| 1 | /* |
| 2 | * liblttdvfs |
| 3 | * |
| 4 | * Linux Trace Toolkit library - Write trace to the virtual file system |
| 5 | * |
| 6 | * This is a simple daemonized library that reads a few LTTng debugfs channels |
| 7 | * and save them in a trace. |
| 8 | * |
| 9 | * CPU hot-plugging is supported using inotify. |
| 10 | * |
| 11 | * Copyright 2005-2010 - |
| 12 | * Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 13 | * Copyright 2010 - |
| 14 | * Michael Sills-Lavoie <michael.sills-lavoie@polymtl.ca> |
| 15 | * Oumarou Dicko <oumarou.dicko@polymtl.ca> |
| 16 | * |
| 17 | * This library is free software; you can redistribute it and/or |
| 18 | * modify it under the terms of the GNU Lesser General Public |
| 19 | * License as published by the Free Software Foundation; either |
| 20 | * version 2.1 of the License, or (at your option) any later version. |
| 21 | * |
| 22 | * This library is distributed in the hope that it will be useful, |
| 23 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 24 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 25 | * Lesser General Public License for more details. |
| 26 | * |
| 27 | * You should have received a copy of the GNU Lesser General Public |
| 28 | * License along with this library; if not, write to the Free Software |
| 29 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 30 | */ |
| 31 | |
| 32 | #ifdef HAVE_CONFIG_H |
| 33 | #include <config.h> |
| 34 | #endif |
| 35 | |
| 36 | #define _REENTRANT |
| 37 | #define _GNU_SOURCE |
| 38 | #define _XOPEN_SOURCE 600 |
| 39 | #include <stdio.h> |
| 40 | #include <stdlib.h> |
| 41 | #include <string.h> |
| 42 | #include <errno.h> |
| 43 | #include <fcntl.h> |
| 44 | #include <dirent.h> |
| 45 | #include <pthread.h> |
| 46 | #include <sys/stat.h> |
| 47 | |
| 48 | #include "liblttdvfs.h" |
| 49 | |
| 50 | struct liblttdvfs_channel_data { |
| 51 | int trace; |
| 52 | }; |
| 53 | |
| 54 | struct liblttdvfs_data { |
| 55 | char path_trace[PATH_MAX]; |
| 56 | char *end_path_trace; |
| 57 | int path_trace_len; |
| 58 | int append_mode; |
| 59 | int verbose_mode; |
| 60 | }; |
| 61 | |
| 62 | static __thread int thread_pipe[2]; |
| 63 | |
| 64 | #define printf_verbose(fmt, args...) \ |
| 65 | do { \ |
| 66 | if (callbacks_data->verbose_mode) \ |
| 67 | printf(fmt, ##args); \ |
| 68 | } while (0) |
| 69 | |
| 70 | int liblttdvfs_on_open_channel(struct liblttd_callbacks *data, struct fd_pair *pair, char *relative_channel_path) |
| 71 | { |
| 72 | int open_ret = 0; |
| 73 | int ret; |
| 74 | struct stat stat_buf; |
| 75 | struct liblttdvfs_channel_data *channel_data; |
| 76 | off_t offset = 0; |
| 77 | |
| 78 | pair->user_data = malloc(sizeof(struct liblttdvfs_channel_data)); |
| 79 | channel_data = pair->user_data; |
| 80 | |
| 81 | struct liblttdvfs_data* callbacks_data = data->user_data; |
| 82 | |
| 83 | strncpy(callbacks_data->end_path_trace, relative_channel_path, PATH_MAX - callbacks_data->path_trace_len); |
| 84 | printf_verbose("Creating trace file %s\n", callbacks_data->path_trace); |
| 85 | |
| 86 | ret = stat(callbacks_data->path_trace, &stat_buf); |
| 87 | if (ret == 0) { |
| 88 | if (callbacks_data->append_mode) { |
| 89 | printf_verbose("Appending to file %s as requested\n", |
| 90 | callbacks_data->path_trace); |
| 91 | |
| 92 | channel_data->trace = open(callbacks_data->path_trace, O_WRONLY, S_IRWXU|S_IRWXG|S_IRWXO); |
| 93 | if (channel_data->trace == -1) { |
| 94 | perror(callbacks_data->path_trace); |
| 95 | open_ret = -1; |
| 96 | goto end; |
| 97 | } |
