properly daemonize, also smaller fixes

diff --git a/fag.c b/fag.c
index 107d67f9e90b94f39b18fe5ad66e8ba020f3810b..3ab2e9980568b5039dc6873b89c849a7f8e4db27 100644 (file)
--- a/fag.c
+++ b/fag.c
@@ -1,7 +1,7 @@
 /* forkaftergrep (C) 2017 Tobias Girstmair, GPLv3 */
 //TODO: if grep exits with an error, fag thinks a match was found (e.g. grep -BEP, killall grep)
-//TODO: allow redirect of both streams to files
-//TODO: grep is missing `-e' and `-f' options
+//TODO: allow redirect of both streams to files (have to simulate `tee(1)' in the pipe-passer and the dummy-proc; instead of closing nontracked fd redirect to logfile/devnull)
+//TODO: grep is missing `-e' and `-f' options; fag's `-e' collides with grep's
 
 #define _XOPEN_SOURCE 500
 #define _DEFAULT_SOURCE
@@ -12,6 +12,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sysexits.h>
+#include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/wait.h>
 #include <unistd.h>
@@ -20,13 +21,12 @@
 pid_t cpid = 0;
 
 void term_child(int s) {
-       (void)s; /* squash -Werror=unused-parameter */
-       if (cpid != 0) kill (cpid, SIGTERM);
+       if (cpid != 0) kill (cpid, s);
        exit(1);
 }
 
 int main (int argc, char** argv) {
-       struct opt opts = {0, 0, 0, NULL, NULL, STDOUT_FILENO, "-q"};
+       struct opt opts = {0, 0, 0, NULL, NULL, "/dev/null", "/dev/null", STDOUT_FILENO, "-q"};
        /* `-q': don't print anything; exit with 0 on match; with 1 on error. used to interface with `grep' */
        int opt;
        opterr = 0;
@@ -42,7 +42,7 @@ int main (int argc, char** argv) {
 
 
        /* the `+' forces getopt to stop at the first non-option */
-       while ((opt = getopt (argc, argv, "+t:k::er:VhvEFGPiwxyU")) != -1) {
+       while ((opt = getopt (argc, argv, "+t:k::el:L:VhvEFGPiwxyU")) != -1) {
                switch (opt) {
                case 't':
                        opts.timeout = atoi (optarg);
@@ -53,6 +53,12 @@ int main (int argc, char** argv) {
                case 'e':
                        opts.stream = STDERR_FILENO;
                        break;
+               case 'l':
+                       opts.logout = optarg;
+                       break;
+               case 'L':
+                       opts.logerr = optarg;
+                       break;
                case 'V':
                        opts.verbose = 1;
                        break;
@@ -60,8 +66,10 @@ int main (int argc, char** argv) {
                        fprintf (stderr, VERTEXT USAGE
                                "Options:\n"
                                "\t-t N\ttimeout after N seconds\n"
-                               "\t-k[M]\tsend signal M to child after timeout (default: 15/SIGTERM)\n"
+                               "\t-k[N]\tsend signal N to child after timeout (default: 15/SIGTERM)\n"
                                "\t-e\tgrep on stderr instead of stdout\n"
+                               "\t-l FILE\tlog PROGRAM's standard output to FILE\n"
+                               "\t-L FILE\tlog PROGRAM's standard error to FILE\n"
                                "\t-V\tbe verbose; print PROGRAM's stdout/stderr to stderr\n"
                                "\t-[EFP]\tgrep: matcher selection\n"
                                "\t-[iwxU]\tgrep: matching control\n", argv[0]);
@@ -104,7 +112,8 @@ int main (int argc, char** argv) {
 
 int fork_after_grep (struct opt opts) {
        int pipefd[2];
-       //pid_t cpid;
+       int pipefd_cpid[2]; /* IPC to extract PID from daemonized userprog */
+       pid_t tmp_cpid;
        int status;
 
        char buf[BUF_SIZE];
@@ -117,14 +126,25 @@ int fork_after_grep (struct opt opts) {
                return EX_OSERR;
        }
 
