refactor(WMTheme): clean up detectOpenbox

Simplify the code and implement stricter checking of xml contents.

src/detection/wmtheme/wmtheme_linux.c

@@ -1,4 +1,5 @@
 #include "wmtheme.h"
+#include "common/io/io.h"
 #include "common/properties.h"
 #include "common/parsing.h"
 #include "common/settings.h"
@@ -142,50 +143,45 @@ static bool detectOpenbox(const FFstrbuf* dePrettyName, FFstrbuf* themeOrError)
     else
         ffStrbufAppendS(&absolutePath, ".config/openbox/rc.xml");
 
-    char* line = NULL;
-    size_t len = 0;
-
-    FILE* file = fopen(absolutePath.chars, "r");
-    if(file == NULL)
+    FF_STRBUF_AUTO_DESTROY content = ffStrbufCreate();
+    if (!ffReadFileBuffer(absolutePath.chars, &content))
     {
-        ffStrbufAppendF(themeOrError, "Couldn't open \"%s\"", absolutePath.chars);
-
+        ffStrbufAppendF(themeOrError, "Couldn't read \"%s\"", absolutePath.chars);
         return false;
     }
 
-    while(getline(&line, &len, file) != -1)
-    {
-        if(strstr(line, "<theme>") != 0)
-            break;
-    }
+    const char *themeStart = strstr(content.chars, "<theme>");
+    if (themeStart == NULL)
+        goto theme_not_found;
 
-    while(getline(&line, &len, file) != -1)
-    {
-        if(strstr(line, "<name>") != 0)
-        {
-            ffStrbufAppendS(themeOrError, line);
-            ffStrbufRemoveStrings(themeOrError, 2, (const char*[]) { "<name>", "</name>" });
-            ffStrbufTrimRight(themeOrError, '\n');
-            ffStrbufTrim(themeOrError, ' ');
-            break;
-        }
+    const char *themeEnd = strstr(themeStart, "</theme>");
+    if (__builtin_expect(themeEnd == NULL, false)) // very rare case
+        goto theme_not_found;
 
-        if(strstr(line, "</theme>") != 0) // sanity check
-            break;
-    }
+    const char *nameStart = strstr(themeStart, "<name>");
+    if (nameStart == NULL)
+        goto name_not_found;
 
-    if(line != NULL)
-        free(line);
+    const char *nameEnd = strstr(nameStart, "</name>");
+    if (nameEnd == NULL || nameEnd > themeEnd) // (nameEnd > themeEnd) means name is not a theme's child
+        goto name_not_found;
 
-    fclose(file);
+    nameStart += strlen("<name>");
+    ffStrbufAppendNS(themeOrError, (uint32_t)(nameEnd - nameStart), nameStart);
+    ffStrbufTrim(themeOrError, ' ');
 
     if(themeOrError->length == 0)
-    {
-        ffStrbufAppendF(themeOrError, "Couldn't find theme name in \"%s\"", absolutePath.chars);
-        return false;
-    }
+        goto name_not_found;
 
     return true;
+
+theme_not_found:
+    ffStrbufAppendF(themeOrError, "Couldn't find theme node in \"%s\"", absolutePath.chars);
+    return false;
+
+name_not_found:
+    ffStrbufAppendF(themeOrError, "Couldn't find theme name in \"%s\"", absolutePath.chars);
+    return false;
 }
 
 bool ffDetectWmTheme(FFstrbuf* themeOrError)