| #include "cache.h" |
| #include "trace2/tr2_dst.h" |
| #include "trace2/tr2_sid.h" |
| #include "trace2/tr2_sysenv.h" |
| |
| /* |
| * How many attempts we will make at creating an automatically-named trace file. |
| */ |
| #define MAX_AUTO_ATTEMPTS 10 |
| |
| /* |
| * Sentinel file used to detect when we should discard new traces to avoid |
| * writing too many trace files to a directory. |
| */ |
| #define DISCARD_SENTINEL_NAME "git-trace2-discard" |
| |
| /* |
| * When set to zero, disables directory file count checks. Otherwise, controls |
| * how many files we can write to a directory before entering discard mode. |
| * This can be overridden via the TR2_SYSENV_MAX_FILES setting. |
| */ |
| static int tr2env_max_files = 0; |
| |
| static int tr2_dst_want_warning(void) |
| { |
| static int tr2env_dst_debug = -1; |
| |
| if (tr2env_dst_debug == -1) { |
| const char *env_value = tr2_sysenv_get(TR2_SYSENV_DST_DEBUG); |
| if (!env_value || !*env_value) |
| tr2env_dst_debug = 0; |
| else |
| tr2env_dst_debug = atoi(env_value) > 0; |
| } |
| |
| return tr2env_dst_debug; |
| } |
| |
| void tr2_dst_trace_disable(struct tr2_dst *dst) |
| { |
| if (dst->need_close) |
| close(dst->fd); |
| dst->fd = 0; |
| dst->initialized = 1; |
| dst->need_close = 0; |
| } |
| |
| /* |
| * Check to make sure we're not overloading the target directory with too many |
| * files. First get the threshold (if present) from the config or envvar. If |
| * it's zero or unset, disable this check. Next check for the presence of a |
| * sentinel file, then check file count. |
| * |
| * Returns 0 if tracing should proceed as normal. Returns 1 if the sentinel file |
| * already exists, which means tracing should be disabled. Returns -1 if there |
| * are too many files but there was no sentinel file, which means we have |
| * created and should write traces to the sentinel file. |
| * |
| * We expect that some trace processing system is gradually collecting files |
| * from the target directory; after it removes the sentinel file we'll start |
| * writing traces again. |
| */ |
| static int tr2_dst_too_many_files(struct tr2_dst *dst, const char *tgt_prefix) |
| { |
| int file_count = 0, max_files = 0, ret = 0; |
| const char *max_files_var; |
| DIR *dirp; |
| struct strbuf path = STRBUF_INIT, sentinel_path = STRBUF_INIT; |
| struct stat statbuf; |
| |
| /* Get the config or envvar and decide if we should continue this check */ |
| max_files_var = tr2_sysenv_get(TR2_SYSENV_MAX_FILES); |
| if (max_files_var && *max_files_var && ((max_files = atoi(max_files_var)) >= 0)) |
| tr2env_max_files = max_files; |
| |
| if (!tr2env_max_files) { |
| ret = 0; |
| goto cleanup; |
| } |
| |
| strbuf_addstr(&path, tgt_prefix); |
| if (!is_dir_sep(path.buf[path.len - 1])) { |
| strbuf_addch(&path, '/'); |
| } |
| |
| /* check sentinel */ |
| strbuf_addbuf(&sentinel_path, &path); |
| strbuf_addstr(&sentinel_path, DISCARD_SENTINEL_NAME); |
| if (!stat(sentinel_path.buf, &statbuf)) { |
| ret = 1; |
| goto cleanup; |
| } |
| |
| /* check file count */ |
| dirp = opendir(path.buf); |
| while (file_count < tr2env_max_files && dirp && readdir(dirp)) |
| file_count++; |
| if (dirp) |
| closedir(dirp); |
| |
| if (file_count >= tr2env_max_files) { |
| dst->too_many_files = 1; |
| dst->fd = open(sentinel_path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666); |
| ret = -1; |
| goto cleanup; |
| } |
| |
| cleanup: |
| strbuf_release(&path); |
| strbuf_release(&sentinel_path); |
| return ret; |
| } |
| |
| static int tr2_dst_try_auto_path(struct tr2_dst *dst, const char *tgt_prefix) |
| { |
| int too_many_files; |
| const char *last_slash, *sid = tr2_sid_get(); |
