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/* amd64-linux.elf-main.c -- stub loader for Linux 64-bit ELF executable
This file is part of the UPX executable compressor.
Copyright (C) 1996-2020 Markus Franz Xaver Johannes Oberhumer
Copyright (C) 1996-2020 Laszlo Molnar
Copyright (C) 2000-2020 John F. Reiser
All Rights Reserved.
UPX and the UCL library are free software; you can redistribute them
and/or modify them under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of
the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; see the file COPYING.
If not, write to the Free Software Foundation, Inc.,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Markus F.X.J. Oberhumer Laszlo Molnar
<markus@oberhumer.com> <ezerotven+github@gmail.com>
John F. Reiser
<jreiser@users.sourceforge.net>
*/
#include "include/linux.h"
#ifndef DEBUG //{
#define DEBUG 0
#endif //}
#if !DEBUG //{
#define DPRINTF(fmt, args...) /*empty*/
#else //}{
// DPRINTF is defined as an expression using "({ ... })"
// so that DPRINTF can be invoked inside an expression,
// and then followed by a comma to ignore the return value.
// The only complication is that percent and backslash
// must be doubled in the format string, because the format
// string is processd twice: once at compile-time by 'asm'
// to produce the assembled value, and once at runtime to use it.
#if defined(__powerpc__) //{
#define DPRINTF(fmt, args...) ({ \
char const *r_fmt; \
asm("bl 0f; .string \"" fmt "\"; .balign 4; 0: mflr %0" \
/*out*/ : "=r"(r_fmt) \
/* in*/ : \
/*und*/ : "lr"); \
dprintf(r_fmt, args); \
})
#elif defined(__x86_64) //}{
#define DPRINTF(fmt, args...) ({ \
char const *r_fmt; \
asm("call 0f; .asciz \"" fmt "\"; 0: pop %0" \
/*out*/ : "=r"(r_fmt) ); \
dprintf(r_fmt, args); \
})
#elif defined(__aarch64__) //}{
#define DPRINTF(fmt, args...) ({ \
char const *r_fmt; \
asm("bl 0f; .string \"" fmt "\"; .balign 4; 0: mov %0,x30" \
/*out*/ : "=r"(r_fmt) \
/* in*/ : \
/*und*/ : "x30"); \
dprintf(r_fmt, args); \
})
#endif //}
static int dprintf(char const *fmt, ...); // forward
#endif /*}*/
/*************************************************************************
// configuration section
**************************************************************************/
// In order to make it much easier to move this code at runtime and execute
// it at an address different from it load address: there must be no
// static data, and no string constants.
#define MAX_ELF_HDR 1024 // Elf64_Ehdr + n*Elf64_Phdr must fit in this
/*************************************************************************
// "file" util
**************************************************************************/
typedef struct {
size_t size; // must be first to match size[0] uncompressed size
char *buf;
} Extent;
static void
xread(Extent *x, char *buf, size_t count)
{
DPRINTF("xread x.size=%%x x.buf=%%p buf=%%p count=%%x\\n",
x->size, x->buf, buf, count);
char *p=x->buf, *q=buf;
size_t j;
if (x->size < count) {
exit(127);
}
for (j = count; 0!=j--; ++p, ++q) {
*q = *p;
}
x->buf += count;
x->size -= count;
DPRINTF("xread done\\n",0);
}
/*************************************************************************
// util
**************************************************************************/
#if 1 //{ save space
#define ERR_LAB error: exit(127);
#define err_exit(a) goto error
#else //}{ save debugging time
#define ERR_LAB /*empty*/
static void
err_exit(int a)
{
(void)a; // debugging convenience
DPRINTF("err_exit %%d\\n", a);
exit(127);
}
#endif //}
/*************************************************************************
// UPX & NRV stuff
**************************************************************************/
typedef void f_unfilter(
nrv_byte *, // also addvalue
nrv_uint,
unsigned cto8, // junk in high 24 bits
unsigned ftid
);
typedef int f_expand(
const nrv_byte *, nrv_uint,
nrv_byte *, size_t *, unsigned );
static void
unpackExtent(
Extent *const xi, // input
Extent *const xo, // output
f_expand *const f_exp,
f_unfilter *f_unf
)
{
while (xo->size) {
DPRINTF("unpackExtent xi=(%%p %%p) xo=(%%p %%p) f_exp=%%p f_unf=%%p\\n",
xi->size, xi->buf, xo->size, xo->buf, f_exp, f_unf);
struct b_info h;
// Note: if h.sz_unc == h.sz_cpr then the block was not
// compressible and is stored in its uncompressed form.
