* prefork-interp [<option>,..],<interpreter> <script> [<args> ...]
* prefork-interp '[<option> ..] <interpreter>' <script> [<args> ...]
*
- * Options must specify argument laundering mode.
- * Currently the only mode supported is:
+ * Options must specify argument mediation approach.
+ * Currently the only argument mediation supported is:
+ *
* -U unlaundered: setup and executor both get all arguments and env vars
* ident covers only env vars specified with -E
* ident covers only arguments interpreter and (if present) script
- */
-/*
- * Process structure:
- * client (C wrapper) connects to server
- * (including reading ack byte)
- * if fails or garbage
- * === acquire lock ===
- * makes new listening socket
- * makes first-instance socketpair
- * forks setup (script, sock fds indicated in env)
- * fd0, fd1, fd2: from-outer
- * other fd: call(client-end)(fake)
- * reaps setup (and reports error)
- * (implicitly releases lock)
- *
- * setup (pre-exec) fd0: null,
- * fd[12]: fd2-from-outer
- * env fds: listener, call(server-end)(fake)
- * close fd: lockfile
- * possibly clean env, argv
*
- * setup (script) runs initialisation parts of the script
- * at prefork establishment point:
- * setup (pm) [1] opens syslog
- * forks for server
- * [2] exits
+ * Options for setting the operation mode:
*
- * server (pm) [1] [fd0: null],
- * [fd[12]: fd2-from-outer]
- * right away, forks init monitor
- * [2] closes outer caller fds and call(fake)
- * [server (pm)] fd[012]: null
- * other fds: listener, syslog
- * runs in loop accepting and forking,
- * reaping and limiting children (incl init monitor)
- * reports failures of monitors to syslog
- *
- * [client (C wrapper)] if client connect succeeds:
- * now fd: call(client-end)
- * sends message with: cmdline, env
- * sends fds
+ * (none) Default: start new server if needed, then run service
+ * -f Force a fresh service (old one is terminated)
+ * --kill Kill any existing service; do not actually run anything
*
- * [server (script)] accepts, forks subseq monitor
+ * Options for controlling whether different invocations share a server:
*
- * monitor [1] [fd0: null]
- * (init [fd[12]: init: fd2-from-outer; subseq: null]
- * or errors: init: fd2; subseq: syslog
- * subseq) other fds: syslog, call(server-end)
- * sends ack byte
- * receives args, env, fds
- * forks executor
+ * -E VAR ident includes env var VAR (or its absence)
+ * -G STRING ident includes string STRING
+ * -g IDENT use IDENT rather than hex(SHA256(... identity things ...))
*
- * executor sorts out fds:
- * fd0, fd1, fd2: from-outer
- * close fds: call(server-end)
- * retained fds: syslog
- *
- * sets cmdline, env
- * runs main part of script
- * exits normally
- *
- * [monitor] [fd[012]: null]
- * [fd[12]: init: fd2-from-outer; subseq: null]
- * [errors: init: fd2; subseq: syslog]
- * reaps executor
- * reports status via socket
- *
- * [client (C wrapper)] [fd0, fd1, fd2: from-outer]
- * [other fd: call(client-end)]
- * receives status, exits appropriately
- * (if was bad signal, reports to stderr, exits 127)
+ * (Ordering of -E and -G options is relevant; invocations with different
+ * -E -G options are different even if the env var settings are the same)
*/
+/*
+***************************************************************************
+\f
+ State during service execution, process parentage and key fds
+
+ CALLER
+ ||
+ ||
+ || listen watch-err/in
+ || call (accept) \ ,------2
+ || ,-----------------------------. SERVER -----0 WATCHER(C)
+ CLIENT 2--=fdpassed>=---------. \ || && | &&
+ (C) 1--=fdpassed>=---------. \ \ || inotify
+ 0--=fdpassed>=---------. \ \ \ || sockpath
+ \ \ \ \ ||
+ | | |\ | ||
+ | | | \ | ||
+ | \ | \ \ ||
+ \ \ \ \ MONITOR &
+ \ \ \ `12 || |
+ \ \ \ || |
+ \ \ \ || |execterm
+ \ \ \ || |
+ \ \ \ || |
+ \ \ 2 || |
+ \ 1 EXECUTOR
+ 0
+ ---- pipes, sockets
+ 012 descriptors
+ -==- fds shared
+ || process parentage
+ && session leader (daemon)
+ & process group leader
+
+***************************************************************************
+\f
+ Control flow and causality
+
+ CALLER
+ |
+ |fork/exec
+ |
+ CLIENT
+ |
+ attempt to connect, and read greeting
+ |failure? \success?
