libremail: Add shared try_mkdir() function

Signed-off-by: Chloe M. <chloe@mirocom.org>

libremail/Makefile

@@ -0,0 +1,25 @@
+# Copyright (c) 2026, Chloe Moffett
+# Provided under the BSD-3 clause
+#
+
+CFILES = $(shell find . -name "*.c")
+OFILES = $(CFILES:.c=.o)
+DFILES = $(CFILES:.c=.d)
+CC = gcc
+
+CFLAGS = 				\
+	-Wall				\
+	-pedantic			\
+	-MMD				\
+	-Iinc
+
+.PHONY: all
+all: $(OFILES)
+
+-include $(DFILES)
+%.o: %.c
+	$(CC) -c $< $(CFLAGS) -o $@
+
+.PHONY: clean
+clean:
+	rm -f $(OFILES) $(DFILES)

libremail/common/file_mkdir.c

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2026, Chloe Moffett
+ * Provided under the BSD-3 clause
+ */
+
+#include <sys/stat.h>
+#include <unistd.h>
+#include <errno.h>
+#include "libremail/file.h"
+
+int
+try_mkdir(const char *path, mode_t mode)
+{
+    if (path == NULL) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (access(path, F_OK) != 0) {
+        return mkdir(path, mode);
+    }
+
+    return 0;
+}

libremail/inc/libremail/file.h

@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2026, Chloe Moffett
+ * Provided under the BSD-3 clause
+ */
+
+#ifndef LIBREMAIL_FILE_H
+#define LIBREMAIL_FILE_H 1
+
+#include <sys/stat.h>
+
+/*
+ * Attempt to create a directory if it doesn't exist
+ *
+ * @path: Path to directory to create
+ * @mode: Desired mode to assign
+ *
+ * Returns zeo on success
+ */
+int try_mkdir(const char *path, mode_t mode);
+
+#endif  /* !LIBREMAIL_FILE_H */