Author: mjg
Date: Thu Nov 6 08:12:34 2014
New Revision: 274167
URL: https://svnweb.freebsd.org/changeset/base/274167
Log:
Add sysctl kern.proc.cwd
It returns only current working directory of given process which saves a lot
of
overhead over kern.proc.filedesc if given proc has a lot of open fds.
Submitted by: Tiwei Bie <btw mail.ustc.edu.cn> (slightly modified)
X-Additional: JuniorJobs project
Modified:
head/sys/kern/kern_descrip.c
head/sys/sys/sysctl.h
head/sys/sys/user.h
Modified: head/sys/kern/kern_descrip.c
==============================================================================
--- head/sys/kern/kern_descrip.c Thu Nov 6 07:44:10 2014
(r274166)
+++ head/sys/kern/kern_descrip.c Thu Nov 6 08:12:34 2014
(r274167)
@@ -3406,6 +3406,73 @@ static SYSCTL_NODE(_kern_proc, KERN_PROC
CTLFLAG_RD|CTLFLAG_MPSAFE, sysctl_kern_proc_filedesc,
"Process filedesc entries");
+/*
+ * Store a process current working directory information to sbuf.
+ *
+ * Takes a locked proc as argument, and returns with the proc unlocked.
+ */
+int
+kern_proc_cwd_out(struct proc *p, struct sbuf *sb, ssize_t maxlen)
+{
+ struct filedesc *fdp;
+ struct export_fd_buf *efbuf;
+ int error;
+
+ PROC_LOCK_ASSERT(p, MA_OWNED);
+
+ fdp = fdhold(p);
+ PROC_UNLOCK(p);
+ if (fdp == NULL)
+ return (EINVAL);
+
+ efbuf = malloc(sizeof(*efbuf), M_TEMP, M_WAITOK);
+ efbuf->fdp = fdp;
+ efbuf->sb = sb;
+ efbuf->remainder = maxlen;
+
+ FILEDESC_SLOCK(fdp);
+ if (fdp->fd_cdir == NULL)
+ error = EINVAL;
+ else {
+ vref(fdp->fd_cdir);
+ error = export_vnode_to_sb(fdp->fd_cdir, KF_FD_TYPE_CWD,
+ FREAD, efbuf);
+ }
+ FILEDESC_SUNLOCK(fdp);
+ fddrop(fdp);
+ free(efbuf, M_TEMP);
+ return (error);
+}
+
+/*
+ * Get per-process current working directory.
+ */
+static int
+sysctl_kern_proc_cwd(SYSCTL_HANDLER_ARGS)
+{
+ struct sbuf sb;
+ struct proc *p;
+ ssize_t maxlen;
+ int error, error2, *name;
+
+ name = (int *)arg1;
+
+ sbuf_new_for_sysctl(&sb, NULL, sizeof(struct kinfo_file), req);
+ error = pget((pid_t)name[0], PGET_CANDEBUG | PGET_NOTWEXIT, &p);
+ if (error != 0) {
+ sbuf_delete(&sb);
+ return (error);
+ }
+ maxlen = req->oldptr != NULL ? req->oldlen : -1;
+ error = kern_proc_cwd_out(p, &sb, maxlen);
+ error2 = sbuf_finish(&sb);
+ sbuf_delete(&sb);
+ return (error != 0 ? error : error2);
+}
+
+static SYSCTL_NODE(_kern_proc, KERN_PROC_CWD, cwd, CTLFLAG_RD|CTLFLAG_MPSAFE,
+ sysctl_kern_proc_cwd, "Process current working directory");
+
#ifdef DDB
/*
* For the purposes of debugging, generate a human-readable string for the
Modified: head/sys/sys/sysctl.h
==============================================================================
--- head/sys/sys/sysctl.h Thu Nov 6 07:44:10 2014 (r274166)
+++ head/sys/sys/sysctl.h Thu Nov 6 08:12:34 2014 (r274167)
@@ -657,6 +657,7 @@ TAILQ_HEAD(sysctl_ctx_list, sysctl_ctx_e
#define KERN_PROC_UMASK 39 /* process umask */
#define KERN_PROC_OSREL 40 /* osreldate for process binary
*/
#define KERN_PROC_SIGTRAMP 41 /* signal trampoline location */
+#define KERN_PROC_CWD 42 /* process current working
directory */
/*
* KERN_IPC identifiers
Modified: head/sys/sys/user.h
==============================================================================
--- head/sys/sys/user.h Thu Nov 6 07:44:10 2014 (r274166)
+++ head/sys/sys/user.h Thu Nov 6 08:12:34 2014 (r274167)
@@ -530,6 +530,7 @@ struct sbuf;
*/
int kern_proc_filedesc_out(struct proc *p, struct sbuf *sb, ssize_t maxlen);
+int kern_proc_cwd_out(struct proc *p, struct sbuf *sb, ssize_t maxlen);
int kern_proc_out(struct proc *p, struct sbuf *sb, int flags);
int kern_proc_vmmap_out(struct proc *p, struct sbuf *sb);
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