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[PATCH] unshare system call -v5: unshare files

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If the file descriptor structure is being shared, allocate a new one and copy
information from the current, shared, structure.

Signed-off-by: Janak Desai <janak@us.ibm.com>
Cc: Al Viro <viro@ftp.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Cc: Andi Kleen <ak@muc.de>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
JANAK DESAI 2006-02-07 12:59:02 -08:00 committed by Linus Torvalds
parent a0a7ec308f
commit a016f3389c
1 changed files with 51 additions and 30 deletions
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81
kernel/fork.c
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@ -620,32 +620,17 @@ out:
return newf; return newf;
} }
static int copy_files(unsigned long clone_flags, struct task_struct * tsk) /*
* Allocate a new files structure and copy contents from the
* passed in files structure.
*/
static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
{ {
struct files_struct *oldf, *newf; struct files_struct *newf;
struct file **old_fds, **new_fds; struct file **old_fds, **new_fds;
int open_files, size, i, error = 0, expand; int open_files, size, i, expand;
struct fdtable *old_fdt, *new_fdt; struct fdtable *old_fdt, *new_fdt;
/*
* A background process may not have any files ...
*/
oldf = current->files;
if (!oldf)
goto out;
if (clone_flags & CLONE_FILES) {
atomic_inc(&oldf->count);
goto out;
}
/*
* Note: we may be using current for both targets (See exec.c)
* This works because we cache current->files (old) as oldf. Don't
* break this.
*/
tsk->files = NULL;
error = -ENOMEM;
newf = alloc_files(); newf = alloc_files();
if (!newf) if (!newf)
goto out; goto out;
@ -674,9 +659,9 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
if (expand) { if (expand) {
spin_unlock(&oldf->file_lock); spin_unlock(&oldf->file_lock);
spin_lock(&newf->file_lock); spin_lock(&newf->file_lock);
error = expand_files(newf, open_files-1); *errorp = expand_files(newf, open_files-1);
spin_unlock(&newf->file_lock); spin_unlock(&newf->file_lock);
if (error < 0) if (*errorp < 0)
goto out_release; goto out_release;
new_fdt = files_fdtable(newf); new_fdt = files_fdtable(newf);
/* /*
@ -725,10 +710,8 @@ static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
memset(&new_fdt->close_on_exec->fds_bits[start], 0, left); memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
} }
tsk->files = newf;
error = 0;
out: out:
return error; return newf;
out_release: out_release:
free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset); free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
@ -738,6 +721,40 @@ out_release:
goto out; goto out;
} }
static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
{
struct files_struct *oldf, *newf;
int error = 0;
/*
* A background process may not have any files ...
*/
oldf = current->files;
if (!oldf)
goto out;
if (clone_flags & CLONE_FILES) {
atomic_inc(&oldf->count);
goto out;
}
/*
* Note: we may be using current for both targets (See exec.c)
* This works because we cache current->files (old) as oldf. Don't
* break this.
*/
tsk->files = NULL;
error = -ENOMEM;
newf = dup_fd(oldf, &error);
if (!newf)
goto out;
tsk->files = newf;
error = 0;
out:
return error;
}
/* /*
* Helper to unshare the files of the current task. * Helper to unshare the files of the current task.
* We don't want to expose copy_files internals to * We don't want to expose copy_files internals to
@ -1463,15 +1480,19 @@ static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
} }
/* /*
* Unsharing of files for tasks created with CLONE_FILES is not supported yet * Unshare file descriptor table if it is being shared
*/ */
static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp) static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
{ {
struct files_struct *fd = current->files; struct files_struct *fd = current->files;
int error = 0;
if ((unshare_flags & CLONE_FILES) && if ((unshare_flags & CLONE_FILES) &&
(fd && atomic_read(&fd->count) > 1)) (fd && atomic_read(&fd->count) > 1)) {
return -EINVAL; *new_fdp = dup_fd(fd, &error);
if (!*new_fdp)
return error;
}
return 0; return 0;
} }