libfdisk: (gpt) add API for raw partition attributes

The existing APIs can only toggle individual bits or get and set bits in
a complex text representation, making it impractical to use libfdisk for
manipulating the GPT partition attribute field in more complex ways such
as updating a value that is multiple bits wide. For example priority
based partition selection originally designed for ChromeOS includes two
integer values that are 4-bits wide.

http://www.chromium.org/chromium-os/chromiumos-design-docs/disk-format#TOC-Trusting-the-GPT

[kzak@redhat.com: - add new symbols to .sym file and docs
                  - remove unused variables from test program]

Signed-off-by: Michael Marineau <michael.marineau@coreos.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

5 files changed, 138 insertions, 0 deletions

diff --git a/libfdisk/docs/libfdisk-sections.txt b/libfdisk/docs/libfdisk-sections.txt
index acee8f855..02b775ea6 100644
--- a/libfdisk/docs/libfdisk-sections.txt
+++ b/libfdisk/docs/libfdisk-sections.txt
@@ -223,6 +223,8 @@ fdisk_sgi_set_bootfile
 <SECTION>
 <FILE>gpt</FILE>
 fdisk_gpt_is_hybrid
+fdisk_gpt_get_partition_attrs
+fdisk_gpt_set_partition_attrs
 GPT_FLAG_REQUIRED
 GPT_FLAG_NOBLOCK
 GPT_FLAG_LEGACYBOOT
diff --git a/libfdisk/src/Makemodule.am b/libfdisk/src/Makemodule.am
index 347ea8e11..00c3d9f0c 100644
--- a/libfdisk/src/Makemodule.am
+++ b/libfdisk/src/Makemodule.am
@@ -64,6 +64,7 @@ EXTRA_DIST += \
 if BUILD_LIBFDISK_TESTS
 check_PROGRAMS += \
 	test_fdisk_ask \
+	test_fdisk_gpt \
 	test_fdisk_script \
 	test_fdisk_utils \
 	test_fdisk_version 
@@ -81,6 +82,11 @@ test_fdisk_ask_CFLAGS = $(libfdisk_tests_cflags)
 test_fdisk_ask_LDFLAGS = $(libfdisk_tests_ldflags)
 test_fdisk_ask_LDADD = $(libfdisk_tests_ldadd)
 
+test_fdisk_gpt_SOURCES = libfdisk/src/gpt.c
+test_fdisk_gpt_CFLAGS = $(libfdisk_tests_cflags)
+test_fdisk_gpt_LDFLAGS = $(libfdisk_tests_ldflags)
+test_fdisk_gpt_LDADD = $(libfdisk_tests_ldadd)
+
 test_fdisk_utils_SOURCES = libfdisk/src/utils.c
 test_fdisk_utils_CFLAGS = $(libfdisk_tests_cflags)
 test_fdisk_utils_LDFLAGS = $(libfdisk_tests_ldflags)
diff --git a/libfdisk/src/gpt.c b/libfdisk/src/gpt.c
index 989fd752c..a7ec5397a 100644
--- a/libfdisk/src/gpt.c
+++ b/libfdisk/src/gpt.c
@@ -2429,6 +2429,73 @@ int fdisk_gpt_is_hybrid(struct fdisk_context *cxt)
 	return valid_pmbr(cxt) == GPT_MBR_HYBRID;
 }
 
+/**
+ * fdisk_gpt_get_partition_attrs:
+ * @cxt: context
+ * @partnum: partition number
+ * @attrs: GPT partition attributes
+ *
+ * Sets @attrs for the given partition
+ *
+ * Returns: 0 on success, <0 on error.
+ */
+int fdisk_gpt_get_partition_attrs(
+		struct fdisk_context *cxt,
+		size_t partnum,
+		uint64_t *attrs)
+{
+	struct fdisk_gpt_label *gpt;
+
+	assert(cxt);
+	assert(cxt->label);
+	assert(fdisk_is_label(cxt, GPT));
+
+	gpt = self_label(cxt);
+
+	if ((uint32_t) partnum >= le32_to_cpu(gpt->pheader->npartition_entries))
+		return -EINVAL;
+
+	*attrs = le64_to_cpu(gpt->ents[partnum].attrs);
+	return 0;
+}
+
+/**
+ * fdisk_gpt_set_partition_attrs:
+ * @cxt: context
+ * @partnum: partition number
+ * @attrs: GPT partition attributes
+ *
+ * Sets the GPT partition attributes field to @attrs.
+ *
+ * Returns: 0 on success, <0 on error.
+ */
+int fdisk_gpt_set_partition_attrs(
+		struct fdisk_context *cxt,
+		size_t partnum,
+		uint64_t attrs)
+{
+	struct fdisk_gpt_label *gpt;
+
+	assert(cxt);
+	assert(cxt->label);
+	assert(fdisk_is_label(cxt, GPT));
+
+	DBG(LABEL, ul_debug("GPT entry attributes change requested partno=%zu", partnum));
+	gpt = self_label(cxt);
+
+	if ((uint32_t) partnum >= le32_to_cpu(gpt->pheader->npartition_entries))
+		return -EINVAL;
+
+	gpt->ents[partnum].attrs = cpu_to_le64(attrs);
+	fdisk_info(cxt, _("The attributes on partition %zu changed to 0x%016" PRIx64 "."),
+			partnum + 1, attrs);
+
+	gpt_recompute_crc(gpt->pheader, gpt->ents);
+	gpt_recompute_crc(gpt->bheader, gpt->ents);
+	fdisk_label_set_changed(cxt->label, 1);
+	return 0;
+}
+
 static int gpt_toggle_partition_flag(
 		struct fdisk_context *cxt,
 		size_t i,
@@ -2668,3 +2735,62 @@ struct fdisk_label *fdisk_new_gpt_label(struct fdisk_context *cxt)
 
