# VFS: add support for redirecting writes of files that are in archives to writable mod directory (required for editor)

This was SVN commit r3818.

source/lib/lib_errors.h

@@ -438,8 +438,9 @@ ERR(-100330, ERR_IO, "Error during IO")
 ERR(-100331, ERR_EOF, "Reading beyond end of file")
 // .. mount
 ERR(-100340, ERR_ALREADY_MOUNTED, "Directory (tree) already mounted")
-ERR(-100341, ERR_INVALID_MOUNT_TYPE, "Invalid mount type (memory corruption?)")
-ERR(-100342, ERR_ROOT_DIR_ALREADY_SET, "Attempting to set FS root dir more than once")
+ERR(-100341, ERR_NOT_MOUNTED, "Specified directory is not mounted")
+ERR(-100342, ERR_INVALID_MOUNT_TYPE, "Invalid mount type (memory corruption?)")
+ERR(-100343, ERR_ROOT_DIR_ALREADY_SET, "Attempting to set FS root dir more than once")
 // .. misc
 ERR(-100350, ERR_UNKNOWN_CMETHOD, "Unknown/unsupported compression method")
 ERR(-100351, ERR_IS_COMPRESSED, "Invalid operation for a compressed file")

source/lib/res/file/file.h

@@ -269,9 +269,13 @@ enum FileFlags
 	// promising they will set atom_fn).
 	FILE_DONT_SET_FN  = 0x80,
 
-	// sum of all flags above. used when validating flag parameters and
-	// by zip.cpp because its flags live alongside these.
-	FILE_FLAG_ALL     = 0xFF
+	// (only relevant for VFS) file will be written into the
+	// appropriate subdirectory of the mount point established by
+	// vfs_mod_set_write_target. see documentation there.
+	FILE_WRITE_TO_MOD  = FILE_WRITE|0x100,
+
+	// sum of all flags above. used when validating flag parameters.
+	FILE_FLAG_ALL     = 0x1FF
 };
 
 

source/lib/res/file/vfs.cpp

@@ -360,9 +360,7 @@ LibError vfs_stat(const char* V_path, struct stat* s)
 }
 
 
-
-
-
+//-----------------------------------------------------------------------------
 
 struct VFile
 {
@@ -423,6 +421,9 @@ static LibError VFile_reload(VFile* vf, const char* V_path, Handle)
 		return err;
 	}
 
+	if(flags & FILE_WRITE_TO_MOD)
+		RETURN_ERR(set_mount_to_mod_target(tf));
+
 	RETURN_ERR(xfile_open(V_path, flags, tf, &vf->f));
 
 	stats_open(vf->f.atom_fn, vf->f.size);

source/lib/res/file/vfs.h

@@ -288,6 +288,15 @@ extern LibError vfs_mount(const char* V_mount_point, const char* P_real_dir, uin
 // unmount a previously mounted item, and rebuild the VFS afterwards.
 extern LibError vfs_unmount(const char* name);
 
+// set current "mod write directory" to P_target_dir, which must
+// already have been mounted into the VFS.
+// all files opened for writing with the FILE_WRITE_TO_MOD flag set will
+// be written into the appropriate subdirectory of this mount point.
+//
+// this allows e.g. the editor to write files that are already
+// stored in archives, which are read-only.
+extern LibError vfs_mod_set_write_target(const char* P_target_dir);
+
 
 //
 // directory entry

source/lib/res/file/vfs_mount.cpp

@@ -676,7 +676,7 @@ struct IsArchiveMount
 {
 	bool operator()(const Mount& m) const
 	{
-		return (m.archive > 0);
+		return (m.type == MT_ARCHIVE);
 	}
 };
 
@@ -740,6 +740,60 @@ LibError mount_make_vfs_path(const char* P_path, char* V_path)
 }
 
 
+
+
+static const Mount* mod_target;
+
+// set current "mod write directory" to P_target_dir, which must
+// already have been mounted into the VFS.
+// all files opened for writing with the FILE_WRITE_TO_MOD flag set will
+// be written into the appropriate subdirectory of this mount point.
+//
+// this allows e.g. the editor to write files that are already
+// stored in archives, which are read-only.
+LibError vfs_mod_set_write_target(const char* P_target_dir)
+{
+	for(MountIt it = mounts.begin(); it != mounts.end(); ++it)
+	{
+		const Mount& m = *it;
+		// skip if not a directory mounting
+		if(m.type != MT_FILE)
+			continue;
+
+		// found it in list of mounted dirs
+		if(!strcmp(m.P_name.c_str(), P_target_dir))
+		{
+			mod_target = &m;
+			return ERR_OK;
+		}
+	}
+
+	WARN_RETURN(ERR_NOT_MOUNTED);
+}
+
+
+// 'relocate' tf to the mounting established by vfs_mod_set_write_target.
+// call if <tf> is being opened with FILE_WRITE_TO_MOD flag set.
+LibError set_mount_to_mod_target(TFile* tf)
+{
+	if(!mod_target)
+		WARN_RETURN(ERR_NOT_MOUNTED);
+
+	tfile_set_mount(tf, mod_target);
+
+	// invalidate the previous values. we don't need to be clever and
+	// set size to that of the file in the new mod_target mount point.
+	// this is because we're only called for files that are being
+	// opened for writing, which will change these values anyway.
+	tree_update_file(tf, 0, 0);
+
+	return ERR_OK;
+}
+
+
+
+
+
 void mount_init()
 {
 	tree_init();

source/lib/res/file/vfs_mount.h

@@ -95,6 +95,10 @@ extern LibError mount_populate(TDir* td, RealDir* rd);
 // because this call leaves the VFS in limbo!!
 extern void mount_release_all_archives();
 
+// 'relocate' tf to the mounting established by vfs_mod_set_write_target.
+// call if <tf> is being opened with FILE_WRITE_TO_MOD flag set.
+extern LibError set_mount_to_mod_target(TFile* tf);
+
 
 // rebuild the VFS, i.e. re-mount everything. open files are not affected.
 // necessary after loose files or directories change, so that the VFS

source/lib/res/file/vfs_tree.cpp

@@ -702,6 +702,11 @@ const char* tfile_get_atom_fn(const TFile* tf)
 
 
 
+void tfile_set_mount(TFile* tf, const Mount* m)
+{
+	tf->m = m;
+}
+
 void tree_update_file(TFile* tf, off_t size, time_t mtime)
 {
 	tf->size  = size;

source/lib/res/file/vfs_tree.h

@@ -113,6 +113,7 @@ extern const Mount* tfile_get_mount(const TFile* tf);
 extern uintptr_t tfile_get_memento(const TFile* tf);
 extern const char* tfile_get_atom_fn(const TFile* tf);
 
+extern void tfile_set_mount(TFile* tf, const Mount* m);
 extern void tree_update_file(TFile* tf, off_t size, time_t mtime);
 
 struct RealDir;