From 880a7817c1a82a93d3f83dfb25dce1f0db629c66 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Wed, 4 Mar 2020 16:38:16 +0100 Subject: misc: Replace zero-length arrays with flexible array member (manual) 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 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 Reviewed-by: David Hildenbrand Signed-off-by: Philippe Mathieu-Daudé Signed-off-by: Paolo Bonzini --- hw/char/sclpconsole-lm.c | 2 +- hw/char/sclpconsole.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'hw/char') diff --git a/hw/char/sclpconsole-lm.c b/hw/char/sclpconsole-lm.c index c420dc066e..2b5f37b6a2 100644 --- 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 1fa124dab9..5c7664905e 100644 --- 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 */ -- cgit v1.2.3