// Read and check block sizes.
xread(xi, (char *)&h, sizeof(h));
DPRINTF("h.sz_unc=%%x h.sz_cpr=%%x h.b_method=%%x\\n",
h.sz_unc, h.sz_cpr, h.b_method);
if (h.sz_unc == 0) { // uncompressed size 0 -> EOF
if (h.sz_cpr != UPX_MAGIC_LE32) // h.sz_cpr must be h->magic
err_exit(2);
if (xi->size != 0) // all bytes must be written
err_exit(3);
break;
}
if (h.sz_cpr <= 0) {
err_exit(4);
ERR_LAB
}
if (h.sz_cpr > h.sz_unc
|| h.sz_unc > xo->size ) {
err_exit(5);
}
// Now we have:
// assert(h.sz_cpr <= h.sz_unc);
// assert(h.sz_unc > 0 && h.sz_unc <= blocksize);
// assert(h.sz_cpr > 0 && h.sz_cpr <= blocksize);
if (h.sz_cpr < h.sz_unc) { // Decompress block
size_t out_len = h.sz_unc; // EOF for lzma
int const j = (*f_exp)((unsigned char *)xi->buf, h.sz_cpr,
(unsigned char *)xo->buf, &out_len,
#if defined(__x86_64) //{
*(int *)(void *)&h.b_method
#elif defined(__powerpc64__) || defined(__aarch64__) //}{
h.b_method
#endif //}
);
if (j != 0 || out_len != (nrv_uint)h.sz_unc) {
DPRINTF("j=%%x out_len=%%x &h=%%p\\n", j, out_len, &h);
err_exit(7);
}
// Skip Ehdr+Phdrs: separate 1st block, not filtered
if (h.b_ftid!=0 && f_unf // have filter
&& ((512 < out_len) // this block is longer than Ehdr+Phdrs
|| (xo->size==(unsigned)h.sz_unc) ) // block is last in Extent
) {
(*f_unf)((unsigned char *)xo->buf, out_len, h.b_cto8, h.b_ftid);
}
xi->buf += h.sz_cpr;
xi->size -= h.sz_cpr;
}
else { // copy literal block
xread(xi, xo->buf, h.sz_cpr);
}
xo->buf += h.sz_unc;
xo->size -= h.sz_unc;
}
}
#if defined(__x86_64__) //{
static void *
make_hatch_x86_64(
Elf64_Phdr const *const phdr,
Elf64_Addr reloc,
unsigned const frag_mask
)
{
unsigned xprot = 0;
unsigned *hatch = 0;
DPRINTF("make_hatch %%p %%x %%x\\n",phdr,reloc,frag_mask);
if (phdr->p_type==PT_LOAD && phdr->p_flags & PF_X) {
if (
// Try page fragmentation just beyond .text .
