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Systemd/src/systemd/sd-journal.h
Zbigniew Jędrzejewski-Szmek 76cbafcdd4 sd-journal: when enumerating, continue even after an inaccessible field 
SD_JOURNAL_FOREACH_DATA() and SD_JOURNAL_FOREACH_UNIQUE() would immediately
terminate when a field couldn't be accessed. This can happen for example when a
field is compressed with an unavailable compression format. But it's likely
that this is the wrong thing to do: the caller for example might want to
iterate over the fields but isn't interested in all of them. coredumpctl is
like this: it uses SD_JOURNAL_FOREACH_DATA() but only uses a subset of the
fields.

Add two new functions sd_journal_enumerate_good_data() and
sd_journal_enumerate_good_unique() that retry sd_journal_enumerate_data() and
sd_journal_enumerate_unique() if the return value is something that applies to
a single field: ENOBUS, E2BIG, EOPNOTSUPP.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1856037.

An alternative would be to make the macros themselves smarter instead of adding
new symbols, and do the looping internally in the macro. I don't like that
approach for two reasons. First, it would embed the logic in the macro, so
recompilation would be required if we decide to update the logic. With the
current version of the patch, recompilation is required to use the new symbols,
but after that, library upgrades are enough. So the current approach is safer
in case further updates are needed. Second, our headers use primitive C, and it
is hard to do the macros without using newer features.
2020-07-21 17:42:11 +02:00

