12046 Provide /proc/<PID>/fdinfo/

Reviewed by: John Levon <john.levon@joyent.com>
Reviewed by: Robert Mustacchi <rm@fingolfin.org>
Approved by: Dan McDonald <danmcd@joyent.com>

11 files changed, 472 insertions, 94 deletions

diff --git a/usr/src/lib/libproc/Makefile b/usr/src/lib/libproc/Makefile
index 1e42afebbb..ad175b0e9d 100644
--- a/usr/src/lib/libproc/Makefile
+++ b/usr/src/lib/libproc/Makefile
@@ -22,6 +22,7 @@
 # Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 # Use is subject to license terms.
 #
+# Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
 #
 
 include ../Makefile.lib
@@ -34,11 +35,10 @@ clean :=	TARGET= clean
 clobber :=	TARGET= clobber
 delete :=	TARGET= delete
 install :=	TARGET= install
-lint :=		TARGET= lint
 _msg :=		TARGET= _msg
 package :=	TARGET= package
 
-LIBRARY= 	libproc.a
+LIBRARY=	libproc.a
 TEXT_DOMAIN=	SUNW_OST_OSLIB
 XGETFLAGS=	-a
 POFILE=		$(LIBRARY:.a=.po)
@@ -61,7 +61,7 @@ $(ROOTHDRDIR)/%: common/%
 
 .KEEP_STATE:
 
-all clean clobber delete install lint package: $(SUBDIRS)
+all clean clobber delete install package: $(SUBDIRS)
 
 install_h: $(ROOTHDRS)
 
diff --git a/usr/src/lib/libproc/Makefile.com b/usr/src/lib/libproc/Makefile.com
index 7ed72f97ed..9bc99f1b40 100644
--- a/usr/src/lib/libproc/Makefile.com
+++ b/usr/src/lib/libproc/Makefile.com
@@ -24,6 +24,7 @@
 # Copyright (c) 2013 by Delphix. All rights reserved.
 #
 # Copyright (c) 2018, Joyent, Inc.
+# Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
 
 LIBRARY = libproc.a
 VERS = .1
@@ -70,6 +71,7 @@ CMNOBJS =	\
 	proc_get_info.o	\
 	proc_names.o	\
 	proc_arg.o	\
+	proc_fd.o	\
 	proc_set.o	\
 	proc_stdio.o
 
@@ -84,13 +86,12 @@ include ../../Makefile.rootfs
 
 SRCS =		$(CMNOBJS:%.o=../common/%.c) $(ISAOBJS:%.o=%.c)
 
-LIBS =		$(DYNLIB) $(LINTLIB)
+LIBS =		$(DYNLIB)
 LDLIBS +=	-lrtld_db -lelf -lctf -lc
 CSTD =	$(CSTD_GNU99)
 CPPFLAGS +=	$($(MACH64)_CPPFLAGS)
 
 SRCDIR =	../common
-$(LINTLIB) :=	SRCS = $(SRCDIR)/$(LINTSRC)
 
 CFLAGS +=	$(CCVERBOSE)
 CPPFLAGS +=	-I$(SRCDIR)
@@ -114,8 +115,6 @@ DYNFLAGS +=	$(BNODIRECT) $(ZDIRECT) $(ZLAZYLOAD)
 
 all: $(LIBS)
 
-lint: lintcheck
-
 # include library targets
 include ../../Makefile.targ
 
diff --git a/usr/src/lib/libproc/common/Pcontrol.c b/usr/src/lib/libproc/common/Pcontrol.c
index 9af5026014..5a135aef17 100644
--- a/usr/src/lib/libproc/common/Pcontrol.c
+++ b/usr/src/lib/libproc/common/Pcontrol.c
@@ -27,6 +27,7 @@
  * Copyright 2012 DEY Storage Systems, Inc.  All rights reserved.
  * Copyright (c) 2013 by Delphix. All rights reserved.
  * Copyright 2015, Joyent, Inc.
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
  */
 
