commit f255336a9301619519045548acb2e1027065a837
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Dec 6 15:39:42 2018 +0100
support: Implement <support/descriptors.h> to track file descriptors
diff --git a/support/Makefile b/support/Makefile
index a2536980d1d5a89b..93a514301654132e 100644
--- a/support/Makefile
+++ b/support/Makefile
@@ -46,6 +46,7 @@ libsupport-routines = \
support_chroot \
support_copy_file_range \
support_descriptor_supports_holes \
+ support_descriptors \
support_enter_mount_namespace \
support_enter_network_namespace \
support_format_address_family \
@@ -195,6 +196,7 @@ tests = \
tst-support-namespace \
tst-support_blob_repeat \
tst-support_capture_subprocess \
+ tst-support_descriptors \
tst-support_format_dns_packet \
tst-support_quote_blob \
tst-support_quote_string \
diff --git a/support/check.h b/support/check.h
index e6765289f2492501..7ea9a86a9c7ed055 100644
--- a/support/check.h
+++ b/support/check.h
@@ -183,6 +183,10 @@ int support_report_failure (int status)
/* Internal function used to test the failure recording framework. */
void support_record_failure_reset (void);
+/* Returns true or false depending on whether there have been test
+ failures or not. */
+int support_record_failure_is_failed (void);
+
__END_DECLS
#endif /* SUPPORT_CHECK_H */
diff --git a/support/descriptors.h b/support/descriptors.h
new file mode 100644
index 0000000000000000..8ec4cbbdfb8f1770
--- /dev/null
+++ b/support/descriptors.h
@@ -0,0 +1,47 @@
+/* Monitoring file descriptor usage.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef SUPPORT_DESCRIPTORS_H
+#define SUPPORT_DESCRIPTORS_H
+
+#include <stdio.h>
+
+/* Opaque pointer, for capturing file descriptor lists. */
+struct support_descriptors;
+
+/* Record the currently open file descriptors and store them in the
+ returned list. Terminate the process if the listing operation
+ fails. */
+struct support_descriptors *support_descriptors_list (void);
+
+/* Deallocate the list of descriptors. */
+void support_descriptors_free (struct support_descriptors *);
+
+/* Write the list of descriptors to STREAM, adding PREFIX to each
+ line. */
+void support_descriptors_dump (struct support_descriptors *,
+ const char *prefix, FILE *stream);
+
+/* Check for file descriptor leaks and other file descriptor changes:
+ Compare the current list of descriptors with the passed list.
+ Record a test failure if there are additional open descriptors,
+ descriptors have been closed, or if a change in file descriptor can
+ be detected. */
+void support_descriptors_check (struct support_descriptors *);
+
+#endif /* SUPPORT_DESCRIPTORS_H */
diff --git a/support/support_descriptors.c b/support/support_descriptors.c
new file mode 100644
index 0000000000000000..d66cf550800201c5
--- /dev/null
+++ b/support/support_descriptors.c
@@ -0,0 +1,274 @@
+/* Monitoring file descriptor usage.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <dirent.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/check.h>
+#include <support/support.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <xunistd.h>
+
+struct procfs_descriptor
+{
+ int fd;
+ char *link_target;
+ dev_t dev;
+ ino64_t ino;
+};
+
+/* Used with qsort. */
+static int
+descriptor_compare (const void *l, const void *r)
+{
+ const struct procfs_descriptor *left = l;
+ const struct procfs_descriptor *right = r;
+ /* Cannot overflow due to limited file descriptor range. */
+ return left->fd - right->fd;
+}
+
+#define DYNARRAY_STRUCT descriptor_list
+#define DYNARRAY_ELEMENT struct procfs_descriptor
+#define DYNARRAY_PREFIX descriptor_list_
+#define DYNARRAY_ELEMENT_FREE(e) free ((e)->link_target)
+#define DYNARRAY_INITIAL_SIZE 0
+#include <malloc/dynarray-skeleton.c>
+
+struct support_descriptors
+{
+ struct descriptor_list list;
+};
+
+struct support_descriptors *
+support_descriptors_list (void)
+{
+ struct support_descriptors *result = xmalloc (sizeof (*result));
+ descriptor_list_init (&result->list);
+
+ DIR *fds = opendir ("/proc/self/fd");
+ if (fds == NULL)
+ FAIL_EXIT1 ("opendir (\"/proc/self/fd\"): %m");
+
+ while (true)
+ {
+ errno = 0;
+ struct dirent64 *e = readdir64 (fds);
+ if (e == NULL)
+ {
+ if (errno != 0)
+ FAIL_EXIT1 ("readdir: %m");
+ break;
+ }
+
+ if (e->d_name[0] == '.')
