query-uuid: initial commit

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

3 files changed, 64 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..4c364c5
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,11 @@
+
+PKG_CONFIG?=pkg-config
+
+PKGCONFIG_LIBS=uuid
+
+CFLAGS+=-std=gnu11 -O2 -g -Wall
+
+CFLAGS+=$(shell $(PKG_CONFIG) --cflags $(PKGCONFIG_LIBS))
+LDLIBS+=$(shell $(PKG_CONFIG) --libs   $(PKGCONFIG_LIBS))
+
+query-uuid: query-uuid.o
diff --git a/README b/README
new file mode 100644
index 0000000..9c9a266
--- /dev/null
+++ b/README
@@ -0,0 +1 @@
+Simple commandline tool for FS_IOC_GETFSUUID
diff --git a/query-uuid.c b/query-uuid.c
new file mode 100644
index 0000000..6cba1b6
--- /dev/null
+++ b/query-uuid.c
@@ -0,0 +1,52 @@
+#include <fcntl.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <linux/types.h>
+
+#include <uuid/uuid.h>
+
+struct fsuuid2 {
+	__u8			len;
+	__u8			uuid[16];
+};
+#define FS_IOC_GETFSUUID               _IOR(0x15, 0, struct fsuuid2)
+
+void die(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vfprintf(stderr, fmt, args);
+	va_end(args);
+	fputc('\n', stderr);
+
+	_exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[])
+{
+	const char *path = argv[1] ?: ".";
+	int fd = open(path, O_RDONLY);
+	if (fd < 0)
+		die("Error opening %s: %m\n", path);
+
+	struct fsuuid2 uuid;
+	if (ioctl(fd, FS_IOC_GETFSUUID, (unsigned long) &uuid))
+		die("FS_IOC_GETFSUUID error: %m\n");
+
+	if (uuid.len == 16) {
+		uuid_t u;
+		memcpy(&u, uuid.uuid, 16);
+
+		char str[37];
+		uuid_unparse(u, str);
+		puts(str);
+	} else {
+		for (unsigned i = 0; i < uuid.len; i++)
+			printf("%x", uuid.uuid[i]);
+	}
+}