chore(win): enrich logs

We add more details to the logs generated by Austin on Windows to
include a timestamp and process information. This allows us to collect
the data in tests for helping with investigations.

src/logging.c

@@ -35,7 +35,7 @@
 
 #else
 #include <windows.h>
-#include <stdio.h>
+#include <time.h>
 
 #define LOG_EMERG   0  /* system is unusable */
 #define LOG_ALERT   1  /* action must be taken immediately */
@@ -61,14 +61,31 @@ _log_writer(int prio, const char * fmt, va_list ap) {
   vsyslog(prio, fmt, ap);
 
   #else
-  if (logfile == NULL) {
-    vfprintf(stderr, fmt, ap); fputc('\n', stderr);
-    fflush(stderr);
-  }
-  else {
-    vfprintf(logfile, fmt, ap); fputc('\n', logfile);
-    fflush(logfile);
-  }
+  time_t timer;
+  char buffer[32];
+  struct tm* tm_info;
+
+  timer = time(NULL);
+  tm_info = localtime(&timer);
+
+  strftime(buffer, 26, "%Y-%m-%d %H:%M:%S", tm_info);
+
+  FILE * stream = isvalid(logfile) ? logfile : stderr;
+
+  // Timestamp
+  fputs(buffer, stream);
+
+  // Process info
+  fprintf(stream, " " PROGRAM_NAME "[%d]: ", GetCurrentProcessId());
+
+  // Log message
+  vfprintf(stream, fmt, ap);
+
+  // Newline
+  fputc('\n', stream);
+
+  // Flush
+  fflush(stream);
 
   #endif
 }

test/utils.py

@@ -36,6 +36,7 @@
 from subprocess import Popen
 from subprocess import TimeoutExpired
 from subprocess import check_output
+from tempfile import gettempdir
 from test import PYTHON_VERSIONS
 from time import sleep
 from types import ModuleType
@@ -149,6 +150,20 @@ def collect_logs(variant: str, pid: int) -> List[str]:
                     ),
                     f" end of logs for {variant}[{pid}] ".center(80, "="),
                 ]
+
+        case "Windows":
+            with Path(gettempdir()) / "austin.log" as logfile:
+                needles = (f"{variant}[{pid}]",)
+                return [
+                    f" logs for {variant}[{pid}] ".center(80, "="),
+                    *(
+                        line.strip()
+                        for line in logfile.readlines()
+                        if any(needle in line for needle in needles)
+                    ),
+                    f" end of logs for {variant}[{pid}] ".center(80, "="),
+                ]
+
         case _:
             return []