15beaaa3d1
Reported-by: Jens Schleusener <Jens.Schleusener@fossies.org> Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
#include "cache.h"
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#include "trace2/tr2_tbuf.h"
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#include "trace2/tr2_sid.h"
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#define TR2_ENVVAR_PARENT_SID "GIT_TRACE2_PARENT_SID"
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static struct strbuf tr2sid_buf = STRBUF_INIT;
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static int tr2sid_nr_git_parents;
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/*
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* Compute the final component of the SID representing the current process.
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* This should uniquely identify the process and be a valid filename (to
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* allow writing trace2 data to per-process files). It should also be fixed
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* length for possible use as a database key.
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*
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* "<yyyymmdd>T<hhmmss>.<fraction>Z-<host>-<process>"
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*
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* where <host> is a 9 character string:
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* "H<first_8_chars_of_sha1_of_hostname>"
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* "Localhost" when no hostname.
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*
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* where <process> is a 9 character string containing the least significant
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* 32 bits in the process-id.
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* "P<pid>"
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* (This is an abribrary choice. On most systems pid_t is a 32 bit value,
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* so limit doesn't matter. On larger systems, a truncated value is fine
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* for our purposes here.)
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*/
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static void tr2_sid_append_my_sid_component(void)
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{
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const struct git_hash_algo *algo = &hash_algos[GIT_HASH_SHA1];
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struct tr2_tbuf tb_now;
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git_hash_ctx ctx;
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pid_t pid = getpid();
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unsigned char hash[GIT_MAX_RAWSZ + 1];
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char hex[GIT_MAX_HEXSZ + 1];
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char hostname[HOST_NAME_MAX + 1];
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tr2_tbuf_utc_datetime(&tb_now);
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strbuf_addstr(&tr2sid_buf, tb_now.buf);
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strbuf_addch(&tr2sid_buf, '-');
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if (xgethostname(hostname, sizeof(hostname)))
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strbuf_add(&tr2sid_buf, "Localhost", 9);
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else {
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algo->init_fn(&ctx);
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algo->update_fn(&ctx, hostname, strlen(hostname));
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algo->final_fn(hash, &ctx);
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hash_to_hex_algop_r(hex, hash, algo);
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strbuf_addch(&tr2sid_buf, 'H');
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strbuf_add(&tr2sid_buf, hex, 8);
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}
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strbuf_addf(&tr2sid_buf, "-P%08"PRIx32, (uint32_t)pid);
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}
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/*
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* Compute a "unique" session id (SID) for the current process. This allows
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* all events from this process to have a single label (much like a PID).
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*
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* Export this into our environment so that all child processes inherit it.
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*
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* If we were started by another git instance, use our parent's SID as a
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* prefix. (This lets us track parent/child relationships even if there
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* is an intermediate shell process.)
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*
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* Additionally, count the number of nested git processes.
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*/
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static void tr2_sid_compute(void)
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{
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const char *parent_sid;
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if (tr2sid_buf.len)
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return;
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parent_sid = getenv(TR2_ENVVAR_PARENT_SID);
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if (parent_sid && *parent_sid) {
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const char *p;
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for (p = parent_sid; *p; p++)
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if (*p == '/')
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tr2sid_nr_git_parents++;
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strbuf_addstr(&tr2sid_buf, parent_sid);
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strbuf_addch(&tr2sid_buf, '/');
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tr2sid_nr_git_parents++;
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}
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tr2_sid_append_my_sid_component();
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setenv(TR2_ENVVAR_PARENT_SID, tr2sid_buf.buf, 1);
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}
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const char *tr2_sid_get(void)
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{
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if (!tr2sid_buf.len)
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tr2_sid_compute();
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return tr2sid_buf.buf;
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}
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int tr2_sid_depth(void)
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{
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if (!tr2sid_buf.len)
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tr2_sid_compute();
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return tr2sid_nr_git_parents;
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}
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void tr2_sid_release(void)
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{
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strbuf_release(&tr2sid_buf);
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}
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