 #include <assert.h>
@@ -1201,6 +1202,7 @@ Pfree(struct ps_prochandle *P)
 	while (P->num_fd > 0) {
 		fd_info_t *fip = list_next(&P->fd_head);
 		list_unlink(fip);
+		proc_fdinfo_free(fip->fd_info);
 		free(fip);
 		P->num_fd--;
 	}
diff --git a/usr/src/lib/libproc/common/Pcontrol.h b/usr/src/lib/libproc/common/Pcontrol.h
index e05ff8b430..a2a875e145 100644
--- a/usr/src/lib/libproc/common/Pcontrol.h
+++ b/usr/src/lib/libproc/common/Pcontrol.h
@@ -26,6 +26,7 @@
  * Copyright 2012 DEY Storage Systems, Inc.  All rights reserved.
  * Copyright (c) 2013 by Delphix. All rights reserved.
  * Copyright 2018 Joyent, Inc.
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
  */
 
 #ifndef	_PCONTROL_H
@@ -147,7 +148,7 @@ typedef struct lwp_info {	/* per-lwp information from core file */
 
 typedef struct fd_info {
 	plist_t	fd_list;	/* linked list */
-	prfdinfo_t fd_info;	/* fd info */
+	prfdinfo_t *fd_info;	/* fd info */
 } fd_info_t;
 
 typedef struct core_info {	/* information specific to core files */
diff --git a/usr/src/lib/libproc/common/Pcore.c b/usr/src/lib/libproc/common/Pcore.c
index dadda5b2a7..0532346922 100644
--- a/usr/src/lib/libproc/common/Pcore.c
+++ b/usr/src/lib/libproc/common/Pcore.c
@@ -27,6 +27,7 @@
  * Copyright (c) 2018, Joyent, Inc. All rights reserved.
  * Copyright (c) 2013 by Delphix. All rights reserved.
  * Copyright 2015 Gary Mills
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
  */
 
 #include <sys/types.h>
@@ -50,6 +51,7 @@
 #include "Pcontrol.h"
 #include "P32ton.h"
 #include "Putil.h"
+#include "proc_fd.h"
 #ifdef __x86
 #include "Pcore_linux.h"
 #endif
@@ -754,7 +756,7 @@ err:
 static int
 note_fdinfo(struct ps_prochandle *P, size_t nbytes)
 {
-	prfdinfo_t prfd;
+	prfdinfo_core_t prfd;
 	fd_info_t *fip;
 
 	if ((nbytes < sizeof (prfd)) ||
@@ -767,7 +769,13 @@ note_fdinfo(struct ps_prochandle *P, size_t nbytes)
 		dprintf("Pgrab_core: failed to add NT_FDINFO\n");
 		return (-1);
 	}
-	(void) memcpy(&fip->fd_info, &prfd, sizeof (prfd));
+	if (fip->fd_info == NULL) {
+		if (proc_fdinfo_from_core(&prfd, &fip->fd_info) != 0) {
+			dprintf("Pgrab_core: failed to convert NT_FDINFO\n");
+			return (-1);
+		}
+	}
+
 	return (0);
 }
 
diff --git a/usr/src/lib/libproc/common/Pfdinfo.c b/usr/src/lib/libproc/common/Pfdinfo.c
index 27264091f8..c822ec8434 100644
--- a/usr/src/lib/libproc/common/Pfdinfo.c
+++ b/usr/src/lib/libproc/common/Pfdinfo.c
@@ -14,6 +14,7 @@
  */
 /*
  * Copyright (c) 2013 Joyent, Inc.  All Rights reserved.
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
  */
 
 #include <limits.h>
@@ -27,6 +28,7 @@
 
 #include "libproc.h"
 #include "Pcontrol.h"
+#include "proc_fd.h"
 
 /*
  * Pfdinfo.c - obtain open file information.
@@ -51,10 +53,13 @@ Pfd2info(struct ps_prochandle *P, int fd)
 	}
 
 	for (i = 0; i < P->num_fd; i++, fip = list_next(fip)) {
-		if (fip->fd_info.pr_fd == fd) {
+		if (fip->fd_info == NULL)
+			continue;
+
+		if (fip->fd_info->pr_fd == fd) {
 			return (fip);
 		}
-		if (fip->fd_info.pr_fd < fd) {
+		if (fip->fd_info->pr_fd < fd) {
 			break;
 		}
 	}
@@ -63,12 +68,34 @@ Pfd2info(struct ps_prochandle *P, int fd)
 	if ((fip = calloc(1, sizeof (*fip))) == NULL)
 		return (NULL);
 