+ | \
+ tidy up stale /run entries *1 (continue from send_fds, below)
+ acquire lock
+ |
+ retry attempt to connect, and read greeting
+ |failure? \success?
+ | \
+ create listening socket release lock
+ | \
+ fork/daemonise *1
+ | `------------------.
+ | WATCHER(C) &&
+ |
+ make "fake" initial call socketpair (C)
+ | prefork-interp
+ fork/exec #########################################################
+ | `-------------. application
+ | # SCRIPT (setup)
+ | # |
+ | # script initialisation
+ | # | application
+ | ###########|#############################################
+ | # | prefork-interp
+ | # identify fds from envirnment (Perl)
+ | # open syslog
+ | # |
+ | # dzemonize
+ | ,.....<....../ |
+ waitpid # fork for initial service
+ | # |child? |parent?
+ | # | |
+ | # | SCRIPT [server] &&
+ | # | |
+ | # | ** accept / event loop **
+ | # | accepted? \ \ \
+ | # | / \ watch\ \idle
+ | # | fork child \stderr\ \timeout?
+ | # | _________/ | | |
+ | # |/ |read? | |
+ | # SCRIPT [monitor] | eof?| |
+ | # setpgrpt & | | |
+ | # | log msg | |
+ read ,....<.....send greeting | | |
+ greeting # | ___________________
+ | # |
+ release # |
+ lock *1 # |
+ | / # |
+ send fds.....>.... |
+ | # \receive fds
+ | # |
+ | # fork for executor (Perl)
+ | # |parent? \child? prefork-interp
+ | # | ######\############################
+ | # | # SCRIPT (executor) application
+ | # | # execute service
+ | # wait for read # |
+ | # (select) # terminates
+ | # | | # |
+ | # | # kernel closes execterm
+ | # | ,......<....../|
+ | # execterm? # |
+ | # | # zombie
+ | # | | ,......<...../
+ | # waitpid # _______________
+ | # | #
+ | ,....<....,..send status #
+ read status # ________________ #
+ _____________ #
+
+
+ ********** Or, if client is killed **********
+
+ | # | # execute service
+ terminates # wait for read # |
+ | # (select) # |
+ kernel # | | # |
+ closes call # | # |
+ \..>......_ | # |
+ _____________ # \|call? # |
+ # | # |
+ # kill whole pgrp... # killled
+ # | # zombie
+ # | | ,......<....../
+ # waitpid # _______________
+ # | #
+ # send exit status #
+ # _____SIGPIPE______ #
+
+ | - \ / process control flow
+ ... < > causes mediated by fds or other IPC etc.
+ && session leader (daemon)
+ & process group leader
+ # language/implementation boundary
+ *1 line continued elsewhere
+ event? condition
+ ______ process termination (after reaping, if shown)
+
+***************************************************************************
+\f
+ Sequence of events and fd pluming.
+ NB INCOMPLETE - does not cover execterm, cleanup
+
+ client (C wrapper) connects to server
+ (including reading ack byte)
+ if fails or garbage
+ === acquires lock ===
+ makes new listening socket
+ makes watcher pipes
+ forks watcher and awaits
+ makes first-instance socketpair
+ forks setup (script, sock fds indicated in env)
+ fd0, fd1, fd2: from-outer
+ other fd: call(client-end)(fake)
+ reaps setup (and reports error)
+ (implicitly releases lock)
+
+ watcher fd[012]: watcher pipes
+ starts watch on socket path
+ sets stderr to line buffered
+ sets stdin to nonblocking
+ daemonises (one fork, becomes session leader)
+ when socket stat changes, quit
+
+ setup (pre-exec) fd0: null,
+ fd[12]: fd2-from-outer
+ env fds: listener, call(server-end)(fake),
+ watcher read, watcher write
+ close fd: lockfile
+ possibly clean env, argv
+
+ setup (script) runs initialisation parts of the script
+ at prefork establishment point:
+ setup (pm) [1] opens syslog
+ forks for server
+ [2] exits
+
+ server (pm) [1] [fd0: null],
+ [fd[12]: fd2-from-outer]
+ setsid
+ right away, forks init monitor
+ [2] closes outer caller fds and call(fake)
+ [server (pm)] fd[012]: null
+ other fds: listener, syslog
+ runs in loop accepting and forking,
+ reaping and limiting children (incl init monitor)