( (hatch = (void *)(phdr->p_memsz + phdr->p_vaddr + reloc)),
( phdr->p_memsz==phdr->p_filesz // don't pollute potential .bss
&& (1*4)<=(frag_mask & -(int)(size_t)hatch) ) ) // space left on page
// Try Elf64_Ehdr.e_ident[12..15] . warning: 'const' cast away
|| ( (hatch = (void *)(&((Elf64_Ehdr *)(phdr->p_vaddr + reloc))->e_ident[12])),
(phdr->p_offset==0) )
// Allocate and use a new page.
|| ( xprot = 1, hatch = mmap(0, PAGE_SIZE, PROT_WRITE|PROT_READ,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) )
)
{
hatch[0] = 0xc35a050f; // syscall; pop %rdx; ret
if (xprot) {
mprotect(hatch, 1*sizeof(unsigned), PROT_EXEC|PROT_READ);
}
}
else {
hatch = 0;
}
}
return hatch;
}
#elif defined(__powerpc64__) //}{
static unsigned
ORRX(unsigned ra, unsigned rs, unsigned rb) // or ra,rs,rb
{
return (31<<26) | ((037&(rs))<<21) | ((037&(ra))<<16) | ((037&(rb))<<11) | (444<<1) | 0;
}
static void *
make_hatch_ppc64(
Elf64_Phdr const *const phdr,
Elf64_Addr reloc,
unsigned const frag_mask
)
{
unsigned xprot = 0;
unsigned *hatch = 0;
DPRINTF("make_hatch %%p %%x %%x\\n",phdr,reloc,frag_mask);
if (phdr->p_type==PT_LOAD && phdr->p_flags & PF_X) {
if (
// Try page fragmentation just beyond .text .
( (hatch = (void *)(phdr->p_memsz + phdr->p_vaddr + reloc)),
( phdr->p_memsz==phdr->p_filesz // don't pollute potential .bss
&& (3*4)<=(frag_mask & -(int)(size_t)hatch) ) ) // space left on page
// Try Elf64_Phdr[1].p_paddr (2 instr) and .p_filesz (1 instr)
|| ( (hatch = (void *)(&((Elf64_Phdr *)(1+ // Ehdr and Phdr are contiguous
((Elf64_Ehdr *)(phdr->p_vaddr + reloc))))[1].p_paddr)),
(phdr->p_offset==0) )
// Allocate and use a new page.
|| ( xprot = 1, hatch = mmap(0, 1<<12, PROT_WRITE|PROT_READ,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) )
)
{
hatch[0]= 0x44000002; // sc
hatch[1]= ORRX(12,31,31); // movr r12,r31 ==> or r12,r31,r31
hatch[2]= 0x4e800020; // blr
if (xprot) {
mprotect(hatch, 3*sizeof(unsigned), PROT_EXEC|PROT_READ);
}
}
else {
hatch = 0;
}
}
return hatch;
}
#elif defined(__aarch64__) //{
static void *
make_hatch_arm64(
Elf64_Phdr const *const phdr,
uint64_t const reloc,
unsigned const frag_mask
)
{
unsigned xprot = 0;
unsigned *hatch = 0;
//DPRINTF((STR_make_hatch(),phdr,reloc));
if (phdr->p_type==PT_LOAD && phdr->p_flags & PF_X) {
// The format of the 'if' is
// if ( ( (hatch = loc1), test_loc1 )
// || ( (hatch = loc2), test_loc2 ) ) {
// action
// }
// which uses the comma to save bytes when test_locj involves locj
// and the action is the same when either test succeeds.
if (
// Try page fragmentation just beyond .text .
( (hatch = (void *)(~3ul & (3+ phdr->p_memsz + phdr->p_vaddr + reloc))),
( phdr->p_memsz==phdr->p_filesz // don't pollute potential .bss
&& (2*4)<=(frag_mask & -(int)(uint64_t)hatch) ) ) // space left on page
// Try Elf64_Ehdr.e_ident[8..15] . warning: 'const' cast away
|| ( (hatch = (void *)(&((Elf64_Ehdr *)(phdr->p_vaddr + reloc))->e_ident[8])),
(phdr->p_offset==0) )
// Allocate and use a new page.
