libfdisk: add fdisk_new_context(), reuse context

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

6 files changed, 83 insertions, 31 deletions

diff --git a/libfdisk/src/alignment.c b/libfdisk/src/alignment.c
index 1ef5796a4..25323d1b5 100644
--- a/libfdisk/src/alignment.c
+++ b/libfdisk/src/alignment.c
@@ -185,7 +185,7 @@ int fdisk_discover_geometry(struct fdisk_context *cxt)
 	unsigned int h = 0, s = 0;
 
 	assert(cxt);
-	assert(!cxt->geom.heads);
+	assert(cxt->geom.heads == 0);
 
 	/* get number of 512-byte sectors, and convert it the real sectors */
 	if (!blkdev_get_sectors(cxt->dev_fd, &nsects))
diff --git a/libfdisk/src/context.c b/libfdisk/src/context.c
index 83420a977..b2929f351 100644
--- a/libfdisk/src/context.c
+++ b/libfdisk/src/context.c
@@ -1,7 +1,7 @@
 
 #include "fdiskP.h"
 
-static struct fdisk_context *fdisk_new_context(void)
+struct fdisk_context *fdisk_new_context(void)
 {
 	struct fdisk_context *cxt;
 	size_t i;
@@ -10,6 +10,9 @@ static struct fdisk_context *fdisk_new_context(void)
 	if (!cxt)
 		return NULL;
 
+	DBG(LABEL, dbgprint("new context %p allocated", cxt));
+	cxt->dev_fd = -1;
+
 	/*
 	 * Allocate label specific structs.
 	 *
@@ -47,8 +50,37 @@ struct fdisk_label *fdisk_context_get_label(struct fdisk_context *cxt, const cha
 	return NULL;
 }
 
+static void reset_context(struct fdisk_context *cxt)
+{
+	size_t nlbs;
+	struct fdisk_label *lbs[ ARRAY_SIZE(cxt->labels) ];
+
+	DBG(CONTEXT, dbgprint("\n-----\nresetting context %p", cxt));
+	fdisk_deinit_label(cxt);	/* reset the current label */
+
+	/* remember permanent setting */
+	memcpy(lbs, cxt->labels, sizeof(lbs));
+	nlbs = cxt->nlabels;
+
+	/* free device specific stuff */
+	if (cxt->dev_fd > -1)
+		close(cxt->dev_fd);
+	free(cxt->dev_path);
+	free(cxt->firstsector);
+
+	/* the reset */
+	memset(cxt, 0, sizeof(*cxt));
+
+	/* initialize */
+	cxt->dev_fd = -1;
+
+	/* set permanent setting */
+	memcpy(cxt->labels, lbs, sizeof(lbs));
+	cxt->nlabels = nlbs;
+}
+
 /**
- * fdisk_new_context_from_filename:
+ * fdisk_context_assign_device:
  * @fname: path to the device to be handled
  * @readonly: how to open the device
  *
@@ -56,25 +88,24 @@ struct fdisk_label *fdisk_context_get_label(struct fdisk_context *cxt, const cha
  * the device with read-write mode and will fallback to read-only if
  * unsuccessful.
  *
- * Returns: newly allocated fdisk context or NULL upon failure.
+ * Returns: 0 on sucess, < 0 on error.
  */
-struct fdisk_context *fdisk_new_context_from_filename(const char *fname, int readonly)
+int fdisk_context_assign_device(struct fdisk_context *cxt,
+				const char *fname, int readonly)
 {
-	int fd, errsv = 0;
-	struct fdisk_context *cxt = NULL;
+	int fd;
 
-	DBG(CONTEXT, dbgprint("initializing context for %s", fname));
+	DBG(CONTEXT, dbgprint("assigning device %s", fname));
+	assert(cxt);
+
+	reset_context(cxt);
 
 	if (readonly == 1 || (fd = open(fname, O_RDWR)) < 0) {
 		if ((fd = open(fname, O_RDONLY)) < 0)
-			return NULL;
+			return -errno;
 		readonly = 1;
 	}
 
-	cxt = fdisk_new_context();
-	if (!cxt)
-		goto fail;
-
 	cxt->dev_fd = fd;
 	cxt->dev_path = strdup(fname);
 	if (!cxt->dev_path)
@@ -89,20 +120,15 @@ struct fdisk_context *fdisk_new_context_from_filename(const char *fname, int rea
 	/* 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;
+	return 0;
 fail:
-	errsv = errno;
-	fdisk_free_context(cxt);
-	errno = errsv;
-
-	DBG(CONTEXT, dbgprint("failed to initialize context for %s: %m", fname));
-	return NULL;
+	DBG(CONTEXT, dbgprint("failed to assign device"));
+	return -errno;
 }
 
 /**
@@ -119,10 +145,7 @@ void fdisk_free_context(struct fdisk_context *cxt)
 		return;
 