| struct strbuf path = STRBUF_INIT; |
| size_t base_path_len; |
| unsigned attempt_count; |
| |
| last_slash = strrchr(sid, '/'); |
| if (last_slash) |
| sid = last_slash + 1; |
| |
| strbuf_addstr(&path, tgt_prefix); |
| if (!is_dir_sep(path.buf[path.len - 1])) |
| strbuf_addch(&path, '/'); |
| strbuf_addstr(&path, sid); |
| base_path_len = path.len; |
| |
| too_many_files = tr2_dst_too_many_files(dst, tgt_prefix); |
| if (!too_many_files) { |
| for (attempt_count = 0; attempt_count < MAX_AUTO_ATTEMPTS; attempt_count++) { |
| if (attempt_count > 0) { |
| strbuf_setlen(&path, base_path_len); |
| strbuf_addf(&path, ".%d", attempt_count); |
| } |
| |
| dst->fd = open(path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666); |
| if (dst->fd != -1) |
| break; |
| } |
| } else if (too_many_files == 1) { |
| strbuf_release(&path); |
| if (tr2_dst_want_warning()) |
| warning("trace2: not opening %s trace file due to too " |
| "many files in target directory %s", |
| tr2_sysenv_display_name(dst->sysenv_var), |
| tgt_prefix); |
| return 0; |
| } |
| |
| if (dst->fd == -1) { |
| if (tr2_dst_want_warning()) |
| warning("trace2: could not open '%.*s' for '%s' tracing: %s", |
| (int) base_path_len, path.buf, |
| tr2_sysenv_display_name(dst->sysenv_var), |
| strerror(errno)); |
| |
| tr2_dst_trace_disable(dst); |
| strbuf_release(&path); |
| return 0; |
| } |
| |
| strbuf_release(&path); |
| |
| dst->need_close = 1; |
| dst->initialized = 1; |
| |
| return dst->fd; |
| } |
| |
| static int tr2_dst_try_path(struct tr2_dst *dst, const char *tgt_value) |
| { |
| int fd = open(tgt_value, O_WRONLY | O_APPEND | O_CREAT, 0666); |
| if (fd == -1) { |
| if (tr2_dst_want_warning()) |
| warning("trace2: could not open '%s' for '%s' tracing: %s", |
| tgt_value, |
| tr2_sysenv_display_name(dst->sysenv_var), |
| strerror(errno)); |
| |
| tr2_dst_trace_disable(dst); |
| return 0; |
| } |
| |
| dst->fd = fd; |
| dst->need_close = 1; |
| dst->initialized = 1; |
| |
| return dst->fd; |
| } |
| |
| #ifndef NO_UNIX_SOCKETS |
| #define PREFIX_AF_UNIX "af_unix:" |
| #define PREFIX_AF_UNIX_STREAM "af_unix:stream:" |
| #define PREFIX_AF_UNIX_DGRAM "af_unix:dgram:" |
| |
| static int tr2_dst_try_uds_connect(const char *path, int sock_type, int *out_fd) |
| { |
| int fd; |
| struct sockaddr_un sa; |
| |
| fd = socket(AF_UNIX, sock_type, 0); |
| if (fd == -1) |
| return errno; |
| |
| sa.sun_family = AF_UNIX; |
| strlcpy(sa.sun_path, path, sizeof(sa.sun_path)); |
| |
| if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) { |
| int e = errno; |
| close(fd); |
| return e; |
| } |
| |
| *out_fd = fd; |
| return 0; |
| } |
| |
| #define TR2_DST_UDS_TRY_STREAM (1 << 0) |
| #define TR2_DST_UDS_TRY_DGRAM (1 << 1) |
| |
| static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst, |
| const char *tgt_value) |
| { |
| unsigned int uds_try = 0; |
| int fd; |
| int e; |
| const char *path = NULL; |
| |
| /* |
| * Allow "af_unix:[<type>:]<absolute_path>" |
| * |
| * Trace2 always writes complete individual messages (without |
| * chunking), so we can talk to either DGRAM or STREAM type sockets. |
| * |
| * Allow the user to explicitly request the socket type. |
| * |
| * If they omit the socket type, try one and then the other. |
| */ |
| |
| if (skip_prefix(tgt_value, PREFIX_AF_UNIX_STREAM, &path)) |
| uds_try |= TR2_DST_UDS_TRY_STREAM; |
| |
| else if (skip_prefix(tgt_value, PREFIX_AF_UNIX_DGRAM, &path)) |
| uds_try |= TR2_DST_UDS_TRY_DGRAM; |
| |
| else if (skip_prefix(tgt_value, PREFIX_AF_UNIX, &path)) |
| uds_try |= TR2_DST_UDS_TRY_STREAM | TR2_DST_UDS_TRY_DGRAM; |
| |
| if (!path || !*path) { |
| if (tr2_dst_want_warning()) |
| warning("trace2: invalid AF_UNIX value '%s' for '%s' tracing", |
