Add path utilities

include/path_utils.h

@@ -0,0 +1,18 @@
+#ifndef PATH_UTILS_H
+#define PATH_UTILS_H
+
+#include "aliases.h"
+
+#define NUMPARTS(...)                                                          \
+  (sizeof((const char *[]){"", __VA_ARGS__}) / sizeof(const char *) - 1)
+
+#define JOIN_PATH(DST, ...) join_path(DST, NUMPARTS(__VA_ARGS__), __VA_ARGS__)
+
+void join_path(char *dst, u64 count, ...);
+
+#define DIRNAME(DST, PATH) dirup(DST, 1, PATH)
+#define DIRUP(DST, COUNT, PATH) dirup(DST, COUNT, PATH)
+
+void dirup(char *dst, u64 levels, const char *path);
+
+#endif // !PATH_UTILS_H

src/path_utils.c

@@ -0,0 +1,76 @@
+#include "path_utils.h"
+#include "aliases.h"
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#if defined(__unix__) || defined(__APPLE__) || defined(__ANDROID__)
+INTERNAL char path_sep = '/';
+#elif defined(_WIN32) || defined(_WIN64)
+INTERNAL char path_sep = '\';
+#endif
+
+void join_root_and_leaf(const char *root, const char *leaf, char *dst);
+
+void join_path(char *dst, u64 count, ...) {
+  va_list args;
+
+  va_start(args, count);
+
+  for (u64 i = 0; i < count; ++i) {
+    join_root_and_leaf(dst, va_arg(args, const char *), dst);
+  }
+
+  va_end(args);
+}
+
+void dirup(char *dst, u64 levels, const char *path) {
+  if (levels < 1) {
+    return;
+  }
+
+  u64 end_index = 0;
+  u64 sep_count = 0;
+
+  u64 length = strlen(path);
+  if (path[length - 1] == path_sep) {
+    --length;
+  }
+
+  for (u64 i = length - 1; i >= 0; --i) {
+    if (path[i] == path_sep) {
+      ++sep_count;
+      end_index = i;
+
+      if (sep_count == levels) {
+        break;
+      }
+    }
+  }
+
+  if (sep_count < levels) {
+    end_index = 0;
+  }
+
+  strncpy(dst, path, end_index);
+}
+
+void join_root_and_leaf(const char *root, const char *leaf, char *dst) {
+  u64 root_length = strlen(root);
+  u64 root_end = root_length - 1;
+
+  u64 leaf_length = strlen(leaf);
+  u64 leaf_start = 0;
+
+  if (root[root_end] == path_sep) {
+    --root_end;
+  }
+
+  if (leaf[leaf_start] == path_sep) {
+    ++leaf_start;
+  }
+
+  strncpy(dst, root, ++root_end);
+  dst[root_end] = path_sep;
+  strncpy(&(dst[++root_end]), &(leaf[leaf_start]), leaf_length - leaf_start);
+}