From 83b78af8033e10e959e7b56c74b1c3c5ee2f8fc5 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Wed, 28 Jul 2021 12:48:21 +0100
Subject: win32: code shrink using is_prefixed_with()

Use is_prefixed_with() rather than strncmp() in a few places,
and the case-insensitive analogues.

Saves 96 bytes in 64-bit build, 192 bytes in 32-bit.
---
 networking/httpd.c |  5 +++++
 shell/ash.c        |  8 ++++----
 win32/mingw.c      | 34 ++++++++++++++++++----------------
 3 files changed, 27 insertions(+), 20 deletions(-)

diff --git a/networking/httpd.c b/networking/httpd.c
index fcc49853a..fcd1627b1 100644
--- a/networking/httpd.c
+++ b/networking/httpd.c
@@ -557,7 +557,12 @@ enum {
 } while (0)
 
 
+#if !ENABLE_PLATFORM_MINGW32
 #define STRNCASECMP(a, str) strncasecmp((a), (str), sizeof(str)-1)
+#else
+/* Not exactly equivalent to strncasecmp(), but OK for its use here */
+#define STRNCASECMP(a, str) (!is_prefixed_with_case((a), (str)))
+#endif
 
 /* Prototypes */
 enum {
diff --git a/shell/ash.c b/shell/ash.c
index 3e02a4e1f..08e34d6e7 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -15269,8 +15269,8 @@ init(void)
 		 * because it appears first.
 		 */
 		for (envp = environ; envp && *envp; envp++) {
-			if (strncasecmp(*envp, "PATH=", 5) == 0 &&
-			    strncmp(*envp, "PATH=", 5) != 0) {
+			if (is_prefixed_with_case(*envp, "PATH=") &&
+					!is_prefixed_with(*envp, "PATH=")) {
 				break;
 			}
 		}
@@ -15295,8 +15295,8 @@ init(void)
 				/* Convert backslashes to forward slashes in value but
 				 * not if we're on Windows XP or for variables known to
 				 * cause problems */
-				if ( !winxp && strncmp(*envp, "SYSTEMROOT=", 11) != 0 &&
-						strncmp(*envp, "COMSPEC=", 8) != 0 ) {
+				if (!winxp && !is_prefixed_with(*envp, "SYSTEMROOT=") &&
+						!is_prefixed_with(*envp, "COMSPEC=")) {
 					bs_to_slash(end+1);
 				}
 
diff --git a/win32/mingw.c b/win32/mingw.c
index 1e3cce17a..943202f41 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -171,7 +171,7 @@ static int rand_fd = -1;
  */
 int get_dev_type(const char *filename)
 {
-	if (filename && !strncmp(filename, "/dev/", 5))
+	if (filename && is_prefixed_with(filename, "/dev/"))
 		return index_in_strings("null\0zero\0urandom\0", filename+5);
 
 	return NOT_DEVICE;
@@ -414,7 +414,8 @@ mode_t mingw_umask(mode_t new_mode)
  */
 static int has_exec_format(const char *name)
 {
-	int n;
+	int n, sig;
+	unsigned int offset;
 	unsigned char buf[1024];
 
 	/* special case: skip DLLs, there are thousands of them! */
@@ -435,19 +436,20 @@ static int has_exec_format(const char *name)
 	 * the magic from the file command.
 	 */
 	if (buf[0] == 'M' && buf[1] == 'Z') {
-		unsigned int offset = (buf[0x19] << 8) | buf[0x18];
+		offset = (buf[0x19] << 8) + buf[0x18];
 		if (offset > 0x3f) {
-			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];
+			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];
 					if (sig == 0x10b || sig == 0x20b) {
-						sig = (ptr[23] << 8) | ptr[22];
-						if ((sig & 0x2000) != 0)	// DLL
+						sig = (buf[offset+23] << 8) + buf[offset+22];
+						if ((sig & 0x2000) != 0) {
+							/* DLL */
 							return 0;
-						sig = ptr[92];
+						}
+						sig = buf[offset+92];
 						return (sig == 1 || sig == 2 || sig == 3 || sig == 7);
 					}
 				}
@@ -1230,13 +1232,13 @@ static char *normalize_ntpathA(char *buf)
 	/* fix absolute path prefixes */
 	if (buf[0] == '\\') {
 		/* strip NT namespace prefixes */
-		if (!strncmp(buf, "\\??\\", 4) ||
-		    !strncmp(buf, "\\\\?\\", 4))
+		if (is_prefixed_with(buf, "\\??\\") ||
+				is_prefixed_with(buf, "\\\\?\\"))
 			buf += 4;
-		else if (!strncasecmp(buf, "\\DosDevices\\", 12))
+		else if (is_prefixed_with_case(buf, "\\DosDevices\\"))
 			buf += 12;
 		/* replace remaining '...UNC\' with '\\' */
-		if (!strncasecmp(buf, "UNC\\", 4)) {
+		if (is_prefixed_with_case(buf, "UNC\\")) {
 			buf += 2;
 			*buf = '\\';
 		}
-- 
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