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

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 Coccinelle script:

  @@
  identifier s, m, a;
  type t, T;
  @@
   struct s {
      ...
      t m;
  -   T a[0];
  +   T a[];
  };
  @@
  identifier s, m, a;
  type t, T;
  @@
   struct s {
      ...
      t m;
  -   T a[0];
  +   T a[];
   } QEMU_PACKED;

[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>

block/linux-aio.c

@@ -121,7 +121,7 @@ struct aio_ring {
     unsigned    incompat_features;
     unsigned    header_length;  /* size of aio_ring */
 
-    struct io_event io_events[0];
+    struct io_event io_events[];
 };
 
 /**

bsd-user/qemu.h

@@ -95,7 +95,7 @@ typedef struct TaskState {
     struct sigqueue *first_free; /* first free siginfo queue entry */
     int signal_pending; /* non zero if a signal may be pending */
 
-    uint8_t stack[0];
+    uint8_t stack[];
 } __attribute__((aligned(16))) TaskState;
 
 void init_task_state(TaskState *ts);

contrib/libvhost-user/libvhost-user.h

@@ -286,7 +286,7 @@ typedef struct VuVirtqInflight {
     uint16_t used_idx;
 
     /* Used to track the state of each descriptor in descriptor table */
-    VuDescStateSplit desc[0];
+    VuDescStateSplit desc[];
 } VuVirtqInflight;
 
 typedef struct VuVirtqInflightDesc {

hw/acpi/nvdimm.c

@@ -485,7 +485,7 @@ struct NvdimmFuncGetLabelDataOut {
     /* the size of buffer filled by QEMU. */
     uint32_t len;
     uint32_t func_ret_status; /* return status code. */
-    uint8_t out_buf[0]; /* the data got via Get Namesapce Label function. */
+    uint8_t out_buf[]; /* the data got via Get Namesapce Label function. */
 } QEMU_PACKED;
 typedef struct NvdimmFuncGetLabelDataOut NvdimmFuncGetLabelDataOut;
 QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncGetLabelDataOut) > NVDIMM_DSM_MEMORY_SIZE);
@@ -493,7 +493,7 @@ QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncGetLabelDataOut) > NVDIMM_DSM_MEMORY_SIZE);
 struct NvdimmFuncSetLabelDataIn {
     uint32_t offset; /* the offset in the namespace label data area. */
     uint32_t length; /* the size of data is to be written via the function. */
-    uint8_t in_buf[0]; /* the data written to label data area. */
+    uint8_t in_buf[]; /* the data written to label data area. */
 } QEMU_PACKED;
 typedef struct NvdimmFuncSetLabelDataIn NvdimmFuncSetLabelDataIn;
 QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncSetLabelDataIn) +
@@ -510,7 +510,7 @@ struct NvdimmFuncReadFITOut {
     /* the size of buffer filled by QEMU. */
     uint32_t len;
     uint32_t func_ret_status; /* return status code. */
-    uint8_t fit[0]; /* the FIT data. */
+    uint8_t fit[]; /* the FIT data. */
 } QEMU_PACKED;
 typedef struct NvdimmFuncReadFITOut NvdimmFuncReadFITOut;
 QEMU_BUILD_BUG_ON(sizeof(NvdimmFuncReadFITOut) > NVDIMM_DSM_MEMORY_SIZE);

hw/dma/soc_dma.c

@@ -80,7 +80,7 @@ struct dma_s {
     } *memmap;
     int memmap_size;
 
-    struct soc_dma_ch_s ch[0];
+    struct soc_dma_ch_s ch[];
 };
 
 static void soc_dma_ch_schedule(struct soc_dma_ch_s *ch, int delay_bytes)

hw/i386/x86.c

@@ -328,7 +328,7 @@ struct setup_data {
     uint64_t next;
     uint32_t type;
     uint32_t len;
-    uint8_t data[0];
+    uint8_t data[];
 } __attribute__((packed));
 
 

hw/m68k/bootinfo.h

@@ -14,7 +14,7 @@
 struct bi_record {
     uint16_t tag;        /* tag ID */
     uint16_t size;       /* size of record */
-    uint32_t data[0];    /* data */
+    uint32_t data[];     /* data */
 };
 
 /* machine independent tags */

hw/misc/omap_l4.c

@@ -24,7 +24,7 @@ struct omap_l4_s {
     MemoryRegion *address_space;
     hwaddr base;
     int ta_num;
-    struct omap_target_agent_s ta[0];
+    struct omap_target_agent_s ta[];
 };
 
 struct omap_l4_s *omap_l4_init(MemoryRegion *address_space,

hw/nvram/eeprom93xx.c

@@ -86,7 +86,7 @@ struct _eeprom_t {
     uint8_t  addrbits;
     uint16_t size;
     uint16_t data;
-    uint16_t contents[0];
+    uint16_t contents[];
 };
 