+ reports failures of monitors to syslog
+
+ [client (C wrapper)] if client connect succeeds:
+ now fd: call(client-end)
+ sends message with: cmdline, env
+ sends fds
+
+ [server (script)] accepts, forks subseq monitor
+
+ monitor [1] [fd0: null]
+ (init [fd[12]: init: fd2-from-outer; subseq: null]
+ or errors: init: fd2; subseq: syslog
+ subseq) other fds: syslog, call(server-end)
+ sends ack byte
+ receives args, env, fds
+ forks executor
+
+ executor sorts out fds:
+ fd0, fd1, fd2: from-outer
+ close fds: call(server-end)
+ retained fds: syslog
+
+ sets cmdline, env
+ runs main part of script
+ exits normally
+
+ [monitor] [fd[012]: null]
+ [fd[12]: init: fd2-from-outer; subseq: null]
+ [errors: init: fd2; subseq: syslog]
+ reaps executor
+ reports status via socket
+
+ [client (C wrapper)] [fd0, fd1, fd2: from-outer]
+ [other fd: call(client-end)]
+ receives status, exits appropriately
+ (if was bad signal, reports to stderr, exits 127)
+
+***************************************************************************
+\f
+ Protocol, and functions of the script
+
+ 1. Script interpreter will be spawned apparently as normal;
+ should run synchronously in the normal way until
+ "initialisation complete" point. At initialisation complete:
+
+ 2. Env var PREFORK_INTERP contains:
+
+ v1,SECS.NSECS[,...] LISTEN,CALL,WATCHE,WATCHI[,...][ ???]
+
+ To parse it: treat as bytes and split on ASCII space, taking
+ the first two words. (There may or may not be
+ further "words"; and if there are they might be binary data.)
+ Then split each of the first two words (which will contain only
+ ASCII printing characters) on comma. Take the first two items:
+
+ v1 Protocol version indicator - literal. If something else,
+ fail (means installation is incompatible somehow).
+
+ SECS.NSECS
+ timestamp just before script started running, as a
+ decimal time_t. NSECS is exactly 9 digits.
+ To be used for auto reloading (see below).
+
+ The 2nd word's items are file descriptors:
+
+ LISTEN listening socket nonblocking
+ CALL call socket for initial call blocking
+ WATCHE liveness watcher stderr nonblocking
+ WATCHI liveness sentinel unspecified
+
+ (any further descriptors should be ignored, not closed)
+
+ 3. Library should do the following:
+
+ 1. Read and understand the PREFORK_INTERP env var.
+ If it is not set, initialisation complete should simply return.
+ (This allows simple synchronous operation.)
+
+ 2. Open syslog
+ 3. fork/exit (fork and have parent exit) (to make server)
+ 4. setsid (to become session leader)
+ 5. fork initial service (monitor) child, using CALL (see below)
+ 6. Replace stdin/stdout/stderr with /dev/null,
+ and make a note to send all error messages to syslog
+ 7. Enter select loop, looking for the following:
+
+ A. accept on LISTEN:
+ i. see if we need to reload: is any file forming part
+ of the program newer than the SECS.NSECS ?
+ If so, log at LOG_INFO, and exit immediately
+ (dropping CALL, LISTEN, WATCHI, etc.)
+ ii. see if we can reap any children, possibly waiting
+ for children if we are at our concurrency limit
+ (limit should be configured through library, default 4)
+ Report child exit status if not zero or SIGPIPE.
+ iii. fork service (monitor) child, using accepted fd
+
+ B. WATCHE is readable:
+ * EOF: log at LOG_INFO, and exit
+ * data to read: read what is available immediately;
+ it will be an error message: log it at LOG_ERR, and exit
+
+ 4. service (monitor) child does the following:
+
+ 1. close all of LISTEN, WATCHI, WATCHE
+ 2. setpgrp
+ 3. send a greeting (on CALL) "PFI\n\0\0\0\0" (8 bytes)
+ 4. read a single byte, fail if it's not zero
+ 5. three times, receive a single byte with a file descriptor
+ attached as ancillary data. (These descriptors will be
+ service stdin, stdout, stderr.)