|| ( xprot = 1, hatch = mmap(0, 1<<12, PROT_WRITE|PROT_READ,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) )
)
{
hatch[0] = 0xd4000001; // svc #0
hatch[1] = 0xd65f03c0; // ret (jmp *lr)
if (xprot) {
mprotect(hatch, 2*sizeof(unsigned), PROT_EXEC|PROT_READ);
}
}
else {
hatch = 0;
}
}
return hatch;
}
#endif //}
#if defined(__powerpc64__) || defined(__aarch64__) //{ bzero
static void
upx_bzero(char *p, size_t len)
{
DPRINTF("bzero %%x %%x\\n", p, len);
if (len) do {
*p++= 0;
} while (--len);
}
#define bzero upx_bzero
#else //}{
#define bzero(a,b) __builtin_memset(a,0,b)
#endif //}
static void
auxv_up(Elf64_auxv_t *av, unsigned const type, uint64_t const value)
{
if (!av || (1& (size_t)av)) { // none, or inhibited for PT_INTERP
return;
}
DPRINTF("\\nauxv_up %%d %%p\\n", type, value);
for (;; ++av) {
DPRINTF(" %%d %%p\\n", av->a_type, av->a_un.a_val);
if (av->a_type==type || (av->a_type==AT_IGNORE && type!=AT_NULL)) {
av->a_type = type;
av->a_un.a_val = value;
return;
}
if (av->a_type==AT_NULL) {
// We can't do this as part of the for loop because we overwrite
// AT_NULL too.
return;
}
}
}
// The PF_* and PROT_* bits are {1,2,4}; the conversion table fits in 32 bits.
#define REP8(x) \
((x)|((x)<<4)|((x)<<8)|((x)<<12)|((x)<<16)|((x)<<20)|((x)<<24)|((x)<<28))
#define EXP8(y) \
((1&(y)) ? 0xf0f0f0f0 : (2&(y)) ? 0xff00ff00 : (4&(y)) ? 0xffff0000 : 0)
#define PF_TO_PROT(pf) \
((PROT_READ|PROT_WRITE|PROT_EXEC) & ( \
( (REP8(PROT_EXEC ) & EXP8(PF_X)) \
|(REP8(PROT_READ ) & EXP8(PF_R)) \
|(REP8(PROT_WRITE) & EXP8(PF_W)) \
) >> ((pf & (PF_R|PF_W|PF_X))<<2) ))
// Find convex hull of PT_LOAD (the minimal interval which covers all PT_LOAD),
// and mmap that much, to be sure that a kernel using exec-shield-randomize
// won't place the first piece in a way that leaves no room for the rest.
static Elf64_Addr // returns relocation constant
xfind_pages(unsigned mflags, Elf64_Phdr const *phdr, int phnum,
Elf64_Addr *const p_brk
, Elf64_Addr const elfaddr
#if defined(__powerpc64__) || defined(__aarch64__)
, size_t const PAGE_MASK
#endif
)
{
Elf64_Addr lo= ~0, hi= 0, addr= 0;
mflags += MAP_PRIVATE | MAP_ANONYMOUS; // '+' can optimize better than '|'
DPRINTF("xfind_pages %%x %%p %%d %%p %%p\\n", mflags, phdr, phnum, elfaddr, p_brk);
for (; --phnum>=0; ++phdr) if (PT_LOAD==phdr->p_type) {
if (phdr->p_vaddr < lo) {
lo = phdr->p_vaddr;
}
if (hi < (phdr->p_memsz + phdr->p_vaddr)) {
hi = phdr->p_memsz + phdr->p_vaddr;
}
}
lo -= ~PAGE_MASK & lo; // round down to page boundary
hi = PAGE_MASK & (hi - lo - PAGE_MASK -1); // page length
if (MAP_FIXED & mflags) {
addr = lo;
}
else if (0==lo) { // -pie ET_DYN
addr = elfaddr;
if (addr) {
mflags |= MAP_FIXED;
}
}
DPRINTF(" addr=%%p lo=%%p hi=%%p\\n", addr, lo, hi);
addr = (Elf64_Addr)mmap((void *)addr, hi, PROT_NONE, mflags, -1, 0);
DPRINTF(" addr=%%p\\n", addr);
*p_brk = hi + addr; // the logical value of brk(0)