-	fip->fd_info.pr_fd = fd;
 	list_link(fip, next ? next : (void *)&(P->fd_head));
 	P->num_fd++;
 	return (fip);
 }
 
+static int
+fdwalk_cb(const prfdinfo_t *info, void *arg)
+{
+	struct ps_prochandle *P = arg;
+	fd_info_t *fip;
+
+	fip = Pfd2info(P, info->pr_fd);
+	if (fip == NULL) {
+		errno = ENOMEM;
+		return (-1);
+	}
+
+	if (fip->fd_info == NULL)
+		fip->fd_info = proc_fdinfo_dup(info);
+
+	if (fip->fd_info == NULL) {
+		errno = ENOMEM;
+		return (-1);
+	}
+
+	return (0);
+}
+
 /*
  * Attempt to load the open file information from a live process.
  */
@@ -81,83 +108,13 @@ load_fdinfo(struct ps_prochandle *P)
 	 * This is an edge case it isn't worth adding additional state to
 	 * to eliminate.
 	 */
-	if (P->num_fd > 0) {
+	if (P->num_fd > 0)
 		return;
-	}
 
-	if (P->state != PS_DEAD && P->state != PS_IDLE) {
-		char dir_name[PATH_MAX];
-		char path[PATH_MAX];
-		struct dirent *ent;
-		DIR	*dirp;
-		int	fd;
-
-		/*
-		 * Try to get the path information first.
-		 */
-		(void) snprintf(dir_name, sizeof (dir_name),
-		    "%s/%d/path", procfs_path, (int)P->pid);
-		dirp = opendir(dir_name);
-		if (dirp == NULL) {
-			return;
-		}
-		ent = NULL;
-		while ((ent = readdir(dirp)) != NULL) {
-			fd_info_t	*fip;
-			prfdinfo_t	*info;
-			int		len;
-			struct stat64	stat;
-
-			if (!isdigit(ent->d_name[0]))
-				continue;
-
-			fd = atoi(ent->d_name);
-
-			fip = Pfd2info(P, fd);
-			info = &fip->fd_info;
-			info->pr_fd = fd;
-
-			if (pr_fstat64(P, fd, &stat) == 0) {
-				info->pr_mode = stat.st_mode;
-				info->pr_uid = stat.st_uid;
-				info->pr_gid = stat.st_gid;
-				info->pr_major = major(stat.st_dev);
-				info->pr_minor = minor(stat.st_dev);
-				info->pr_rmajor = major(stat.st_rdev);
-				info->pr_rminor = minor(stat.st_rdev);
-				info->pr_size = stat.st_size;
-				info->pr_ino = stat.st_ino;
-			}
-
-			info->pr_fileflags = pr_fcntl(P, fd, F_GETXFL, 0);
-			info->pr_fdflags = pr_fcntl(P, fd, F_GETFD, 0);
-			info->pr_offset = pr_llseek(P, fd, 0, SEEK_CUR);
-
-			/* attempt to determine the path to it */
-			switch (info->pr_mode & S_IFMT) {
-			case S_IFDOOR:
-			case S_IFSOCK:
-				/* not applicable */
-				len = -1;
-				break;
-			default:
-				(void) snprintf(path, sizeof (path),
-				    "%s/%d/path/%d", procfs_path, (int)P->pid,
-				    fd);
-				len = readlink(path, info->pr_path,
-				    sizeof (info->pr_path) - 1);
-				break;
-			}
-
-			if (len < 0) {
-				info->pr_path[0] = 0;
-			} else {
-				info->pr_path[len] = 0;
-			}
-		}
-		(void) closedir(dirp);
+	if (P->state == PS_DEAD || P->state == PS_IDLE)
+		return;
 
