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upx_itoa() in assembler to enforce no relocation

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Makefile l_lx_exec.c upx_itoa.asm

committer: jreiser <jreiser> 1037070863 +0000
This commit is contained in:
John Reiser
2002-11-12 03:14:23 +00:00
parent f3b64cfe78
commit de6e8c8020
3 changed files with 90 additions and 31 deletions
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src/stub/l_lx_exec.c
+31 -29
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@@ -73,33 +73,35 @@ static __inline__ int xwrite(int fd, const void *buf, int count)
// util
**************************************************************************/
// FIXME: all code in this source file must be relocatible, so
// we have to use `volatile' here.
// FIXME: rewrite upx_itoa() in assembly
static char *upx_itoa(char *buf, unsigned long v)
{
// const unsigned TEN = 10;
volatile unsigned TEN = 10;
char *p = buf;
{
unsigned long k = v;
do {
p++;
k /= TEN;
} while (k > 0);
}
buf = p;
*p = 0;
{
unsigned long k = v;
do {
*--p = '0' + k % TEN;
k /= TEN;
} while (k > 0);
}
return buf;
}
extern char *
__attribute__ ((regparm(2), stdcall)) // be ruthless
upx_itoa(unsigned long v, char *buf);
// Some versions of gcc optimize the division and/or remainder using
// a multiplication by (2**32)/10, and use a relocatable 32-bit address
// to reference the constant. We require no relocations because we move
// the code at runtime. See upx_itoa.asm for replacement [also smaller.]
//static char *upx_itoa(unsigned long v, char *buf)
//{
// volatile unsigned TEN = 10; // an ugly way to achieve no relocation
// char *p = buf;
// {
// unsigned long k = v;
// do {
// p++;
// k /= TEN;
// } while (k > 0);
// }
// buf = p;
// *p = 0;
// {
// unsigned long k = v;
// do {
// *--p = '0' + k % TEN;
// k /= TEN;
// } while (k > 0);
// }
// return buf;
//}
static uint32_t ascii5(char *p, uint32_t v, unsigned n)
{
@@ -159,9 +161,9 @@ go_self(char const *tmpname, char *argv[], char *envp[])
SET4(procself_buf + 0, '/', 'p', 'r', 'o');
SET4(procself_buf + 4, 'c', '/', 0 , 0 );
{
char *const procself = upx_itoa(procself_buf + 6, getpid());
char *const procself = upx_itoa(getpid(), procself_buf + 6);
SET4(procself, '/', 'f', 'd', '/');
upx_itoa(procself + 4, fdi);
upx_itoa(fdi, procself + 4);
}
// Check for working /proc/self/fd/X by accessing the