94 lines
3.3 KiB
Diff
94 lines
3.3 KiB
Diff
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From 7a2349072e165c27ed0655934b05530c19d23779 Mon Sep 17 00:00:00 2001
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From: Yu Watanabe <watanabe.yu+github@gmail.com>
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Date: Thu, 15 Feb 2024 07:01:17 +0900
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Subject: [PATCH] fs-util: readlinkat() supports an empty string
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From readlinkat(2):
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Since Linux 2.6.39, pathname can be an empty string, in which case the
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call operates on the symbolic link referred to by dirfd (which should
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have been obtained using open(2) with the O_PATH and O_NOFOLLOW flags).
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(cherry picked from commit e4c094c05543410ba05a16f757d1e11652f4f6bd)
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(cherry picked from commit 30142e781d7afcfa93185d2543f59e9cf90dc882)
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Conflict:NA
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Reference:https://github.com/systemd/systemd-stable/commit/7a2349072e165c27ed0655934b05530c19d23779
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---
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src/basic/fs-util.c | 8 ++++++--
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src/test/test-fs-util.c | 35 +++++++++++++++++++++++++++++++++++
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2 files changed, 41 insertions(+), 2 deletions(-)
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diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
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index ee38e0266a..9ba9268d77 100644
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--- a/src/basic/fs-util.c
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+++ b/src/basic/fs-util.c
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@@ -116,7 +116,11 @@ int rename_noreplace(int olddirfd, const char *oldpath, int newdirfd, const char
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int readlinkat_malloc(int fd, const char *p, char **ret) {
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size_t l = PATH_MAX;
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- assert(p);
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+ assert(fd >= 0 || fd == AT_FDCWD);
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+
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+ if (fd < 0 && isempty(p))
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+ return -EISDIR; /* In this case, the fd points to the current working directory, and is
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+ * definitely not a symlink. Let's return earlier. */
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for (;;) {
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_cleanup_free_ char *c = NULL;
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@@ -126,7 +130,7 @@ int readlinkat_malloc(int fd, const char *p, char **ret) {
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if (!c)
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return -ENOMEM;
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- n = readlinkat(fd, p, c, l);
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+ n = readlinkat(fd, strempty(p), c, l);
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if (n < 0)
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return -errno;
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diff --git a/src/test/test-fs-util.c b/src/test/test-fs-util.c
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index 5de1eea0d4..ef335b43ae 100644
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--- a/src/test/test-fs-util.c
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+++ b/src/test/test-fs-util.c
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@@ -758,4 +758,39 @@ static int intro(void) {
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return EXIT_SUCCESS;
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}
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+TEST(readlinkat_malloc) {
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+ _cleanup_(rm_rf_physical_and_freep) char *t = NULL;
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+ _cleanup_close_ int tfd = -EBADF, fd = -EBADF;
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+ _cleanup_free_ char *p = NULL, *q = NULL;
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+ const char *expect = "hgoehogefoobar";
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+
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+ tfd = mkdtemp_open(NULL, O_PATH, &t);
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+ assert_se(tfd >= 0);
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+
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+ assert_se(symlinkat(expect, tfd, "linkname") >= 0);
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+
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+ assert_se(readlinkat_malloc(tfd, "linkname", &p) >= 0);
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+ assert_se(streq(p, expect));
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+ p = mfree(p);
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+
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+ fd = openat(tfd, "linkname", O_PATH | O_NOFOLLOW | O_CLOEXEC);
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+ assert_se(fd >= 0);
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+ assert_se(readlinkat_malloc(fd, NULL, &p) >= 0);
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+ assert_se(streq(p, expect));
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+ p = mfree(p);
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+ assert_se(readlinkat_malloc(fd, "", &p) >= 0);
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+ assert_se(streq(p, expect));
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+ p = mfree(p);
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+ fd = safe_close(fd);
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+
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+ assert_se(q = path_join(t, "linkname"));
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+ assert_se(readlinkat_malloc(AT_FDCWD, q, &p) >= 0);
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+ assert_se(streq(p, expect));
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+ p = mfree(p);
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+ assert_se(readlinkat_malloc(INT_MAX, q, &p) >= 0);
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+ assert_se(streq(p, expect));
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+ p = mfree(p);
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+ q = mfree(q);
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+}
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+
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DEFINE_TEST_MAIN_WITH_INTRO(LOG_INFO, intro);
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--
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2.33.0
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