 	DBG(CONTEXT, dbgprint("freeing context %p for %s", cxt, cxt->dev_path));
-	if (cxt->dev_fd > -1)
-		close(cxt->dev_fd);
-	free(cxt->dev_path);
-	free(cxt->firstsector);
+	reset_context(cxt);
 
 	/* deallocate label's private stuff */
 	for (i = 0; i < cxt->nlabels; i++) {
diff --git a/libfdisk/src/fdiskP.h b/libfdisk/src/fdiskP.h
index 01dd71f51..4d352b5d4 100644
--- a/libfdisk/src/fdiskP.h
+++ b/libfdisk/src/fdiskP.h
@@ -143,6 +143,8 @@ struct fdisk_label_operations {
 
 	/* free in-memory label stuff */
 	void (*free)(struct fdisk_label *lb);
+	/* deinit in-memory label stuff */
+	void (*deinit)(struct fdisk_label *lb);
 };
 
 /*
@@ -231,5 +233,6 @@ extern int fdisk_read_firstsector(struct fdisk_context *cxt);
 
 /* label.c */
 extern int fdisk_probe_labels(struct fdisk_context *cxt);
+extern void fdisk_deinit_label(struct fdisk_context *cxt);
 
 #endif /* _LIBFDISK_PRIVATE_H */
diff --git a/libfdisk/src/label.c b/libfdisk/src/label.c
index 8f9934835..5fb40adc7 100644
--- a/libfdisk/src/label.c
+++ b/libfdisk/src/label.c
@@ -9,15 +9,23 @@ int fdisk_probe_labels(struct fdisk_context *cxt)
 	size_t i;
 
 	cxt->disklabel = FDISK_DISKLABEL_ANY;
+	cxt->label = NULL;
 
 	for (i = 0; i < cxt->nlabels; i++) {
-		if (!cxt->labels[i]->op->probe ||
-		     cxt->labels[i]->op->probe(cxt) != 1)
+		struct fdisk_label *lb = cxt->labels[i];
+
+		if (!lb->op->probe)
 			continue;
 
-		cxt->label = cxt->labels[i];
+		DBG(LABEL, dbgprint("probing for %s", lb->name));
+		if (lb->op->probe(cxt) != 1) {
+			if (lb->op->deinit)
+				lb->op->deinit(lb);	/* for sure */
+			continue;
+		}
 
-		DBG(LABEL, dbgprint("detected a %s label", cxt->label->name));
+		cxt->label = lb;
+		DBG(LABEL, dbgprint("detected a %s label", lb->name));
 		return 0;
 	}
 
@@ -151,6 +159,8 @@ int fdisk_create_disklabel(struct fdisk_context *cxt, const char *name)
 #endif
 	}
 
+	fdisk_deinit_label(cxt);		/* deinitialize the current label */
+
 	cxt->label = fdisk_context_get_label(cxt, name);
 	if (!cxt->label)
 		return -EINVAL;
@@ -210,3 +220,16 @@ size_t fdisk_get_nparttypes(struct fdisk_context *cxt)
 
 	return cxt->label->nparttypes;
 }
+
+/*
+ * Resets the current used label driver to initial state
+ */
+void fdisk_deinit_label(struct fdisk_context *cxt)
+{
+	assert(cxt);
+
+	if (!cxt->label || !cxt->label->op->deinit)
+		return;
+
+	cxt->label->op->deinit(cxt->label);
+}
diff --git a/libfdisk/src/libfdisk.h b/libfdisk/src/libfdisk.h
index d72a60889..d803fc2dc 100644
--- a/libfdisk/src/libfdisk.h
+++ b/libfdisk/src/libfdisk.h
@@ -47,10 +47,12 @@ enum fdisk_labeltype {
 extern void fdisk_init_debug(int mask);
 
 /* context.h */
-extern struct fdisk_context *fdisk_new_context_from_filename(
-				const char *fname, int readonly);
+extern struct fdisk_context *fdisk_new_context(void);
 extern void fdisk_free_context(struct fdisk_context *cxt);
 
+extern int fdisk_context_assign_device(struct fdisk_context *cxt,
+				const char *fname, int readonly);
+
 extern struct fdisk_label *fdisk_context_get_label(struct fdisk_context *cxt,
 				const char *name);
 
diff --git a/libfdisk/src/utils.c b/libfdisk/src/utils.c
index 6668e23e3..1360e8467 100644
--- a/libfdisk/src/utils.c
+++ b/libfdisk/src/utils.c
@@ -35,6 +35,7 @@ int fdisk_read_firstsector(struct fdisk_context *cxt)
 	if (r != cxt->sector_size) {
 		if (!errno)
 			errno = EINVAL;	/* probably too small file/device */
+		DBG(TOPOLOGY, dbgprint("failed to read first sector %m"));
 		return -errno;
 	}