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From fae45af368a90cdce95680d82b66d8e460ab939f Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Wed, 23 Mar 2022 17:47:33 +0100
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Subject: [PATCH] basic/stat-util: add null_or_empty_path_with_root()
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(cherry picked from commit 48542eac39999f58f6c331b4b3cdf2d78bf15979)
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Related: #2082131
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---
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src/basic/stat-util.c | 15 ++++++++++-----
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src/basic/stat-util.h | 6 +++++-
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src/test/test-stat-util.c | 24 ++++++++++++++++++++++++
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3 files changed, 39 insertions(+), 6 deletions(-)
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diff --git a/src/basic/stat-util.c b/src/basic/stat-util.c
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index efac7b002e..21e71794b4 100644
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--- a/src/basic/stat-util.c
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+++ b/src/basic/stat-util.c
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@@ -127,17 +127,22 @@ bool null_or_empty(struct stat *st) {
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return false;
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}
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-int null_or_empty_path(const char *fn) {
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+int null_or_empty_path_with_root(const char *fn, const char *root) {
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struct stat st;
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+ int r;
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assert(fn);
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- /* If we have the path, let's do an easy text comparison first. */
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- if (path_equal(fn, "/dev/null"))
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+ /* A symlink to /dev/null or an empty file?
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+ * When looking under root_dir, we can't expect /dev/ to be mounted,
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+ * so let's see if the path is a (possibly dangling) symlink to /dev/null. */
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+
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+ if (path_equal_ptr(path_startswith(fn, root ?: "/"), "dev/null"))
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return true;
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- if (stat(fn, &st) < 0)
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- return -errno;
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+ r = chase_symlinks_and_stat(fn, root, CHASE_PREFIX_ROOT, NULL, &st, NULL);
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+ if (r < 0)
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+ return r;
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return null_or_empty(&st);
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}
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diff --git a/src/basic/stat-util.h b/src/basic/stat-util.h
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index a566114f7c..2c5edeb891 100644
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--- a/src/basic/stat-util.h
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+++ b/src/basic/stat-util.h
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@@ -31,9 +31,13 @@ static inline int dir_is_populated(const char *path) {
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}
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bool null_or_empty(struct stat *st) _pure_;
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-int null_or_empty_path(const char *fn);
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+int null_or_empty_path_with_root(const char *fn, const char *root);
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int null_or_empty_fd(int fd);
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+static inline int null_or_empty_path(const char *fn) {
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+ return null_or_empty_path_with_root(fn, NULL);
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+}
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+
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int path_is_read_only_fs(const char *path);
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int files_same(const char *filea, const char *fileb, int flags);
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diff --git a/src/test/test-stat-util.c b/src/test/test-stat-util.c
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index 5f744b0288..9975a1848d 100644
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--- a/src/test/test-stat-util.c
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+++ b/src/test/test-stat-util.c
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@@ -18,6 +18,30 @@
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#include "tests.h"
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#include "tmpfile-util.h"
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+TEST(null_or_empty_path) {
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+ assert_se(null_or_empty_path("/dev/null") == 1);
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+ assert_se(null_or_empty_path("/dev/tty") == 1); /* We assume that any character device is "empty", bleh. */
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+ assert_se(null_or_empty_path("../../../../../../../../../../../../../../../../../../../../dev/null") == 1);
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+ assert_se(null_or_empty_path("/proc/self/exe") == 0);
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+ assert_se(null_or_empty_path("/nosuchfileordir") == -ENOENT);
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+}
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+
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+TEST(null_or_empty_path_with_root) {
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+ assert_se(null_or_empty_path_with_root("/dev/null", NULL) == 1);
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+ assert_se(null_or_empty_path_with_root("/dev/null", "/") == 1);
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+ assert_se(null_or_empty_path_with_root("/dev/null", "/.././../") == 1);
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+ assert_se(null_or_empty_path_with_root("/dev/null", "/.././..") == 1);
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+ assert_se(null_or_empty_path_with_root("../../../../../../../../../../../../../../../../../../../../dev/null", NULL) == 1);
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+ assert_se(null_or_empty_path_with_root("../../../../../../../../../../../../../../../../../../../../dev/null", "/") == 1);
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+ assert_se(null_or_empty_path_with_root("/proc/self/exe", NULL) == 0);
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+ assert_se(null_or_empty_path_with_root("/proc/self/exe", "/") == 0);
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+ assert_se(null_or_empty_path_with_root("/nosuchfileordir", NULL) == -ENOENT);
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+ assert_se(null_or_empty_path_with_root("/nosuchfileordir", "/.././../") == -ENOENT);
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+ assert_se(null_or_empty_path_with_root("/nosuchfileordir", "/.././..") == -ENOENT);
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+ assert_se(null_or_empty_path_with_root("/foobar/barbar/dev/null", "/foobar/barbar") == 1);
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+ assert_se(null_or_empty_path_with_root("/foobar/barbar/dev/null", "/foobar/barbar/") == 1);
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+}
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+
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TEST(files_same) {
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_cleanup_close_ int fd = -1;
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char name[] = "/tmp/test-files_same.XXXXXX";
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