 /* Code for saving and restoring of EEPROM state. */

hw/rdma/vmw/pvrdma_qp_ops.c

@@ -34,13 +34,13 @@ typedef struct CompHandlerCtx {
 /* Send Queue WQE */
 typedef struct PvrdmaSqWqe {
     struct pvrdma_sq_wqe_hdr hdr;
-    struct pvrdma_sge sge[0];
+    struct pvrdma_sge sge[];
 } PvrdmaSqWqe;
 
 /* Recv Queue WQE */
 typedef struct PvrdmaRqWqe {
     struct pvrdma_rq_wqe_hdr hdr;
-    struct pvrdma_sge sge[0];
+    struct pvrdma_sge sge[];
 } PvrdmaRqWqe;
 
 /*

hw/usb/dev-network.c

@@ -626,7 +626,7 @@ static const uint32_t oid_supported_list[] =
 struct rndis_response {
     QTAILQ_ENTRY(rndis_response) entries;
     uint32_t length;
-    uint8_t buf[0];
+    uint8_t buf[];
 };
 
 typedef struct USBNetState {

hw/usb/dev-smartcard-reader.c

@@ -227,7 +227,7 @@ typedef struct QEMU_PACKED CCID_Parameter {
 typedef struct QEMU_PACKED CCID_DataBlock {
     CCID_BULK_IN b;
     uint8_t      bChainParameter;
-    uint8_t      abData[0];
+    uint8_t      abData[];
 } CCID_DataBlock;
 
 /* 6.1.4 PC_to_RDR_XfrBlock */
@@ -235,7 +235,7 @@ typedef struct QEMU_PACKED CCID_XferBlock {
     CCID_Header  hdr;
     uint8_t      bBWI; /* Block Waiting Timeout */
     uint16_t     wLevelParameter; /* XXX currently unused */
-    uint8_t      abData[0];
+    uint8_t      abData[];
 } CCID_XferBlock;
 
 typedef struct QEMU_PACKED CCID_IccPowerOn {

hw/virtio/virtio.c

@@ -54,7 +54,7 @@ typedef struct VRingAvail
 {
     uint16_t flags;
     uint16_t idx;
-    uint16_t ring[0];
+    uint16_t ring[];
 } VRingAvail;
 
 typedef struct VRingUsedElem
@@ -67,7 +67,7 @@ typedef struct VRingUsed
 {
     uint16_t flags;
     uint16_t idx;
-    VRingUsedElem ring[0];
+    VRingUsedElem ring[];
 } VRingUsed;
 
 typedef struct VRingMemoryRegionCaches {

hw/xen/xen_pt.h

@@ -203,7 +203,7 @@ typedef struct XenPTMSIX {
     uint64_t mmio_base_addr;
     MemoryRegion mmio;
     void *phys_iomem_base;
-    XenPTMSIXEntry msix_entry[0];
+    XenPTMSIXEntry msix_entry[];
 } XenPTMSIX;
 
 struct XenPCIPassthroughState {

include/hw/acpi/acpi-defs.h

@@ -518,7 +518,7 @@ struct AcpiDmarDeviceScope {
     struct {
         uint8_t device;
         uint8_t function;
-    } path[0];
+    } path[];
 } QEMU_PACKED;
 typedef struct AcpiDmarDeviceScope AcpiDmarDeviceScope;
 
@@ -530,7 +530,7 @@ struct AcpiDmarHardwareUnit {
     uint8_t reserved;
     uint16_t pci_segment;   /* The PCI Segment associated with this unit */
     uint64_t address;   /* Base address of remapping hardware register-set */
-    AcpiDmarDeviceScope scope[0];
+    AcpiDmarDeviceScope scope[];
 } QEMU_PACKED;
 typedef struct AcpiDmarHardwareUnit AcpiDmarHardwareUnit;
 
@@ -541,7 +541,7 @@ struct AcpiDmarRootPortATS {
     uint8_t flags;
     uint8_t reserved;
     uint16_t pci_segment;
-    AcpiDmarDeviceScope scope[0];
+    AcpiDmarDeviceScope scope[];
 } QEMU_PACKED;
 typedef struct AcpiDmarRootPortATS AcpiDmarRootPortATS;
 