return (Elf64_Addr)(addr - lo);
}
static Elf64_Addr // entry address
do_xmap(
Elf64_Ehdr const *const ehdr,
Extent *const xi,
int const fdi,
Elf64_auxv_t *const av,
f_expand *const f_exp,
f_unfilter *const f_unf,
Elf64_Addr *p_reloc
#if defined(__powerpc64__) || defined(__aarch64__)
, size_t const PAGE_MASK
#endif
)
{
Elf64_Phdr const *phdr = (Elf64_Phdr const *)(void const *)(ehdr->e_phoff +
(char const *)ehdr);
Elf64_Addr v_brk;
Elf64_Addr const reloc = xfind_pages(
((ET_DYN!=ehdr->e_type) ? MAP_FIXED : 0), phdr, ehdr->e_phnum, &v_brk
, *p_reloc
#if defined(__powerpc64__) || defined(__aarch64__)
, PAGE_MASK
#endif
);
DPRINTF("do_xmap reloc=%%p\\n", reloc);
int j;
for (j=0; j < ehdr->e_phnum; ++phdr, ++j)
if (xi && PT_PHDR==phdr->p_type) {
auxv_up(av, AT_PHDR, phdr->p_vaddr + reloc);
} else
if (PT_LOAD==phdr->p_type) {
if (xi && !phdr->p_offset /*&& ET_EXEC==ehdr->e_type*/) { // 1st PT_LOAD
// ? Compressed PT_INTERP must not overwrite values from compressed a.out?
auxv_up(av, AT_PHDR, phdr->p_vaddr + reloc + ehdr->e_phoff);
auxv_up(av, AT_PHNUM, ehdr->e_phnum);
auxv_up(av, AT_PHENT, ehdr->e_phentsize); /* ancient kernels might omit! */
//auxv_up(av, AT_PAGESZ, PAGE_SIZE); /* ld-linux.so.2 does not need this */
}
unsigned const prot = PF_TO_PROT(phdr->p_flags);
Extent xo;
size_t mlen = xo.size = phdr->p_filesz;
char *addr = xo.buf = reloc + (char *)phdr->p_vaddr;
char *haddr = phdr->p_memsz + addr;
size_t frag = (size_t)addr &~ PAGE_MASK;
mlen += frag;
addr -= frag;
if (addr != mmap(addr, mlen, prot | (xi ? PROT_WRITE : 0),
MAP_FIXED | MAP_PRIVATE | (xi ? MAP_ANONYMOUS : 0),
(xi ? -1 : fdi), phdr->p_offset - frag) ) {
err_exit(8);
}
if (xi) {
unpackExtent(xi, &xo, f_exp, f_unf);
}
// Linux does not fixup the low end, so neither do we.
//if (PROT_WRITE & prot) {
// bzero(addr, frag); // fragment at lo end
//}
frag = (-mlen) &~ PAGE_MASK; // distance to next page boundary
if (PROT_WRITE & prot) { // note: read-only .bss not supported here
bzero(mlen+addr, frag); // fragment at hi end
}
if (xi) {
#if defined(__x86_64) //{
void *const hatch = make_hatch_x86_64(phdr, reloc, ~PAGE_MASK);
#elif defined(__powerpc64__) //}{
void *const hatch = make_hatch_ppc64(phdr, reloc, ~PAGE_MASK);
#elif defined(__aarch64__) //}{
void *const hatch = make_hatch_arm64(phdr, reloc, ~PAGE_MASK);
#endif //}
if (0!=hatch) {
auxv_up((Elf64_auxv_t *)(~1 & (size_t)av), AT_NULL, (size_t)hatch);
}
if (0!=mprotect(addr, mlen, prot)) {
err_exit(10);
ERR_LAB
}
}
addr += mlen + frag; /* page boundary on hi end */
if (addr < haddr) { // need pages for .bss
if (addr != mmap(addr, haddr - addr, prot,
MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0 ) ) {
err_exit(9);
}
}
}
if (xi) { // 1st call (main); also have (0!=av) here
if (ET_DYN!=ehdr->e_type) {
// Needed only if compressed shell script invokes compressed shell.
