From 5776a5f8d5bfe83b72dc3d9788e92a2a11b22cd2 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Tue, 27 Jul 2021 13:09:09 +0100
Subject: win32: code shrink has_exec_format()
In the code to detect binaries:
- use '|' rather than '+' to combine bytes;
- fix the test that the PE header is within the buffer;
- once we have the offset to the PE header make a pointer to it;
- cosmetic changes.
Saves 96 bytes.
---
win32/mingw.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/win32/mingw.c b/win32/mingw.c
index 82316e69d..1e3cce17a 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -414,8 +414,7 @@ mode_t mingw_umask(mode_t new_mode)
*/
static int has_exec_format(const char *name)
{
- int n, sig;
- unsigned int offset;
+ int n;
unsigned char buf[1024];
/* special case: skip DLLs, there are thousands of them! */
@@ -436,20 +435,19 @@ static int has_exec_format(const char *name)
* the magic from the file command.
*/
if (buf[0] == 'M' && buf[1] == 'Z') {
- offset = (buf[0x19] << 8) + buf[0x18];
+ unsigned int offset = (buf[0x19] << 8) | buf[0x18];
if (offset > 0x3f) {
- offset = (buf[0x3f] << 24) + (buf[0x3e] << 16) +
- (buf[0x3d] << 8) + buf[0x3c];
- if (offset < sizeof(buf)-100) {
- if (memcmp(buf+offset, "PE\0\0", 4) == 0) {
- sig = (buf[offset+25] << 8) + buf[offset+24];
+ offset = (buf[0x3f] << 24) | (buf[0x3e] << 16) |
+ (buf[0x3d] << 8) | buf[0x3c];
+ if (offset + 100 < n) {
+ unsigned char *ptr = buf + offset;
+ if (memcmp(ptr, "PE\0\0", 4) == 0) {
+ unsigned int sig = (ptr[25] << 8) | ptr[24];
if (sig == 0x10b || sig == 0x20b) {
- sig = (buf[offset+23] << 8) + buf[offset+22];
- if ((sig & 0x2000) != 0) {
- /* DLL */
+ sig = (ptr[23] << 8) | ptr[22];
+ if ((sig & 0x2000) != 0) // DLL
return 0;
- }
- sig = buf[offset+92];
+ sig = ptr[92];
return (sig == 1 || sig == 2 || sig == 3 || sig == 7);
}
}
--
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