Added a set_current_dir() function.

dlib/misc_api/misc_api_kernel_1.cpp

@@ -4,6 +4,7 @@
 #define DLIB_MISC_API_KERNEL_1_CPp_
 
 #include "../platform.h"
+#include "../threads.h"
 
 #ifdef WIN32
 
@@ -30,9 +31,17 @@ namespace dlib
 
 // ----------------------------------------------------------------------------------------
 
+    namespace
+    {
+        mutex cwd_mutex;
+    }
+
     std::string get_current_dir (
     )
     {
+        // need to lock a mutex here because getting and setting the
+        // current working directory is not thread safe on windows.
+        auto_mutex lock(cwd_mutex);
         char buf[1024];
         if (GetCurrentDirectoryA(sizeof(buf),buf) == 0)
         {
@@ -44,6 +53,21 @@ namespace dlib
         }
     }
 
+// ----------------------------------------------------------------------------------------
+
+    void set_current_dir (
+        const std::string& new_dir
+    )
+    {
+        // need to lock a mutex here because getting and setting the
+        // current working directory is not thread safe on windows.
+        auto_mutex lock(cwd_mutex);
+        if (SetCurrentDirectory(new_dir.c_str()) == 0)
+        {
+            throw set_current_dir_error("Error changing current dir to '" + new_dir + "'" + GetLastError());
+        }
+    }
+
 // ----------------------------------------------------------------------------------------
 
     uint64 timestamper::

dlib/misc_api/misc_api_kernel_1.h

@@ -27,6 +27,20 @@ namespace dlib
     std::string get_current_dir (
     );
 
+// ----------------------------------------------------------------------------------------
+
+    class set_current_dir_error : public error
+    {
+    public:
+        set_current_dir_error(
+            const std::string& a
+        ): error(a) {}
+    };
+
+    void set_current_dir (
+        const std::string& new_dir
+    );
+
 // ----------------------------------------------------------------------------------------
 
     class timestamper 

dlib/misc_api/misc_api_kernel_2.cpp

@@ -55,6 +55,18 @@ namespace dlib
         }
     }
 
+// ----------------------------------------------------------------------------------------
+
+    void set_current_dir (
+        const std::string& new_dir
+    )
+    {
+        if (chdir(new_dir.c_str()))
+        {
+            throw set_current_dir_error("Error changing current dir to '" + new_dir + "'");
+        }
+    }
+
 // ----------------------------------------------------------------------------------------
 
     uint64 timestamper::

dlib/misc_api/misc_api_kernel_2.h

@@ -27,6 +27,20 @@ namespace dlib
     std::string get_current_dir (
     );
 
+// ----------------------------------------------------------------------------------------
+
+    class set_current_dir_error : public error
+    {
+    public:
+        set_current_dir_error(
+            const std::string& a
+        ): error(a) {}
+    };
+
+    void set_current_dir (
+        const std::string& new_dir
+    );
+
 // ----------------------------------------------------------------------------------------
 
     class timestamper 

dlib/misc_api/misc_api_kernel_abstract.h

@@ -34,7 +34,7 @@ namespace dlib
     );
     /*!
         ensures
-            - if (no errors occurr) then
+            - if (no errors occur) then
                 - returns the path to the current working directory
             - else
                 - returns ""
@@ -42,6 +42,23 @@ namespace dlib
             - std::bad_alloc
     !*/
 
+// ----------------------------------------------------------------------------------------
+
+    class set_current_dir_error : public error;
+
+    void set_current_dir (
+        const std::string& new_dir
+    );
+    /*!
+        ensures
+            - sets the current working directory to new_dir
+        throws
+            - std::bad_alloc
+            - set_current_dir_error
+              This exception is thrown if there is an error when attempting
+              to change the current working directory.
+    !*/
+
 // ----------------------------------------------------------------------------------------
 
     class dir_create_error : public error { 
@@ -85,7 +102,7 @@ namespace dlib
         /*!
             ensures
                 - returns a timestamp that measures the time in microseconds since an 
-                  arbitrary point in the past.  Note that this arbitray point remains
+                  arbitrary point in the past.  Note that this arbitrary point remains
                   the same between all calls to get_timestamp().
         !*/
     };