// brk(v_brk); // SIGSEGV when is_big [unmaps ourself!]
}
}
if (p_reloc) {
*p_reloc = reloc;
}
return ehdr->e_entry + reloc;
}
/*************************************************************************
// upx_main - called by our entry code
//
// This function is optimized for size.
**************************************************************************/
void *
upx_main( // returns entry address
struct b_info const *const bi, // 1st block header
size_t const sz_compressed, // total length
Elf64_Ehdr *const ehdr, // temp char[sz_ehdr] for decompressing
Elf64_auxv_t *const av,
f_expand *const f_exp,
f_unfilter *const f_unf
#if defined(__x86_64) //{
, Elf64_Addr elfaddr // In: &Elf64_Ehdr for stub
#elif defined(__powerpc64__) //}{
, Elf64_Addr *p_reloc // In: &Elf64_Ehdr for stub; Out: 'slide' for PT_INTERP
, size_t const PAGE_MASK
#elif defined(__aarch64__) //}{
, Elf64_Addr elfaddr
, size_t const PAGE_MASK
#endif //}
)
{
Extent xo, xi1, xi2;
xo.buf = (char *)ehdr;
xo.size = bi->sz_unc;
xi2.buf = CONST_CAST(char *, bi); xi2.size = bi->sz_cpr + sizeof(*bi);
xi1.buf = CONST_CAST(char *, bi); xi1.size = sz_compressed;
// ehdr = Uncompress Ehdr and Phdrs
unpackExtent(&xi2, &xo, f_exp, 0); // never filtered?
#if defined(__x86_64) || defined(__aarch64__) //{
Elf64_Addr *const p_reloc = &elfaddr;
#endif //}
DPRINTF("upx_main1 .e_entry=%%p p_reloc=%%p *p_reloc=%%p PAGE_MASK=%%p\\n",
ehdr->e_entry, p_reloc, *p_reloc, PAGE_MASK);
Elf64_Phdr *phdr = (Elf64_Phdr *)(1+ ehdr);
// De-compress Ehdr again into actual position, then de-compress the rest.
Elf64_Addr entry = do_xmap(ehdr, &xi1, 0, av, f_exp, f_unf, p_reloc
#if defined(__powerpc64__) || defined(__aarch64__)
, PAGE_MASK
#endif
);
DPRINTF("upx_main2 entry=%%p *p_reloc=%%p\\n", entry, *p_reloc);
auxv_up(av, AT_ENTRY , entry);
{ // Map PT_INTERP program interpreter
phdr = (Elf64_Phdr *)(1+ ehdr);
unsigned j;
for (j=0; j < ehdr->e_phnum; ++phdr, ++j) if (PT_INTERP==phdr->p_type) {
char const *const iname = *p_reloc + (char const *)phdr->p_vaddr;
int const fdi = open(iname, O_RDONLY, 0);
if (0 > fdi) {
err_exit(18);
}
if (MAX_ELF_HDR!=read(fdi, (void *)ehdr, MAX_ELF_HDR)) {
ERR_LAB
err_exit(19);
}
// We expect PT_INTERP to be ET_DYN at 0.
// Thus do_xmap will set *p_reloc = slide.