| tgt_value, |
| tr2_sysenv_display_name(dst->sysenv_var)); |
| |
| tr2_dst_trace_disable(dst); |
| return 0; |
| } |
| |
| if (!is_absolute_path(path) || |
| strlen(path) >= sizeof(((struct sockaddr_un *)0)->sun_path)) { |
| if (tr2_dst_want_warning()) |
| warning("trace2: invalid AF_UNIX path '%s' for '%s' tracing", |
| path, tr2_sysenv_display_name(dst->sysenv_var)); |
| |
| tr2_dst_trace_disable(dst); |
| return 0; |
| } |
| |
| if (uds_try & TR2_DST_UDS_TRY_STREAM) { |
| e = tr2_dst_try_uds_connect(path, SOCK_STREAM, &fd); |
| if (!e) |
| goto connected; |
| if (e != EPROTOTYPE) |
| goto error; |
| } |
| if (uds_try & TR2_DST_UDS_TRY_DGRAM) { |
| e = tr2_dst_try_uds_connect(path, SOCK_DGRAM, &fd); |
| if (!e) |
| goto connected; |
| } |
| |
| error: |
| if (tr2_dst_want_warning()) |
| warning("trace2: could not connect to socket '%s' for '%s' tracing: %s", |
| path, tr2_sysenv_display_name(dst->sysenv_var), |
| strerror(e)); |
| |
| tr2_dst_trace_disable(dst); |
| return 0; |
| |
| connected: |
| dst->fd = fd; |
| dst->need_close = 1; |
| dst->initialized = 1; |
| |
| return dst->fd; |
| } |
| #endif |
| |
| static void tr2_dst_malformed_warning(struct tr2_dst *dst, |
| const char *tgt_value) |
| { |
| warning("trace2: unknown value for '%s': '%s'", |
| tr2_sysenv_display_name(dst->sysenv_var), tgt_value); |
| } |
| |
| int tr2_dst_get_trace_fd(struct tr2_dst *dst) |
| { |
| const char *tgt_value; |
| |
| /* don't open twice */ |
| if (dst->initialized) |
| return dst->fd; |
| |
| dst->initialized = 1; |
| |
| tgt_value = tr2_sysenv_get(dst->sysenv_var); |
| |
| if (!tgt_value || !strcmp(tgt_value, "") || !strcmp(tgt_value, "0") || |
| !strcasecmp(tgt_value, "false")) { |
| dst->fd = 0; |
| return dst->fd; |
| } |
| |
| if (!strcmp(tgt_value, "1") || !strcasecmp(tgt_value, "true")) { |
| dst->fd = STDERR_FILENO; |
| return dst->fd; |
| } |
| |
| if (strlen(tgt_value) == 1 && isdigit(*tgt_value)) { |
| dst->fd = atoi(tgt_value); |
| return dst->fd; |
| } |
| |
| if (is_absolute_path(tgt_value)) { |
| if (is_directory(tgt_value)) |
| return tr2_dst_try_auto_path(dst, tgt_value); |
| else |
| return tr2_dst_try_path(dst, tgt_value); |
| } |
| |
| #ifndef NO_UNIX_SOCKETS |
| if (starts_with(tgt_value, PREFIX_AF_UNIX)) |
| return tr2_dst_try_unix_domain_socket(dst, tgt_value); |
| #endif |
| |
| /* Always warn about malformed values. */ |
| tr2_dst_malformed_warning(dst, tgt_value); |
| tr2_dst_trace_disable(dst); |
| return 0; |
| } |
| |
| int tr2_dst_trace_want(struct tr2_dst *dst) |
| { |
| return !!tr2_dst_get_trace_fd(dst); |
| } |
| |
| void tr2_dst_write_line(struct tr2_dst *dst, struct strbuf *buf_line) |
| { |
| int fd = tr2_dst_get_trace_fd(dst); |
| |
| strbuf_complete_line(buf_line); /* ensure final NL on buffer */ |
| |
| /* |
| * We do not use write_in_full() because we do not want |
| * a short-write to try again. We are using O_APPEND mode |
| * files and the kernel handles the atomic seek+write. If |
| * another thread or git process is concurrently writing to |
| * this fd or file, our remainder-write may not be contiguous |
| * with our initial write of this message. And that will |
| * confuse readers. So just don't bother. |
| * |
| * It is assumed that TRACE2 messages are short enough that |
| * the system can write them in 1 attempt and we won't see |
| * a short-write. |
| * |
| * If we get an IO error, just close the trace dst. |
| */ |
| if (write(fd, buf_line->buf, buf_line->len) >= 0) |
| return; |
| |
| if (tr2_dst_want_warning()) |
| warning("unable to write trace to '%s': %s", |
| tr2_sysenv_display_name(dst->sysenv_var), |
| strerror(errno)); |
| tr2_dst_trace_disable(dst); |
| } |