X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsd_journal_get_data.xml;fp=man%2Fsd_journal_get_data.xml;h=9d8a4a2221440fb0207db9dd81c76cdb9b4c2b3f;hb=4171a6676c74846c9c189f3a92b97bbcd4a11a13;hp=0000000000000000000000000000000000000000;hpb=67c3cf4f9ea35c1f789526b24a4d052d071902c0;p=elogind.git diff --git a/man/sd_journal_get_data.xml b/man/sd_journal_get_data.xml new file mode 100644 index 000000000..9d8a4a222 --- /dev/null +++ b/man/sd_journal_get_data.xml @@ -0,0 +1,199 @@ + + + + + + + + + sd_journal_get_data + systemd + + + + Developer + Lennart + Poettering + lennart@poettering.net + + + + + + sd_journal_get_data + 3 + + + + sd_journal_get_data + sd_journal_enumerate_data + sd_journal_restart_data + SD_JOURNAL_FOREACH_DATA + Read data fields from the current journal entry + + + + + #include <systemd/sd-journal.h> + + + int sd_journal_get_data + sd_journal* j + const char* field + const void** data + size_t* length + + + + int sd_journal_enumerate_data + sd_journal* j + const void** data + size_t* length + + + + int sd_journal_restart_data + sd_journal* j + + + + SD_JOURNAL_FOREACH_DATA + sd_journal* j + const void* data + size_t length + + + + + + + Description + + sd_journal_get_data() gets + the data object associated with a specific field from + the current journal entry. It takes four arguments: + the journal context object, a string with the field + name to request, plus a pair of pointers to + pointer/size variables where the data object and its + size shall be stored in. The field name should be an + entry field name. Well-known field names are listed in + systemd.journal-fields7. The + returned data is in a read-only memory map and is only + valid until the next invocation of + sd_journal_get_data() or + sd_journal_enumerate_data(), or + the read pointer is altered. Note that the data + returned will be prefixed with the field name and + '='. + + sd_journal_enumerate_data() + may be used to iterate through all fields of the + current entry. On each invocation the data for the + next field is returned. The order of these fields is + not defined. The data returned is in the same format + as with sd_journal_get_data() and + also follows the same life-time semantics. + + sd_journal_restart_data() + resets the data enumeration index to the beginning of + the entry. The next invocation of + sd_journal_enumerate_data() will return the first + field of the entry again. + + Note that the + SD_JOURNAL_FOREACH_DATA() macro + may be used as a wrapper around + sd_journal_restart_data() and + sd_journal_enumerate_data(). + + Note that these functions will not work before + sd_journal_next3 + (or related call) has not been called at least + once. + + + + Return Value + + sd_journal_get_data() + returns 0 on success or a negative errno-style error + code. If the current entry does not include the + specified field -ENOENT is returned. If + sd_journal_next3 + has not been called at least once -EADDRNOTAVAIL is + returned. sd_journal_enumerate_data() + returns a positive integer if the next field has been + read, 0 when no more fields are known, or a negative + errno-style error + code. sd_journal_restart_data() + returns nothing. + + + + Notes + + The sd_journal_get_data(), + sd_journal_enumerate_data() and + sd_journal_restart_data() + interfaces are available as shared library, which can + be compiled and linked to with the + libsystemd-journal + pkg-config1 + file. + + + + Examples + + See + sd_journal_next3 + for a complete example how to use + sd_journal_get_data(). + + Use the + SD_JOURNAL_FOREACH_DATA macro to + iterate through all fields of the current journal + entry: + + ... +int print_fields(sd_journal *j) { + const void *data; + size_t l; + SD_JOURNAL_FOREACH_DATA(j, data, length) + printf("%.*s\n", (int) length, data); +} +... + + + + + See Also + + + systemd1, + systemd.journal-fields7, + sd-journal3, + sd_journal_open3, + sd_journal_next3 + + + +