ftcat: add -p (ping) option

Ask ftcat to store its PID when it is done with initialization.

1 files changed, 17 insertions, 1 deletions

diff --git a/src/ftcat.c b/src/ftcat.c
index 483bc6e..548498d 100644
--- a/src/ftcat.c
+++ b/src/ftcat.c
@@ -112,6 +112,14 @@ static void cat2stdout(int fd)
         }
 }
 
+static void ping(const char* fname)
+{
+        FILE* f = fopen(fname, "a");
+        if (f) {
+                fprintf(f, "%d\n", getpid());
+                fclose(f);
+        }
+}
 
 static void _usage(void)
 {
@@ -120,6 +128,7 @@ static void _usage(void)
                 "\nOptions:\n"
                 "   -s SIZE   --  stop tracing afer recording SIZE bytes\n"
                 "   -c        --  calibrate the CPU cycle counter offsets\n"
+                "   -p FILE   --  ping: write PID to FILE after initialization\n"
                 "   -v        --  enable verbose output\n"
                 "\n");
         exit(1);
@@ -135,7 +144,7 @@ static void shutdown(int sig)
                 fprintf(stderr, "disable_all: %m\n");
 }
 
-#define OPTSTR "s:cv"
+#define OPTSTR "s:cvp:"
 
 int main(int argc, char** argv)
 {
@@ -143,6 +152,7 @@ int main(int argc, char** argv)
         int want_calibrate = 0;
 
         const char* trace_file;
+        const char* ping_file = NULL;
 
         while ((opt = getopt(argc, argv, OPTSTR)) != -1) {
                 switch (opt) {
@@ -157,6 +167,9 @@ int main(int argc, char** argv)
                 case 'v':
                         verbose = 1;
                         break;
+                case 'p':
+                        ping_file = optarg;
+                        break;
                 case ':':
                         usage("Argument missing.");
                         break;
@@ -198,6 +211,9 @@ int main(int argc, char** argv)
                 argv++;
         }
 
+        if (ping_file)
+                ping(ping_file);
+
         cat2stdout(fd);
         close(fd);
         fflush(stdout);