misc: Replace zero-length arrays with flexible array member (manual)

Description copied from Linux kernel commit from Gustavo A. R. Silva
(see [3]):

--v-- description start --v--

  The current codebase makes use of the zero-length array language
  extension to the C90 standard, but the preferred mechanism to
  declare variable-length types such as these ones is a flexible
  array member [1], introduced in C99:

  struct foo {
      int stuff;
      struct boo array[];
  };

  By making use of the mechanism above, we will get a compiler
  warning in case the flexible array does not occur last in the
  structure, which will help us prevent some kind of undefined
  behavior bugs from being unadvertenly introduced [2] to the
  Linux codebase from now on.

--^-- description end --^--

Do the similar housekeeping in the QEMU codebase (which uses
C99 since commit 7be41675f7cb).

All these instances of code were found with the help of the
following command (then manual analysis, without modifying
structures only having a single flexible array member, such
QEDTable in block/qed.h):

  git grep -F '[0];'

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=76497732932f
[3] https://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux.git/commit/?id=17642a2fbd2c1

Inspired-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/block/vmdk.c b/block/vmdk.c
index 20e909d9979486f8e9e9ac26f7a8cc72a416ac0e..8466051bc90329cb51d16aeeb46604e816f9189c 100644 (file)
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -187,7 +187,7 @@ typedef struct VmdkMetaData {
 typedef struct VmdkGrainMarker {
     uint64_t lba;
     uint32_t size;
-    uint8_t  data[0];
+    uint8_t  data[];
 } QEMU_PACKED VmdkGrainMarker;
 
 enum {

diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 401652397cac6dcb736df745d180502002eabbd7..3b1b6602c77932101e1e3b098e35c2497f5b0260 100644 (file)
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -568,7 +568,7 @@ For split virtqueue, queue region can be implemented as:
       uint16_t used_idx;
 
       /* Used to track the state of each descriptor in descriptor table */
-      DescStateSplit desc[0];
+      DescStateSplit desc[];
   } QueueRegionSplit;
 
 To track inflight I/O, the queue region should be processed as follows:
@@ -690,7 +690,7 @@ For packed virtqueue, queue region can be implemented as:
       uint8_t padding[7];
 
       /* Used to track the state of each descriptor fetched from descriptor ring */
-      DescStatePacked desc[0];
+      DescStatePacked desc[];
   } QueueRegionPacked;
 
 To track inflight I/O, the queue region should be processed as follows:

diff --git a/hw/char/sclpconsole-lm.c b/hw/char/sclpconsole-lm.c
index c420dc066e2aef3bf214c906b459b7e37400c3a9..2b5f37b6a2a12e8c80e7f2f5289efc2e6cf3889f 100644 (file)
--- a/hw/char/sclpconsole-lm.c
+++ b/hw/char/sclpconsole-lm.c
@@ -31,7 +31,7 @@
 typedef struct OprtnsCommand {
     EventBufferHeader header;
     MDMSU message_unit;
-    char data[0];
+    char data[];
 } QEMU_PACKED OprtnsCommand;
 
 /* max size for line-mode data in 4K SCCB page */

diff --git a/hw/char/sclpconsole.c b/hw/char/sclpconsole.c
index 1fa124dab933913c4d9b15b06cee8da196dd2435..5c7664905e479f159ffe384f0e59135f106da801 100644 (file)
--- a/hw/char/sclpconsole.c
+++ b/hw/char/sclpconsole.c
@@ -25,7 +25,7 @@
 
 typedef struct ASCIIConsoleData {
     EventBufferHeader ebh;
-    char data[0];
+    char data[];
 } QEMU_PACKED ASCIIConsoleData;
 
 /* max size for ASCII data in 4K SCCB page */

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 50cf95b78121393320f602f5e8626906de05802a..64f928fc7d234b71a7b8ecd28d2e9f937524dcc2 100644 (file)
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -193,7 +193,7 @@ typedef struct VirtioThinintInfo {
 typedef struct VirtioRevInfo {
     uint16_t revision;
     uint16_t length;
-    uint8_t data[0];
+    uint8_t data[];
 } QEMU_PACKED VirtioRevInfo;
 