-	}
+	proc_fdwalk(P->pid, fdwalk_cb, P);
 }
 
 int
@@ -174,7 +131,7 @@ Pfdinfo_iter(struct ps_prochandle *P, proc_fdinfo_f *func, void *cd)
 	for (fip = list_prev(&P->fd_head);
 	    fip != (void *)&P->fd_head && fip != NULL;
 	    fip = list_prev(fip)) {
-		if ((rv = func(cd, &fip->fd_info)) != 0)
+		if ((rv = func(cd, fip->fd_info)) != 0)
 			return (rv);
 	}
 	return (0);
diff --git a/usr/src/lib/libproc/common/Pgcore.c b/usr/src/lib/libproc/common/Pgcore.c
index 64ef98065b..e4d4437baa 100644
--- a/usr/src/lib/libproc/common/Pgcore.c
+++ b/usr/src/lib/libproc/common/Pgcore.c
@@ -27,6 +27,7 @@
  * Copyright 2012 DEY Storage Systems, Inc.  All rights reserved.
  * Copyright 2018 Joyent, Inc.
  * Copyright (c) 2013 by Delphix. All rights reserved.
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
  */
 
 #define	_STRUCTURED_PROC	1
@@ -49,6 +50,7 @@
 
 #include "Pcontrol.h"
 #include "P32ton.h"
+#include "proc_fd.h"
 
 typedef enum {
 	STR_NONE,
@@ -611,12 +613,19 @@ new_per_lwp(void *data, const lwpstatus_t *lsp, const lwpsinfo_t *lip)
 }
 
 static int
-iter_fd(void *data, prfdinfo_t *fdinfo)
+iter_fd(void *data, const prfdinfo_t *fdinfo)
 {
 	fditer_t *iter = data;
+	prfdinfo_core_t core;
+	int ret = 0;
 
-	if (write_note(iter->fd_fd, NT_FDINFO, fdinfo,
-	    sizeof (*fdinfo), iter->fd_doff) != 0)
+	if (proc_fdinfo_to_core(fdinfo, &core) != 0)
+		return (1);
+
+	ret = write_note(iter->fd_fd, NT_FDINFO, &core,
+	    sizeof (core), iter->fd_doff);
+
+	if (ret != 0)
 		return (1);
 	return (0);
 }
diff --git a/usr/src/lib/libproc/common/libproc.h b/usr/src/lib/libproc/common/libproc.h
index f783026060..cdf789a621 100644
--- a/usr/src/lib/libproc/common/libproc.h
+++ b/usr/src/lib/libproc/common/libproc.h
@@ -28,7 +28,7 @@
  * Copyright 2019 Joyent, Inc.
  * Copyright (c) 2013 by Delphix. All rights reserved.
  * Copyright 2019, Carlos Neira <cneirabustos@gmail.com>
- * Copyright 2019 OmniOS Community Edition (OmniOSce) Association.
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
  */
 
 /*
@@ -469,6 +469,18 @@ extern int proc_walk(proc_walk_f *, void *, int);
 #define	PR_WALK_INCLUDE_SYS	0x80000000	/* include SSYS processes */
 
 /*
+ * File descriptor iteration.
+ */
+typedef int proc_fdwalk_f(const prfdinfo_t *, void *);
+extern int proc_fdwalk(pid_t, proc_fdwalk_f *, void *);
+
+/*
+ * fdinfo iteration.
+ */
+typedef int proc_fdinfowalk_f(uint_t, const void *, size_t, void *);
+extern int proc_fdinfowalk(const prfdinfo_t *, proc_fdinfowalk_f *, void *);
+
+/*
  * Determine if an lwp is in a set as returned from proc_arg_xgrab().
  */
 extern int proc_lwp_in_set(const char *, lwpid_t);
@@ -706,6 +718,9 @@ extern void proc_free_priv(prpriv_t *);
 extern int proc_get_psinfo(pid_t, psinfo_t *);
 extern int proc_get_status(pid_t, pstatus_t *);
 extern int proc_get_secflags(pid_t, prsecflags_t **);
+extern prfdinfo_t *proc_get_fdinfo(pid_t, int);
+extern const void *proc_fdinfo_misc(const prfdinfo_t *, uint_t, size_t *);
+extern void proc_fdinfo_free(prfdinfo_t *);
 