+ continue;
+
+ char *endptr;
+ long int fd = strtol (e->d_name, &endptr, 10);
+ if (*endptr != '\0' || fd < 0 || fd > INT_MAX)
+ FAIL_EXIT1 ("readdir: invalid file descriptor name: /proc/self/fd/%s",
+ e->d_name);
+
+ /* Skip the descriptor which is used to enumerate the
+ descriptors. */
+ if (fd == dirfd (fds))
+ continue;
+
+ char *target;
+ {
+ char *path = xasprintf ("/proc/self/fd/%ld", fd);
+ target = xreadlink (path);
+ free (path);
+ }
+ struct stat64 st;
+ if (fstat64 (fd, &st) != 0)
+ FAIL_EXIT1 ("readdir: fstat64 (%ld) failed: %m", fd);
+
+ struct procfs_descriptor *item = descriptor_list_emplace (&result->list);
+ if (item == NULL)
+ FAIL_EXIT1 ("descriptor_list_emplace: %m");
+ item->fd = fd;
+ item->link_target = target;
+ item->dev = st.st_dev;
+ item->ino = st.st_ino;
+ }
+
+ closedir (fds);
+
+ /* Perform a merge join between descrs and current. This assumes
+ that the arrays are sorted by file descriptor. */
+
+ qsort (descriptor_list_begin (&result->list),
+ descriptor_list_size (&result->list),
+ sizeof (struct procfs_descriptor), descriptor_compare);
+
+ return result;
+}
+
+void
+support_descriptors_free (struct support_descriptors *descrs)
+{
+ descriptor_list_free (&descrs->list);
+ free (descrs);
+}
+
+void
+support_descriptors_dump (struct support_descriptors *descrs,
+ const char *prefix, FILE *fp)
+{
+ struct procfs_descriptor *end = descriptor_list_end (&descrs->list);
+ for (struct procfs_descriptor *d = descriptor_list_begin (&descrs->list);
+ d != end; ++d)
+ {
+ char *quoted = support_quote_string (d->link_target);
+ fprintf (fp, "%s%d: target=\"%s\" major=%lld minor=%lld ino=%lld\n",
+ prefix, d->fd, quoted,
+ (long long int) major (d->dev),
+ (long long int) minor (d->dev),
+ (long long int) d->ino);
+ free (quoted);
+ }
+}
+
+static void
+dump_mismatch (bool *first,
+ struct support_descriptors *descrs,
+ struct support_descriptors *current)
+{
+ if (*first)
+ *first = false;
+ else
+ return;
+
+ puts ("error: Differences found in descriptor set");
+ puts ("Reference descriptor set:");
+ support_descriptors_dump (descrs, " ", stdout);
+ puts ("Current descriptor set:");
+ support_descriptors_dump (current, " ", stdout);
+ puts ("Differences:");
+}
+
+static void
+report_closed_descriptor (bool *first,
+ struct support_descriptors *descrs,
+ struct support_descriptors *current,
+ struct procfs_descriptor *left)
+{
+ support_record_failure ();
+ dump_mismatch (first, descrs, current);
+ printf ("error: descriptor %d was closed\n", left->fd);
+}
+
+static void
+report_opened_descriptor (bool *first,
+ struct support_descriptors *descrs,
+ struct support_descriptors *current,
+ struct procfs_descriptor *right)
+{
+ support_record_failure ();
+ dump_mismatch (first, descrs, current);
+ char *quoted = support_quote_string (right->link_target);
+ printf ("error: descriptor %d was opened (\"%s\")\n", right->fd, quoted);
+ free (quoted);
+}
+
+void
+support_descriptors_check (struct support_descriptors *descrs)
+{
+ struct support_descriptors *current = support_descriptors_list ();
+
+ /* Perform a merge join between descrs and current. This assumes
+ that the arrays are sorted by file descriptor. */
+
+ struct procfs_descriptor *left = descriptor_list_begin (&descrs->list);
+ struct procfs_descriptor *left_end = descriptor_list_end (&descrs->list);
+ struct procfs_descriptor *right = descriptor_list_begin (¤t->list);
+ struct procfs_descriptor *right_end = descriptor_list_end (¤t->list);
+
+ bool first = true;
+ while (left != left_end && right != right_end)
+ {
+ if (left->fd == right->fd)
+ {
+ if (strcmp (left->link_target, right->link_target) != 0)
+ {
+ support_record_failure ();
+ char *left_quoted = support_quote_string (left->link_target);
+ char *right_quoted = support_quote_string (right->link_target);
+ dump_mismatch (&first, descrs, current);
+ printf ("error: descriptor %d changed from \"%s\" to \"%s\"\n",
+ left->fd, left_quoted, right_quoted);
+ free (left_quoted);
+ free (right_quoted);
+ }
