* [PATCH 2/2] spawn: better error handling
2019-12-30 5:04 6% [PATCH 0/2] more spawn improvements Eric Wong
@ 2019-12-30 5:04 7% ` Eric Wong
0 siblings, 0 replies; 2+ results
From: Eric Wong @ 2019-12-30 5:04 UTC (permalink / raw)
To: meta
Since vfork always shares memory between the child and parent,
we can propagate errors to the parent errno using shared memory
instead of just dumping to stderr and hoping somebody sees it.
---
lib/PublicInbox/Spawn.pm | 42 +++++++++++++++-------------------------
1 file changed, 16 insertions(+), 26 deletions(-)
diff --git a/lib/PublicInbox/Spawn.pm b/lib/PublicInbox/Spawn.pm
index d624c521..6eea2b9c 100644
--- a/lib/PublicInbox/Spawn.pm
+++ b/lib/PublicInbox/Spawn.pm
@@ -56,26 +56,10 @@ my $vfork_spawn = <<'VFORK_SPAWN';
dst[real_len] = 0; \
} while (0)
-static void *deconst(const char *s)
-{
- union { const char *in; void *out; } u;
- u.in = s;
- return u.out;
-}
-
/* needs to be safe inside a vfork'ed process */
-static void xerr(const char *msg)
+static void exit_err(int *cerrnum)
{
- struct iovec iov[3];
- const char *err = strerror(errno); /* should be safe in practice */
-
- iov[0].iov_base = deconst(msg);
- iov[0].iov_len = strlen(msg);
- iov[1].iov_base = deconst(err);
- iov[1].iov_len = strlen(err);
- iov[2].iov_base = deconst("\n");
- iov[2].iov_len = 1;
- writev(2, iov, 3);
+ *cerrnum = errno;
_exit(1);
}
@@ -95,7 +79,7 @@ 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, errnum;
+ int ret, perrnum, cerrnum = 0;
AV2C_COPY(argv, cmd);
AV2C_COPY(envp, env);
@@ -115,12 +99,12 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
if (parent_fd == child_fd)
continue;
if (dup2(parent_fd, child_fd) < 0)
- xerr("dup2");
+ exit_err(&cerrnum);
}
for (sig = 1; sig < NSIG; sig++)
signal(sig, SIG_DFL); /* ignore errors on signals */
if (*cd && chdir(cd) < 0)
- xerr("chdir");
+ exit_err(&cerrnum);
max = av_len(rlim);
for (i = 0; i < max; i += 3) {
@@ -132,7 +116,7 @@ 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)
- xerr("sertlimit");
+ exit_err(&cerrnum);
}
/*
@@ -140,13 +124,19 @@ int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
* to the group taking out a subprocess
*/
execve(filename, argv, envp);
- xerr("execve failed");
+ exit_err(&cerrnum);
}
- errnum = errno;
+ perrnum = errno;
ret = sigprocmask(SIG_SETMASK, &old, NULL);
assert(ret == 0 && "BUG calling sigprocmask to restore");
- errno = errnum;
-
+ if (cerrnum) {
+ if (pid > 0)
+ waitpid(pid, NULL, 0);
+ pid = -1;
+ errno = cerrnum;
+ } else if (perrnum) {
+ errno = perrnum;
+ }
return (int)pid;
}
VFORK_SPAWN
^ permalink raw reply related [relevance 7%]
* [PATCH 0/2] more spawn improvements
@ 2019-12-30 5:04 6% Eric Wong
2019-12-30 5:04 7% ` [PATCH 2/2] spawn: better error handling Eric Wong
0 siblings, 1 reply; 2+ results
From: Eric Wong @ 2019-12-30 5:04 UTC (permalink / raw)
To: meta
Less code overall and improved git compatibility. Maybe one day
posix_spawn(3) can get rlimit support and we can just use that:
http://austingroupbugs.net/view.php?id=603
Eric Wong (2):
spawn: support chdir via -C option
spawn: better error handling
lib/PublicInbox/Admin.pm | 31 +++++++----------------
lib/PublicInbox/SolverGit.pm | 6 ++---
lib/PublicInbox/Spawn.pm | 48 ++++++++++++++++--------------------
lib/PublicInbox/SpawnPP.pm | 7 ++++--
4 files changed, 38 insertions(+), 54 deletions(-)
^ permalink raw reply [relevance 6%]
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