/* * Simple tool to produce an utterly basic ELF executable * from an absolute ack.out file. Suitable for operating * systems like Linux. * * This tool produces an executable with a program header * only and no section header. * * Mostly pinched from the ARM cv (and then rewritten in * ANSI C). Which, according to the comment, was pinched * from m68k2; therefore I am merely continuing a time- * honoured tradition. * * (I was 10 when the original for this was checked into * CVS...) * * dtrg, 2006-10-17 */ #include #include #include #include #include #include #include #include #include #include "out.h" #define ASSERT(x) switch (2) { case 0: case (x): ; } /* Global settings. */ int bigendian = 0; int elfabi = 3; /* abi = Linux */ int elfmachine = 3; /* machine = EM_386 */ uint32_t elfflags = 0; /* elf processor flags */ /* Header and section table of an ack object file. */ struct outhead outhead; struct outsect outsect[S_MAX]; struct outname* outname = NULL; char* stringarea; uint32_t ack_off_char; int nstab = 0; /* S_STB symbol count */ int nsym = 0; /* other symbol count */ int nlocal = 0; /* local symbols */ char* outputfile = NULL; /* Name of output file, or NULL */ char* program; /* Name of current program: argv[0] */ FILE* input; /* Input stream */ FILE* output; /* Output stream */ #define readf(a, b, c) fread((a), (b), (int)(c), input) #define writef(a, b, c) fwrite((a), (b), (int)(c), output) /* Contents of an ELF object file. */ #define ELF_HEADER_SIZE 0x34 #define PROGRAM_HEADER_SIZE 0x20 #define PROGRAM_HEADER_COUNT 1 #define SECTION_HEADER_SIZE 0x28 #define STAB_SYMBOL_SIZE 12 #define ELF_SYMBOL_SIZE 16 uint32_t code_offset; /* ELF segment */ uint32_t stab_offset; /* Debugger symbol table */ uint32_t symtab_offset; /* ELF symbol table */ uint32_t strtab_offset; /* String table */ uint32_t shstrtab_offset; /* Section header string table */ uint32_t sh_offset; /* ELF section headers */ int sh_count = 0; /* Number of ELF sections */ int shstrtab_nr = 0; /* Section number of .shstrtab */ int shstrtab_size; const char elf_le_ident_string[] = { 0x7F, 'E', 'L', 'F' }; bool verbose = false; /* Segment numbers understood by aelflod. */ enum { TEXT = 0, ROM, DATA, BSS, NUM_SEGMENTS }; /* * ELF section numbers count up in the order that we write the ELF * section headers. If we have no debugger symbols, we will skip * .stab and .stabstr, then subtract 2 from all later numbers. */ enum { N_UNDEF = 0, N_TEXT, N_RODATA, N_DATA, N_BSS, N_STAB, N_STABSTR, N_SYMTAB, N_STRTAB, N_SHSTRTAB, NUM_ELF_SECTIONS, }; const char shstrtab[] = "\0.text\0.rodata\0.data\0.bss\0.stab\0.stabstr\0" ".symtab\0.strtab\0.shstrtab"; /* Compiler appends one more "\0". */ const int sh_name[] = { /* Index of each name in shstrtab: */ 0, 1, 7, 15, 21, 26, 32, 41, 49, 57, }; /* Produce an error message and exit. */ void fatal(const char* s, ...) { va_list ap; fprintf(stderr, "%s: ",program) ; va_start(ap, s); vfprintf(stderr, s, ap); va_end(ap); fprintf(stderr, "\n"); if (outputfile) unlink(outputfile); exit(1); } /* Calculate the result of a aligned to b (rounding up if necessary). * b must be a power of two. */ long align(long a, long b) { a += b - 1; return a & ~(b-1); } int follows(struct outsect* pa, struct outsect* pb) { /* return 1 if pa follows pb */ return (pa->os_base >= align(pb->os_base+pb->os_size, pa->os_lign)); } /* Convert a symbol's name index from ack.out to ELF. */ uint32_t cvname(struct outname* n) { if (n->on_foff) { /* ack.out: offset from beginning of file * ELF: index in string table * the + 1 because we prepend a '\0' */ return n->on_foff - ack_off_char + 1; } else return 0; /* no name */ } /* Convert a symbol's type and binding from ack.out to ELF. */ int cvinfo(struct outname* n) { int bind, type; switch (n->on_type & S_ETC) { case S_SCT: type = 3; /* STT_SECTION */ break; case S_FIL: case S_MOD: type = 4; /* STT_FILE */ break; default: switch (n->on_type & S_TYP) { case S_MIN + TEXT: type = 2; /* STT_FUNC */ break; case S_MIN + ROM: case S_MIN + DATA: case S_MIN + BSS: case S_MIN + NUM_SEGMENTS: type = 1; /* STT_OBJECT */ break; default: type = 0; /* STT_NOTYPE */ break; } break; } if (n->on_type & S_EXT) bind = 1; /* STB_GLOBAL */ else bind = 0; /* STB_LOCAL */ return (bind << 4) | type; } /* Convert a symbol's section index from ack.out to ELF. */ int cvsect(struct outname* n) { switch (n->on_type & S_TYP) { case S_ABS: return 0xfff1; /* SHN_ABS */ case S_MIN + TEXT: return N_TEXT; case S_MIN + ROM: return N_RODATA; case S_MIN + DATA: return N_DATA; case S_MIN + BSS: case S_MIN + NUM_SEGMENTS: return N_BSS; default: return N_UNDEF; } } /* Writes a byte. */ void emit8(unsigned char value) { writef(&value, 1, 1); } /* Writes out 16 and 32 bit words in the appropriate endianness. */ void emit16(unsigned short value) { unsigned char buffer[2]; if (bigendian) { buffer[0] = (value >> 8) & 0xFF; buffer[1] = (value >> 0) & 0xFF; } else { buffer[1] = (value >> 8) & 0xFF; buffer[0] = (value >> 0) & 0xFF; } writef(buffer, 1, sizeof(buffer)); } void emit32(unsigned long value) { unsigned char buffer[4]; if (bigendian) { buffer[0] = (value >> 24) & 0xFF; buffer[1] = (value >> 16) & 0xFF; buffer[2] = (value >> 8) & 0xFF; buffer[3] = (value >> 0) & 0xFF; } else { buffer[3] = (value >> 24) & 0xFF; buffer[2] = (value >> 16) & 0xFF; buffer[1] = (value >> 8) & 0xFF; buffer[0] = (value >> 0) & 0xFF; } writef(buffer, 1, sizeof(buffer)); } /* Copies the contents of a section from the input stream * to the output stream. */ void emits(struct outsect* section) { char buffer[BUFSIZ]; long n = section->os_flen; while (n > 0) { int blocksize = (n > BUFSIZ) ? BUFSIZ : n; readf(buffer, 1, blocksize); writef(buffer, 1, blocksize); n -= blocksize; } /* Zero fill any remaining space. */ if (section->os_flen != section->os_size) { long n = section->os_size - section->os_flen; memset(buffer, 0, BUFSIZ); while (n > 0) { int blocksize = (n > BUFSIZ) ? BUFSIZ : n; writef(buffer, 1, blocksize); n -= blocksize; } } } /* Writes out an ELF program header. */ void emitphdr(unsigned long address, unsigned long filesize, unsigned int memsize, unsigned int alignment, int flags) { static unsigned long fileoffset = 0; emit32(1); /* type = PT_LOAD */ emit32(fileoffset); /* file offset */ emit32(address); /* virtual address */ emit32(0); /* physical address */ emit32(filesize); /* file size */ emit32(memsize); /* memory size */ emit32(flags); /* executable, readable, writable */ emit32(alignment); /* alignment */ fileoffset += filesize; } /* The next few functions write parts of the symbol table. */ void emit_stab(void) { struct outname* n; int i; for (i = 0; i < outhead.oh_nname; i++) { n = &outname[i]; if (n->on_type & S_STB) { emit32(cvname(n)); /* name index */ emit8(n->on_type >> 8); /* type */ emit8(cvsect(n)); /* section */ emit16(n->on_desc); /* desc */ emit32(n->on_valu); /* value */ } } } void emit_symtab(void) { struct outname* n; int i, pass; bool global; /* ELF .symtab must have local symbols before other symbols. * We emit locals in pass 0, globals in pass 1. */ for (pass = 0; pass < 