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>

1 files changed, 350 insertions, 0 deletions

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);
+}