Add pwd command utility

1 files changed, 63 insertions, 0 deletions

diff --git a/bin/pwd/pwd.c b/bin/pwd/pwd.c
new file mode 100644
index 00000000..564b22e7
--- /dev/null
+++ b/bin/pwd/pwd.c
@@ -0,0 +1,63 @@
+#include <err.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int argc, char **argv)
+{
+	const char *out = NULL;
+	struct iovec iov[2];
+	char opt, mode = 'L';
+	char cwd[PATH_MAX];
+
+	while ((opt = getopt(argc, argv, "")) != -1) {
+		switch (opt) {
+		case 'L':
+		case 'P':
+			mode = opt;
+			break;
+		default:
+			write(STDERR_FILENO, "usage: pwd [-L|-P]\n", 20);
+			return 1;
+		}
+	}
+
+	if (getcwd(cwd, sizeof(cwd)) == NULL) {
+		perror("pwd: getcwd");
+		return 1;
+	}
+
+	if (mode == 'L') {
+		const char *pwd;
+		struct stat cst, pst;
+
+		if ((pwd = getenv("PWD")) == NULL || *pwd != '/' ||
+		    stat(pwd, &pst) < 0) {
+			out = cwd;
+		}
+
+		if (stat(cwd, &cst) < 0) {
+			perror("pwd: stat");
+		}
+
+		out = (pst.st_dev == cst.st_dev && pst.st_ino == cst.st_ino) ?
+			      pwd :
+			      cwd;
+	}
+
+	iov[0].iov_base = (char *)out;
+	iov[0].iov_len = strlen(out);
+
+	iov[1].iov_base = "\n";
+	iov[1].iov_len = 1;
+
+	if (writev(STDOUT_FILENO, iov, 2) < 0) {
+		err(1, "pwd");
+	}
+
+	return 0;
+}