| Message ID | 1370193044-24535-1-git-send-email-peter.maydell@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 06/02/2013 10:10 AM, Peter Maydell wrote: > + tde->d_ino = tswapal(ino); > + tde->d_off = tswapal(off); > + tde->d_reclen = tswap16(treclen); > + memmove(tde->d_name, de->d_name, namelen + 1); Wouldn't it be better to do the memmove first? Then you really are reading all of the dirent64 data first, like your comment says. > + /* The target_dirent type is in what was formerly a padding > + * byte at the end of the structure: > + */ > + *(((char *)tde) + treclen - 1) = type; Maybe easier to read as ((char *)tde)[treclen - 1] = type ? r~
On 3 June 2013 16:15, Richard Henderson <rth@twiddle.net> wrote: > On 06/02/2013 10:10 AM, Peter Maydell wrote: >> + tde->d_ino = tswapal(ino); >> + tde->d_off = tswapal(off); >> + tde->d_reclen = tswap16(treclen); >> + memmove(tde->d_name, de->d_name, namelen + 1); > > Wouldn't it be better to do the memmove first? Then you really are reading all > of the dirent64 data first, like your comment says. It doesn't actually make a difference, in fact, but I agree it would be clearer that way round. >> + /* The target_dirent type is in what was formerly a padding >> + * byte at the end of the structure: >> + */ >> + *(((char *)tde) + treclen - 1) = type; > > Maybe easier to read as > > ((char *)tde)[treclen - 1] = type > > ? Dunno. It's not actually a char array, so I kind of prefer to use plain pointer arithmetic for this kind of thing. -- PMM
On 06/03/2013 08:45 AM, Peter Maydell wrote: >>> >> + /* The target_dirent type is in what was formerly a padding >>> >> + * byte at the end of the structure: >>> >> + */ >>> >> + *(((char *)tde) + treclen - 1) = type; >> > >> > Maybe easier to read as >> > >> > ((char *)tde)[treclen - 1] = type >> > >> > ? > Dunno. It's not actually a char array, so I kind of prefer > to use plain pointer arithmetic for this kind of thing. Then drop the unnecessary parenthesis *((char *)tde + trelen - 1) = type; ? r~
On 3 June 2013 16:58, Richard Henderson <rth@twiddle.net> wrote: > On 06/03/2013 08:45 AM, Peter Maydell wrote: >> Dunno. It's not actually a char array, so I kind of prefer >> to use plain pointer arithmetic for this kind of thing. > > Then drop the unnecessary parenthesis > > *((char *)tde + trelen - 1) = type; > > ? That parenthesis is there under my "if you can't immediately say what the relative precedence of two operators is then add brackets" rule. (ie I don't offhand know precedence of the cast operator). -- PMM
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 053fa14..15c771a 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -208,8 +208,11 @@ static int gettid(void) { return -ENOSYS; } #endif +#ifdef __NR_getdents _syscall3(int, sys_getdents, uint, fd, struct linux_dirent *, dirp, uint, count); -#if defined(TARGET_NR_getdents64) && defined(__NR_getdents64) +#endif +#if !defined(__NR_getdents) || \ + (defined(TARGET_NR_getdents64) && defined(__NR_getdents64)) _syscall3(int, sys_getdents64, uint, fd, struct linux_dirent64 *, dirp, uint, count); #endif #if defined(TARGET_NR__llseek) && defined(__NR_llseek) @@ -6963,6 +6966,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; #endif case TARGET_NR_getdents: +#ifdef __NR_getdents #if TARGET_ABI_BITS == 32 && HOST_LONG_BITS == 64 { struct target_dirent *target_dirp; @@ -7035,6 +7039,60 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, unlock_user(dirp, arg2, ret); } #endif +#else + /* Implement getdents in terms of getdents64 */ + { + struct linux_dirent64 *dirp; + abi_long count = arg3; + + dirp = lock_user(VERIFY_WRITE, arg2, count, 0); + if (!dirp) { + goto efault; + } + ret = get_errno(sys_getdents64(arg1, dirp, count)); + if (!is_error(ret)) { + /* Convert the dirent64 structs to target dirent. We do this + * in-place, since we can guarantee that a target_dirent is no + * larger than a dirent64; however this means we have to be + * careful to read everything before writing in the new format. + */ + struct linux_dirent64 *de; + struct target_dirent *tde; + int len = ret; + int tlen = 0; + + de = dirp; + tde = (struct target_dirent *)dirp; + while (len > 0) { + int namelen, treclen; + int reclen = de->d_reclen; + uint64_t ino = de->d_ino; + int64_t off = de->d_off; + uint8_t type = de->d_type; + + namelen = strlen(de->d_name); + treclen = offsetof(struct target_dirent, d_name) + namelen + 2; + treclen = QEMU_ALIGN_UP(treclen, sizeof(abi_long)); + + tde->d_ino = tswapal(ino); + tde->d_off = tswapal(off); + tde->d_reclen = tswap16(treclen); + memmove(tde->d_name, de->d_name, namelen + 1); + /* The target_dirent type is in what was formerly a padding + * byte at the end of the structure: + */ + *(((char *)tde) + treclen - 1) = type; + + de = (struct linux_dirent64 *)((char *)de + reclen); + tde = (struct target_dirent *)((char *)tde + treclen); + len -= reclen; + tlen += treclen; + } + ret = tlen; + } + unlock_user(dirp, arg2, ret); + } +#endif break; #if defined(TARGET_NR_getdents64) && defined(__NR_getdents64) case TARGET_NR_getdents64:
Newer architectures may only implement the getdents64 syscall, not getdents. Provide an implementation of getdents in terms of getdents64 so that we can run getdents-using targets on a getdents64-only host. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- Guess which exciting new architecture doesn't have getdents :-) Tested on i386 by temporarily nobbling the #ifdefs so we use the via-getdents64 path rather than via-getdents, and with the test program from the getdents(2) manpage as the guest binary. linux-user/syscall.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 59 insertions(+), 1 deletion(-)