From f7795e4096d8bd1c767c5ddb450fa859ff20490e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Wed, 4 Mar 2020 16:38:15 +0100 Subject: misc: Replace zero-length arrays with flexible array member (automatic) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: David Hildenbrand Signed-off-by: Philippe Mathieu-Daudé Signed-off-by: Paolo Bonzini --- hw/usb/dev-network.c | 2 +- hw/usb/dev-smartcard-reader.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'hw/usb') diff --git a/hw/usb/dev-network.c b/hw/usb/dev-network.c index 9a78ad9..6210427 100644 --- a/hw/usb/dev-network.c +++ b/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 { diff --git a/hw/usb/dev-smartcard-reader.c b/hw/usb/dev-smartcard-reader.c index 02693a2..ef72738 100644 --- a/hw/usb/dev-smartcard-reader.c +++ b/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 { -- cgit v1.1