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report: make report-files listing and lookup agree on masked entries

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The metric list is built with conf_files_list_strv(), but each metric's
value is then looked up again by walking report_files_dirs[] by hand,
and the two disagreed whenever an earlier directory had an entry that is
not a regular file:

 - conf_files_list_strv() skipped such an entry and listed the one from
   a later directory, so the metric was advertised by Describe();
 - file_metric_generate() only moved on to the next directory on
   -ENOENT, so it hit the non-regular entry, logged a warning and
   produced nothing.

The practical case is masking a vendor-supplied entry with a symlink to
/dev/null: the metric kept being described, was never listed, and every
scrape logged "Failed to open ..., skipping: File descriptor in bad
state".

Honour masks in the enumeration via CONF_FILES_FILTER_MASKED_BY_SYMLINK,
as other conf dirs do, and make the lookup skip non-regular entries the
same way the enumeration does. Document the masking in the man page and
cover both cases in TEST-74-AUX-UTILS.report.

(cherry picked from commit 08be8677539642f45c6127085283cf08b6a410b7)
This commit is contained in:
Armaan Sandhu
2026-10-16 11:36:32 +01:00
committed by Luca Boccassi
parent f9b52a6be3
commit f41defc034
3 changed files with 62 additions and 6 deletions
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src/report/report-files.c
+36 -5
View File
@@ -12,6 +12,7 @@
#include "metrics.h"
#include "path-util.h"
#include "report-files.h"
#include "stat-util.h"
#include "string-util.h"
#include "strv.h"
#include "utf8.h"
@@ -68,15 +69,40 @@ static int file_metric_generate(const MetricFamily *mf, sd_varlink *link, void *
if (!path)
return log_oom();
/* Mirror what conf_files_list_strv() does when building the metric list: skip entries that
* cannot be resolved or are not regular files, and stop at a mask, which hides the entries in
* all later directories. The mask check is repeated here since the directories may have
* changed since the list was built. */
_cleanup_free_ char *resolved = NULL;
_cleanup_close_ int fd = chase_and_open(path, /* root= */ NULL, CHASE_MUST_BE_REGULAR, O_RDONLY|O_CLOEXEC, &resolved);
if (fd == -ENOENT) /* Not in this directory (or dangling symlink): try the next one. */
_cleanup_close_ int pfd = -EBADF;
r = chase(path, /* root= */ NULL, /* flags= */ 0, &resolved, &pfd);
if (r == -ENOENT)
continue;
if (fd < 0) {
log_warning_errno(fd, "Failed to open '%s', skipping: %m", path);
if (r < 0) {
log_warning_errno(r, "Failed to resolve '%s', ignoring: %m", path);
continue;
}
struct stat st;
if (fstat(pfd, &st) < 0) {
log_warning_errno(errno, "Failed to stat '%s', ignoring: %m", path);
continue;
}
if (stat_may_be_dev_null(&st)) {
log_debug("File for metric '%s' is masked, skipping.", mf->name);
return 0;
}
if (!S_ISREG(st.st_mode))
continue;
_cleanup_close_ int fd = fd_reopen(pfd, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
log_warning_errno(fd, "Failed to open '%s', ignoring: %m", path);
continue;
}
r = read_full_file_full(
fd,
/* filename= */ NULL,
@@ -120,7 +146,12 @@ static int build_file_metrics(MetricFamily **ret) {
/* Enumerate the files to report across all our directories, deduplicated by name. The entry name is
* used as the metric field name. */
r = conf_files_list_strv(&files, /* suffix= */ NULL, /* root= */ NULL, CONF_FILES_REGULAR, report_files_dirs);
r = conf_files_list_strv(
&files,
/* suffix= */ NULL,
/* root= */ NULL,
CONF_FILES_REGULAR|CONF_FILES_FILTER_MASKED_BY_SYMLINK,
report_files_dirs);
if (r < 0)
return log_error_errno(r, "Failed to enumerate report files: %m");