 /*
  * Utility functions for debugging tools to convert numeric fault,
@@ -774,7 +789,7 @@ extern int proc_finistdio(void);
 /*
  * Iterate over all open files.
  */
-typedef int proc_fdinfo_f(void *, prfdinfo_t *);
+typedef int proc_fdinfo_f(void *, const prfdinfo_t *);
 extern int Pfdinfo_iter(struct ps_prochandle *, proc_fdinfo_f *, void *);
 
 #ifdef	__cplusplus
diff --git a/usr/src/lib/libproc/common/mapfile-vers b/usr/src/lib/libproc/common/mapfile-vers
index 6e5ff2c21a..1da5918393 100644
--- a/usr/src/lib/libproc/common/mapfile-vers
+++ b/usr/src/lib/libproc/common/mapfile-vers
@@ -24,7 +24,7 @@
 # Copyright 2018 Joyent, Inc.
 # Copyright (c) 2013 by Delphix. All rights reserved.
 # Copyright (c) 2019 Carlos Neira <cneirabustos@gmail.com>
-# Copyright 2019 OmniOS Community Edition (OmniOSce) Association.
+# Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
 #
 
 #
@@ -207,6 +207,10 @@ SYMBOL_VERSION SUNWprivate_1.1 {
 	proc_arg_xpsinfo;
 	proc_content2str;
 	proc_dmodelname;
+	proc_fdinfo_free;
+	proc_fdinfo_misc;
+	proc_fdinfowalk;
+	proc_fdwalk;
 	proc_finistdio;
 	proc_fltname;
 	proc_fltset2str;
@@ -214,6 +218,7 @@ SYMBOL_VERSION SUNWprivate_1.1 {
 	proc_free_priv;
 	proc_get_auxv;
 	proc_get_cred;
+	proc_get_fdinfo;
 	proc_get_priv;
 	proc_get_psinfo;
         proc_get_secflags;
diff --git a/usr/src/lib/libproc/common/proc_fd.c b/usr/src/lib/libproc/common/proc_fd.c
new file mode 100644
index 0000000000..e491934c16
--- /dev/null
+++ b/usr/src/lib/libproc/common/proc_fd.c
@@ -0,0 +1,350 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/proc.h>
+#include <sys/sysmacros.h>
+
+#include <libgen.h>
+#include <limits.h>
+#include <alloca.h>
+#include <unistd.h>
+#include <string.h>
+#include <strings.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <errno.h>
+#include <dirent.h>
+
+#include "Pcontrol.h"
+
+/*
+ * Walk all file descriptors open for a process and call func() for each.
+ */
+int
+proc_fdwalk(pid_t pid, proc_fdwalk_f *func, void *arg)
+{
+	struct dirent *dirent;
+	DIR *fddir;
+	char *dir;
+	int ret = 0;
+
+	if (asprintf(&dir, "%s/%d/fd", procfs_path, (int)pid) == -1)
+		return (-1);
+
+	if ((fddir = opendir(dir)) == NULL) {
+		free(dir);
+		return (-1);
+	}
+
+	free(dir);
+
+	while ((dirent = readdir(fddir)) != NULL) {
+		prfdinfo_t *info;
+		char *errptr;
+		int fd;
+
+		if (!isdigit(dirent->d_name[0]))
+			continue;
+
+		fd = (int)strtol(dirent->d_name, &errptr, 10);
+		if (errptr != NULL && *errptr != '\0')
+			continue;
+
+		if ((info = proc_get_fdinfo(pid, fd)) == NULL)
+			continue;
+
+		ret = func(info, arg);
+
+		free(info);
+
+		if (ret != 0)
+			break;
+	}
+
+	(void) closedir(fddir);
+	return (ret);
+}
+
+int
+proc_fdinfowalk(const prfdinfo_t *info, proc_fdinfowalk_f *func, void *arg)
+{
+	off_t off = offsetof(prfdinfo_t, pr_misc);
+	int ret = 0;
+
+	for (;;) {
+		const pr_misc_header_t *misc;
+		uint_t type;
+		size_t size;
+
+		misc = (pr_misc_header_t *)((uint8_t *)info + off);
+
+		/* Found terminating record */
