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Re: [Qemu-devel] [PATCH] linux-user, fix getgroups/getgroups32 when both
From: |
Kirill A. Shutemov |
Subject: |
Re: [Qemu-devel] [PATCH] linux-user, fix getgroups/getgroups32 when both args are zero. |
Date: |
Sat, 23 Feb 2008 09:25:30 +0200 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
On [Sat, 23.02.2008 12:00], Takashi Yoshii wrote:
> getgroups() and getgroups32() returns NGROUPS_MAX when both its two args are
> zero. But because we pass a ptr to allocated space as 2nd arg, this function
> are interfered. The patch attached fixed it.
> /yoshii
> ---
> linux-user/syscall.c: fix getgroups{,32} when both args are zero.
>
My version of patch to fix same problem:
getgroups: return total number of supplementary group IDs for the
process if size == 0
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ad97871..96a11a9 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5029,6 +5029,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
grouplist = alloca(gidsetsize * sizeof(gid_t));
ret = get_errno(getgroups(gidsetsize, grouplist));
+ if (gidsetsize == 0)
+ break;
if (!is_error(ret)) {
target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize *
2, 0);
if (!target_grouplist)
@@ -5179,6 +5181,8 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
grouplist = alloca(gidsetsize * sizeof(gid_t));
ret = get_errno(getgroups(gidsetsize, grouplist));
+ if (gidsetsize == 0)
+ break;
if (!is_error(ret)) {
target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize *
4, 0);
if (!target_grouplist) {
Another patch for getgroups:
Trivial optimization of getgroups syscall implementation:
swap only returned groups, not all group in list.
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 6f2872f..ad97871 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5033,7 +5033,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
target_grouplist = lock_user(VERIFY_WRITE, arg2, gidsetsize *
2, 0);
if (!target_grouplist)
goto efault;
- for(i = 0;i < gidsetsize; i++)
+ for(i = 0;i < ret; i++)
target_grouplist[i] = tswap16(grouplist[i]);
unlock_user(target_grouplist, arg2, gidsetsize * 2);
}
@@ -5185,7 +5185,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
ret = -TARGET_EFAULT;
goto fail;
}
- for(i = 0;i < gidsetsize; i++)
+ for(i = 0;i < ret; i++)
target_grouplist[i] = tswap32(grouplist[i]);
unlock_user(target_grouplist, arg2, gidsetsize * 4);
}
It makes getgroups much faster in some cases.
--
Regards, Kirill A. Shutemov
+ Belarus, Minsk
+ Velesys Ltd, http://www.velesys.com/
+ ALT Linux Team, http://www.altlinux.com/
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