[PATCH] Code style fix for open_exec - Kernel

This is a discussion on [PATCH] Code style fix for open_exec - Kernel ; From d2a6c5d29dc34cfea892124ab72b4eb55d2f8a80 Mon Sep 17 00:00:00 2001 From: Casey Dahlin Date: Wed, 3 Oct 2007 22:01:49 -0400 Subject: [PATCH] Code style fix for open_exec Fix a horribly mangled 5 level indent and severe abuse of goto in the open_exec function. ...

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Thread: [PATCH] Code style fix for open_exec

  1. [PATCH] Code style fix for open_exec

    From d2a6c5d29dc34cfea892124ab72b4eb55d2f8a80 Mon Sep 17 00:00:00 2001
    From: Casey Dahlin
    Date: Wed, 3 Oct 2007 22:01:49 -0400
    Subject: [PATCH] Code style fix for open_exec

    Fix a horribly mangled 5 level indent and severe abuse of goto in the
    open_exec
    function.

    Signed-off-by: Casey Dahlin

    diff --git a/fs/exec.c b/fs/exec.c
    index c21a8cc..d73da5a 100644
    --- a/fs/exec.c
    +++ b/fs/exec.c
    @@ -676,32 +676,32 @@ struct file *open_exec(const char *name)
    struct file *file;

    err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
    FMODE_READ|FMODE_EXEC);
    +
    + if (err) return ERR_PTR(err);
    +
    + file = ERR_PTR(-EACCES);
    + if ((nd.mnt->mnt_flags & MNT_NOEXEC) ||
    + !S_ISREG(nd.dentry->d_inode->i_mode))
    + goto fail;
    +
    + err = vfs_permission(&nd, MAY_EXEC);
    file = ERR_PTR(err);
    + if (err) goto fail;

    - if (!err) {
    - struct inode *inode = nd.dentry->d_inode;
    - file = ERR_PTR(-EACCES);
    - if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
    - S_ISREG(inode->i_mode)) {
    - int err = vfs_permission(&nd, MAY_EXEC);
    - file = ERR_PTR(err);
    - if (!err) {
    - file = nameidata_to_filp(&nd, O_RDONLY);
    - if (!IS_ERR(file)) {
    - err = deny_write_access(file);
    - if (err) {
    - fput(file);
    - file = ERR_PTR(err);
    - }
    - }
    -out:
    - return file;
    - }
    - }
    - release_open_intent(&nd);
    - path_release(&nd);
    + file = nameidata_to_filp(&nd, O_RDONLY);
    + if (IS_ERR(file)) return file;
    +
    + err = deny_write_access(file);
    + if (err) {
    + fput(file);
    + file = ERR_PTR(err);
    }
    - goto out;
    +
    + return file;
    +fail:
    + release_open_intent(&nd);
    + path_release(&nd);
    + return file;
    }

    EXPORT_SYMBOL(open_exec);
    -
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  2. Re: [PATCH] Code style fix for open_exec

    On Wed, Oct 03, 2007 at 10:40:25PM -0400, Casey Dahlin wrote:
    > From d2a6c5d29dc34cfea892124ab72b4eb55d2f8a80 Mon Sep 17 00:00:00 2001
    > From: Casey Dahlin
    > Date: Wed, 3 Oct 2007 22:01:49 -0400
    > Subject: [PATCH] Code style fix for open_exec
    >
    > Fix a horribly mangled 5 level indent and severe abuse of goto in the
    > open_exec
    > function.


    While the function is not nice your version makes it even worse.

    Try this one instead which has been in my pending testing tree for a while:



    Index: linux-2.6/fs/exec.c
    ================================================== =================
    --- linux-2.6.orig/fs/exec.c 2007-09-16 20:29:01.000000000 +0200
    +++ linux-2.6/fs/exec.c 2007-09-16 20:29:56.000000000 +0200
    @@ -669,41 +669,55 @@ EXPORT_SYMBOL(setup_arg_pages);

    #endif /* CONFIG_MMU */

    +/**
    + * open_exec - open file for execution
    + * @name: filename to open
    + *
    + * Open the file pointed to by @filename in the current namespace
    + * for execution. Error out if the file is not a regular file or
    + * this mount does not allow executing files on it.
    + */
    struct file *open_exec(const char *name)
    {
    struct nameidata nd;
    - int err;
    struct file *file;
    + int err;

    - err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
    - file = ERR_PTR(err);
    + err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
    + FMODE_READ|FMODE_EXEC);
    + if (unlikely(err))
    + goto out;

    - if (!err) {
    - struct inode *inode = nd.dentry->d_inode;
    - file = ERR_PTR(-EACCES);
    - if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
    - S_ISREG(inode->i_mode)) {
    - int err = vfs_permission(&nd, MAY_EXEC);
    - file = ERR_PTR(err);
    - if (!err) {
    - file = nameidata_to_filp(&nd, O_RDONLY);
    - if (!IS_ERR(file)) {
    - err = deny_write_access(file);
    - if (err) {
    - fput(file);
    - file = ERR_PTR(err);
    - }
    - }
    -out:
    - return file;
    - }
    - }
    - release_open_intent(&nd);
    - path_release(&nd);
    + err = -EACCES;
    + if (unlikely(nd.mnt->mnt_flags & MNT_NOEXEC))
    + goto out_path_release;
    + if (unlikely(!S_ISREG(nd.dentry->d_inode->i_mode)))
    + goto out_path_release;
    +
    + err = vfs_permission(&nd, MAY_EXEC);
    + if (unlikely(err))
    + goto out_path_release;
    +
    + file = nameidata_to_filp(&nd, O_RDONLY);
    + if (unlikely(IS_ERR(file))) {
    + err = PTR_ERR(file);
    + goto out;
    + }
    +
    + err = deny_write_access(file);
    + if (unlikely(err)) {
    + fput(file);
    + goto out;
    }
    - goto out;
    -}

