[Qemu-devel] [PATCH v3 17/32] blockdev: Separate bochs probe from its driver

[Colin Lord <clord@redhat.com>]

Modifies the bochs probe to return the format name as well as the
score as the final step of separating the probe function from the
driver. This keeps the probe completely independent of the driver,
making future modularization easier to accomplish. Returning the format
name as well as the score allows the score to be correlated to the
driver without the probe function needing to be part of the driver.

Signed-off-by: Colin Lord <clord@redhat.com>
---
 block.c               | 19 +++++++++++++++++++
 block/bochs.c         |  1 -
 block/probe/bochs.c   | 25 ++++++++++++++++---------
 include/block/probe.h |  3 ++-
 4 files changed, 37 insertions(+), 11 deletions(-)

diff --git a/block.c b/block.c
index 88a05b2..eab8a6e 100644
--- a/block.c
+++ b/block.c
@@ -25,6 +25,7 @@
 #include "trace.h"
 #include "block/block_int.h"
 #include "block/blockjob.h"
+#include "block/probe.h"
 #include "qemu/error-report.h"
 #include "module_block.h"
 #include "qemu/module.h"
@@ -56,6 +57,13 @@
 
 #define NOT_DONE 0x7fffffff /* used while emulated sync operation in progress */
 
+typedef const char *BdrvProbeFunc(const uint8_t *buf, int buf_size,
+                                  const char *filename, int *score);
+
+static BdrvProbeFunc *format_probes[] = {
+    bochs_probe,
+};
+
 static QTAILQ_HEAD(, BlockDriverState) graph_bdrv_states =
     QTAILQ_HEAD_INITIALIZER(graph_bdrv_states);
 
@@ -576,6 +584,8 @@ BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
                             const char *filename)
 {
     int score_max = 0, score;
+    const char *format_max = NULL;
+    const char *format;
     size_t i;
     BlockDriver *drv = NULL, *d;
 
@@ -595,6 +605,15 @@ BlockDriver *bdrv_probe_all(const uint8_t *buf, int buf_size,
         }
     }
 
+    for (i = 0; i < ARRAY_SIZE(format_probes); i++) {
+        format = format_probes[i](buf, buf_size, filename, &score);
+        if (score > score_max) {
+            score_max = score;
+            format_max = format;
+            drv = bdrv_find_format(format_max);
+        }
+    }
+
     return drv;
 }
 
diff --git a/block/bochs.c b/block/bochs.c
index 11da0fd..5c94bc6 100644
--- a/block/bochs.c
+++ b/block/bochs.c
@@ -230,7 +230,6 @@ static void bochs_close(BlockDriverState *bs)
 static BlockDriver bdrv_bochs = {
     .format_name	= "bochs",
     .instance_size	= sizeof(BDRVBochsState),
-    .bdrv_probe		= bochs_probe,
     .bdrv_open		= bochs_open,
     .bdrv_co_preadv = bochs_co_preadv,
     .bdrv_close		= bochs_close,
diff --git a/block/probe/bochs.c b/block/probe/bochs.c
index 8adc09f..8206930 100644
--- a/block/probe/bochs.c
+++ b/block/probe/bochs.c
@@ -3,19 +3,26 @@
 #include "block/probe.h"
 #include "block/driver/bochs.h"
 
-int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
+const char *bochs_probe(const uint8_t *buf, int buf_size, const char *filename,
+                        int *score)
 {
+    const char *format = "bochs";
     const struct bochs_header *bochs = (const void *)buf;
+    assert(score);
+    *score = 0;
 
-    if (buf_size < HEADER_SIZE)
-	return 0;
+    if (buf_size < HEADER_SIZE) {
+        return format;
+    }
 
     if (!strcmp(bochs->magic, HEADER_MAGIC) &&
-	!strcmp(bochs->type, REDOLOG_TYPE) &&
-	!strcmp(bochs->subtype, GROWING_TYPE) &&
-	((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
-	(le32_to_cpu(bochs->version) == HEADER_V1)))
-	return 100;
+        !strcmp(bochs->type, REDOLOG_TYPE) &&
+        !strcmp(bochs->subtype, GROWING_TYPE) &&
+        ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
+        (le32_to_cpu(bochs->version) == HEADER_V1))) {
+        *score = 100;
+        return format;
+    }
 
-    return 0;
+    return format;
 }
diff --git a/include/block/probe.h b/include/block/probe.h
index 6cf878b..13c08bd 100644
--- a/include/block/probe.h
+++ b/include/block/probe.h
@@ -1,7 +1,6 @@
 #ifndef PROBE_H
 #define PROBE_H
 
-int bochs_probe(const uint8_t *buf, int buf_size, const char *filename);
 int cloop_probe(const uint8_t *buf, int buf_size, const char *filename);
 int block_crypto_probe_luks(const uint8_t *buf, int buf_size,
                             const char *filename);
@@ -15,5 +14,7 @@ int vdi_probe(const uint8_t *buf, int buf_size, const char *filename);
 int vhdx_probe(const uint8_t *buf, int buf_size, const char *filename);
 int vmdk_probe(const uint8_t *buf, int buf_size, const char *filename);
 int vpc_probe(const uint8_t *buf, int buf_size, const char *filename);
+const char *bochs_probe(const uint8_t *buf, int buf_size, const char *filename,
+                        int *score);
 
 #endif
-- 
2.5.5