| 1 | // SPDX-License-Identifier: GPL-3.0-or-later |
| 2 | |
| 3 | #include "nd_log-internals.h" |
| 4 | |
| 5 | void chown_open_file(int fd, uid_t uid, gid_t gid) { |
| 6 | if(fd == -1) return; |
| 7 | |
| 8 | struct stat buf; |
| 9 | |
| 10 | if(fstat(fd, &buf) == -1) { |
| 11 | netdata_log_error("Cannot fstat() fd %d", fd); |
| 12 | return; |
| 13 | } |
| 14 | |
| 15 | if((buf.st_uid != uid || buf.st_gid != gid) && S_ISREG(buf.st_mode)) { |
| 16 | if(fchown(fd, uid, gid) == -1) |
| 17 | netdata_log_error("Cannot fchown() fd %d.", fd); |
| 18 | } |
| 19 | } |
| 20 | |
| 21 | void nd_log_chown_log_files(uid_t uid, gid_t gid) { |
| 22 | for(size_t i = 0 ; i < _NDLS_MAX ; i++) { |
| 23 | if(nd_log.sources[i].fd != -1 && nd_log.sources[i].fd != STDIN_FILENO) |
| 24 | chown_open_file(nd_log.sources[i].fd, uid, gid); |
| 25 | } |
| 26 | } |
| 27 | |
| 28 | bool nd_logger_file(int fd, FILE *fp, netdata_mutex_t *mutex, ND_LOG_FORMAT format, struct log_field *fields, size_t fields_max) { |
| 29 | (void)fp; |
| 30 | |
| 31 | BUFFER *wb = buffer_create(1024, NULL); |
| 32 | |
| 33 | if(format == NDLF_JSON) |
| 34 | nd_logger_json(wb, fields, fields_max); |
| 35 | else |
| 36 | nd_logger_logfmt(wb, fields, fields_max); |
| 37 | |
| 38 | buffer_strcat(wb, "\n"); |
| 39 | |
| 40 | // Serialize writes with a Netdata-owned mutex and use write() on the raw fd. |
| 41 | // |
| 42 | // We avoid libc's stdio locking (flockfile/funlockfile) because spawn-server |
| 43 | // children inherit FILE* state across fork(). In those post-fork children we |
| 44 | // disable logger mutexes entirely, since they are single-threaded at that point. |
| 45 | // |
| 46 | // A netdata_mutex_t sleeps on contention rather than busy-waiting, so blocked |
| 47 | // I/O (full pipe, slow disk) does not burn CPU in other logging threads. |
| 48 | // |
| 49 | // Logger-owned streams are configured unbuffered when opened, so the logger |
| 50 | // can stay on raw fd writes here without taking stdio-internal locks. |
| 51 | |
| 52 | const char *buf = buffer_tostring(wb); |
| 53 | size_t remaining = buffer_strlen(wb); |
| 54 | |
| 55 | if(mutex) |
| 56 | netdata_mutex_lock(mutex); |
| 57 | |
| 58 | while(remaining > 0) { |
| 59 | size_t chunk = remaining; |
| 60 | if(chunk > (size_t)SSIZE_MAX) |
| 61 | chunk = (size_t)SSIZE_MAX; |
| 62 | |
| 63 | ssize_t written = write(fd, buf, chunk); |
| 64 | if(written > 0) { |
| 65 | buf += written; |
| 66 | remaining -= written; |
| 67 | } |
| 68 | else if(written == 0) |
| 69 | break; |
| 70 | else if(errno != EINTR) |
| 71 | break; |
| 72 | } |
| 73 | |
| 74 | if(mutex) |
| 75 | netdata_mutex_unlock(mutex); |
| 76 | |
| 77 | buffer_free(wb); |
| 78 | return remaining == 0; |
| 79 | } |