Merge branch '22-exec-files-only' into 'public_next'

Fix exec crashing with out of memory if opening a directory

See merge request STJr/SRB2Internal!634

src/doomdef.h

@@ -104,6 +104,8 @@
 #include <io.h>
 #endif
 
+FILE *fopenfile(const char*, const char*);
+
 //#define NOMD5
 
 // Uncheck this to compile debugging code

src/filesrch.c

@@ -39,6 +39,7 @@
 
 #define SUFFIX	"*"
 #define	SLASH	"\\"
+#define	S_ISREG(m)	(((m) & S_IFMT) == S_IFREG)
 #define	S_ISDIR(m)	(((m) & S_IFMT) == S_IFDIR)
 
 #ifndef INVALID_FILE_ATTRIBUTES
@@ -307,6 +308,39 @@ closedir (DIR * dirp)
 }
 #endif
 
+// fopen but it REALLY only works on regular files
+// Turns out, on linux, anyway, you can fopen directories
+// in read mode. (It's supposed to fail in write mode
+// though!!)
+FILE *fopenfile(const char *path, const char *mode)
+{
+	FILE *h = fopen(path, mode);
+
+	if (h != NULL)
+	{
+		struct stat st;
+		int eno;
+
+		if (fstat(fileno(h), &st) == -1)
+		{
+			eno = errno;
+		}
+		else if (!S_ISREG(st.st_mode))
+		{
+			eno = EACCES; // set some kinda error
+		}
+		else
+		{
+			return h; // ok
+		}
+
+		fclose(h);
+		errno = eno;
+	}
+
+	return NULL;
+}
+
 static CV_PossibleValue_t addons_cons_t[] = {{0, "Default"},
 #if 1
 												{1, "HOME"}, {2, "SRB2"},

src/m_misc.c

@@ -273,8 +273,8 @@ size_t FIL_ReadFileTag(char const *name, UINT8 **buffer, INT32 tag)
 	size_t count, length;
 	UINT8 *buf;
 
-	if (FIL_ReadFileOK(name))
-		handle = fopen(name, "rb");
+	//if (FIL_ReadFileOK(name))
+		handle = fopenfile(name, "rb");
 
 	if (!handle)
 		return 0;