[PATCH 3/4] trace2: refactor Windows process ancestry trace2 event
From: Matthew John Cheetham via GitGitGadget <hidden>
Date: 2026-02-05 16:05:18
Subsystem:
the rest · Maintainer:
Linus Torvalds
From: Matthew John Cheetham <redacted> In 353d3d77 (trace2: collect Windows-specific process information) we added process ancestry information for Windows to TRACE2 via a data_json event. It was only later in 2f732bf1 (tr2: log parent process name) that the specific cmd_ancestry event was added to TRACE2. In a future commit we will emit the ancestry information with the newer cmd_ancestry TRACE2 event. Right now, we rework this implementation of trace2_collect_process_info to separate the calculation of ancestors from building and emiting the JSON array via a data_json event. Signed-off-by: Matthew John Cheetham <redacted> --- compat/win32/trace2_win32_process_info.c | 50 ++++++++++++------------ 1 file changed, 25 insertions(+), 25 deletions(-)
diff --git a/compat/win32/trace2_win32_process_info.c b/compat/win32/trace2_win32_process_info.c
index f147da706a..aceea05430 100644
--- a/compat/win32/trace2_win32_process_info.c
+++ b/compat/win32/trace2_win32_process_info.c@@ -3,6 +3,7 @@ #include "../../git-compat-util.h" #include "../../json-writer.h" #include "../../repository.h" +#include "../../strvec.h" #include "../../trace2.h" #include "lazyload.h" #include <psapi.h>
@@ -32,12 +33,7 @@ static int find_pid(DWORD pid, HANDLE hSnapshot, PROCESSENTRY32 *pe32) } /* - * Accumulate JSON array of our parent processes: - * [ - * exe-name-parent, - * exe-name-grand-parent, - * ... - * ] + * Accumulate array of our parent process names. * * Note: we only report the filename of the process executable; the * only way to get its full pathname is to use OpenProcess()
@@ -73,7 +69,7 @@ static int find_pid(DWORD pid, HANDLE hSnapshot, PROCESSENTRY32 *pe32) * simple and avoid the alloc/realloc overhead. It is OK if we * truncate the search and return a partial answer. */ -static void get_processes(struct json_writer *jw, HANDLE hSnapshot) +static void get_processes(struct strvec *names, HANDLE hSnapshot) { PROCESSENTRY32 pe32; DWORD pid;
@@ -82,19 +78,19 @@ static void get_processes(struct json_writer *jw, HANDLE hSnapshot) pid = GetCurrentProcessId(); while (find_pid(pid, hSnapshot, &pe32)) { - /* Only report parents. Omit self from the JSON output. */ + /* Only report parents. Omit self from the output. */ if (nr_pids) - jw_array_string(jw, pe32.szExeFile); + strvec_push(names, pe32.szExeFile); /* Check for cycle in snapshot. (Yes, it happened.) */ for (k = 0; k < nr_pids; k++) if (pid == pid_list[k]) { - jw_array_string(jw, "(cycle)"); + strvec_push(names, "(cycle)"); return; } if (nr_pids == NR_PIDS_LIMIT) { - jw_array_string(jw, "(truncated)"); + strvec_push(names, "(truncated)"); return; }
@@ -105,24 +101,14 @@ static void get_processes(struct json_writer *jw, HANDLE hSnapshot) } /* - * Emit JSON data for the current and parent processes. Individual - * trace2 targets can decide how to actually print it. + * Collect the list of parent process names. */ -static void get_ancestry(void) +static void get_ancestry(struct strvec *names) { HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0); if (hSnapshot != INVALID_HANDLE_VALUE) { - struct json_writer jw = JSON_WRITER_INIT; - - jw_array_begin(&jw, 0); - get_processes(&jw, hSnapshot); - jw_end(&jw); - - trace2_data_json("process", the_repository, "windows/ancestry", - &jw); - - jw_release(&jw); + get_processes(names, hSnapshot); CloseHandle(hSnapshot); } }
@@ -176,13 +162,27 @@ static void get_peak_memory_info(void) void trace2_collect_process_info(enum trace2_process_info_reason reason) { + struct strvec names = STRVEC_INIT; + if (!trace2_is_enabled()) return; switch (reason) { case TRACE2_PROCESS_INFO_STARTUP: get_is_being_debugged(); - get_ancestry(); + get_ancestry(&names); + if (names.nr) { + struct json_writer jw = JSON_WRITER_INIT; + jw_array_begin(&jw, 0); + for (size_t i = 0; i < names.nr; i++) + jw_array_string(&jw, names.v[i]); + jw_end(&jw); + trace2_data_json("process", the_repository, + "windows/ancestry", &jw); + jw_release(&jw); + } + + strvec_clear(&names); return; case TRACE2_PROCESS_INFO_EXIT:
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