+ 6. read a 4-byte big-endian length
+ 7. read that many bytes, the initial service request message,
+ which contains the following nul-terminated strings:
+ * environment variable settings in the format NAME=value
+ * an empty string
+ * arguments NOT INCLUDING argv[0] or script filename
+ (not that this means the service request must end in a nul)
+ 8. make a new pipe EXECTERM
+ 9. fork for the service executor; in the child
+ i. redirect stdin/stdout/stderr to the recevied fds
+ ii. replace environment and arguments with those received,
+ iii. close descriptors: close the original received descriptors;
+ close CALL; keep only the writing end of EXECTERM
+ iv. if the script programming language does things with SIGINT,
+ set it set back to default handling (immediate termination).
+ v. return back to script, now in the grandchild
+
+ 10. in the parent, close EXECTERM writing end, and
+ 11. select, looking for one of the following:
+ * CALL is readable
+ * EXECTERM reading end is readable
+ No need to actually read, since these shouldn't produce
+ spurious wakeups (but do loop on EINTR).
+ 12. set SIGINT to ignored
+ 13. send SIGINT to the entire process group
+ 14. wait, blocking, for the executor child
+ 15. write the wait status, in 32-bit big-endian, to CAL
+ 16. exit 0
+
+ Errors detected in the service monitor should be sent to
+ syslog, or stderr, depending on whether this is the initial
+ service monitor (from part 3 step 5) or an accepted socket
+ service monitor (from part 4 step 9); this can be achieved
+ easily by having a global flag (set at part 3 step 6),
+ or perhaps using logger(8) and redirecting stderr (but
+ then be careful to ensure everyone gets only the necessary fds).
+
+ EOF on CALL, or EPIPE/SIGPIPE writing to it, are not errors.
+ In this case, exit zero or die with SIGPIPE, so parent
+ won't report error either (part 3 step 7(A)(ii)).
+
+***************************************************************************
+\f
+*/
+
#include <arpa/inet.h>
+#include <sys/utsname.h>
+
+#include <uv.h>
#include "prefork.h"
const char our_name[] = "prefork-interp";
-struct sockaddr_un sockaddr_sun;
+static struct sockaddr_un sockaddr_sun;
+static FILE *call_sock;
#define ACK_BYTE '\n'
static const char *const *executor_argv;
+static const char header_magic[4] = "PFI\n";
+
void fusagemessage(FILE *f) {
fprintf(f, "usage: #!/usr/bin/prefork-interp [<options>]\n");
}
-static int laundering;
+#define MODE_NORMAL 0
+#define MODE_KILL 'k'
+#define MODE_FRESH 'f'
+
+#define MEDIATION_UNSPECIFIED 0
+#define MEDIATION_UNLAUNDERED 'U'
+
+static int mediation = MEDIATION_UNSPECIFIED;
+static int mode = MODE_NORMAL;
+static int max_sockets = 100; // maximum entries in the run dir is 2x this
+
+static struct stat initial_stab;
const struct cmdinfo cmdinfos[]= {
PREFORK_CMDINFOS
- { 0, 'U', 0, .iassignto= &laundering, .arg= 'U' },
+ { 0, 'U', 0, .iassignto= &mediation, .arg= MEDIATION_UNLAUNDERED },
+ { "kill", 0, 0, .iassignto= &mode, .arg= MODE_KILL },
+ { 0, 'f', 0, .iassignto= &mode, .arg= MODE_FRESH },
{ 0 }
};
+static void ident_add_stat(const char *path) {
+ struct stat stab;
+ int r = stat(path, &stab);
+ if (r) diee("failed to stat %s", path);
+
+ IDENT_ADD_OBJ(path[0], stab.st_dev);
+ IDENT_ADD_OBJ('i', stab.st_ino);
+}
+
void ident_addinit(void) {
- char ident_magic[1] = { 0 };
- sha256_update(&identsc, sizeof(ident_magic), ident_magic);
+ ident_add_key_byte(1);
+
+ struct utsname uts = { };
+ size_t utslen = sizeof(uts);
+ int r = uname(&uts);
+ if (r) diee("uname failed!");
+ IDENT_ADD_OBJ('u', utslen);
+ IDENT_ADD_OBJ('u', uts);
+
+ ident_add_stat(".");
+ ident_add_stat("/");
}
static void propagate_exit_status(int status, const char *what) {
int r;