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/* SPDX-License-Identifier: LGPL-2.1+ */
#ifndef foosdjournalhfoo
#define foosdjournalhfoo
/***
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <inttypes.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <syslog.h>
#include "sd-id128.h"
#include "_sd-common.h"
/* Journal APIs. See sd-journal(3) for more information. */
_SD_BEGIN_DECLARATIONS;
/* Write to daemon */
int sd_journal_print(int priority, const char *format, ...) _sd_printf_(2, 3);
int sd_journal_printv(int priority, const char *format, va_list ap) _sd_printf_(2, 0);
int sd_journal_send(const char *format, ...) _sd_printf_(1, 0) _sd_sentinel_;
int sd_journal_sendv(const struct iovec *iov, int n);
int sd_journal_perror(const char *message);
/* Used by the macros below. You probably don't want to call this directly. */
int sd_journal_print_with_location(int priority, const char *file, const char *line, const char *func, const char *format, ...) _sd_printf_(5, 6);
int sd_journal_printv_with_location(int priority, const char *file, const char *line, const char *func, const char *format, va_list ap) _sd_printf_(5, 0);
int sd_journal_send_with_location(const char *file, const char *line, const char *func, const char *format, ...) _sd_printf_(4, 0) _sd_sentinel_;
int sd_journal_sendv_with_location(const char *file, const char *line, const char *func, const struct iovec *iov, int n);
int sd_journal_perror_with_location(const char *file, const char *line, const char *func, const char *message);
/* implicitly add code location to messages sent, if this is enabled */
#ifndef SD_JOURNAL_SUPPRESS_LOCATION
#define sd_journal_print(priority, ...) sd_journal_print_with_location(priority, "CODE_FILE=" __FILE__, "CODE_LINE=" _SD_STRINGIFY(__LINE__), __func__, __VA_ARGS__)
#define sd_journal_printv(priority, format, ap) sd_journal_printv_with_location(priority, "CODE_FILE=" __FILE__, "CODE_LINE=" _SD_STRINGIFY(__LINE__), __func__, format, ap)
#define sd_journal_send(...) sd_journal_send_with_location("CODE_FILE=" __FILE__, "CODE_LINE=" _SD_STRINGIFY(__LINE__), __func__, __VA_ARGS__)
#define sd_journal_sendv(iovec, n) sd_journal_sendv_with_location("CODE_FILE=" __FILE__, "CODE_LINE=" _SD_STRINGIFY(__LINE__), __func__, iovec, n)
#define sd_journal_perror(message) sd_journal_perror_with_location("CODE_FILE=" __FILE__, "CODE_LINE=" _SD_STRINGIFY(__LINE__), __func__, message)
#endif
int sd_journal_stream_fd(const char *identifier, int priority, int level_prefix);
/* Browse journal stream */
typedef struct sd_journal sd_journal;
/* Open flags */
enum {
SD_JOURNAL_LOCAL_ONLY = 1 << 0,
SD_JOURNAL_RUNTIME_ONLY = 1 << 1,
SD_JOURNAL_SYSTEM = 1 << 2,
SD_JOURNAL_CURRENT_USER = 1 << 3,
SD_JOURNAL_OS_ROOT = 1 << 4,
SD_JOURNAL_ALL_NAMESPACES = 1 << 5, /* Show all namespaces, not just the default or specified one */
SD_JOURNAL_INCLUDE_DEFAULT_NAMESPACE = 1 << 6, /* Show default namespace in addition to specified one */
SD_JOURNAL_SYSTEM_ONLY _sd_deprecated_ = SD_JOURNAL_SYSTEM /* old name */
};
/* Wakeup event types */
enum {
SD_JOURNAL_NOP,
SD_JOURNAL_APPEND,
SD_JOURNAL_INVALIDATE
};
int sd_journal_open(sd_journal **ret, int flags);
int sd_journal_open_namespace(sd_journal **ret, const char *name_space, int flags);
int sd_journal_open_directory(sd_journal **ret, const char *path, int flags);
int sd_journal_open_directory_fd(sd_journal **ret, int fd, int flags);
int sd_journal_open_files(sd_journal **ret, const char **paths, int flags);
int sd_journal_open_files_fd(sd_journal **ret, int fds[], unsigned n_fds, int flags);
int sd_journal_open_container(sd_journal **ret, const char *machine, int flags) _sd_deprecated_;
void sd_journal_close(sd_journal *j);
int sd_journal_previous(sd_journal *j);
int sd_journal_next(sd_journal *j);
int sd_journal_previous_skip(sd_journal *j, uint64_t skip);
int sd_journal_next_skip(sd_journal *j, uint64_t skip);
int sd_journal_get_realtime_usec(sd_journal *j, uint64_t *ret);
int sd_journal_get_monotonic_usec(sd_journal *j, uint64_t *ret, sd_id128_t *ret_boot_id);
int sd_journal_set_data_threshold(sd_journal *j, size_t sz);
int sd_journal_get_data_threshold(sd_journal *j, size_t *sz);
int sd_journal_get_data(sd_journal *j, const char *field, const void **data, size_t *l);
int sd_journal_enumerate_data(sd_journal *j, const void **data, size_t *l);
int sd_journal_enumerate_available_data(sd_journal *j, const void **data, size_t *l);
void sd_journal_restart_data(sd_journal *j);
int sd_journal_add_match(sd_journal *j, const void *data, size_t size);
int sd_journal_add_disjunction(sd_journal *j);
int sd_journal_add_conjunction(sd_journal *j);
void sd_journal_flush_matches(sd_journal *j);
int sd_journal_seek_head(sd_journal *j);
int sd_journal_seek_tail(sd_journal *j);
int sd_journal_seek_monotonic_usec(sd_journal *j, sd_id128_t boot_id, uint64_t usec);
int sd_journal_seek_realtime_usec(sd_journal *j, uint64_t usec);
int sd_journal_seek_cursor(sd_journal *j, const char *cursor);
int sd_journal_get_cursor(sd_journal *j, char **cursor);
int sd_journal_test_cursor(sd_journal *j, const char *cursor);
int sd_journal_get_cutoff_realtime_usec(sd_journal *j, uint64_t *from, uint64_t *to);
int sd_journal_get_cutoff_monotonic_usec(sd_journal *j, const sd_id128_t boot_id, uint64_t *from, uint64_t *to);
int sd_journal_get_usage(sd_journal *j, uint64_t *bytes);
int sd_journal_query_unique(sd_journal *j, const char *field);
int sd_journal_enumerate_unique(sd_journal *j, const void **data, size_t *l);
int sd_journal_enumerate_available_unique(sd_journal *j, const void **data, size_t *l);
void sd_journal_restart_unique(sd_journal *j);
int sd_journal_enumerate_fields(sd_journal *j, const char **field);
void sd_journal_restart_fields(sd_journal *j);
int sd_journal_get_fd(sd_journal *j);
int sd_journal_get_events(sd_journal *j);
int sd_journal_get_timeout(sd_journal *j, uint64_t *timeout_usec);
int sd_journal_process(sd_journal *j);
int sd_journal_wait(sd_journal *j, uint64_t timeout_usec);
int sd_journal_reliable_fd(sd_journal *j);
int sd_journal_get_catalog(sd_journal *j, char **text);
int sd_journal_get_catalog_for_message_id(sd_id128_t id, char **text);
int sd_journal_has_runtime_files(sd_journal *j);
int sd_journal_has_persistent_files(sd_journal *j);
/* The inverse condition avoids ambiguity of dangling 'else' after the macro */
#define SD_JOURNAL_FOREACH(j) \
if (sd_journal_seek_head(j) < 0) { } \
else while (sd_journal_next(j) > 0)
/* The inverse condition avoids ambiguity of dangling 'else' after the macro */
#define SD_JOURNAL_FOREACH_BACKWARDS(j) \
if (sd_journal_seek_tail(j) < 0) { } \
else while (sd_journal_previous(j) > 0)
/* Iterate through all available data fields of the current journal entry */
#define SD_JOURNAL_FOREACH_DATA(j, data, l) \
for (sd_journal_restart_data(j); sd_journal_enumerate_available_data((j), &(data), &(l)) > 0; )
/* Iterate through all available values of a specific field */
#define SD_JOURNAL_FOREACH_UNIQUE(j, data, l) \
for (sd_journal_restart_unique(j); sd_journal_enumerate_available_unique((j), &(data), &(l)) > 0; )
/* Iterate through all known field names */
#define SD_JOURNAL_FOREACH_FIELD(j, field) \
for (sd_journal_restart_fields(j); sd_journal_enumerate_fields((j), &(field)) > 0; )
_SD_DEFINE_POINTER_CLEANUP_FUNC(sd_journal, sd_journal_close);
_SD_END_DECLARATIONS;
#endif
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