 /* Specify where the virtqueues for the subchannel are in guest memory. */

diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index 19f7ba7b7084a7aad7d3e610c5a38ebf7d19fc0d..c13327fa7867f50eddd7393b8170a9438b7cffd8 100644 (file)
--- a/include/hw/acpi/acpi-defs.h
+++ b/include/hw/acpi/acpi-defs.h
@@ -152,7 +152,7 @@ typedef struct AcpiSerialPortConsoleRedirection
  */
 struct AcpiRsdtDescriptorRev1 {
     ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
-    uint32_t table_offset_entry[0];  /* Array of pointers to other */
+    uint32_t table_offset_entry[];  /* Array of pointers to other */
     /* ACPI tables */
 } QEMU_PACKED;
 typedef struct AcpiRsdtDescriptorRev1 AcpiRsdtDescriptorRev1;
@@ -162,7 +162,7 @@ typedef struct AcpiRsdtDescriptorRev1 AcpiRsdtDescriptorRev1;
  */
 struct AcpiXsdtDescriptorRev2 {
     ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
-    uint64_t table_offset_entry[0];  /* Array of pointers to other */
+    uint64_t table_offset_entry[];  /* Array of pointers to other */
     /* ACPI tables */
 } QEMU_PACKED;
 typedef struct AcpiXsdtDescriptorRev2 AcpiXsdtDescriptorRev2;

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 9bc42dfb2254c75444d4de8a5efa6b2c1a0a32c3..c96120d15f6f01c41e0147e910c45b10911204f9 100644 (file)
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -71,7 +71,7 @@ typedef struct CPUArchId {
  */
 typedef struct {
     int len;
-    CPUArchId cpus[0];
+    CPUArchId cpus[];
 } CPUArchIdList;
 
 /**

diff --git a/include/hw/s390x/event-facility.h b/include/hw/s390x/event-facility.h
index bdc32a3c0917f8379e72fa74ed765be61f9cbaf0..700a610f33c032b005411a6a708e2983409978ee 100644 (file)
--- a/include/hw/s390x/event-facility.h
+++ b/include/hw/s390x/event-facility.h
@@ -122,7 +122,7 @@ typedef struct MDBO {
 
 typedef struct MDB {
     MdbHeader header;
-    MDBO mdbo[0];
+    MDBO mdbo[];
 } QEMU_PACKED MDB;
 
 typedef struct SclpMsg {

diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
index c54413b78cf01b274cc249b1409bb36892446a9a..cd7b24359f28deb4b659b1f284f6204427517abf 100644 (file)
--- a/include/hw/s390x/sclp.h
+++ b/include/hw/s390x/sclp.h
@@ -132,7 +132,7 @@ typedef struct ReadInfo {
     uint16_t highest_cpu;
     uint8_t  _reserved5[124 - 122];     /* 122-123 */
     uint32_t hmfai;
-    struct CPUEntry entries[0];
+    struct CPUEntry entries[];
 } QEMU_PACKED ReadInfo;
 
 typedef struct ReadCpuInfo {
@@ -142,7 +142,7 @@ typedef struct ReadCpuInfo {
     uint16_t nr_standby;            /* 12-13 */
     uint16_t offset_standby;        /* 14-15 */
     uint8_t reserved0[24-16];       /* 16-23 */
-    struct CPUEntry entries[0];
+    struct CPUEntry entries[];
 } QEMU_PACKED ReadCpuInfo;
 
 typedef struct ReadStorageElementInfo {
@@ -151,7 +151,7 @@ typedef struct ReadStorageElementInfo {
     uint16_t assigned;
     uint16_t standby;
     uint8_t _reserved0[16 - 14]; /* 14-15 */
-    uint32_t entries[0];
+    uint32_t entries[];
 } QEMU_PACKED ReadStorageElementInfo;
 
 typedef struct AttachStorageElement {
@@ -159,7 +159,7 @@ typedef struct AttachStorageElement {
     uint8_t _reserved0[10 - 8];  /* 8-9 */
     uint16_t assigned;
     uint8_t _reserved1[16 - 12]; /* 12-15 */
-    uint32_t entries[0];
+    uint32_t entries[];
 } QEMU_PACKED AttachStorageElement;
 
 typedef struct AssignStorage {

diff --git a/target/s390x/ioinst.c b/target/s390x/ioinst.c
index c437a1d8c6afed80199034ab6f6a6126fd0a33b1..0e840cc5792afe02d543568ba88016cde531f0ac 100644 (file)
--- a/target/s390x/ioinst.c
+++ b/target/s390x/ioinst.c
@@ -347,7 +347,7 @@ typedef struct ChscResp {
     uint16_t len;
     uint16_t code;
     uint32_t param;
-    char data[0];
+    char data[];
 } QEMU_PACKED ChscResp;
 
 #define CHSC_MIN_RESP_LEN 0x0008