spawn: pi_fork_exec: support "pgid"

[public-inbox.git] / lib / PublicInbox / Spawn.pm

diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index bac24dd1a7c883dd2f4ba94161ce25b884c2acd9..00e6829e9483918c92bccefef153c1477c084b2f 100644 (file)
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -61,9 +61,10 @@ my $all_libc = <<'ALL_LIBC'; # all *nix systems we support
 } while (0)
 
 /* needs to be safe inside a vfork'ed process */
-static void exit_err(int *cerrnum)
+static void exit_err(const char *fn, volatile int *cerrnum)
 {
        *cerrnum = errno;
+       write(2, fn, strlen(fn));
        _exit(1);
 }
 
@@ -73,7 +74,7 @@ static void exit_err(int *cerrnum)
  * Be sure to update PublicInbox::SpawnPP if this changes
  */
 int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
-                const char *cd)
+                const char *cd, int pgid)
 {
        AV *redir = (AV *)SvRV(redirref);
        AV *cmd = (AV *)SvRV(cmdref);
@@ -83,8 +84,10 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
        pid_t pid;
        char **argv, **envp;
        sigset_t set, old;
-       int ret, perrnum, cerrnum = 0;
+       int ret, perrnum;
+       volatile int cerrnum = 0; /* shared due to vfork */
        int chld_is_member;
+       I32 max_fd = av_len(redir);
 
        AV2C_COPY(argv, cmd);
        AV2C_COPY(envp, env);
@@ -99,23 +102,25 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
        pid = vfork();
        if (pid == 0) {
                int sig;
-               I32 i, child_fd, max = av_len(redir);
+               I32 i, child_fd, max_rlim;
 
-               for (child_fd = 0; child_fd <= max; child_fd++) {
+               for (child_fd = 0; child_fd <= max_fd; child_fd++) {
                        SV **parent = av_fetch(redir, child_fd, 0);
                        int parent_fd = SvIV(*parent);
                        if (parent_fd == child_fd)
                                continue;
                        if (dup2(parent_fd, child_fd) < 0)
-                               exit_err(&cerrnum);
+                               exit_err("dup2", &cerrnum);
                }
+               if (pgid >= 0 && setpgid(0, pgid) < 0)
+                       exit_err("setpgid", &cerrnum);
                for (sig = 1; sig < NSIG; sig++)
                        signal(sig, SIG_DFL); /* ignore errors on signals */
                if (*cd && chdir(cd) < 0)
-                       exit_err(&cerrnum);
+                       exit_err("chdir", &cerrnum);
 
-               max = av_len(rlim);
-               for (i = 0; i < max; i += 3) {
+               max_rlim = av_len(rlim);
+               for (i = 0; i < max_rlim; i += 3) {
                        struct rlimit rl;
                        SV **res = av_fetch(rlim, i, 0);
                        SV **soft = av_fetch(rlim, i + 1, 0);
@@ -124,12 +129,12 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
                        rl.rlim_cur = SvIV(*soft);
                        rl.rlim_max = SvIV(*hard);
                        if (setrlimit(SvIV(*res), &rl) < 0)
-                               exit_err(&cerrnum);
+                               exit_err("setrlimit", &cerrnum);
                }
 
                (void)sigprocmask(SIG_SETMASK, &old, NULL);
                execve(filename, argv, envp);
-               exit_err(&cerrnum);
+               exit_err("execve", &cerrnum);
        }
        perrnum = errno;
        if (chld_is_member > 0)
@@ -137,9 +142,16 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
        ret = sigprocmask(SIG_SETMASK, &old, NULL);
        assert(ret == 0 && "BUG calling sigprocmask to restore");
        if (cerrnum) {
+               int err_fd = STDERR_FILENO;
+               if (err_fd <= max_fd) {
+                       SV **parent = av_fetch(redir, err_fd, 0);
+                       err_fd = SvIV(*parent);
+               }
                if (pid > 0)
                        waitpid(pid, NULL, 0);
                pid = -1;
+               /* continue message started by exit_err in child */
+               dprintf(err_fd, ": %s\n", strerror(cerrnum));
                errno = cerrnum;
        } else if (perrnum) {
                errno = perrnum;
@@ -373,7 +385,8 @@ sub spawn ($;$$) {
                push @$rlim, $r, @$v;
        }
        my $cd = $opts->{'-C'} // ''; # undef => NULL mapping doesn't work?
-       my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd);
+       my $pgid = $opts->{pgid} // -1;
+       my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd, $pgid);
        die "fork_exec @$cmd failed: $!\n" unless $pid > 0;
        $pid;
 }