+		if (misc->pr_misc_size == 0)
+			break;
+
+		off += misc->pr_misc_size;
+
+		type = misc->pr_misc_type;
+		size = misc->pr_misc_size - sizeof (pr_misc_header_t);
+		misc++;
+
+		ret = func(type, misc, size, arg);
+
+		if (ret != 0)
+			break;
+	}
+
+	return (ret);
+}
+
+prfdinfo_t *
+proc_get_fdinfo(pid_t pid, int fd)
+{
+	prfdinfo_t *info = NULL;
+	char *fname;
+	uint_t retries;
+	int ifd, err = EIO;
+
+	if (asprintf(&fname, "%s/%d/fdinfo/%d",
+	    procfs_path, (int)pid, fd) == -1) {
+		return (NULL);
+	}
+
+	if ((ifd = open(fname, O_RDONLY)) == -1) {
+		free(fname);
+		return (NULL);
+	}
+
+	free(fname);
+
+	/*
+	 * There is a race between stat()-ing the file and reading from
+	 * it where the size may change. To protect against that, we
+	 * walk the returned data to ensure that it is properly
+	 * terminated. If not, increase the buffer size and try again.
+	 */
+
+	for (retries = 1; retries < 5; retries++) {
+		struct stat st;
+		off_t off;
+		size_t l;
+
+		if (fstat(ifd, &st) == -1) {
+			err = errno;
+			break;
+		}
+
+		st.st_size *= retries;
+
+		if ((info = reallocf(info, st.st_size)) == NULL) {
+			err = errno;
+			break;
+		}
+
+		if ((l = read(ifd, info, st.st_size)) == -1) {
+			err = errno;
+			break;
+		}
+
+		/* Walk the data to check that is properly terminated. */
+
+		off = offsetof(prfdinfo_t, pr_misc);
+
+		while (off <= l - sizeof (pr_misc_header_t)) {
+			pr_misc_header_t *misc;
+
+			misc = (pr_misc_header_t *)((uint8_t *)info + off);
+
+			if (misc->pr_misc_size == 0) {
+				/* Found terminator record */
+				(void) close(ifd);
+				return (info);
+			}
+
+			/* Next record */
+			off += misc->pr_misc_size;
+		}
+	}
+
+	(void) close(ifd);
+	free(info);
+
+	errno = err;
+
+	return (NULL);
+}
+
+typedef struct proc_fdinfo_misc_cbdata {
+	uint_t type;
+	const void *data;
+	size_t len;
+} pfm_data_t;
+
+static int
+proc_fdinfo_misc_cb(uint_t type, const void *data, size_t len, void *datap)
+{
+	pfm_data_t *cb = (pfm_data_t *)datap;
+
+	if (type == cb->type) {
+		cb->data = data;
+		cb->len = len;
+		return (1);
+	}
+	return (0);
+}
+
+const void *
+proc_fdinfo_misc(const prfdinfo_t *info, uint_t type, size_t *buflen)
+{
+	pfm_data_t cb;
+
+	cb.data = NULL;
+	cb.type = type;
+
+	(void) proc_fdinfowalk(info, proc_fdinfo_misc_cb, (void *)&cb);
+
+	if (cb.data != NULL) {
+		if (buflen != NULL)
+			*buflen = cb.len;
+
+		return (cb.data);
+	}
+
+	return (NULL);
+}
+
+static int
+proc_fdinfo_dup_cb(uint_t type, const void *data, size_t len, void *datap)
+{
+	size_t *sz = (size_t *)datap;
+
+	*sz += len + sizeof (pr_misc_header_t);
+	return (0);
+}
+
+
+prfdinfo_t *
+proc_fdinfo_dup(const prfdinfo_t *old)
+{
+	prfdinfo_t *new;
+	size_t sz = offsetof(prfdinfo_t, pr_misc);
+
+	/* Determine the size of the miscellaneous items */
+	(void) proc_fdinfowalk(old, proc_fdinfo_dup_cb, (void *)&sz);
+
+	/* Add the size of the terminator record */
+	sz += sizeof (pr_misc_header_t);
+
+	if ((new = calloc(1, sz)) == NULL)
