[PATCH v2] vfio: selftests: Remove libuuid dependency

[Samiullah Khawaja <skhawaja@google.com>]

Libvfio depends on an external dependency libuuid for parsing vf_tokens.
Building it in cross compilation environments gives the following error,

 ld: cannot find -luuid: No such file or directory

It also complicates building with glibc alternatives like musl, see
https://lore.kernel.org/kvm/c2f7e904-2646-4b01-864d-d185221c7f56@gmail.com/

As it is only used for parsing vf_tokens, remove the dependency by
adding a minimal uuid_t and uuid_parse() to libvfio.

Tested by running vfio_pci_sriov_uapi_test selftest.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
v2:
- Move the parser to lib/uuid.c and lib/include/libvfio/uuid.h (David)
- Drop the vfio_ prefixes and add a uuid_t (David)
- Mention musl in the commit message (David)

v1: https://lore.kernel.org/all/20260925013110.3447626-1-skhawaja@google.com/
---
 .../selftests/vfio/lib/include/libvfio.h      |  1 +
 .../selftests/vfio/lib/include/libvfio/uuid.h | 11 +++++
 tools/testing/selftests/vfio/lib/libvfio.mk   |  3 +-
 tools/testing/selftests/vfio/lib/uuid.c       | 47 +++++++++++++++++++
 .../selftests/vfio/lib/vfio_pci_device.c      |  2 -
 5 files changed, 60 insertions(+), 4 deletions(-)
 create mode 100644 tools/testing/selftests/vfio/lib/include/libvfio/uuid.h
 create mode 100644 tools/testing/selftests/vfio/lib/uuid.c

diff --git a/tools/testing/selftests/vfio/lib/include/libvfio.h b/tools/testing/selftests/vfio/lib/include/libvfio.h
index 07862b470777..e9d513c3a08e 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio.h
@@ -6,6 +6,7 @@
 #include <libvfio/iommu.h>
 #include <libvfio/iova_allocator.h>
 #include <libvfio/sysfs.h>
+#include <libvfio/uuid.h>
 #include <libvfio/vfio_pci_device.h>
 #include <libvfio/vfio_pci_driver.h>
 
diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/uuid.h b/tools/testing/selftests/vfio/lib/include/libvfio/uuid.h
new file mode 100644
index 000000000000..52406f3409b7
--- /dev/null
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/uuid.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_UUID_H
+#define SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_UUID_H
+
+#define UUID_SIZE	16
+
+typedef unsigned char uuid_t[UUID_SIZE];
+
+int uuid_parse(const char *in, uuid_t uu);
+
+#endif /* SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_UUID_H */
diff --git a/tools/testing/selftests/vfio/lib/libvfio.mk b/tools/testing/selftests/vfio/lib/libvfio.mk
index eff95828719e..d1d1b2b05af1 100644
--- a/tools/testing/selftests/vfio/lib/libvfio.mk
+++ b/tools/testing/selftests/vfio/lib/libvfio.mk
@@ -7,6 +7,7 @@ LIBVFIO_C := iommu.c
 LIBVFIO_C += iova_allocator.c
 LIBVFIO_C += libvfio.c
 LIBVFIO_C += sysfs.c
+LIBVFIO_C += uuid.c
 LIBVFIO_C += vfio_pci_device.c
 LIBVFIO_C += vfio_pci_driver.c
 
@@ -30,8 +31,6 @@ $(LIBVFIO_O_DIRS):
 
 CFLAGS += -I$(LIBVFIO_SRCDIR)/include
 
-LDLIBS += -luuid
-
 $(LIBVFIO_O): $(LIBVFIO_OUTPUT)/%.o : $(LIBVFIO_SRCDIR)/%.c | $(LIBVFIO_O_DIRS)
 	$(CC) $(CFLAGS) $(CPPFLAGS) $(TARGET_ARCH) -c $< -o $@
 
diff --git a/tools/testing/selftests/vfio/lib/uuid.c b/tools/testing/selftests/vfio/lib/uuid.c
new file mode 100644
index 000000000000..378904d9340a
--- /dev/null
+++ b/tools/testing/selftests/vfio/lib/uuid.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <string.h>
+
+#include <libvfio.h>
+
+/*
+ * Minimal replacement for libuuid's uuid_parse(). libuuid is part of
+ * util-linux and is routinely absent from cross-compilation sysroots, which
+ * makes the vfio selftests unbuildable for non-native architectures.
+ */
+#define UUID_STRING_LEN	36
+
+static int hexval(char c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	if (c >= 'a' && c <= 'f')
+		return c - 'a' + 10;
+	if (c >= 'A' && c <= 'F')
+		return c - 'A' + 10;
+	return -1;
+}
+
+int uuid_parse(const char *in, uuid_t uu)
+{
+	const char *p = in;
+	int i, hi, lo;
+
+	if (strlen(in) != UUID_STRING_LEN)
+		return -1;
+
+	for (i = 0; i < UUID_SIZE; i++) {
+		if (i == 4 || i == 6 || i == 8 || i == 10) {
+			if (*p++ != '-')
+				return -1;
+		}
+
+		hi = hexval(*p++);
+		lo = hexval(*p++);
+		if (hi < 0 || lo < 0)
+			return -1;
+
+		uu[i] = (hi << 4) | lo;
+	}
+
+	return 0;
+}
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index 4063a0e2b3df..4ae6ac1f8ed8 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -23,8 +23,6 @@
 #include <linux/types.h>
 #include <linux/vfio.h>
 
-#include <uuid/uuid.h>
-
 #include "kselftest.h"
 #include <libvfio.h>
 

base-commit: 2637bdec0535a2044cd830eba9a79363651d9043
-- 
2.56.0.385.gac671c819a-goog