Kernel: Make a more convenient wrapper for basename() and dirname()

kernel/include/std/libgen.h

@@ -1,4 +1,7 @@
 #pragma once
 
 char* basename(char* path);
-char* dirname(char* path);
+char* dirname(char* path);
+
+char* better_basename(const char* path);
+char* better_dirname(const char* path);

kernel/src/fs/VFS.cpp

@@ -208,36 +208,30 @@ int VFS::do_mkdir(const char* path, const char* name, int uid, int gid, mode_t m
 
 int VFS::mkdir(const char* pathname)
 {
-    char* bstr = strdup(pathname);
-    char* dstr = strdup(pathname);
-
-    char* base = basename(bstr);
-    char* dir = dirname(dstr);
+    char* base = better_basename(pathname);
+    char* dir = better_dirname(pathname);
 
     kdbgln("mkdir(): creating %s in directory %s", base, dir);
 
     int result = mkdir(dir, base);
 
-    kfree(bstr);
-    kfree(dstr);
+    kfree(base);
+    kfree(dir);
 
     return result;
 }
 
 int VFS::do_mkdir(const char* pathname, int uid, int gid, mode_t mode)
 {
-    char* bstr = strdup(pathname);
-    char* dstr = strdup(pathname);
-
-    char* base = basename(bstr);
-    char* dir = dirname(dstr);
+    char* base = better_basename(pathname);
+    char* dir = better_dirname(pathname);
 
     kdbgln("mkdir(): creating %s in directory %s", base, dir);
 
     int result = do_mkdir(dir, base, uid, gid, mode);
 
-    kfree(bstr);
-    kfree(dstr);
+    kfree(base);
+    kfree(dir);
 
     return result;
 }

kernel/src/std/libgen.cpp

@@ -1,4 +1,5 @@
 #include "std/libgen.h"
+#include "std/stdlib.h"
 #include "std/string.h"
 
 static char dot[] = ".";
@@ -44,4 +45,23 @@ char* dirname(char* path)
     else
         *(end + 1) = 0;
     return path;
+}
+
+char* better_basename(const char* path)
+{
+    char* mut = strdup(path);   // create a mutable copy of path
+    char* ptr = basename(mut);  // get a pointer to the start of the base name
+    char* result = strdup(ptr); // create a copy of it, so the caller can free the returned pointer directly
+    kfree(mut);                 // free the original mutable copy
+    return result;
+}
+
+char* better_dirname(const char* path)
+{
+    // same as above
+    char* mut = strdup(path);
+    char* ptr = dirname(mut);
+    char* result = strdup(ptr);
+    kfree(mut);
+    return result;
 }