+ if (left->dev != right->dev)
+ {
+ support_record_failure ();
+ dump_mismatch (&first, descrs, current);
+ printf ("error: descriptor %d changed device"
+ " from %lld:%lld to %lld:%lld\n",
+ left->fd,
+ (long long int) major (left->dev),
+ (long long int) minor (left->dev),
+ (long long int) major (right->dev),
+ (long long int) minor (right->dev));
+ }
+ if (left->ino != right->ino)
+ {
+ support_record_failure ();
+ dump_mismatch (&first, descrs, current);
+ printf ("error: descriptor %d changed ino from %lld to %lld\n",
+ left->fd,
+ (long long int) left->ino, (long long int) right->ino);
+ }
+ ++left;
+ ++right;
+ }
+ else if (left->fd < right->fd)
+ {
+ /* Gap on the right. */
+ report_closed_descriptor (&first, descrs, current, left);
+ ++left;
+ }
+ else
+ {
+ /* Gap on the left. */
+ TEST_VERIFY_EXIT (left->fd > right->fd);
+ report_opened_descriptor (&first, descrs, current, right);
+ ++right;
+ }
+ }
+
+ while (left != left_end)
+ {
+ /* Closed descriptors (more descriptors on the left). */
+ report_closed_descriptor (&first, descrs, current, left);
+ ++left;
+ }
+
+ while (right != right_end)
+ {
+ /* Opened descriptors (more descriptors on the right). */
+ report_opened_descriptor (&first, descrs, current, right);
+ ++right;
+ }
+
+ support_descriptors_free (current);
+}
diff --git a/support/support_record_failure.c b/support/support_record_failure.c
index 356798f55608ca71..17ab1d80ef2bbdea 100644
--- a/support/support_record_failure.c
+++ b/support/support_record_failure.c
@@ -104,3 +104,11 @@ support_record_failure_reset (void)
__atomic_store_n (&state->failed, 0, __ATOMIC_RELAXED);
__atomic_add_fetch (&state->counter, 0, __ATOMIC_RELAXED);
}
+
+int
+support_record_failure_is_failed (void)
+{
+ /* Relaxed MO is sufficient because we need (blocking) external
+ synchronization for reliable test error reporting anyway. */
+ return __atomic_load_n (&state->failed, __ATOMIC_RELAXED);
+}
diff --git a/support/tst-support_descriptors.c b/support/tst-support_descriptors.c
new file mode 100644
index 0000000000000000..5e9e824bc3820499
--- /dev/null
+++ b/support/tst-support_descriptors.c
@@ -0,0 +1,198 @@
+/* Tests for monitoring file descriptor usage.
+ Copyright (C) 2018 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <support/capture_subprocess.h>
+#include <support/check.h>
+#include <support/descriptors.h>
+#include <support/support.h>
+#include <support/xunistd.h>
+
+/* This is the next free descriptor that the subprocess will pick. */
+static int free_descriptor;
+
+static void
+subprocess_no_change (void *closure)
+{
+ struct support_descriptors *descrs = support_descriptors_list ();
+ int fd = xopen ("/dev/null", O_WRONLY, 0);
+ TEST_COMPARE (fd, free_descriptor);
+ xclose (fd);
+ support_descriptors_free (descrs);
+}
+
+static void
+subprocess_closed_descriptor (void *closure)
+{
+ int fd = xopen ("/dev/null", O_WRONLY, 0);
+ TEST_COMPARE (fd, free_descriptor);
+ struct support_descriptors *descrs = support_descriptors_list ();
+ xclose (fd);
+ support_descriptors_check (descrs); /* Will report failure. */
+ puts ("EOT");
+ support_descriptors_free (descrs);
+}
+
+static void
+subprocess_opened_descriptor (void *closure)
+{
+ struct support_descriptors *descrs = support_descriptors_list ();
+ int fd = xopen ("/dev/null", O_WRONLY, 0);
+ TEST_COMPARE (fd, free_descriptor);
+ support_descriptors_check (descrs); /* Will report failure. */
+ puts ("EOT");
+ support_descriptors_free (descrs);
+}
+
+static void
+subprocess_changed_descriptor (void *closure)
+{
+ int fd = xopen ("/dev/null", O_WRONLY, 0);
+ TEST_COMPARE (fd, free_descriptor);
+ struct support_descriptors *descrs = support_descriptors_list ();
+ xclose (fd);
+ TEST_COMPARE (xopen ("/dev", O_DIRECTORY | O_RDONLY, 0), fd);
+ support_descriptors_check (descrs); /* Will report failure. */
+ puts ("EOT");
+ support_descriptors_free (descrs);
+}
+
+static void
+report_subprocess_output (const char *name,
+ struct support_capture_subprocess *proc)
+{
+ printf ("info: BEGIN %s output\n"
