[Qemu-devel] [PATCH] Fix getgroups() syscall emulation

[Qemu-devel] [PATCH] Fix getgroups() syscall emulation

[Kirill A. Shutemov]

According to man page getgroups(2):

If size is zero, list is not modified, but the total number of
supplementary group IDs for the process is returned.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 linux-user/syscall.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 2abdc83..1f0ab34 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5242,6 +5242,8 @@ 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)
@@ -5392,6 +5394,8 @@ 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) {
-- 
1.5.6.5.GIT

[Qemu-devel] [PATCH] Swap only altered elements of the grouplist

[Kirill A. Shutemov]

getgroups returns the number of supplementary group IDs is returned.
So it's unnessary to swap the entire array. It can dramatically speed up
the syscall: on recent Linux kernel NGROUPS_MAX=65536.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 linux-user/syscall.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1f0ab34..9d76ade 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5248,7 +5248,7 @@ 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);
             }
@@ -5402,7 +5402,7 @@ 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);
             }
-- 
1.5.6.5.GIT

[Qemu-devel] [PATCH] Fix vfork() syscall emulation

[Kirill A. Shutemov]

vfork() is a kind of fork, not thread despite CLONE_VM

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 linux-user/syscall.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index eba2c02..ae7a5a2 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2787,7 +2787,7 @@ static int do_fork(CPUState *env, unsigned int flags, abi_ulong newsp,
     sigset_t sigmask;
 #endif
 
-    if (flags & CLONE_VM) {
+    if (!(flags & CLONE_VFORK) && (flags & CLONE_VM)) {
 #if defined(USE_NPTL)
         new_thread_info info;
         pthread_attr_t attr;
@@ -2856,8 +2856,8 @@ static int do_fork(CPUState *env, unsigned int flags, abi_ulong newsp,
 #endif
 #endif
     } else {
-        /* if no CLONE_VM, we consider it is a fork */
-        if ((flags & ~(CSIGNAL | CLONE_NPTL_FLAGS2)) != 0)
+        /* we consider it is a fork or vfork */
+        if ((flags & ~(CSIGNAL | CLONE_NPTL_FLAGS2 | CLONE_VFORK | CLONE_VM)) != 0)
             return -EINVAL;
         fork_start();
         ret = fork();
-- 
1.5.6.5.GIT

[Qemu-devel] [PATCH] Fix getgroups() syscall emulation

[Kirill A. Shutemov]

According to man page getgroups(2):

If size is zero, list is not modified, but the total number of
supplementary group IDs for the process is returned.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 linux-user/syscall.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index ae7a5a2..9d8542d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5242,6 +5242,8 @@ 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)
@@ -5392,6 +5394,8 @@ 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) {
-- 
1.5.6.5.GIT

[Qemu-devel] [PATCH] Fix vfork() syscall emulation

[Kirill A. Shutemov]

vfork() is a kind of fork, not thread despite CLONE_VM

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 linux-user/syscall.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 56b4138..124d14e 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -2788,7 +2788,7 @@ static int do_fork(CPUState *env, unsigned int flags, abi_ulong newsp,
     sigset_t sigmask;
 #endif
 
-    if (flags & CLONE_VM) {
+    if (!(flags & CLONE_VFORK) && (flags & CLONE_VM)) {
 #if defined(USE_NPTL)
         new_thread_info info;
         pthread_attr_t attr;
@@ -2857,8 +2857,8 @@ static int do_fork(CPUState *env, unsigned int flags, abi_ulong newsp,
 #endif
 #endif
     } else {
-        /* if no CLONE_VM, we consider it is a fork */
-        if ((flags & ~(CSIGNAL | CLONE_NPTL_FLAGS2)) != 0)
+        /* we consider it is a fork or vfork */
+        if ((flags & ~(CSIGNAL | CLONE_NPTL_FLAGS2 | CLONE_VFORK | CLONE_VM)) != 0)
             return -EINVAL;
         fork_start();
         ret = fork();
-- 
1.5.6.5.GIT

[Qemu-devel] [PATCH] Fix getgroups() syscall emulation

[Kirill A. Shutemov]

According to man page getgroups(2):

If size is zero, list is not modified, but the total number of
supplementary group IDs for the process is returned.

Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
---
 linux-user/syscall.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 124d14e..948ea3b 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -5247,6 +5247,8 @@ 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)
@@ -5397,6 +5399,8 @@ 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) {
-- 
1.5.6.5.GIT

Re: [Qemu-devel] [PATCH] Fix getgroups() syscall emulation

[Riku Voipio]

On Thu, Sep 18, 2008 at 06:07:00PM +0300, Kirill A. Shutemov wrote:
> According to man page getgroups(2):
> 
> If size is zero, list is not modified, but the total number of
> supplementary group IDs for the process is returned.

Looks ok to me.

> Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
> ---
>  linux-user/syscall.c |    4 ++++
>  1 files changed, 4 insertions(+), 0 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 124d14e..948ea3b 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -5247,6 +5247,8 @@ 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)
> @@ -5397,6 +5399,8 @@ 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) {
> -- 
> 1.5.6.5.GIT
> 
> 

-- 
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