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