+ "%s"
+ "info: END %s output\n",
+ name, proc->out.buffer, name);
+}
+
+/* Use an explicit flag to preserve failure status across
+ support_record_failure_reset calls. */
+static bool good = true;
+
+static void
+test_run (void)
+{
+ struct support_capture_subprocess proc = support_capture_subprocess
+ (&subprocess_no_change, NULL);
+ support_capture_subprocess_check (&proc, "subprocess_no_change",
+ 0, sc_allow_none);
+ support_capture_subprocess_free (&proc);
+
+ char *expected = xasprintf ("\nDifferences:\n"
+ "error: descriptor %d was closed\n"
+ "EOT\n",
+ free_descriptor);
+ good = good && !support_record_failure_is_failed ();
+ proc = support_capture_subprocess (&subprocess_closed_descriptor, NULL);
+ good = good && support_record_failure_is_failed ();
+ support_record_failure_reset (); /* Discard the reported error. */
+ report_subprocess_output ("subprocess_closed_descriptor", &proc);
+ TEST_VERIFY (strstr (proc.out.buffer, expected) != NULL);
+ support_capture_subprocess_check (&proc, "subprocess_closed_descriptor",
+ 0, sc_allow_stdout);
+ support_capture_subprocess_free (&proc);
+ free (expected);
+
+ expected = xasprintf ("\nDifferences:\n"
+ "error: descriptor %d was opened (\"/dev/null\")\n"
+ "EOT\n",
+ free_descriptor);
+ good = good && !support_record_failure_is_failed ();
+ proc = support_capture_subprocess (&subprocess_opened_descriptor, NULL);
+ good = good && support_record_failure_is_failed ();
+ support_record_failure_reset (); /* Discard the reported error. */
+ report_subprocess_output ("subprocess_opened_descriptor", &proc);
+ TEST_VERIFY (strstr (proc.out.buffer, expected) != NULL);
+ support_capture_subprocess_check (&proc, "subprocess_opened_descriptor",
+ 0, sc_allow_stdout);
+ support_capture_subprocess_free (&proc);
+ free (expected);
+
+ expected = xasprintf ("\nDifferences:\n"
+ "error: descriptor %d changed from \"/dev/null\""
+ " to \"/dev\"\n"
+ "error: descriptor %d changed ino ",
+ free_descriptor, free_descriptor);
+ good = good && !support_record_failure_is_failed ();
+ proc = support_capture_subprocess (&subprocess_changed_descriptor, NULL);
+ good = good && support_record_failure_is_failed ();
+ support_record_failure_reset (); /* Discard the reported error. */
+ report_subprocess_output ("subprocess_changed_descriptor", &proc);
+ TEST_VERIFY (strstr (proc.out.buffer, expected) != NULL);
+ support_capture_subprocess_check (&proc, "subprocess_changed_descriptor",
+ 0, sc_allow_stdout);
+ support_capture_subprocess_free (&proc);
+ free (expected);
+}
+
+static int
+do_test (void)
+{
+ puts ("info: initial descriptor set");
+ {
+ struct support_descriptors *descrs = support_descriptors_list ();
+ support_descriptors_dump (descrs, "info: ", stdout);
+ support_descriptors_free (descrs);
+ }
+
+ free_descriptor = xopen ("/dev/null", O_WRONLY, 0);
+ puts ("info: descriptor set with additional free descriptor");
+ {
+ struct support_descriptors *descrs = support_descriptors_list ();
+ support_descriptors_dump (descrs, "info: ", stdout);
+ support_descriptors_free (descrs);
+ }
+ TEST_VERIFY (free_descriptor >= 3);
+ xclose (free_descriptor);
+
+ /* Initial test run without a sentinel descriptor. The presence of
+ such a descriptor exercises different conditions in the list
+ comparison in support_descriptors_check. */
+ test_run ();
+
+ /* Allocate a sentinel descriptor at the end of the descriptor list,
+ after free_descriptor. */
+ int sentinel_fd;
+ {
+ int fd = xopen ("/dev/full", O_WRONLY, 0);
+ TEST_COMPARE (fd, free_descriptor);
+ sentinel_fd = dup (fd);
+ TEST_VERIFY_EXIT (sentinel_fd > fd);
+ xclose (fd);
+ }
+ puts ("info: descriptor set with sentinel descriptor");
+ {
+ struct support_descriptors *descrs = support_descriptors_list ();
+ support_descriptors_dump (descrs, "info: ", stdout);
+ support_descriptors_free (descrs);
+ }
+
+ /* Second test run with sentinel descriptor. */
+ test_run ();
+
+ xclose (sentinel_fd);
+
+ return !good;
+}
+
+#include <support/test-driver.c>