From c8bae7493d2f2910b57f13ded012e86bdcfb0532 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 16:47:53 +0200 Subject: Adding upstream version 1:2.39.2. Signed-off-by: Daniel Baumann --- trace2/tr2_sid.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 112 insertions(+) create mode 100644 trace2/tr2_sid.c (limited to 'trace2/tr2_sid.c') diff --git a/trace2/tr2_sid.c b/trace2/tr2_sid.c new file mode 100644 index 0000000..dc6e75e --- /dev/null +++ b/trace2/tr2_sid.c @@ -0,0 +1,112 @@ +#include "cache.h" +#include "trace2/tr2_tbuf.h" +#include "trace2/tr2_sid.h" + +#define TR2_ENVVAR_PARENT_SID "GIT_TRACE2_PARENT_SID" + +static struct strbuf tr2sid_buf = STRBUF_INIT; +static int tr2sid_nr_git_parents; + +/* + * Compute the final component of the SID representing the current process. + * This should uniquely identify the process and be a valid filename (to + * allow writing trace2 data to per-process files). It should also be fixed + * length for possible use as a database key. + * + * "T.Z--" + * + * where is a 9 character string: + * "H" + * "Localhost" when no hostname. + * + * where is a 9 character string containing the least significant + * 32 bits in the process-id. + * "P" + * (This is an abribrary choice. On most systems pid_t is a 32 bit value, + * so limit doesn't matter. On larger systems, a truncated value is fine + * for our purposes here.) + */ +static void tr2_sid_append_my_sid_component(void) +{ + const struct git_hash_algo *algo = &hash_algos[GIT_HASH_SHA1]; + struct tr2_tbuf tb_now; + git_hash_ctx ctx; + pid_t pid = getpid(); + unsigned char hash[GIT_MAX_RAWSZ + 1]; + char hex[GIT_MAX_HEXSZ + 1]; + char hostname[HOST_NAME_MAX + 1]; + + tr2_tbuf_utc_datetime(&tb_now); + strbuf_addstr(&tr2sid_buf, tb_now.buf); + + strbuf_addch(&tr2sid_buf, '-'); + if (xgethostname(hostname, sizeof(hostname))) + strbuf_add(&tr2sid_buf, "Localhost", 9); + else { + algo->init_fn(&ctx); + algo->update_fn(&ctx, hostname, strlen(hostname)); + algo->final_fn(hash, &ctx); + hash_to_hex_algop_r(hex, hash, algo); + strbuf_addch(&tr2sid_buf, 'H'); + strbuf_add(&tr2sid_buf, hex, 8); + } + + strbuf_addf(&tr2sid_buf, "-P%08"PRIx32, (uint32_t)pid); +} + +/* + * Compute a "unique" session id (SID) for the current process. This allows + * all events from this process to have a single label (much like a PID). + * + * Export this into our environment so that all child processes inherit it. + * + * If we were started by another git instance, use our parent's SID as a + * prefix. (This lets us track parent/child relationships even if there + * is an intermediate shell process.) + * + * Additionally, count the number of nested git processes. + */ +static void tr2_sid_compute(void) +{ + const char *parent_sid; + + if (tr2sid_buf.len) + return; + + parent_sid = getenv(TR2_ENVVAR_PARENT_SID); + if (parent_sid && *parent_sid) { + const char *p; + for (p = parent_sid; *p; p++) + if (*p == '/') + tr2sid_nr_git_parents++; + + strbuf_addstr(&tr2sid_buf, parent_sid); + strbuf_addch(&tr2sid_buf, '/'); + tr2sid_nr_git_parents++; + } + + tr2_sid_append_my_sid_component(); + + setenv(TR2_ENVVAR_PARENT_SID, tr2sid_buf.buf, 1); +} + +const char *tr2_sid_get(void) +{ + if (!tr2sid_buf.len) + tr2_sid_compute(); + + return tr2sid_buf.buf; +} + +int tr2_sid_depth(void) +{ + if (!tr2sid_buf.len) + tr2_sid_compute(); + + return tr2sid_nr_git_parents; +} + +void tr2_sid_release(void) +{ + strbuf_release(&tr2sid_buf); +} -- cgit v1.2.3