3 files changed, 123 insertions, 0 deletions
diff --git a/lib/common/Makemodule.am b/lib/common/Makemodule.am
index 75f771d..db366af 100644
--- a/lib/common/Makemodule.am
+++ b/lib/common/Makemodule.am
@@ -5,5 +5,6 @@ libcommon_a_SOURCES += lib/common/compress.c lib/common/comp_opt.c
 libcommon_a_SOURCES += lib/common/data_writer.c include/common.h
 libcommon_a_SOURCES += lib/common/get_path.c lib/common/io_stdin.c
 libcommon_a_SOURCES += lib/common/writer.c lib/common/perror.c
+libcommon_a_SOURCES += lib/common/dirstack.c lib/common/mkdir_p.c
 
 noinst_LIBRARIES += libcommon.a
diff --git a/lib/common/dirstack.c b/lib/common/dirstack.c
new file mode 100644
index 0000000..8f73898
--- /dev/null
+++ b/lib/common/dirstack.c
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * dirstack.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "common.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+#define STACK_DEPTH 128
+
+static int dirstack[STACK_DEPTH];
+static int stacktop = 0;
+
+int pushd(const char *path)
+{
+	int fd;
+
+	assert(stacktop < STACK_DEPTH);
+
+	fd = open(".", O_DIRECTORY | O_PATH | O_RDONLY | O_CLOEXEC);
+
+	if (fd < 0) {
+		perror("open ./");
+		return -1;
+	}
+
+	if (chdir(path)) {
+		perror(path);
+		close(fd);
+		return -1;
+	}
+
+	dirstack[stacktop++] = fd;
+	return 0;
+}
+
+int pushdn(const char *path, size_t len)
+{
+	char *temp;
+	int ret;
+
+	temp = strndup(path, len);
+	if (temp == NULL) {
+		perror("pushd");
+		return -1;
+	}
+
+	ret = pushd(temp);
+
+	free(temp);
+	return ret;
+}
+
+int popd(void)
+{
+	int fd;
+
+	assert(stacktop > 0);
+
+	fd = dirstack[stacktop - 1];
+
+	if (fchdir(fd)) {
+		perror("popd");
+		return -1;
+	}
+
+	--stacktop;
+	close(fd);
+	return 0;
+}
diff --git a/lib/common/mkdir_p.c b/lib/common/mkdir_p.c
new file mode 100644
index 0000000..cb433b3
--- /dev/null
+++ b/lib/common/mkdir_p.c
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * mkdir_p.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "common.h"
+
+#include <string.h>
+#include <alloca.h>
+#include <stdio.h>
+#include <errno.h>
+
+int mkdir_p(const char *path)
+{
+	size_t i, len;
+	char *buffer;
+
+	while (path[0] == '/' && path[1] == '/')
+		++path;
+
+	if (*path == '\0' || (path[0] == '/' && path[1] == '\0'))
+		return 0;
+
+	len = strlen(path) + 1;
+	buffer = alloca(len);
+
+	for (i = 0; i < len; ++i) {
+		if (i > 0 && (path[i] == '/' || path[i] == '\0')) {
+			buffer[i] = '\0';
+
+			if (mkdir(buffer, 0755) != 0) {
+				if (errno != EEXIST) {
+					fprintf(stderr, "mkdir %s: %s\n",
+						buffer, strerror(errno));
+					return -1;
+				}
+			}
+		}
+
+		buffer[i] = path[i];
+	}
+
+	return 0;
+}