block: feature detection for host block support

On Darwin (iOS), there are no system level APIs for directly accessing
host block devices. We detect this at configure time.

Signed-off-by: Joelle van Dyne <j@getutm.app>
Message-Id: <20210315180341.31638-2-j@getutm.app>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 37 insertions, 16 deletions

diff --git a/block/file-posix.c b/block/file-posix.c
index ea102483b0..e56bb491a1 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -42,6 +42,8 @@
 #include "scsi/constants.h"
 
 #if defined(__APPLE__) && (__MACH__)
+#include <sys/ioctl.h>
+#if defined(HAVE_HOST_BLOCK_DEVICE)
 #include <paths.h>
 #include <sys/param.h>
 #include <IOKit/IOKitLib.h>
@@ -52,6 +54,7 @@
 //#include <IOKit/storage/IOCDTypes.h>
 #include <IOKit/storage/IODVDMedia.h>
 #include <CoreFoundation/CoreFoundation.h>
+#endif /* defined(HAVE_HOST_BLOCK_DEVICE) */
 #endif
 
 #ifdef __sun__
@@ -178,7 +181,17 @@ typedef struct BDRVRawReopenState {
     bool check_cache_dropped;
 } BDRVRawReopenState;
 
-static int fd_open(BlockDriverState *bs);
+static int fd_open(BlockDriverState *bs)
+{
+    BDRVRawState *s = bs->opaque;
+
+    /* this is just to ensure s->fd is sane (its called by io ops) */
+    if (s->fd >= 0) {
+        return 0;
+    }
+    return -EIO;
+}
+
 static int64_t raw_getlength(BlockDriverState *bs);
 
 typedef struct RawPosixAIOData {
@@ -3033,6 +3046,7 @@ static BlockStatsSpecific *raw_get_specific_stats(BlockDriverState *bs)
     return stats;
 }
 
+#if defined(HAVE_HOST_BLOCK_DEVICE)
 static BlockStatsSpecific *hdev_get_specific_stats(BlockDriverState *bs)
 {
     BlockStatsSpecific *stats = g_new(BlockStatsSpecific, 1);
@@ -3042,6 +3056,7 @@ static BlockStatsSpecific *hdev_get_specific_stats(BlockDriverState *bs)
 
     return stats;
 }
+#endif /* HAVE_HOST_BLOCK_DEVICE */
 
 static QemuOptsList raw_create_opts = {
     .name = "raw-create-opts",
@@ -3257,6 +3272,8 @@ BlockDriver bdrv_file = {
 /***********************************************/
 /* host device */
 
+#if defined(HAVE_HOST_BLOCK_DEVICE)
+
 #if defined(__APPLE__) && defined(__MACH__)
 static kern_return_t GetBSDPath(io_iterator_t mediaIterator, char *bsdPath,
                                 CFIndex maxPathSize, int flags);
@@ -3549,16 +3566,6 @@ hdev_co_ioctl(BlockDriverState *bs, unsigned long int req, void *buf)
 }
 #endif /* linux */
 
-static int fd_open(BlockDriverState *bs)
-{
-    BDRVRawState *s = bs->opaque;
-
-    /* this is just to ensure s->fd is sane (its called by io ops) */
-    if (s->fd >= 0)
-        return 0;
-    return -EIO;
-}
-
 static coroutine_fn int
 hdev_co_pdiscard(BlockDriverState *bs, int64_t offset, int bytes)
 {
@@ -3882,6 +3889,8 @@ static BlockDriver bdrv_host_cdrom = {
 };
 #endif /* __FreeBSD__ */
 