*p_reloc = 0; // kernel picks where PT_INTERP goes
entry = do_xmap(ehdr, 0, fdi, 0, 0, 0, p_reloc
#if defined(__powerpc64__) || defined(__aarch64__)
, PAGE_MASK
#endif
);
auxv_up(av, AT_BASE, *p_reloc); // musl
close(fdi);
}
}
return (void *)entry;
}
#if DEBUG //{
#if defined(__powerpc64__) //{
#define __NR_write 4
typedef unsigned long size_t;
#if 0 //{
static int
write(int fd, char const *ptr, size_t len)
{
register int sys asm("r0") = __NR_write;
register int a0 asm("r3") = fd;
register void const *a1 asm("r4") = ptr;
register size_t const a2 asm("r5") = len;
__asm__ __volatile__("sc"
: "=r"(a0)
: "r"(sys), "r"(a0), "r"(a1), "r"(a2)
: "r0", "r4", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "r13"
);
return a0;
}
#else //}{
ssize_t
write(int fd, void const *ptr, size_t len)
{
register int sys asm("r0") = __NR_write;
register int a0 asm("r3") = fd;
register void const *a1 asm("r4") = ptr;
register size_t a2 asm("r5") = len;
__asm__ __volatile__("sc"
: "+r"(sys), "+r"(a0), "+r"(a1), "+r"(a2)
:
: "r6", "r7", "r8", "r9", "r10", "r11", "r12", "r13"
);
return a0;
}
#endif //}
#endif //}
static int
unsimal(unsigned x, char *ptr, int n)
{
unsigned m = 10;
while (10 <= (x / m)) m *= 10;
while (10 <= x) {
unsigned d = x / m;
x -= m * d;
m /= 10;
ptr[n++] = '0' + d;
}
ptr[n++] = '0' + x;
return n;
}
static int
decimal(int x, char *ptr, int n)
{
if (x < 0) {
x = -x;
ptr[n++] = '-';
}
return unsimal(x, ptr, n);
}
static int
heximal(unsigned long x, char *ptr, int n)
{
unsigned j = -1+ 2*sizeof(unsigned long);
unsigned long m = 0xful << (4 * j);
for (; j; --j, m >>= 4) { // omit leading 0 digits
if (m & x) break;
}
for (; m; --j, m >>= 4) {
unsigned d = 0xf & (x >> (4 * j));
ptr[n++] = ((10<=d) ? ('a' - 10) : '0') + d;
}
return n;
}
#define va_arg __builtin_va_arg
#define va_end __builtin_va_end
#define va_list __builtin_va_list
#define va_start __builtin_va_start
static int
dprintf(char const *fmt, ...)
{
int n= 0;
char const *literal = 0; // NULL
char buf[24]; // ~0ull == 18446744073709551615 ==> 20 chars
va_list va; va_start(va, fmt);
for (;;) {
char c = *fmt++;
if (!c) { // end of fmt
if (literal) {
goto finish;
}
break; // goto done
}
if ('%'!=c) {
if (!literal) {
literal = fmt; // 1 beyond start of literal
}
continue;
}
// '%' == c
if (literal) {
finish:
n += write(2, -1+ literal, fmt - literal);
literal = 0; // NULL
if (!c) { // fmt already ended
break; // goto done
}
}
switch (c= *fmt++) { // deficiency: does not handle _long_
default: { // un-implemented conversion
n+= write(2, -1+ fmt, 1);
} break;
case 0: { // fmt ends with "%\0" ==> ignore
goto done;
} break;
case 'u': {
n+= write(2, buf, unsimal(va_arg(va, unsigned), buf, 0));
} break;
case 'd': {
n+= write(2, buf, decimal(va_arg(va, int), buf, 0));
} break;
case 'p': {
buf[0] = '0';
buf[1] = 'x';
n+= write(2, buf, heximal((unsigned long)va_arg(va, void *), buf, 2));
} break;
case 'x': {
buf[0] = '0';
buf[1] = 'x';
n+= write(2, buf, heximal(va_arg(va, int), buf, 2));
} break;
} // 'switch'
}
done:
va_end(va);
return n;
}
#endif //}
/* vim:set ts=4 sw=4 et: */
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