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avoid copying (faster for same instruction size)

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committer: jreiser <jreiser> 958949861 +0000
This commit is contained in:
John Reiser 2000-05-21 22:57:41 +00:00
parent 6bb104b39f
commit f443210ded
1 changed files with 26 additions and 37 deletions
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63
src/stub/l_lx_exec.c
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@ -49,14 +49,14 @@
#undef xwrite
struct Extent {
size_t size; // must be first to match size[0] uncompressed size
int size; // must be first to match size[0] uncompressed size
char *buf;
};
static void
xread(struct Extent *const x, char *const buf, size_t const count)
{
if (x->size < count) {
if (x->size < (int)count) {
exit(127);
}
#if 0 //{
@ -81,7 +81,7 @@ xread(struct Extent *const x, char *const buf, size_t const count)
}
#if 1
static __inline__ int xwrite(int fd, const void *buf, int count)
static int xwrite(int fd, const void *buf, int count)
{
// note: we can assert(count > 0);
do {
@ -126,6 +126,17 @@ static char *upx_itoa(char *buf, unsigned long v)
return buf;
}
static uint32_t ascii5(uint32_t r, unsigned k, char *p)
{
do {
unsigned char d = r % 32;
if (d >= 26) d += '0' - 'Z' - 1;
*--p += d;
r /= 32;
} while (--k > 0);
return r;
}
#if defined(__i386__)
# define SET2(p, c0, c1) \
@ -246,19 +257,9 @@ void upx_main(
// Protect against Denial-of-Service attacks.
{
char *p = tmpname_buf + sizeof(tmpname_buf) - 1;
uint32_t r;
// Compute the last 4 characters (20 bits) from getpid().
{
unsigned k = 4;
r = (uint32_t) pid;
do {
unsigned char d = r % 32;
if (d >= 26) d += '0' - 'Z' - 1;
*--p += d;
r /= 32;
} while (--k > 0);
}
uint32_t r = ascii5((uint32_t)pid, 4, p); p-=4;
// Provide 4 random bytes from our program id.
r ^= header.p_progid;
@ -280,15 +281,7 @@ void upx_main(
#endif
}
// Compute 7 more characters from the 32 random bits.
{
unsigned k = 7;
do {
unsigned char d = r % 32;
if (d >= 26) d += '0' - 'Z' - 1;
*--p += d;
r /= 32;
} while (--k > 0);
}
ascii5(r, 7, p);
}
// Just in case, remove the file.
@ -358,24 +351,21 @@ void upx_main(
// assert(h.sz_unc > 0 && h.sz_unc <= blocksize);
// assert(h.sz_cpr > 0 && h.sz_cpr <= blocksize);
// Read compressed block.
i = header.p_blocksize + OVERHEAD - h.sz_cpr;
xread(&xi, buf+i, h.sz_cpr);
// Decompress block.
if (h.sz_cpr < h.sz_unc)
{
// in-place decompression
header.p_filesize -= h.sz_unc;
if (h.sz_cpr < h.sz_unc) { // Decompress block.
nrv_uint out_len;
i = (*f_decompress)(buf+i, h.sz_cpr, buf, &out_len);
i = (*f_decompress)(xi.buf, h.sz_cpr, buf, &out_len);
if (i != 0 || out_len != (nrv_uint)h.sz_unc)
goto error;
// i == 0 now
i = xwrite(fdo, buf, h.sz_unc);
}
else { // Incompressible block
i = xwrite(fdo, xi.buf, h.sz_unc);
}
xi.buf += h.sz_cpr;
xi.size -= h.sz_cpr;
// Write uncompressed block.
if (xwrite(fdo, buf+i, h.sz_unc) != 0)
{
if (xi.size < 0 || i != 0) {
// error exit is here in the middle to keep the jumps short.
error:
(void) unlink(tmpname);
@ -385,7 +375,6 @@ void upx_main(
for (;;)
(void) exit(127);
}
header.p_filesize -= h.sz_unc;
// We will never touch these pages again.
i = (PAGE_MASK & (unsigned)xi.buf) - (unsigned)next_unmap;