-       if ((cpid = fork()) == -1) {
-               fprintf (stderr, "fork error (userprog): %s", strerror (errno));
+       if(pipe(pipefd_cpid) == -1) {
+               fprintf (stderr, "pipe error (cpid-ipc)\n");
+               close (pipefd[0]);
+               close (pipefd[1]);
+               return EX_OSERR;
+       }
+
+       if ((tmp_cpid = fork()) == -1) {
+               fprintf (stderr, "fork error (daemonizer): %s", strerror (errno));
                close (pipefd[0]);
                close (pipefd[1]);
+               close (pipefd_cpid[0]);
+               close (pipefd_cpid[1]);
                return EX_OSERR;
        }
 
-       if (cpid == 0) {
+       if (tmp_cpid == 0) {
+               pid_t cpid_userprog;
+
                close (pipefd[0]);
                dup2 (pipefd[1], opts.stream);
                close (pipefd[1]);
@@ -132,18 +152,37 @@ int fork_after_grep (struct opt opts) {
                close (opts.stream==STDOUT_FILENO?STDERR_FILENO:STDOUT_FILENO);
 
                if (setsid () == -1) {
-                       fprintf (stderr, "setsid error (userprog): %s", strerror (errno));
+                       fprintf (stderr, "setsid error (daemonizer): %s", strerror (errno));
+                       _exit (EX_OSERR);
+               }
+
+               if ((cpid_userprog = fork()) == -1) {
+                       fprintf (stderr, "fork error (userprog): %s", strerror (errno));
                        _exit (EX_OSERR);
                }
+               if (cpid_userprog == 0) {
+                       close(pipefd_cpid[0]);
+                       close(pipefd_cpid[1]);
 
-               execvp (opts.argv[0], opts.argv);
-               fprintf (stderr, "exec error (userprog): %s", strerror (errno));
+                       execvp (opts.argv[0], opts.argv);
+                       fprintf (stderr, "exec error (userprog): %s", strerror (errno));
+               } else {
+                       /* only way to get final child's pid to main is through IPC */
+                       write(pipefd_cpid[1], &cpid_userprog, sizeof(pid_t));
+                       close(pipefd_cpid[0]);
+                       close(pipefd_cpid[1]);
+               }
                _exit (EX_UNAVAILABLE);
        } else {
                pid_t grep_cpid;
                int grep_pipefd[2];
                int grep_status;
 
+               /* read userprog's PID from IPC: */
+               read(pipefd_cpid[0], &cpid, sizeof(pid_t));
+               close(pipefd_cpid[0]);
+               close(pipefd_cpid[1]);
+
                close (pipefd[1]);
                fcntl (pipefd[0], F_SETFL, fcntl (pipefd[0], F_GETFL, 0) | O_NONBLOCK);
 
@@ -213,16 +252,18 @@ int fork_after_grep (struct opt opts) {
                                        if (WEXITSTATUS(grep_status) == 0) {
                                                /* grep exited with match found */
                                                printf ("%d\n", cpid);
+                                               fflush (stdout);
 
-                                               /* create a new child to keep pipe alive (will exit with exec'd program) */
-                                               if (!fork ()) {
+                                               /* create a new child to keep pipe alive, empty it and write log files (will exit with exec'd program) */
+                                               if (!fork()){setsid();if(!fork()) {
+                                                       close(0); close(1); close(2); umask(0); chdir("/");
                                                        int devnull = open("/dev/null", O_WRONLY);
                                                        dup2 (devnull, pipefd[0]);
                                                        close  (devnull);
                                                        while (kill(cpid, 0) != -1 && errno != ESRCH ) sleep (1);
                                                        close (pipefd[0]);
                                                        _exit(0);
-                                               }
+                                               }}
                                                close (pipefd[0]);
                                                return EX_OK;
                                        } else {

diff --git a/fag.h b/fag.h
index 5d765bcecbdb5b90f8d1fb911d71a62295014f12..25c0a41f6a022ca8e199dacb85cb1bc9b6b4ed13 100644 (file)
--- a/fag.h
+++ b/fag.h
@@ -2,9 +2,9 @@
 #define __FAG_H__
 
 #define PROGRNAME "fag"
-#define VERSION "1.1"
+#define VERSION "1.2"
 #define AUTHOR "Tobias Girstmair"
-#define YEAR "2017"
+#define YEAR "2018"
 #define LICENSE "GNU GPLv3"
 
 #define BUF_SIZE 4096
@@ -18,6 +18,8 @@ struct opt {
        int verbose;
        char* pattern;
        char** argv;
+       char* logout;
+       char* logerr;
        int stream;
        char grepopt[16];
 };