@@ -604,7 +604,7 @@ typedef struct AcpiIortMemoryAccess AcpiIortMemoryAccess;
 struct AcpiIortItsGroup {
     ACPI_IORT_NODE_HEADER_DEF
     uint32_t its_count;
-    uint32_t identifiers[0];
+    uint32_t identifiers[];
 } QEMU_PACKED;
 typedef struct AcpiIortItsGroup AcpiIortItsGroup;
 
@@ -621,7 +621,7 @@ struct AcpiIortSmmu3 {
     uint32_t pri_gsiv;
     uint32_t gerr_gsiv;
     uint32_t sync_gsiv;
-    AcpiIortIdMapping id_mapping_array[0];
+    AcpiIortIdMapping id_mapping_array[];
 } QEMU_PACKED;
 typedef struct AcpiIortSmmu3 AcpiIortSmmu3;
 
@@ -630,7 +630,7 @@ struct AcpiIortRC {
     AcpiIortMemoryAccess memory_properties;
     uint32_t ats_attribute;
     uint32_t pci_segment_number;
-    AcpiIortIdMapping id_mapping_array[0];
+    AcpiIortIdMapping id_mapping_array[];
 } QEMU_PACKED;
 typedef struct AcpiIortRC AcpiIortRC;
 

include/hw/arm/smmu-common.h

@@ -85,7 +85,7 @@ typedef struct SMMUDevice {
 
 typedef struct SMMUPciBus {
     PCIBus       *bus;
-    SMMUDevice   *pbdev[0]; /* Parent array is sparse, so dynamically alloc */
+    SMMUDevice   *pbdev[]; /* Parent array is sparse, so dynamically alloc */
 } SMMUPciBus;
 
 typedef struct SMMUIOTLBKey {

include/hw/i386/intel_iommu.h

@@ -114,7 +114,8 @@ struct VTDAddressSpace {
 
 struct VTDBus {
     PCIBus* bus;		/* A reference to the bus to provide translation for */
-    VTDAddressSpace *dev_as[0];	/* A table of VTDAddressSpace objects indexed by devfn */
+    /* A table of VTDAddressSpace objects indexed by devfn */
+    VTDAddressSpace *dev_as[];
 };
 
 struct VTDIOTLBEntry {

include/hw/virtio/virtio-iommu.h

@@ -41,7 +41,7 @@ typedef struct IOMMUDevice {
 
 typedef struct IOMMUPciBus {
     PCIBus       *bus;
-    IOMMUDevice  *pbdev[0]; /* Parent array is sparse, so dynamically alloc */
+    IOMMUDevice  *pbdev[]; /* Parent array is sparse, so dynamically alloc */
 } IOMMUPciBus;
 
 typedef struct VirtIOIOMMU {

include/sysemu/cryptodev.h

@@ -143,7 +143,7 @@ typedef struct CryptoDevBackendSymOpInfo {
     uint8_t *dst;
     uint8_t *aad_data;
     uint8_t *digest_result;
-    uint8_t data[0];
+    uint8_t data[];
 } CryptoDevBackendSymOpInfo;
 
 typedef struct CryptoDevBackendClass {

include/tcg/tcg.h

@@ -267,7 +267,7 @@ struct TCGLabel {
 typedef struct TCGPool {
     struct TCGPool *next;
     int size;
-    uint8_t data[0] __attribute__ ((aligned));
+    uint8_t data[] __attribute__ ((aligned));
 } TCGPool;
 
 #define TCG_POOL_CHUNK_SIZE 32768

net/queue.c

@@ -46,7 +46,7 @@ struct NetPacket {
     unsigned flags;
     int size;
     NetPacketSent *sent_cb;
-    uint8_t data[0];
+    uint8_t data[];
 };
 
 struct NetQueue {

pc-bios/s390-ccw/bootmap.h

@@ -136,7 +136,7 @@ typedef struct BootMapScriptHeader {
 
 typedef struct BootMapScript {
     BootMapScriptHeader header;
-    BootMapScriptEntry  entry[0];
+    BootMapScriptEntry  entry[];
 } __attribute__ ((packed)) BootMapScript;
 
 /*

pc-bios/s390-ccw/sclp.h

@@ -95,7 +95,7 @@ typedef struct EventBufferHeader {
 typedef struct WriteEventData {
     SCCBHeader h;
     EventBufferHeader ebh;
-    char data[0];
+    char data[];
 } __attribute__((packed)) WriteEventData;
 
 typedef struct ReadEventData {

tests/qtest/libqos/ahci.h

@@ -351,7 +351,7 @@ typedef struct AHCIQState {
 typedef struct FIS {
     uint8_t fis_type;
     uint8_t flags;
-    char data[0];
+    char data[];
 } __attribute__((__packed__)) FIS;
 
 /**