| 98 | offset = lseek(channel_data->trace, 0, SEEK_END); |
| 99 | if (offset < 0) { |
| 100 | perror(callbacks_data->path_trace); |
| 101 | open_ret = -1; |
| 102 | close(channel_data->trace); |
| 103 | goto end; |
| 104 | } |
| 105 | } else { |
| 106 | printf("File %s exists, cannot open. Try append mode.\n", callbacks_data->path_trace); |
| 107 | open_ret = -1; |
| 108 | goto end; |
| 109 | } |
| 110 | } else { |
| 111 | if (errno == ENOENT) { |
| 112 | channel_data->trace = |
| 113 | open(callbacks_data->path_trace, O_WRONLY|O_CREAT|O_EXCL, S_IRWXU|S_IRWXG|S_IRWXO); |
| 114 | if (channel_data->trace == -1) { |
| 115 | perror(callbacks_data->path_trace); |
| 116 | open_ret = -1; |
| 117 | goto end; |
| 118 | } |
| 119 | offset = 0; |
| 120 | } else { |
| 121 | perror("Channel output file open"); |
| 122 | open_ret = -1; |
| 123 | goto end; |
| 124 | } |
| 125 | } |
| 126 | end: |
| 127 | return open_ret; |
| 128 | |
| 129 | } |
| 130 | |
| 131 | int liblttdvfs_on_close_channel(struct liblttd_callbacks *data, struct fd_pair *pair) |
| 132 | { |
| 133 | int ret; |
| 134 | ret = close(((struct liblttdvfs_channel_data *)(pair->user_data))->trace); |
| 135 | free(pair->user_data); |
| 136 | return ret; |
| 137 | } |
| 138 | |
| 139 | int liblttdvfs_on_new_channels_folder(struct liblttd_callbacks *data, char *relative_folder_path) |
| 140 | { |
| 141 | int ret; |
| 142 | int open_ret = 0; |
| 143 | struct liblttdvfs_data* callbacks_data = data->user_data; |
| 144 | |
| 145 | strncpy(callbacks_data->end_path_trace, relative_folder_path, PATH_MAX - callbacks_data->path_trace_len); |
| 146 | printf_verbose("Creating trace subdirectory %s\n", callbacks_data->path_trace); |
| 147 | |
| 148 | ret = mkdir(callbacks_data->path_trace, S_IRWXU|S_IRWXG|S_IRWXO); |
| 149 | if (ret == -1) { |
| 150 | if (errno != EEXIST) { |
| 151 | perror(callbacks_data->path_trace); |
| 152 | open_ret = -1; |
| 153 | goto end; |
| 154 | } |
| 155 | } |
| 156 | |
| 157 | end: |
| 158 | return open_ret; |
| 159 | } |
| 160 | |
| 161 | int liblttdvfs_on_read_subbuffer(struct liblttd_callbacks *data, struct fd_pair *pair, unsigned int len) |
| 162 | { |
| 163 | long ret; |
| 164 | off_t offset = 0; |
| 165 | off_t orig_offset = pair->offset; |
| 166 | int outfd = ((struct liblttdvfs_channel_data *)(pair->user_data))->trace; |
| 167 | |
| 168 | struct liblttdvfs_data* callbacks_data = data->user_data; |
| 169 | |
| 170 | while (len > 0) { |
| 171 | printf_verbose("splice chan to pipe offset %lu\n", |
| 172 | (unsigned long)offset); |
| 173 | ret = splice(pair->channel, &offset, thread_pipe[1], NULL, |
| 174 | len, SPLICE_F_MOVE | SPLICE_F_MORE); |
| 175 | printf_verbose("splice chan to pipe ret %ld\n", ret); |
| 176 | if (ret < 0) { |
| 177 | perror("Error in relay splice"); |
| 178 | goto write_end; |
| 179 | } |
| 180 | ret = splice(thread_pipe[0], NULL, outfd, |
| 181 | NULL, ret, SPLICE_F_MOVE | SPLICE_F_MORE); |
| 182 | printf_verbose("splice pipe to file %ld\n", ret); |
| 183 | if (ret < 0) { |
| 184 | perror("Error in file splice"); |
| 185 | goto write_end; |
| 186 | } |
| 187 | len -= ret; |
| 188 | /* This won't block, but will start writeout asynchronously */ |
| 189 | sync_file_range(outfd, pair->offset, ret, |
| 190 | SYNC_FILE_RANGE_WRITE); |
| 191 | pair->offset += ret; |
| 192 | } |
| 193 | write_end: |
| 194 | /* |
| 195 | * This does a blocking write-and-wait on any page that belongs to the |
| 196 | * subbuffer prior to the one we just wrote. |
| 197 | * Don't care about error values, as these are just hints and ways to |