if (WIFEXITED(status)) {
- _exit(status);
+ _exit(WEXITSTATUS(status));
}
if (WIFSIGNALED(status)) {
if (! WCOREDUMP(status) &&
(sig == SIGINT ||
+ sig == SIGTERM ||
sig == SIGHUP ||
sig == SIGPIPE ||
sig == SIGKILL)) {
struct sigaction sa;
FILLZERO(sa);
sa.sa_handler = SIG_DFL;
- r = sigaction(sig, &sa, 0);
- if (r) diee("failed to reset signal handler while propagating %s",
- signame);
-
- sigset_t sset;
- sigemptyset(&sset);
- sigaddset(&sset, sig);
- r = sigprocmask(SIG_UNBLOCK, &sset, 0);
- if (r) diee("failed to reset signal block while propagating %s",
- signame);
+ if (sig != SIGKILL) {
+ r = sigaction(sig, &sa, 0);
+ if (r) diee("failed to reset signal handler while propagating %s",
+ signame);
+
+ sigset_t sset;
+ sigemptyset(&sset);
+ sigaddset(&sset, sig);
+ r = sigprocmask(SIG_UNBLOCK, &sset, 0);
+ if (r) diee("failed to reset signal block while propagating %s",
+ signame);
+ }
raise(sig);
die("unexpectedly kept running after raising (to propagate) %s",
die("%s failed with weird wait status %d 0x%x", what, status, status);
}
+typedef struct {
+ char *name_hash;
+ time_t atime;
+} PrecleanEntry;
+
+static int preclean_entry_compar_name(const void *av, const void *bv) {
+ const PrecleanEntry *a = av;
+ const PrecleanEntry *b = bv;
+ return strcmp(a->name_hash, b->name_hash);
+}
+
+static int preclean_entry_compar_atime(const void *av, const void *bv) {
+ const PrecleanEntry *ae = av; time_t a = ae->atime;
+ const PrecleanEntry *be = bv; time_t b = be->atime;
+ return (a > b ? +1 :
+ a < b ? -1 : 0);
+}
+
+static time_t preclean_stat_atime(const char *s_path) {
+ struct stat stab;
+ int r= lstat(s_path, &stab);
+ if (r) {
+ if (errno!=ENOENT) diee("pre-cleanup: stat socket (%s)", s_path);
+ return 0;
+ }
+ return stab.st_atime;
+}
+
+static void preclean(void) {
+ DIR *dir = opendir(run_base);
+ if (!dir) {
+ if (errno == ENOENT) return;
+ diee("pre-cleanup: open run dir (%s)", run_base);
+ }
+
+ PrecleanEntry *entries=0;
+ size_t avail_entries=0;
+ size_t used_entries=0;
+
+ struct dirent *de;
+ while ((errno = 0, de = readdir(dir))) {
+ char c0 = de->d_name[0];
+ if (!(c0 == 'l' || c0 == 's')) continue;
+ char *name_hash = m_asprintf("%s", de->d_name+1);
+ char *s_path = m_asprintf("%s/s%s", run_base, name_hash);
+ time_t atime = preclean_stat_atime(s_path);
+
+ if (avail_entries == used_entries) {
+ assert(avail_entries < INT_MAX / 4 / sizeof(PrecleanEntry));
+ avail_entries <<= 1;
+ avail_entries += 10;
+ entries = realloc(entries, avail_entries * sizeof(PrecleanEntry));
+ }
+ entries[used_entries].name_hash = name_hash;
+ entries[used_entries].atime = atime;
+ used_entries++;
+ }
+ if (errno) diee("pre-cleanup: read run dir (%s)", run_base);
+
+ // First we dedupe (after sorting by path)
+ qsort(entries, used_entries, sizeof(PrecleanEntry),
+ preclean_entry_compar_name);
+ PrecleanEntry *p, *q;
+ for (p=entries, q=entries; p < entries + used_entries; p++) {
+ if (q > entries && !strcmp(p->name_hash, (q-1)->name_hash))
+ continue;
+ *q++ = *p;
+ }
+ used_entries = q - entries;
+
+ // Now maybe delete some things
+ //
+ // Actually this has an off-by-one error since we are about
+ // to create a socket, so the actual number of sockets is one more.
+ // But, *actually*, since there might be multiple of us running at once,
+ // we might have even more than that. This doesn't really matter.
+ if (used_entries > max_sockets) {
+ qsort(entries, used_entries, sizeof(PrecleanEntry),
+ preclean_entry_compar_atime);
+ for (p=entries; p < entries + max_sockets; p++) {
+ char *l_path = m_asprintf("%s/l%s", run_base, p->name_hash);
+ char *s_path = m_asprintf("%s/s%s", run_base, p->name_hash);
+ int lock_fd = flock_file(l_path);
+ // Recheck atime - we might have raced!
