Commit 27932742 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds
Browse files

add file position info to proc 



Add support for finding out the current file position, open flags and
possibly other info in the future.

These new entries are added:

  /proc/PID/fdinfo/FD
  /proc/PID/task/TID/fdinfo/FD

For each fd the information is provided in the following format:

pos:	1234
flags:	0100002

[bunk@stusta.de: make struct proc_fdinfo_file_operations static]
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Cc: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c5141e6d

fs/proc/base.c

+114 −18
Original line number Diff line number Diff line
@@ -1238,7 +1238,10 @@ out: 
	return ~0U;

}



static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsmount **mnt)

#define PROC_FDINFO_MAX 64



static int proc_fd_info(struct inode *inode, struct dentry **dentry,

			struct vfsmount **mnt, char *info)

{

	struct task_struct *task = get_proc_task(inode);

	struct files_struct *files = NULL;
@@ -1257,8 +1260,16 @@ static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsm 
		spin_lock(&files->file_lock);

		file = fcheck_files(files, fd);

		if (file) {

			if (mnt)

				*mnt = mntget(file->f_path.mnt);

			if (dentry)

				*dentry = dget(file->f_path.dentry);

			if (info)

				snprintf(info, PROC_FDINFO_MAX,

					 "pos:\t%lli\n"

					 "flags:\t0%o\n",

					 (long long) file->f_pos,

					 file->f_flags);

			spin_unlock(&files->file_lock);

			put_files_struct(files);

			return 0;
@@ -1269,6 +1280,12 @@ static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsm 
	return -ENOENT;

}



static int proc_fd_link(struct inode *inode, struct dentry **dentry,

			struct vfsmount **mnt)

{

	return proc_fd_info(inode, dentry, mnt, NULL);

}



static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)

{

	struct inode *inode = dentry->d_inode;
@@ -1364,7 +1381,9 @@ out_iput: 
	goto out;

}



static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry, struct nameidata *nd)

static struct dentry *proc_lookupfd_common(struct inode *dir,

					   struct dentry *dentry,

					   instantiate_t instantiate)

{

	struct task_struct *task = get_proc_task(dir);

	unsigned fd = name_to_int(dentry);
@@ -1375,23 +1394,15 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry, 
	if (fd == ~0U)

		goto out;



	result = proc_fd_instantiate(dir, dentry, task, &fd);

	result = instantiate(dir, dentry, task, &fd);

out:

	put_task_struct(task);

out_no_task:

	return result;

}



static int proc_fd_fill_cache(struct file *filp, void *dirent, filldir_t filldir,

	struct task_struct *task, int fd)

{

	char name[PROC_NUMBUF];

	int len = snprintf(name, sizeof(name), "%d", fd);

	return proc_fill_cache(filp, dirent, filldir, name, len,

				proc_fd_instantiate, task, &fd);

}



static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)

static int proc_readfd_common(struct file * filp, void * dirent,

			      filldir_t filldir, instantiate_t instantiate)

{

	struct dentry *dentry = filp->f_path.dentry;

	struct inode *inode = dentry->d_inode;
@@ -1427,12 +1438,17 @@ static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir) 
			for (fd = filp->f_pos-2;

			     fd < fdt->max_fds;

			     fd++, filp->f_pos++) {

				char name[PROC_NUMBUF];

				int len;



				if (!fcheck_files(files, fd))

					continue;

				rcu_read_unlock();



				if (proc_fd_fill_cache(filp, dirent, filldir, p, fd) < 0) {

				len = snprintf(name, sizeof(name), "%d", fd);

				if (proc_fill_cache(filp, dirent, filldir,

						    name, len, instantiate,

						    p, &fd) < 0) {

					rcu_read_lock();

					break;

				}
@@ -1447,6 +1463,32 @@ out_no_task: 
	return retval;

}



static struct dentry *proc_lookupfd(struct inode *dir, struct dentry *dentry,

				    struct nameidata *nd)

{

	return proc_lookupfd_common(dir, dentry, proc_fd_instantiate);

}



static int proc_readfd(struct file *filp, void *dirent, filldir_t filldir)

{

	return proc_readfd_common(filp, dirent, filldir, proc_fd_instantiate);

}



static ssize_t proc_fdinfo_read(struct file *file, char __user *buf,

				      size_t len, loff_t *ppos)