    + return file;
    +
    + out_path_release:
    + release_open_intent(&nd);
    + path_release(&nd);
    + out:
    + return ERR_PTR(err);
    +}
    EXPORT_SYMBOL(open_exec);

    int kernel_read(struct file *file, unsigned long offset,
    -
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  3. Re: [PATCH] Code style fix for open_exec

    Christoph Hellwig wrote:
    > On Wed, Oct 03, 2007 at 10:40:25PM -0400, Casey Dahlin wrote:
    >
    >> From d2a6c5d29dc34cfea892124ab72b4eb55d2f8a80 Mon Sep 17 00:00:00 2001
    >> From: Casey Dahlin
    >> Date: Wed, 3 Oct 2007 22:01:49 -0400
    >> Subject: [PATCH] Code style fix for open_exec
    >>
    >> Fix a horribly mangled 5 level indent and severe abuse of goto in the
    >> open_exec
    >> function.
    >>

    >
    > While the function is not nice your version makes it even worse.
    >

    Ouch I don't think I did so bad.
    > Try this one instead which has been in my pending testing tree for a while:
    >

    Pretty much all of the stylistic changes were recommended to me already
    off list by Joe Perches. I have that in my branch now, and was waiting
    on any further feedback before resubmitting. There's a couple of things
    here though (particularly the unlikelys) that are worth having. This is
    the better code.
    >
    >
    > Index: linux-2.6/fs/exec.c
    > ================================================== =================
    > --- linux-2.6.orig/fs/exec.c 2007-09-16 20:29:01.000000000 +0200
    > +++ linux-2.6/fs/exec.c 2007-09-16 20:29:56.000000000 +0200
    > @@ -669,41 +669,55 @@ EXPORT_SYMBOL(setup_arg_pages);
    >
    > #endif /* CONFIG_MMU */
    >
    > +/**
    > + * open_exec - open file for execution
    > + * @name: filename to open
    > + *
    > + * Open the file pointed to by @filename in the current namespace
    > + * for execution. Error out if the file is not a regular file or
    > + * this mount does not allow executing files on it.
    > + */
    > struct file *open_exec(const char *name)
    > {
    > struct nameidata nd;
    > - int err;
    > struct file *file;
    > + int err;
    >
    > - err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd, FMODE_READ|FMODE_EXEC);
    > - file = ERR_PTR(err);
    > + err = path_lookup_open(AT_FDCWD, name, LOOKUP_FOLLOW, &nd,
    > + FMODE_READ|FMODE_EXEC);
    > + if (unlikely(err))
    > + goto out;
    >
    > - if (!err) {
    > - struct inode *inode = nd.dentry->d_inode;
    > - file = ERR_PTR(-EACCES);
    > - if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
    > - S_ISREG(inode->i_mode)) {
    > - int err = vfs_permission(&nd, MAY_EXEC);
    > - file = ERR_PTR(err);
    > - if (!err) {
    > - file = nameidata_to_filp(&nd, O_RDONLY);
    > - if (!IS_ERR(file)) {
    > - err = deny_write_access(file);
    > - if (err) {
    > - fput(file);
    > - file = ERR_PTR(err);
    > - }
    > - }
    > -out:
    > - return file;
    > - }
    > - }
    > - release_open_intent(&nd);
    > - path_release(&nd);
    > + err = -EACCES;
    > + if (unlikely(nd.mnt->mnt_flags & MNT_NOEXEC))
    > + goto out_path_release;
    > + if (unlikely(!S_ISREG(nd.dentry->d_inode->i_mode)))
    > + goto out_path_release;
    > +
    > + err = vfs_permission(&nd, MAY_EXEC);
    > + if (unlikely(err))
    > + goto out_path_release;
    > +
    > + file = nameidata_to_filp(&nd, O_RDONLY);
    > + if (unlikely(IS_ERR(file))) {
    > + err = PTR_ERR(file);
    > + goto out;
    > + }
    > +
    > + err = deny_write_access(file);
    > + if (unlikely(err)) {
    > + fput(file);
    > + goto out;
    > }
    > - goto out;
    > -}
    >
    > + return file;
    > +
    > + out_path_release:
    > + release_open_intent(&nd);
    > + path_release(&nd);
    > + out:
    > + return ERR_PTR(err);
    > +}
    > EXPORT_SYMBOL(open_exec);
    >
    > int kernel_read(struct file *file, unsigned long offset,
    > -
    > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    > the body of a message to majordomo@vger.kernel.org
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    > Please read the FAQ at http://www.tux.org/lkml/
    >


    -
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