+#endif /* HAVE_HOST_BLOCK_DEVICE */
+
 static void bdrv_file_init(void)
 {
     /*
@@ -3889,6 +3898,7 @@ static void bdrv_file_init(void)
      * registered last will get probed first.
      */
     bdrv_register(&bdrv_file);
+#if defined(HAVE_HOST_BLOCK_DEVICE)
     bdrv_register(&bdrv_host_device);
 #ifdef __linux__
     bdrv_register(&bdrv_host_cdrom);
@@ -3896,6 +3906,7 @@ static void bdrv_file_init(void)
 #if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
     bdrv_register(&bdrv_host_cdrom);
 #endif
+#endif /* HAVE_HOST_BLOCK_DEVICE */
 }
 
 block_init(bdrv_file_init);
diff --git a/meson.build b/meson.build
index 64e23175ab..6419d4ee41 100644
--- a/meson.build
+++ b/meson.build
@@ -183,7 +183,7 @@ if targetos == 'windows'
                                       include_directories: include_directories('.'))
 elif targetos == 'darwin'
   coref = dependency('appleframeworks', modules: 'CoreFoundation')
-  iokit = dependency('appleframeworks', modules: 'IOKit')
+  iokit = dependency('appleframeworks', modules: 'IOKit', required: false)
 elif targetos == 'sunos'
   socket = [cc.find_library('socket'),
             cc.find_library('nsl'),
@@ -1148,6 +1148,9 @@ if get_option('cfi')
   add_global_link_arguments(cfi_flags, native: false, language: ['c', 'cpp', 'objc'])
 endif
 
+have_host_block_device = (targetos != 'darwin' or
+    cc.has_header('IOKit/storage/IOMedia.h'))
+
 #################
 # config-host.h #
 #################
@@ -1247,6 +1250,7 @@ config_host_data.set('HAVE_PTY_H', cc.has_header('pty.h'))
 config_host_data.set('HAVE_SYS_IOCCOM_H', cc.has_header('sys/ioccom.h'))
 config_host_data.set('HAVE_SYS_KCOV_H', cc.has_header('sys/kcov.h'))
 config_host_data.set('HAVE_SYSTEM_FUNCTION', cc.has_function('system', prefix: '#include <stdlib.h>'))
+config_host_data.set('HAVE_HOST_BLOCK_DEVICE', have_host_block_device)
 
 config_host_data.set('CONFIG_PREADV', cc.has_function('preadv', prefix: '#include <sys/uio.h>'))
 
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 2ea294129e..a54f37dbef 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -897,7 +897,8 @@
   'discriminator': 'driver',
   'data': {
       'file': 'BlockStatsSpecificFile',
-      'host_device': 'BlockStatsSpecificFile',
+      'host_device': { 'type': 'BlockStatsSpecificFile',
+                       'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
       'nvme': 'BlockStatsSpecificNvme' } }
 
 ##
@@ -2814,7 +2815,10 @@
 { 'enum': 'BlockdevDriver',
   'data': [ 'blkdebug', 'blklogwrites', 'blkreplay', 'blkverify', 'bochs',
             'cloop', 'compress', 'copy-on-read', 'dmg', 'file', 'ftp', 'ftps',
-            'gluster', 'host_cdrom', 'host_device', 'http', 'https', 'iscsi',
+            'gluster',
+            {'name': 'host_cdrom', 'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
+            {'name': 'host_device', 'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
+            'http', 'https', 'iscsi',
             'luks', 'nbd', 'nfs', 'null-aio', 'null-co', 'nvme', 'parallels',
             'preallocate', 'qcow', 'qcow2', 'qed', 'quorum', 'raw', 'rbd',
             { 'name': 'replication', 'if': 'defined(CONFIG_REPLICATION)' },
@@ -3995,8 +3999,10 @@
       'ftp':        'BlockdevOptionsCurlFtp',
       'ftps':       'BlockdevOptionsCurlFtps',
       'gluster':    'BlockdevOptionsGluster',
-      'host_cdrom': 'BlockdevOptionsFile',
-      'host_device':'BlockdevOptionsFile',
+      'host_cdrom':  { 'type': 'BlockdevOptionsFile',
+                       'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
+      'host_device': { 'type': 'BlockdevOptionsFile',
+                       'if': 'defined(HAVE_HOST_BLOCK_DEVICE)' },
       'http':       'BlockdevOptionsCurlHttp',
       'https':      'BlockdevOptionsCurlHttps',
       'iscsi':      'BlockdevOptionsIscsi',