| 198 | * limit the amount of page cache used. |
| 199 | */ |
| 200 | if (orig_offset >= pair->max_sb_size) { |
| 201 | sync_file_range(outfd, orig_offset - pair->max_sb_size, |
| 202 | pair->max_sb_size, |
| 203 | SYNC_FILE_RANGE_WAIT_BEFORE |
| 204 | | SYNC_FILE_RANGE_WRITE |
| 205 | | SYNC_FILE_RANGE_WAIT_AFTER); |
| 206 | /* |
| 207 | * Give hints to the kernel about how we access the file: |
| 208 | * POSIX_FADV_DONTNEED : we won't re-access data in a near |
| 209 | * future after we write it. |
| 210 | * We need to call fadvise again after the file grows because |
| 211 | * the kernel does not seem to apply fadvise to non-existing |
| 212 | * parts of the file. |
| 213 | * Call fadvise _after_ having waited for the page writeback to |
| 214 | * complete because the dirty page writeback semantic is not |
| 215 | * well defined. So it can be expected to lead to lower |
| 216 | * throughput in streaming. |
| 217 | */ |
| 218 | posix_fadvise(outfd, orig_offset - pair->max_sb_size, |
| 219 | pair->max_sb_size, POSIX_FADV_DONTNEED); |
| 220 | } |
| 221 | |
| 222 | return ret; |
| 223 | } |
| 224 | |
| 225 | int liblttdvfs_on_new_thread(struct liblttd_callbacks *data, unsigned long thread_num) |
| 226 | { |
| 227 | int ret; |
| 228 | ret = pipe(thread_pipe); |
| 229 | if (ret < 0) { |
| 230 | perror("Error creating pipe"); |
| 231 | return ret; |
| 232 | } |
| 233 | return 0; |
| 234 | } |
| 235 | |
| 236 | int liblttdvfs_on_close_thread(struct liblttd_callbacks *data, unsigned long thread_num) |
| 237 | { |
| 238 | close(thread_pipe[0]); /* close read end */ |
| 239 | close(thread_pipe[1]); /* close write end */ |
| 240 | return 0; |
| 241 | } |
| 242 | |
| 243 | int liblttdvfs_on_trace_end(struct liblttd_instance *instance) |
| 244 | { |
| 245 | struct liblttd_callbacks *callbacks = instance->callbacks; |
| 246 | struct liblttdvfs_data *data = callbacks->user_data; |
| 247 | |
| 248 | free(data); |
| 249 | free(callbacks); |
| 250 | } |
| 251 | |
| 252 | struct liblttd_callbacks* liblttdvfs_new_callbacks(char* trace_name, |
| 253 | int append_mode, int verbose_mode) |
| 254 | { |
| 255 | struct liblttdvfs_data *data; |
| 256 | struct liblttd_callbacks *callbacks; |
| 257 | |
| 258 | if (!trace_name) |
| 259 | goto error; |
| 260 | |
| 261 | data = malloc(sizeof(struct liblttdvfs_data)); |
| 262 | if (!data) |
| 263 | goto error; |
| 264 | |
| 265 | strncpy(data->path_trace, trace_name, PATH_MAX-1); |
| 266 | data->path_trace_len = strlen(data->path_trace); |
| 267 | data->end_path_trace = data->path_trace + data->path_trace_len; |
| 268 | data->append_mode = append_mode; |
| 269 | data->verbose_mode = verbose_mode; |
| 270 | |
| 271 | callbacks = malloc(sizeof(struct liblttd_callbacks)); |
| 272 | if (!callbacks) |
| 273 | goto alloc_cb_error; |
| 274 | |
| 275 | callbacks->on_open_channel = liblttdvfs_on_open_channel; |
| 276 | callbacks->on_close_channel = liblttdvfs_on_close_channel; |
| 277 | callbacks->on_new_channels_folder = liblttdvfs_on_new_channels_folder; |
| 278 | callbacks->on_read_subbuffer = liblttdvfs_on_read_subbuffer; |
| 279 | callbacks->on_trace_end = liblttdvfs_on_trace_end; |
| 280 | callbacks->on_new_thread = liblttdvfs_on_new_thread; |
| 281 | callbacks->on_close_thread = liblttdvfs_on_close_thread; |
| 282 | callbacks->user_data = data; |
| 283 | |
| 284 | return callbacks; |
| 285 | |
| 286 | /* Error handling */ |
| 287 | alloc_cb_error: |
| 288 | free(data); |
| 289 | error: |
| 290 | return NULL; |
| 291 | } |