 	return lb;
 }
+
+#ifdef TEST_PROGRAM
+int test_getattr(struct fdisk_test *ts, int argc, char *argv[])
+{
+	const char *disk = argv[1];
+	size_t part = strtoul(argv[2], NULL, 0) - 1;
+	struct fdisk_context *cxt;
+	uint64_t atters = 0;
+
+	cxt = fdisk_new_context();
+	fdisk_assign_device(cxt, disk, 1);
+
+	if (!fdisk_is_label(cxt, GPT))
+		return EXIT_FAILURE;
+
+	if (fdisk_gpt_get_partition_attrs(cxt, part, &atters))
+		return EXIT_FAILURE;
+
+	printf("%s: 0x%016" PRIx64 "\n", argv[2], atters);
+
+	fdisk_unref_context(cxt);
+	return 0;
+}
+
+int test_setattr(struct fdisk_test *ts, int argc, char *argv[])
+{
+	const char *disk = argv[1];
+	size_t part = strtoul(argv[2], NULL, 0) - 1;
+	uint64_t atters = strtoull(argv[3], NULL, 0);
+	struct fdisk_context *cxt;
+
+	cxt = fdisk_new_context();
+	fdisk_assign_device(cxt, disk, 0);
+
+	if (!fdisk_is_label(cxt, GPT))
+		return EXIT_FAILURE;
+
+	if (fdisk_gpt_set_partition_attrs(cxt, part, atters))
+		return EXIT_FAILURE;
+
+	if (fdisk_write_disklabel(cxt))
+		return EXIT_FAILURE;
+
+	fdisk_unref_context(cxt);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct fdisk_test tss[] = {
+		{ "--getattr",  test_getattr,  "<disk> <partition>             print attributes" },
+		{ "--setattr",  test_setattr,  "<disk> <partition> <value>     set attributes" },
+		{ NULL }
+	};
+
+	return fdisk_run_test(tss, argc, argv);
+}
+
+#endif
diff --git a/libfdisk/src/libfdisk.h.in b/libfdisk/src/libfdisk.h.in
index 5f75ecd14..a5a465674 100644
--- a/libfdisk/src/libfdisk.h.in
+++ b/libfdisk/src/libfdisk.h.in
@@ -531,6 +531,8 @@ extern int fdisk_sgi_create_info(struct fdisk_context *cxt);
 #define GPT_FLAG_GUIDSPECIFIC	4
 
 extern int fdisk_gpt_is_hybrid(struct fdisk_context *cxt);
+extern int fdisk_gpt_get_partition_attrs(struct fdisk_context *cxt, size_t partnum, uint64_t *attrs);
+extern int fdisk_gpt_set_partition_attrs(struct fdisk_context *cxt, size_t partnum, uint64_t attrs);
 
 
 /* script.c */
diff --git a/libfdisk/src/libfdisk.sym b/libfdisk/src/libfdisk.sym
index 456a52d83..1e6394465 100644
--- a/libfdisk/src/libfdisk.sym
+++ b/libfdisk/src/libfdisk.sym
@@ -247,4 +247,6 @@ FDISK_2.27 {
 	fdisk_enable_bootbits_protection;
 	fdisk_has_protected_bootbits;
 	fdisk_table_get_partition_by_partno;
+	fdisk_gpt_get_partition_attrs;
+	fdisk_gpt_set_partition_attrs;
 } FDISK_2.26;