[[ Bug 21918 ]] Memory leak when manipulating four-char-codes on macOS

runrevmark · runrevmark · commit a9b1a7d2a53d · 2019-03-26T08:47:52.000Z
This patch fixes a leak in the macOS platform specific FourCharCodeFromString
function. In order to convert a string into a FourCharCode integer, the
string is temporarily converted to a CString. Previously, however, this
temporary CString was not being deleted. The explicit conversion has been replaced
by an AutoStringRefAsCString auto class which fixes the leak.
diff --git a/docs/notes/bugfix-21918.md b/docs/notes/bugfix-21918.md
@@ -0,0 +1,2 @@
+# Fix memory leak when using legacy macOS features relying on four-char-codes
+
diff --git a/engine/src/dskmac.cpp b/engine/src/dskmac.cpp
@@ -87,14 +87,14 @@ inline FourCharCode FourCharCodeFromString(const char *p_string)
 
 bool FourCharCodeFromString(MCStringRef p_string, uindex_t p_start, FourCharCode& r_four_char_code)
 {
-    char *temp;
+    MCAutoStringRefAsCString t_temp;
     uint32_t t_four_char_code;
-    if (!MCStringConvertToCString(p_string, temp))
+    if (!t_temp.Lock(p_string))
         return false;
     
-    memcpy(&t_four_char_code, temp + p_start, 4);
+    memcpy(&t_four_char_code, *t_temp + p_start, 4);
     r_four_char_code = MCSwapInt32HostToNetwork(t_four_char_code);
-    delete temp;
+    
     return true;
 }
 
@@ -109,7 +109,7 @@ inline char *FourCharCodeToString(FourCharCode p_code)
 
 bool FourCharCodeToStringRef(FourCharCode p_code, MCStringRef& r_string)
 {
-    return MCStringCreateWithCString(FourCharCodeToString(p_code), r_string);
+    return MCStringCreateWithCStringAndRelease(FourCharCodeToString(p_code), r_string);
 }
 
 struct triplets

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+# Fix memory leak when using legacy macOS features relying on four-char-codes`
	`2`	`+`
Original file line number	Diff line number	Diff line change
`@@ -87,14 +87,14 @@ inline FourCharCode FourCharCodeFromString(const char *p_string)`
`87`	`87`
`88`	`88`	`bool FourCharCodeFromString(MCStringRef p_string, uindex_t p_start, FourCharCode& r_four_char_code)`
`89`	`89`	`{`
`90`		`- char *temp;`
	`90`	`+ MCAutoStringRefAsCString t_temp;`
`91`	`91`	`uint32_t t_four_char_code;`
`92`		`- if (!MCStringConvertToCString(p_string, temp))`
	`92`	`+ if (!t_temp.Lock(p_string))`
`93`	`93`	`return false;`
`94`	`94`
`95`		`- memcpy(&t_four_char_code, temp + p_start, 4);`
	`95`	`+ memcpy(&t_four_char_code, *t_temp + p_start, 4);`
`96`	`96`	`r_four_char_code = MCSwapInt32HostToNetwork(t_four_char_code);`
`97`		`- delete temp;`
	`97`	`+`
`98`	`98`	`return true;`
`99`	`99`	`}`
`100`	`100`
`@@ -109,7 +109,7 @@ inline char *FourCharCodeToString(FourCharCode p_code)`
`109`	`109`
`110`	`110`	`bool FourCharCodeToStringRef(FourCharCode p_code, MCStringRef& r_string)`
`111`	`111`	`{`
`112`		`- return MCStringCreateWithCString(FourCharCodeToString(p_code), r_string);`
	`112`	`+ return MCStringCreateWithCStringAndRelease(FourCharCodeToString(p_code), r_string);`
`113`	`113`	`}`
`114`	`114`
`115`	`115`	`struct triplets`