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.

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 = '\\';
                 }