From 4723ca7ac8c907919243121a6529ea57ecb4093f Mon Sep 17 00:00:00 2001
From: tdijck <tvandijck@blizzard.com>
Date: Tue, 24 Mar 2015 17:22:41 -0700
Subject: [PATCH] add os.writefile_ifnotequal

---
 src/host/os_writefile_ifnotequal.c | 91 ++++++++++++++++++++++++++++++
 src/host/premake.c                 | 43 +++++++-------
 src/host/premake.h                 |  1 +
 3 files changed, 114 insertions(+), 21 deletions(-)
 create mode 100644 src/host/os_writefile_ifnotequal.c

diff --git a/src/host/os_writefile_ifnotequal.c b/src/host/os_writefile_ifnotequal.c
new file mode 100644
index 00000000..b0e0a7f3
--- /dev/null
+++ b/src/host/os_writefile_ifnotequal.c
@@ -0,0 +1,91 @@
+/**
+ * \file   os_copyfile.c
+ * \brief  Copy a file from one location to another.
+ * \author Copyright (c) 2002-2008 Jason Perkins and the Premake project
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "premake.h"
+
+#ifndef FALSE
+#define FALSE 0
+#endif
+#ifndef TRUE
+#define TRUE 1
+#endif
+
+static int compare_file(const char* content, size_t length, const char* dst)
+{
+	FILE* file = fopen(dst, "rb");
+	long size;
+	char buffer[4096];
+	int num;
+
+	if (file == NULL)
+	{
+		return FALSE;
+	}
+
+	// check sizes.
+	fseek(file, 0, SEEK_END);
+	size = ftell(file);
+	fseek(file, 0, SEEK_SET);
+
+	if (length != size)
+	{
+		fclose(file);
+		return FALSE;
+	}
+
+	while (size > 0)
+	{
+		num = size > 4096 ? 4096 : size;
+
+		fread(buffer, 1, num, file);
+
+		if (memcmp(content, buffer, num) != 0)
+		{
+			fclose(file);
+			return FALSE;
+		}
+
+		size    -= num;
+		content += num;
+	}
+
+	fclose(file);
+	return TRUE;
+}
+
+
+int os_writefile_ifnotequal(lua_State* L)
+{
+	FILE* file;
+	size_t length;
+	const char* content = luaL_checklstring(L, 1, &length);
+	const char* dst     = luaL_checkstring(L, 2);
+
+	// if destination exist, and they are the same, no need to copy.
+	if (do_isfile(dst) && compare_file(content, length, dst))
+	{
+		lua_pushinteger(L, 0);
+		return 1;
+	}
+
+
+	file = fopen(dst, "wb");
+	if (file != NULL)
+	{
+		fwrite(content, 1, length, file);
+		fclose(file);
+
+		lua_pushinteger(L, 1);
+		return 1;
+	}
+
+	lua_pushinteger(L, -1);
+	lua_pushfstring(L, "unable to write file to '%s'", dst);
+	return 2;
+}
diff --git a/src/host/premake.c b/src/host/premake.c
index bf18c42f..e6e131d3 100644
--- a/src/host/premake.c
+++ b/src/host/premake.c
@@ -53,27 +53,28 @@ static const luaL_Reg path_functions[] = {
 };
 
 static const luaL_Reg os_functions[] = {
-	{ "chdir",       os_chdir       },
-	{ "chmod",       os_chmod       },
-	{ "copyfile",    os_copyfile    },
-	{ "_is64bit",    os_is64bit     },
-	{ "isdir",       os_isdir       },
-	{ "getcwd",      os_getcwd      },
-	{ "getversion",  os_getversion  },
-	{ "isfile",      os_isfile      },
-	{ "islink",      os_islink      },
-	{ "locate",      os_locate      },
-	{ "matchdone",   os_matchdone   },
-	{ "matchisfile", os_matchisfile },
-	{ "matchname",   os_matchname   },
-	{ "matchnext",   os_matchnext   },
-	{ "matchstart",  os_matchstart  },
-	{ "mkdir",       os_mkdir       },
-	{ "pathsearch",  os_pathsearch  },
-	{ "realpath",    os_realpath    },
-	{ "rmdir",       os_rmdir       },
-	{ "stat",        os_stat        },
-	{ "uuid",        os_uuid        },
+	{ "chdir",                  os_chdir                },
+	{ "chmod",                  os_chmod                },
+	{ "copyfile",               os_copyfile             },
+	{ "_is64bit",               os_is64bit              },
+	{ "isdir",                  os_isdir                },
+	{ "getcwd",                 os_getcwd               },
+	{ "getversion",             os_getversion           },
+	{ "isfile",                 os_isfile               },
+	{ "islink",                 os_islink               },
+	{ "locate",                 os_locate               },
+	{ "matchdone",              os_matchdone            },
+	{ "matchisfile",            os_matchisfile          },
+	{ "matchname",              os_matchname            },
+	{ "matchnext",              os_matchnext            },
+	{ "matchstart",             os_matchstart           },
+	{ "mkdir",                  os_mkdir                },
+	{ "pathsearch",             os_pathsearch           },
+	{ "realpath",               os_realpath             },
+	{ "rmdir",                  os_rmdir                },
+	{ "stat",                   os_stat                 },
+	{ "uuid",                   os_uuid                 },
+	{ "writefile_ifnotequal",   os_writefile_ifnotequal },
 	{ NULL, NULL }
 };
 
diff --git a/src/host/premake.h b/src/host/premake.h
index f82b346d..08cebfb3 100644
--- a/src/host/premake.h
+++ b/src/host/premake.h
@@ -116,6 +116,7 @@ int os_realpath(lua_State* L);
 int os_rmdir(lua_State* L);
 int os_stat(lua_State* L);
 int os_uuid(lua_State* L);
+int os_writefile_ifnotequal(lua_State* L);
 int string_endswith(lua_State* L);
 int string_hash(lua_State* L);
 int string_sha1(lua_State* L);