Add pushd/popd utility

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 74 insertions, 0 deletions

diff --git a/lib/util/dirstack.c b/lib/util/dirstack.c
new file mode 100644
index 0000000..7bfd1a2
--- /dev/null
+++ b/lib/util/dirstack.c
@@ -0,0 +1,74 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+#include "util.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;
+}