2; pass++) { for (i = 0; i < outhead.oh_nname; i++) { n = &outname[i]; /* Don't emit .stab symbol in .symtab. */ if (n->on_type & S_STB) continue; global = (n->on_type & S_EXT); if ((pass == 0 && !global) || (pass == 1 && global)) { emit32(cvname(n)); /* name index */ emit32(n->on_valu); /* value */ emit32(0); /* size = unknown */ emit8(cvinfo(n)); /* info */ emit8(0); /* other */ emit16(cvsect(n)); /* section */ } } } } void emit_strtab(void) { /* We prepend a '\0' because ELF uses offset 0 for symbols * without a name. */ emit8('\0'); writef(stringarea, outhead.oh_nchar, 1); } void emit_shstrtab(void) { if (nstab) { writef(shstrtab, sizeof(shstrtab), 1); } else { /* Skip .stab and .stabstr */ int i = sh_name[N_SYMTAB]; writef(shstrtab, sh_name[N_STAB], 1); writef(shstrtab + i, sizeof(shstrtab) - i, 1); } } /* Writes out an ELF section header. */ void emit_sh(int i) { uint32_t name, type, flags, addr, offset, size, link, info, addralign, entsize; /* If no debugger symbols, skip .stab and .stabstr */ if (nstab == 0 && (i == N_STAB || i == N_STABSTR)) return; name = sh_name[i]; if (nstab == 0 && i >= N_STAB) name -= (sh_name[N_SYMTAB] - sh_name[N_STAB]); switch (i) { case N_TEXT: case N_RODATA: case N_DATA: case N_STAB: type = 1; /* SHT_PROGBITS */ break; case N_BSS: type = 8; /* SHT_NOBITS */ break; case N_SYMTAB: type = 2; /* SHT_SYMTAB */ break; case N_STABSTR: case N_STRTAB: case N_SHSTRTAB: type = 3; /* SHT_STRTAB */ break; default: type = 0; /* SHT_NULL */ break; } switch (i) { case N_TEXT: flags = 4|2; /* SHF_EXECINSTR|SHF_ALLOC */ addr = outsect[TEXT].os_base; offset = code_offset; size = outsect[TEXT].os_size; addralign = outsect[TEXT].os_lign; break; case N_RODATA: flags = 2; /* SHF_ALLOC */ addr = outsect[ROM].os_base; offset = code_offset + outsect[TEXT].os_size; size = outsect[ROM].os_size; addralign = outsect[ROM].os_lign; break; case N_DATA: flags = 2|1; /* SHF_ALLOC|SHF_WRITE */ addr = outsect[DATA].os_base; offset = code_offset + outsect[TEXT].os_size + outsect[ROM].os_size; size = outsect[DATA].os_size; addralign = outsect[DATA].os_lign; break; case N_BSS: flags = 2|1; /* SHF_ALLOC|SHF_WRITE */ addr = outsect[BSS].os_base; offset = code_offset + outsect[TEXT].os_size + outsect[ROM].os_size + outsect[DATA].os_size; size = outsect[BSS].os_size; addralign = outsect[BSS].os_lign; break; default: flags = addr = offset = size = addralign = 0; break; } entsize = 0; switch (i) { case N_STAB: offset = stab_offset; size = STAB_SYMBOL_SIZE * nstab; entsize = STAB_SYMBOL_SIZE; break; case N_SYMTAB: offset = symtab_offset; size = ELF_SYMBOL_SIZE * nsym; entsize = ELF_SYMBOL_SIZE; break; case N_STABSTR: case N_STRTAB: /* .stabstr, .strtab share the string area */ offset = strtab_offset; /* the + 1 because we prepend a '\0' */ size = 1 + outhead.oh_nchar; break; case N_SHSTRTAB: offset = shstrtab_offset; size = shstrtab_size; break; } /* Link .stab to .stabstr and .symtab to .strtab */ switch (i) { case N_STAB: link = N_STABSTR; break; case N_SYMTAB: link = N_STRTAB; if (nstab == 0) link -= 2; break; default: link = 0; break; } switch (i) { case N_SYMTAB: info = nlocal; break; default: info = 0; break; } emit32(name); emit32(type); emit32(flags); emit32(addr); emit32(offset); emit32(size); emit32(link); emit32(info); emit32(addralign); emit32(entsize); } /* Macros from modules/src/object/obj.h */ #define Xchar(ch) ((ch) & 0377) #define uget2(c) (Xchar((c)[0]) | ((unsigned) Xchar((c)[1]) << 8)) #define get4(c) (uget2(c) | ((long) uget2((c)+2) << 16)) /* Read the ack.out file