{

	char tmp[PROC_FDINFO_MAX];

	int err = proc_fd_info(file->f_path.dentry->d_inode, NULL, NULL, tmp);

	if (!err)

		err = simple_read_from_buffer(buf, len, ppos, tmp, strlen(tmp));

	return err;

}



static const struct file_operations proc_fdinfo_file_operations = {

	.open		= nonseekable_open,

	.read		= proc_fdinfo_read,

};



static const struct file_operations proc_fd_operations = {

	.read		= generic_read_dir,

	.readdir	= proc_readfd,
@@ -1478,6 +1520,58 @@ static const struct inode_operations proc_fd_inode_operations = { 
	.setattr	= proc_setattr,

};



static struct dentry *proc_fdinfo_instantiate(struct inode *dir,

	struct dentry *dentry, struct task_struct *task, const void *ptr)

{

	unsigned fd = *(unsigned *)ptr;

 	struct inode *inode;

 	struct proc_inode *ei;

	struct dentry *error = ERR_PTR(-ENOENT);



	inode = proc_pid_make_inode(dir->i_sb, task);

	if (!inode)

		goto out;

	ei = PROC_I(inode);

	ei->fd = fd;

	inode->i_mode = S_IFREG | S_IRUSR;

	inode->i_fop = &proc_fdinfo_file_operations;

	dentry->d_op = &tid_fd_dentry_operations;

	d_add(dentry, inode);

	/* Close the race of the process dying before we return the dentry */

	if (tid_fd_revalidate(dentry, NULL))

		error = NULL;



 out:

	return error;

}



static struct dentry *proc_lookupfdinfo(struct inode *dir,

					struct dentry *dentry,

					struct nameidata *nd)

{

	return proc_lookupfd_common(dir, dentry, proc_fdinfo_instantiate);

}



static int proc_readfdinfo(struct file *filp, void *dirent, filldir_t filldir)

{

	return proc_readfd_common(filp, dirent, filldir,

				  proc_fdinfo_instantiate);

}



static const struct file_operations proc_fdinfo_operations = {

	.read		= generic_read_dir,

	.readdir	= proc_readfdinfo,

};



/*

 * proc directories can do almost nothing..

 */

static const struct inode_operations proc_fdinfo_inode_operations = {

	.lookup		= proc_lookupfdinfo,

	.setattr	= proc_setattr,

};





static struct dentry *proc_pident_instantiate(struct inode *dir,

	struct dentry *dentry, struct task_struct *task, const void *ptr)

{
@@ -1888,6 +1982,7 @@ static const struct inode_operations proc_task_inode_operations; 
static const struct pid_entry tgid_base_stuff[] = {

	DIR("task",       S_IRUGO|S_IXUGO, task),

	DIR("fd",         S_IRUSR|S_IXUSR, fd),

	DIR("fdinfo",     S_IRUSR|S_IXUSR, fdinfo),

	INF("environ",    S_IRUSR, pid_environ),

	INF("auxv",       S_IRUSR, pid_auxv),

	INF("status",     S_IRUGO, pid_status),
@@ -2041,7 +2136,7 @@ static struct dentry *proc_pid_instantiate(struct inode *dir, 
	inode->i_op = &proc_tgid_base_inode_operations;

	inode->i_fop = &proc_tgid_base_operations;

	inode->i_flags|=S_IMMUTABLE;

	inode->i_nlink = 4;

	inode->i_nlink = 5;

#ifdef CONFIG_SECURITY

	inode->i_nlink += 1;

#endif
@@ -2171,6 +2266,7 @@ out_no_task: 
 */

static const struct pid_entry tid_base_stuff[] = {

	DIR("fd",        S_IRUSR|S_IXUSR, fd),

	DIR("fdinfo",    S_IRUSR|S_IXUSR, fdinfo),

	INF("environ",   S_IRUSR, pid_environ),

	INF("auxv",      S_IRUSR, pid_auxv),

	INF("status",    S_IRUGO, pid_status),
@@ -2251,7 +2347,7 @@ static struct dentry *proc_task_instantiate(struct inode *dir, 
	inode->i_op = &proc_tid_base_inode_operations;

	inode->i_fop = &proc_tid_base_operations;

	inode->i_flags|=S_IMMUTABLE;

	inode->i_nlink = 3;

	inode->i_nlink = 4;

#ifdef CONFIG_SECURITY

	inode->i_nlink += 1;

#endif

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