libfdisk: add context functions

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/libfdisk/src/context.c b/libfdisk/src/context.c
new file mode 100644
index 000000000..302020590
--- /dev/null
+++ b/libfdisk/src/context.c
@@ -0,0 +1,78 @@
+
+#include "fdiskP.h"
+
+/**
+ * fdisk_new_context:
+ * @fname: path to the device to be handled
+ * @readonly: how to open the device
+ *
+ * If the @readonly flag is set to false, fdisk will attempt to open
+ * the device with read-write mode and will fallback to read-only if
+ * unsuccessful.
+ *
+ * Returns: newly allocated fdisk context or NULL upon failure.
+ */
+struct fdisk_context *fdisk_new_context_from_filename(const char *fname, int readonly)
+{
+	int fd, errsv = 0;
+	struct fdisk_context *cxt = NULL;
+
+	DBG(CONTEXT, dbgprint("initializing context for %s", fname));
+
+	if (readonly == 1 || (fd = open(fname, O_RDWR)) < 0) {
+		if ((fd = open(fname, O_RDONLY)) < 0)
+			return NULL;
+		readonly = 1;
+	}
+
+	cxt = calloc(1, sizeof(*cxt));
+	if (!cxt)
+		goto fail;
+
+	cxt->dev_fd = fd;
+	cxt->dev_path = strdup(fname);
+	if (!cxt->dev_path)
+		goto fail;
+
+	fdisk_discover_topology(cxt);
+	fdisk_discover_geometry(cxt);
+
+	if (fdisk_read_firstsector(cxt) < 0)
+		goto fail;
+
+	/* detect labels and apply labes specific stuff (e.g geomery)
+	 * to the context */
+	fdisk_probe_labels(cxt);
+
+	fdisk_reset_alignment(cxt);
+
+	DBG(CONTEXT, dbgprint("context %p initialized for %s [%s]",
+			      cxt, fname,
+			      readonly ? "READ-ONLY" : "READ-WRITE"));
+	return cxt;
+fail:
+	errsv = errno;
+	fdisk_free_context(cxt);
+	errno = errsv;
+
+	DBG(CONTEXT, dbgprint("failed to initialize context for %s: %m", fname));
+	return NULL;
+}
+
+/**
+ * fdisk_free_context:
+ * @cxt: fdisk context
+ *
+ * Deallocates context struct.
+ */
+void fdisk_free_context(struct fdisk_context *cxt)
+{
+	if (!cxt)
+		return;
+
+	DBG(CONTEXT, dbgprint("freeing context %p for %s", cxt, cxt->dev_path));
+	close(cxt->dev_fd);
+	free(cxt->dev_path);
+	free(cxt->firstsector);
+	free(cxt);
+}