header. */ int rhead(FILE* f, struct outhead* head) { char buf[SZ_HEAD], *c; if (fread(buf, sizeof(buf), 1, f) != 1) return 0; c = buf; head->oh_magic = uget2(c); c += 2; head->oh_stamp = uget2(c); c += 2; head->oh_flags = uget2(c); c += 2; head->oh_nsect = uget2(c); c += 2; head->oh_nrelo = uget2(c); c += 2; head->oh_nname = uget2(c); c += 2; head->oh_nemit = get4(c); c += 4; head->oh_nchar = get4(c); return 1; } /* Read an ack.out section header. */ int rsect(FILE* f, struct outsect* sect) { char buf[SZ_SECT], *c; if (fread(buf, sizeof(buf), 1, f) != 1) return 0; c = buf; sect->os_base = get4(c); c += 4; sect->os_size = get4(c); c += 4; sect->os_foff = get4(c); c += 4; sect->os_flen = get4(c); c += 4; sect->os_lign = get4(c); return 1 ; } /* * Read the ack.out symbol table and string area. Count symbols. * Seek back to the current file position. */ int rnames(FILE* f) { long told; int i; /* If no symbols, then do nothing successfully. */ if (outhead.oh_nname == 0) return 1; /* Seek to the symbol table. */ told = ftell(f); if (told == -1) return 0; ack_off_char = OFF_CHAR(outhead); /* for cvname() */ if (fseek(f, OFF_NAME(outhead), SEEK_SET)) return 0; /* Using calloc(a, b) to check if a * b would overflow. */ outname = calloc(outhead.oh_nname, sizeof(outname[0])); if (outname == NULL) fatal("out of memory."); for (i = 0; i < outhead.oh_nname; i++) { char buf[SZ_NAME], *c; if (fread(buf, SZ_NAME, 1, f) != 1) return 0; c = buf; outname[i].on_foff = get4(c); c += 4; outname[i].on_type = uget2(c); c += 2; outname[i].on_desc = uget2(c); c += 2; outname[i].on_valu = get4(c); if (outname[i].on_type & S_STB) { nstab++; } else { nsym++; if (!(outname[i].on_type & S_EXT)) nlocal++; } } stringarea = malloc(outhead.oh_nchar); if (stringarea == NULL) fatal("out of memory."); if (fread(stringarea, outhead.oh_nchar, 1, f) != 1) return 0; if (fseek(f, told, SEEK_SET)) return 0; return 1; } int main(int argc, char* argv[]) { /* General housecleaning and setup. */ input = stdin; output = stdout; program = argv[0]; /* Read in and process any flags. */ while ((argc > 1) && (argv[1][0] == '-')) { switch (argv[1][1]) { case 'a': elfabi = strtoul(&argv[1][2], NULL, 0); break; case 'b': bigendian = 1; break; case 'h': fprintf(stderr, "%s: Syntax: aelflod [-a] [-b] [-h] [-l]\n\t[-m] [-v] \n", program); exit(0); case 'l': bigendian = 0; break; case 'm': elfmachine = strtoul(&argv[1][2], NULL, 0); break; case 'f': elfflags = strtoul(&argv[1][2], NULL, 0); break; case 'v': verbose = true; break; default: syntaxerror: fatal("syntax error --- try -h for help"); } argv++; argc--; } /* Process the rest of the arguments. */ switch (argc) { case 1: /* No parameters --- read from stdin, write to stdout. */ break; case 3: /* Both input and output files specified. */ output = fopen(argv[2], "w"); if (!output) fatal("unable to open output file."); outputfile = argv[2]; /* fall through */ case 2: /* Input file specified. */ input = fopen(argv[1], "r"); if (!input) fatal("unable to open input file."); break; default: goto syntaxerror; } /* Read and check the ack.out file header. */ if (!rhead(input,&outhead)) fatal("failed to read file header."); if (BADMAGIC(outhead)) fatal("this isn't an ack object file."); if (outhead.oh_nrelo > 0) fprintf(stderr, "Warning: relocation information present."); if (!((outhead.oh_nsect == NUM_SEGMENTS) || (outhead.oh_nsect == (NUM_SEGMENTS+1)))) fatal("the input file must have %d sections, not %ld.", NUM_SEGMENTS, outhead.oh_nsect); /* Read in the section headers. */ { int i; for (i=0; i