+		return (NULL);
+
+	bcopy(old, new, sz);
+
+	return (new);
+}
+
+void
+proc_fdinfo_free(prfdinfo_t *info)
+{
+	free(info);
+}
+
+/*
+ * Convert a prfdinfo_core_t to prfdinfo_t
+ */
+int
+proc_fdinfo_from_core(const prfdinfo_core_t *core, prfdinfo_t **infop)
+{
+	prfdinfo_t *info;
+	size_t len, slen = 0;
+
+	len = offsetof(prfdinfo_t, pr_misc) + sizeof (pr_misc_header_t);
+	if (*core->pr_path != '\0') {
+		slen = strlen(core->pr_path) + 1;
+		len += PRFDINFO_ROUNDUP(slen) + sizeof (pr_misc_header_t);
+	}
+
+	if ((info = calloc(1, len)) == NULL)
+		return (-1);
+
+	*infop = info;
+
+	info->pr_fd = core->pr_fd;
+	info->pr_mode = core->pr_mode;
+	info->pr_uid = core->pr_uid;
+	info->pr_gid = core->pr_gid;
+	info->pr_major = core->pr_major;
+	info->pr_minor = core->pr_minor;
+	info->pr_rmajor = core->pr_rmajor;
+	info->pr_rminor = core->pr_rminor;
+	info->pr_size = core->pr_size;
+	info->pr_ino = core->pr_ino;
+	info->pr_fileflags = core->pr_fileflags;
+	info->pr_fdflags = core->pr_fdflags;
+	info->pr_offset = core->pr_offset;
+
+	if (slen != 0) {
+		pr_misc_header_t *misc;
+
+		misc = (pr_misc_header_t *)&info->pr_misc;
+
+		misc->pr_misc_size = sizeof (*misc) + PRFDINFO_ROUNDUP(slen);
+		misc->pr_misc_type = PR_PATHNAME;
+		misc++;
+		bcopy(core->pr_path, misc, slen);
+	}
+
+	return (0);
+}
+
+/*
+ * Convert a prfdinfo_t to prfdinfo_core_t
+ */
+int
+proc_fdinfo_to_core(const prfdinfo_t *info, prfdinfo_core_t *core)
+{
+	const char *path;
+	size_t pathl;
+
+	bzero(core, sizeof (*core));
+
+	core->pr_fd = info->pr_fd;
+	core->pr_mode = info->pr_mode;
+	core->pr_uid = info->pr_uid;
+	core->pr_gid = info->pr_gid;
+	core->pr_major = info->pr_major;
+	core->pr_minor = info->pr_minor;
+	core->pr_rmajor = info->pr_rmajor;
+	core->pr_rminor = info->pr_rminor;
+	core->pr_size = info->pr_size;
+	core->pr_ino = info->pr_ino;
+	core->pr_fileflags = info->pr_fileflags;
+	core->pr_fdflags = info->pr_fdflags;
+	core->pr_offset = info->pr_offset;
+
+	path = proc_fdinfo_misc(info, PR_PATHNAME, &pathl);
+	if (path != NULL) {
+		/*
+		 * Rather than provide a truncated path in the pr_path field
+		 * just leave it empty if the path will not fit.
+		 */
+		if (pathl <= sizeof (core->pr_path) - 1)
+			bcopy(path, core->pr_path, pathl + 1);
+	}
+
+	return (0);
+}
diff --git a/usr/src/lib/libproc/common/proc_fd.h b/usr/src/lib/libproc/common/proc_fd.h
new file mode 100644
index 0000000000..0ada83fca7
--- /dev/null
+++ b/usr/src/lib/libproc/common/proc_fd.h
@@ -0,0 +1,32 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2020 OmniOS Community Edition (OmniOSce) Association.
+ */
+
+#ifndef	_PROC_FD_H
+#define	_PROC_FD_H
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+/* Private functions */
+extern int proc_fdinfo_from_core(const prfdinfo_core_t *, prfdinfo_t **);
+extern int proc_fdinfo_to_core(const prfdinfo_t *, prfdinfo_core_t *);
+extern prfdinfo_t *proc_fdinfo_dup(const prfdinfo_t *);
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif	/* _PROC_FD_H */