sections. Zero-fill any gaps less than 64k;
* complain about any zero-filling, and die if we're asked to
* zero-fill more than 64k.
*/
for (i = 0; i < ex.e_phnum; i++) {
/*
* Unprocessable sections were handled above, so just verify
* that the section can be loaded before copying.
*/
if (ph[i].p_type == PT_LOAD && ph[i].p_filesz) {
if (cur_vma != ph[i].p_vaddr) {
unsigned long gap = ph[i].p_vaddr - cur_vma;
char obuf[1024];
if (gap > 65536) {
fprintf(stderr,
"Intersegment gap (%d bytes) too large.\n",
gap);
exit(1);
}
fprintf(stderr,
"Warning: %d byte intersegment gap.\n", gap);
memset(obuf, 0, sizeof obuf);
while (gap) {
int count = write(outfile, obuf,
(gap > sizeof obuf ? sizeof obuf : gap));
if (count < 0) {
fprintf(stderr,
"Error writing gap: %s\n",
strerror(errno));
exit(1);
}
gap -= count;
}
}
copy(outfile, infile, ph[i].p_offset, ph[i].p_filesz);
cur_vma = ph[i].p_vaddr + ph[i].p_filesz;
}
}
/* Copy and translate the symbol table... */
translate_syms(outfile, infile, sh[symtabix].sh_offset,
sh[symtabix].sh_size,
sh[strtabix].sh_offset, sh[strtabix].sh_size);
/* Looks like we won... */
exit(0);
}
/*
* translate_syms (out, in, offset, size)
*
* Read the ELF symbol table from in at offset; translate it into a.out nlist
* format and write it to out.
*/
translate_syms(int out, int in, off_t symoff, off_t symsize, off_t stroff,
off_t strsize)
{
#define SYMS_PER_PASS 64
struct sym inbuf[64];
struct nlist outbuf[64];
int i, remaining, cur;
char *oldstrings;
char *newstrings, *nsp;
int newstringsize;
/* Zero the unused fields in the output buffer.. */
memset(outbuf, 0, sizeof outbuf);
/* Find number of symbols to process... */
remaining = symsize / sizeof(struct sym);
/* Suck in the old string table... */
oldstrings = saveRead(in, stroff, strsize, "string table");
/*
* Allocate space for the new one. XXX We make the wild assumption
* that no two symbol table entries will point at the same place in
* the string table - if that assumption is bad, this could easily
* blow up.
*/
newstringsize = strsize + remaining;
newstrings = (char *) malloc(newstringsize);
if (!newstrings) {
fprintf(stderr, "No memory for new string table!\n");
exit(1);
}
/* Initialize the table pointer... */
nsp = newstrings;
/* Go to the start of the ELF symbol table... */
if (lseek(in, symoff, SEEK_SET) < 0) {
perror("translate_syms: lseek");
exit(1);
}
/* Translate and copy symbols... */
while (remaining) {
cur = remaining;
if (cur > SYMS_PER_PASS)
cur = SYMS_PER_PASS;
remaining -= cur;
if ((i = read(in, inbuf, cur * sizeof(struct sym)))
!= cur * sizeof(struct sym)) {
if (i < 0)
perror("translate_syms");
else
fprintf(stderr,
"translate_syms: premature end of file.\n");
exit(1);
}
/* Do the translation... */
for (i = 0; i < cur; i++) {
/*
* Copy the symbol into the new table, but prepend an
* underscore.
*/
*nsp = '_';
strcpy(nsp + 1, oldstrings + inbuf[i].name);
outbuf[i].n_un.n_strx = nsp - newstrings + 4;
nsp += strlen(nsp) + 1;
/*
* Convert ELF symbol type/section/etc info into
* a.out type info.
*/
if (inbuf[i].type == STT_FILE)
outbuf[i].n_type = N_FN;
else if (inbuf[i].shndx == SHN_UNDEF)
outbuf[i].n_type = N_UNDF;
else if (inbuf[i].shndx == SHN_ABS)
outbuf[i].n_type = N_ABS;
else if (inbuf[i].shndx == SHN_COMMON ||
inbuf[i].shndx == SHN_MIPS_ACOMMON)
outbuf[i].n_type = N_COMM;
else
outbuf[i].n_type = symTypeTable[inbuf[i].shndx];
if (inbuf[i].binding == STB_GLOBAL)
outbuf[i].n_type |= N_EXT;
/* Symbol values in executables should be compatible. */
outbuf[i].n_value = inbuf[i].value;
}
/* Write out the symbols... */
if ((i = write(out, outbuf, cur * sizeof(struct nlist)))
!= cur * sizeof(struct nlist)) {
fprintf(stderr, "translate_syms: write: %s\n", strerror(errno));
exit(1);
}
}
/* Write out the string table length... */
if (write(out, &newstringsize, sizeof newstringsize)
!= sizeof newstringsize) {
fprintf(stderr,
"translate_syms: newstringsize: %s\n", strerror(errno));
exit(1);
}
/* Write out the string table... */
if (write(out, newstrings, newstringsize) != newstringsize) {
fprintf(stderr, "translate_syms: newstrings: %s\n", strerror(errno));
exit(1);
}
}
copy(int out, int in, off_t offset, off_t size)
{
char ibuf[4096];
int remaining, cur, count;
/* Go to the start of the ELF symbol table... */
if (lseek(in, offset, SEEK_SET) < 0) {
perror("copy: lseek");
exit(1);
}
remaining = size;
while (remaining) {
cur = remaining;
if (cur > sizeof ibuf)
cur = sizeof ibuf;
remaining -= cur;
if ((count = read(in, ibuf, cur)) != cur) {
fprintf(stderr, "copy: read: %s\n",
count ? strerror(errno) : "premature end of file");
exit(1);
}
if ((count = write(out, ibuf, cur)) != cur) {
perror("copy: write");
exit(1);
}
}
}
/*
* Combine two segments, which must be contiguous. If pad is true, it's
* okay for there to be padding between.
*/
combine(struct sect * base, struct sect * new, int pad)
{
if (!base->len)
*base = *new;
else if (new->len) {
if (base->vaddr + base->len != new->vaddr) {
if (pad)
base->len = new->vaddr - base->vaddr;
else {
fprintf(stderr,
"Non-contiguous data can't be converted.\n");
exit(1);
}
}
base->len += new->len;
}
}
phcmp(struct phdr * h1, struct phdr * h2)
{
if (h1->vaddr > h2->vaddr)
return 1;
else if (h1->vaddr < h2->vaddr)
return -1;
else
return 0;
}
char *
saveRead(int file, off_t offset, off_t len, char *name)
{
char *tmp;
int count;
off_t off;
if ((off = lseek(file, offset, SEEK_SET)) < 0) {
fprintf(stderr, "%s: fseek: %s\n", name, strerror(errno));
exit(1);
}
if (!(tmp = (char *) malloc(len))) {
fprintf(stderr, "%s: Can't allocate %d bytes.\n", name, len);
exit(1);
}
count = read(file, tmp, len);
if (count != len) {
fprintf(stderr, "%s: read: %s.\n",
name, count ? strerror(errno) : "End of file reached");
exit(1);
}
return tmp;
}
|