On 12/07/2017 05:05 AM, Peter Maydell wrote:
> On 5 December 2017 at 04:48, Richard Henderson
> <richard.hender...@linaro.org> wrote:
>> From: Richard Henderson <r...@twiddle.net>
>>
>> If the interp_prefix is a complete chroot, it may have a *lot* of files.
>> Setting up the cache for this is quite expensive. Instead, use the *at
>> versions of various syscalls to attempt the operation in the prefix.
>>
>> Signed-off-by: Richard Henderson <r...@twiddle.net>
>> ---
>>
>> Changes since v1 (Nov 2016):
>> * Require interp_dirfd set before trying the *at path.
>>
>>
>> r~
>> ---
>> linux-user/qemu.h | 1 +
>> linux-user/elfload.c | 12 ++-
>> linux-user/main.c | 3 +-
>> linux-user/syscall.c | 236
>> ++++++++++++++++++++++++++++++++++++++++++---------
>> 4 files changed, 208 insertions(+), 44 deletions(-)
>>
>> diff --git a/linux-user/qemu.h b/linux-user/qemu.h
>> index 4edd7d0c08..d04924fd2e 100644
>> --- a/linux-user/qemu.h
>> +++ b/linux-user/qemu.h
>> @@ -437,6 +437,7 @@ void mmap_fork_start(void);
>> void mmap_fork_end(int child);
>>
>> /* main.c */
>> +extern int interp_dirfd;
>> extern unsigned long guest_stack_size;
>>
>> /* user access */
>> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
>> index 20f3d8c2c3..5d3f7aa11d 100644
>> --- a/linux-user/elfload.c
>> +++ b/linux-user/elfload.c
>> @@ -2203,7 +2203,17 @@ static void load_elf_interp(const char *filename,
>> struct image_info *info,
>> {
>> int fd, retval;
>>
>> - fd = open(path(filename), O_RDONLY);
>> + switch (interp_dirfd > 0 && filename[0] == '/') {
>> + case true:
>
> gcc doesn't like this pattern:
>
> /home/petmay01/linaro/qemu-from-laptop/qemu/linux-user/syscall.c: In
> function ‘do_name_to_handle_at’:
> /home/petmay01/linaro/qemu-from-laptop/qemu/linux-user/syscall.c:7231:13:
> error: switch condition has boolean value [-Werror=switch-bool]
> switch (interp_dirfd > 0 && name[0] == '/') {
> ^
>
> It seems like an odd way to write an if().
Huh. My gcc likes it just fine. What version are you using?
It's an IF with a /* fallthru */, so there are very few
less ugly ways to write it...
r~
