Centralise stripslashes() and make it OS-sensitive.

I noticed that Unix PSCP was unwantedly renaming downloaded files
which had a backslash in their names, because pscp.c's stripslashes()
treated \ as a path component separator, since it hadn't been modified
since PSCP ran on Windows only.

It also turns out that pscp.c, psftp.c and winsftp.c all had a
stripslashes(), and they didn't all have quite the same prototype. So
now there's one in winsftp.c and one in uxsftp.c, with appropriate
OS-dependent behaviour, and the ones in pscp.c and psftp.c are gone.

pscp.c

@@ -605,35 +605,6 @@ static char *colon(char *str)
 	return (NULL);
 }
 
-/*
- * Return a pointer to the portion of str that comes after the last
- * slash (or backslash or colon, if `local' is TRUE).
- *
- * This function has the annoying strstr() property of taking a const
- * char * and returning a char *. You should treat it as if it was a
- * pair of overloaded functions, one mapping mutable->mutable and the
- * other const->const :-(
- */
-static char *stripslashes(const char *str, int local)
-{
-    char *p;
-
-    if (local) {
-        p = strchr(str, ':');
-        if (p) str = p+1;
-    }
-
-    p = strrchr(str, '/');
-    if (p) str = p+1;
-
-    if (local) {
-	p = strrchr(str, '\\');
-	if (p) str = p+1;
-    }
-
-    return (char *)str;
-}
-
 /*
  * Determine whether a string is entirely composed of dots.
  */

psftp.c

@@ -169,35 +169,6 @@ char *canonify(const char *name)
     }
 }
 
-/*
- * Return a pointer to the portion of str that comes after the last
- * slash (or backslash or colon, if `local' is TRUE).
- *
- * This function has the annoying strstr() property of taking a const
- * char * and returning a char *. You should treat it as if it was a
- * pair of overloaded functions, one mapping mutable->mutable and the
- * other const->const :-(
- */
-static char *stripslashes(const char *str, int local)
-{
-    char *p;
-
-    if (local) {
-        p = strchr(str, ':');
-        if (p) str = p+1;
-    }
-
-    p = strrchr(str, '/');
-    if (p) str = p+1;
-
-    if (local) {
-	p = strrchr(str, '\\');
-	if (p) str = p+1;
-    }
-
-    return (char *)str;
-}
-
 /*
  * qsort comparison routine for fxp_name structures. Sorts by real
  * file name.

psftp.h

@@ -177,4 +177,21 @@ int create_directory(const char *name);
  */
 char *dir_file_cat(const char *dir, const char *file);
 
+/*
+ * Return a pointer to the portion of str that comes after the last
+ * path component separator.
+ *
+ * If 'local' is false, path component separators are taken to just be
+ * '/', on the assumption that we're discussing the path syntax on the
+ * server. But if 'local' is true, the separators are whatever the
+ * local OS will treat that way - so that includes '\' and ':' on
+ * Windows.
+ *
+ * This function has the annoying strstr() property of taking a const
+ * char * and returning a char *. You should treat it as if it was a
+ * pair of overloaded functions, one mapping mutable->mutable and the
+ * other const->const :-(
+ */
+char *stripslashes(const char *str, int local);
+
 #endif /* PUTTY_PSFTP_H */

unix/uxsftp.c

@@ -413,6 +413,20 @@ void finish_wildcard_matching(WildcardMatcher *dir) {
     sfree(dir);
 }
 
+char *stripslashes(const char *str, int local)
+{
+    char *p;
+
+    /*
+     * On Unix, we do the same thing regardless of the 'local'
+     * parameter.
+     */
+    p = strrchr(str, '/');
+    if (p) str = p+1;
+
+    return (char *)str;
+}
+
 int vet_filename(const char *name)
 {
     if (strchr(name, '/'))

windows/winsftp.c

@@ -340,14 +340,14 @@ struct WildcardMatcher {
     char *srcpath;
 };
 
-/*
- * Return a pointer to the portion of str that comes after the last
- * slash (or backslash or colon, if `local' is TRUE).
- */
-static char *stripslashes(char *str, int local)
+char *stripslashes(const char *str, int local)
 {
     char *p;
 
+    /*
+     * On Windows, \ / : are all path component separators.
+     */
+
     if (local) {
         p = strchr(str, ':');
         if (p) str = p+1;
@@ -361,7 +361,7 @@ static char *stripslashes(char *str, int local)
 	if (p) str = p+1;
     }
 
-    return str;
+    return (char *)str;
 }
 
 WildcardMatcher *begin_wildcard_matching(const char *name)