+ time_t atime = preclean_stat_atime(s_path);
+ if (atime != p->atime) {
+ // Raced. This will leave use deleting too few things. Whatever.
+ } else {
+ int r= unlink(s_path);
+ if (r && errno!=ENOENT) diee("preclean: delete stale (%s)", s_path);
+ r= unlink(l_path);
+ if (r) diee("preclean: delete stale lock (%s)", s_path);
+ // NB we don't hold the lock any more now.
+ }
+ close(lock_fd);
+ free(l_path);
+ free(s_path);
+ }
+ }
+
+ for (p=entries; p < entries + used_entries; p++)
+ free(p->name_hash);
+ free(entries);
+}
+
static __attribute((noreturn)) void die_data_overflow(void) {
die("cannot handle data with length >2^32");
}
*buf += dl;
}
}
-
+
static void prepare_length(size_t *len, char **buf, size_t dl_sz) {
if (dl_sz > UINT32_MAX) die_data_overflow();
uint32_t dl = htonl(dl_sz);
prepare_string(len, buf, s);
}
-static void send_fd(FILE *call_sock, int payload_fd) {
+static void send_fd(int payload_fd) {
int via_fd = fileno(call_sock);
union {
}
}
-static void send_request(FILE *call_sock) {
- // Sending these first makes it easier for the script to
+static void send_request(void) {
+ char ibyte= 0;
+ ssize_t sr = fwrite(&ibyte, 1, 1, call_sock);
+ if (sr != 1) diee("write signalling byte");
+
+ // Sending these before the big message makes it easier for the script to
// use buffered IO for the message.
- send_fd(call_sock, 0);
- send_fd(call_sock, 1);
- send_fd(call_sock, 2);
+ send_fd(0);
+ send_fd(1);
+ send_fd(2);
- size_t len = 4;
+ size_t len = 0;
prepare_message(&len, 0);
- char *m = malloc(len);
- if (!m) diee("failed to allocate for message");
+
+ size_t tlen = len + 4;
+ char *m = xmalloc(tlen);
char *p = m;
- prepare_length(0, &p, len - 4);
+ prepare_length(0, &p, len);
prepare_message(0, &p);
- assert(p == m + len);
+ assert(p == m + tlen);
+
+ sr = fwrite(m, tlen, 1, call_sock);
+ if (sr != 1) diee("write request (buffer)");
- ssize_t sr = fwrite(p, len, 1, call_sock);
- if (sr != 1) diee("write request");
+ if (fflush(call_sock)) diee("write request");
}
static FILE *call_sock_from_fd(int fd) {
return feof(call_sock) || errno==ECONNRESET;
}
+// Returns -1 on EOF
+static int protocol_read_maybe(void *data, size_t sz) {
+ if (!sz) return 0;
+ size_t sr = fread(data, sz, 1, call_sock);
+ if (sr != 1) {
+ if (was_eof(call_sock)) return -1;
+ diee("read() on monitor call socket (%zd)", sz);
+ }
+ return 0;
+}
+
+static void protocol_read(void *data, size_t sz) {
+ if (protocol_read_maybe(data, sz) < 0)
+ die("monitor process quit unexpectedly");
+}
+
+// Returns 0 if OK, error msg if peer was garbage.
