misc: Add string utility functions.

It's more readable to write "M_StringEndsWith(..." than doing a bunch of
pointer arithmetic, and this is a common pattern. Also add
M_StringStartsWith, M_StringJoin and M_StringCopy. The latter is a
safe alternative for strcpy() that works the same as OpenBSD's
strlcpy(). Use these functions in a few places where it makes sense.

1 files changed, 4 insertions, 5 deletions

diff --git a/src/d_iwad.c b/src/d_iwad.c
index f4155349..293553a2 100644
--- a/src/d_iwad.c
+++ b/src/d_iwad.c
@@ -423,7 +423,7 @@ static char *CheckDirectoryHasIWAD(char *dir, char *iwadname)
 
     // As a special case, the "directory" may refer directly to an
     // IWAD file if the path comes from DOOMWADDIR or DOOMWADPATH.
-    
+
     if (DirIsFile(dir, iwadname) && M_FileExists(dir))
     {
         return strdup(dir);
@@ -432,15 +432,14 @@ static char *CheckDirectoryHasIWAD(char *dir, char *iwadname)
     // Construct the full path to the IWAD if it is located in
     // this directory, and check if it exists.
 
-    filename = malloc(strlen(dir) + strlen(iwadname) + 3);
-
     if (!strcmp(dir, "."))
     {
-        strcpy(filename, iwadname);
+        filename = strdup(iwadname);
     }
     else
     {
-        sprintf(filename, "%s%c%s", dir, DIR_SEPARATOR, iwadname);
+        char sep[] = {DIR_SEPARATOR, '\0'};
+        filename = M_StringJoin(dir, sep, iwadname);
     }
 
     if (M_FileExists(filename))