Nikita Ivanov <niva...@cloudlinux.com> writes:
> Summing up the discussion above, I suggest the following patch for TFR()
> macro refactoring. (The patch is sequential to the first one I introduced
> in the start of the discussion).
>
>>From 6318bee052900aa93bba6620b53c7cb2290e5001 Mon Sep 17 00:00:00 2001
> From: Nikita Ivanov <niva...@cloudlinux.com>
> Date: Mon, 8 Aug 2022 09:30:34 +0300
> Subject: [PATCH] Refactoring: rename TFR() to TEMP_FAILURE_RETRY()
>
> glibc's unistd.h header provides the same macro with the
> subtle difference in type casting. Adjust macro name to the
> common standard and define conditionally.
>
> Signed-off-by: Nikita Ivanov <niva...@cloudlinux.com>
> ---
> chardev/char-fd.c | 2 +-
> chardev/char-pipe.c | 12 +++++++++---
> hw/9pfs/9p-local.c | 6 ++++--
> include/qemu/osdep.h | 6 ++++--
> net/l2tpv3.c | 8 +++++---
> net/tap-linux.c | 2 +-
> net/tap.c | 10 ++++++----
> os-posix.c | 2 +-
> qga/commands-posix.c | 2 +-
> tests/qtest/libqtest.c | 2 +-
> util/main-loop.c | 2 +-
> util/osdep.c | 2 +-
> 12 files changed, 35 insertions(+), 21 deletions(-)
>
> diff --git a/chardev/char-fd.c b/chardev/char-fd.c
> index cf78454841..7f5ed9aba3 100644
> --- a/chardev/char-fd.c
> +++ b/chardev/char-fd.c
> @@ -198,7 +198,7 @@ int qmp_chardev_open_file_source(char *src, int flags,
> Error **errp)
> {
> int fd = -1;
>
> - TFR(fd = qemu_open_old(src, flags, 0666));
> + TEMP_FAILURE_RETRY(fd = qemu_open_old(src, flags, 0666));
> if (fd == -1) {
> error_setg_file_open(errp, errno, src);
> }
> diff --git a/chardev/char-pipe.c b/chardev/char-pipe.c
> index 66d3b85091..aed97e306b 100644
> --- a/chardev/char-pipe.c
> +++ b/chardev/char-pipe.c
> @@ -131,8 +131,12 @@ static void qemu_chr_open_pipe(Chardev *chr,
>
> filename_in = g_strdup_printf("%s.in", filename);
> filename_out = g_strdup_printf("%s.out", filename);
> - TFR(fd_in = qemu_open_old(filename_in, O_RDWR | O_BINARY));
> - TFR(fd_out = qemu_open_old(filename_out, O_RDWR | O_BINARY));
> + TEMP_FAILURE_RETRY(
> + fd_in = qemu_open_old(filename_in, O_RDWR | O_BINARY)
> + );
> + TEMP_FAILURE_RETRY(
> + fd_out = qemu_open_old(filename_out, O_RDWR | O_BINARY)
> + );
Style question: do we want the ");" on its own line? I think we
generally don't do that for function and function-like macro calls.
> g_free(filename_in);
> g_free(filename_out);
> if (fd_in < 0 || fd_out < 0) {
> @@ -142,7 +146,9 @@ static void qemu_chr_open_pipe(Chardev *chr,
> if (fd_out >= 0) {
> close(fd_out);
> }
> - TFR(fd_in = fd_out = qemu_open_old(filename, O_RDWR | O_BINARY));
> + TEMP_FAILURE_RETRY(
> + fd_in = fd_out = qemu_open_old(filename, O_RDWR | O_BINARY)
> + );
> if (fd_in < 0) {
> error_setg_file_open(errp, errno, filename);
> return;
> diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
> index c90ab947ba..e803c05d0c 100644
> --- a/hw/9pfs/9p-local.c
> +++ b/hw/9pfs/9p-local.c
> @@ -470,7 +470,7 @@ static ssize_t local_readlink(FsContext *fs_ctx,
> V9fsPath *fs_path,
> if (fd == -1) {
> return -1;
> }
> - TFR(tsize = read(fd, (void *)buf, bufsz));
> + TEMP_FAILURE_RETRY(tsize = read(fd, (void *)buf, bufsz));
> close_preserve_errno(fd);
> } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
> (fs_ctx->export_flags & V9FS_SM_NONE)) {
> @@ -906,7 +906,9 @@ static int local_symlink(FsContext *fs_ctx, const char
> *oldpath,
> }
> /* Write the oldpath (target) to the file. */
> oldpath_size = strlen(oldpath);
> - TFR(write_size = write(fd, (void *)oldpath, oldpath_size));
> + TEMP_FAILURE_RETRY(
> + write_size = write(fd, (void *)oldpath, oldpath_size)
> + );
> close_preserve_errno(fd);
>
> if (write_size != oldpath_size) {
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index b1c161c035..55f2927d8b 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -242,8 +242,10 @@ void QEMU_ERROR("code path is reachable")
> #if !defined(ESHUTDOWN)
> #define ESHUTDOWN 4099
> #endif
> -
> -#define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
> +#if !defined(TEMP_FAILURE_RETRY)
> +#define TEMP_FAILURE_RETRY(expr) \
> + do { if ((expr) != -1) break; } while (errno == EINTR)
> +#endif
GLibc's version is
# define TEMP_FAILURE_RETRY(expression) \
(__extension__ \
({ long int __result; \
do __result = (long int) (expression);
\
while (__result == -1L && errno == EINTR); \
__result; }))
The difference isn't just "type casting", it's also statement
vs. expression.
Is it a good idea to have the macro expand into a statement on some
hosts, and into an expression on others? Sure, CI should catch any uses
as expression, but delaying compile errors to CI wastes developer time.
>
> /* time_t may be either 32 or 64 bits depending on the host OS, and
> * can be either signed or unsigned, so we can't just hardcode a
[...]