+static const char *read_greeting(void) {
+ char got_magic[sizeof(header_magic)];
+
+ if (protocol_read_maybe(&got_magic, sizeof(got_magic)) < 0)
+ return "initial monitor process quit"
+ " (maybe script didn't call preform_initialisation_complete?)";
+
+ if (memcmp(got_magic, header_magic, sizeof(header_magic)))
+ die("got unexpected protocol magic 0x%02x%02x%02x%02x",
+ got_magic[0], got_magic[1], got_magic[2], got_magic[3]);
+
+ uint32_t xdata_len;
+ protocol_read(&xdata_len, sizeof(xdata_len));
+ void *xdata = xmalloc(xdata_len);
+ protocol_read(xdata, xdata_len);
+
+ return 0;
+}
+
// Returns: call(client-end), or 0 to mean "is garbage"
// find_socket_path must have been called
static FILE *connect_existing(void) {
int r;
int fd = -1;
- FILE *call_sock = 0;
+
+ if (mode != MODE_NORMAL) return 0;
fd = socket(AF_UNIX, SOCK_STREAM, 0);
if (fd==-1) diee("socket() for client");
call_sock = call_sock_from_fd(fd);
fd = -1;
- char ack;
- size_t sr = fread(&ack, sizeof(ack), 1, call_sock);
- if (sr != 1) {
- if (was_eof(call_sock)) goto x_garbage;
- diee("read() ack byte");
- }
- if (ack != '\n') die("got ack byte 0x%02x, not '\n'", ack);
-
- // We're committed now, send the request (or bail out)
- send_request(call_sock);
+ if (read_greeting())
+ goto x_garbage;
return call_sock;
x_garbage:
- if (call_sock) fclose(call_sock);
+ if (call_sock) { fclose(call_sock); call_sock=0; }
if (fd >= 0) close(fd);
return 0;
}
+static void watcher_cb_stdin(uv_poll_t *handle, int status, int events) {
+ char c;
+ int r;
+
+ if ((errno = -status)) diee("watcher: poll stdin");
+ for (;;) {
+ r= read(0, &c, 1);
+ if (r!=-1) _exit(0);
+ if (!(errno==EINTR || errno==EWOULDBLOCK || errno==EAGAIN))
+ diee("watcher: read sentinel stdin");
+ }
+}
+
+static void watcher_cb_sockpath(uv_fs_event_t *handle, const char *filename,
+ int events, int status) {
+ int r;
+ struct stat now_stab;
+
+ if ((errno = -status)) diee("watcher: poll stdin");
+ for (;;) {
+ r= stat(socket_path, &now_stab);
+ if (r==-1) {
+ if (errno==ENOENT) _exit(0);
+ if (errno==EINTR) continue;
+ diee("stat socket: %s", socket_path);
+ }
+ if (!stabs_same_inode(&now_stab, &initial_stab))
+ _exit(0);
+ }
+}
+
+// On entry, stderr is still inherited, but 0 and 1 are the pipes
static __attribute__((noreturn))
-void become_setup(int sfd, int fake_pair[2]) {
+void become_watcher(void) {
+ uv_loop_t loop;
+ uv_poll_t uvhandle_stdin;
+ uv_fs_event_t uvhandle_sockpath;
+ int r;
+
+ nonblock(0);
+
+ errno= -uv_loop_init(&loop);
+ if (errno) diee("watcher: uv_loop_init");
+
+ errno= -uv_poll_init(&loop, &uvhandle_stdin, 0);
+ if (errno) diee("watcher: uv_poll_init");
+ errno= -uv_poll_start(&uvhandle_stdin,
+ UV_READABLE | UV_WRITABLE | UV_DISCONNECT,
+ watcher_cb_stdin);
+ if (errno) diee("watcher: uv_poll_start");
+
+ errno= -uv_fs_event_init(&loop, &uvhandle_sockpath);
+ if (errno) diee("watcher: uv_fs_event_init");
+
+ errno= -uv_fs_event_start(&uvhandle_sockpath, watcher_cb_sockpath,
+ socket_path, 0);
+ if (errno) diee("watcher: uv_fs_event_start");
+
+ // OK everything is set up, let us daemonise
+ if (dup2(1,2) != 2) diee("watcher: set daemonised stderr");
+ r= setvbuf(stderr, 0, _IOLBF, BUFSIZ);
+ if (r) diee("watcher: setvbuf stderr");
+
+ pid_t child = fork();
+ if (child == (pid_t)-1) diee("watcher: fork");
+ if (child) _exit(0);
+
+ if (setsid() == (pid_t)-1) diee("watcher: setsid");
+
+ r= uv_run(&loop, UV_RUN_DEFAULT);
+ die("uv_run returned (%d)", r);
+}
+
+static __attribute__((noreturn))
+void become_setup(int sfd, int lockfd, int fake_pair[2],
+ int watcher_stdin, int watcher_stderr) {
+ close(lockfd);
close(fake_pair[0]);
int call_fd = fake_pair[1];
- int fd0_save = dup(0); if (fd0_save < 0) diee("dup stdin");
- int fd1_save = dup(1); if (fd1_save < 0) diee("dup stdin");
-
int null_0 = open("/dev/null", O_RDONLY); if (null_0 < 0) diee("open null");
if (dup2(null_0, 0)) diee("dup2 /dev/null onto stdin");
+ close(null_0);
if (dup2(2, 1) != 1) die("dup2 stderr onto stdout");
- putenv(m_asprintf("PREFORK_INTERP=%d,%d,%d,%d,%s",
- sfd, call_fd, fd0_save, fd1_save, socket_path));
+ nonblock(sfd);
+
+ // Extension could work like this:
+ //
+ // We could advertise a new protocol (perhaps one which is nearly entirely
+ // different after the connect) by putting a name for it comma-separated
+ // next to "v1". Simple extension can be done by having the script
+ // side say something about it in the ack xdata, which we currently ignore.
+ // Or we could add other extra data after v1.
+ putenv(m_asprintf("PREFORK_INTERP=v1,%jd.%09ld %d,%d,%d,%d",
+ (intmax_t)initial_stab.st_mtim.tv_sec,
+ (long)initial_stab.st_mtim.tv_nsec,
+ sfd, call_fd, watcher_stdin, watcher_stderr));
execvp(executor_argv[0], (char**)executor_argv);
diee("execute %s", executor_argv[0]);
}
-static FILE *connect_or_spawn(void) {
+static void connect_or_spawn(void) {
int r;
- FILE *call_sock = connect_existing();
- if (call_sock) return call_sock;
+ call_sock = connect_existing();
+ if (call_sock) return;
+
+ // We're going to make a new one, so clean out old ones
+ preclean();
int lockfd = acquire_lock();
+
+ if (mode == MODE_KILL) {
+ r= unlink(socket_path);
+ if (r && errno != ENOENT) diee("remove socket %s", socket_path);
+
+ r= unlink(lock_path);
+ if (r) diee("rmeove lock %s", lock_path);
+ _exit(0);
+ }
+
call_sock = connect_existing();
- if (call_sock) { close(lockfd); return call_sock; }
+ if (call_sock) { close(lockfd); return; }
// We must start a fresh one, and we hold the lock
if (r<0 && errno!=ENOENT)
diee("failed to remove stale socket %s", socket_path);
- int fake_pair[2];
- r = socketpair(AF_UNIX, SOCK_STREAM, 0, fake_pair);
- if (r<0) diee("socketpair() for fake initial connection");
-
int sfd = socket(AF_UNIX, SOCK_STREAM, 0);
if (sfd<0) diee("socket() for new listener");
r= bind(sfd, (const struct sockaddr*)&sockaddr_sun, salen);
if (r<0) diee("bind() on new listener");
+ r= stat(socket_path, &initial_stab);
+ if (r<0) diee("stat() fresh socket");
+
// We never want callers to get ECONNREFUSED. But:
// There is a race here: from my RTFM they may get ECONNREFUSED
// if they try between our bind() and listen(). But if they do, they'll
r = listen(sfd, INT_MAX);
if (r<0) diee("listen() for new listener");
+ // Fork watcher
+
+ int watcher_stdin[2];
+ int watcher_stderr[2];
+ if (pipe(watcher_stdin) || pipe(watcher_stderr))
+ diee("pipe() for socket inode watcher");
+
+ pid_t watcher = fork();
+ if (watcher == (pid_t)-1) diee("fork for watcher");
+ if (!watcher) {
+ close(sfd);
+ close(lockfd);
+ close(watcher_stdin[1]);
+ close(watcher_stderr[0]);
+ if (dup2(watcher_stdin[0], 0) != 0 ||
+ dup2(watcher_stderr[1], 1) != 1)
+ diee("initial dup2() for watcher");
+ close(watcher_stdin[0]);
+ close(watcher_stderr[1]);
+ become_watcher();
+ }
+
+ close(watcher_stdin[0]);
+ close(watcher_stderr[1]);
+ nonblock(watcher_stderr[0]);
+
+ // Fork setup
+
+ int fake_pair[2];
+ r = socketpair(AF_UNIX, SOCK_STREAM, 0, fake_pair);
+ if (r<0) diee("socketpair() for fake initial connection");
+
pid_t setup_pid = fork();
if (setup_pid == (pid_t)-1) diee("fork for spawn setup");
- if (!setup_pid) become_setup(sfd, fake_pair);
+ if (!setup_pid) become_setup(sfd, lockfd, fake_pair,
+ watcher_stdin[1], watcher_stderr[0]);
close(fake_pair[1]);
close(sfd);
+ call_sock = call_sock_from_fd(fake_pair[0]);
+
int status;
pid_t got = waitpid(setup_pid, &status, 0);
if (got == (pid_t)-1) diee("waitpid setup [%ld]", (long)setup_pid);
(long)setup_pid, (long)got);
if (status != 0) propagate_exit_status(status, "setup");
+ const char *emsg = read_greeting();
+ if (emsg) die("setup failed: %s", emsg);
+
close(lockfd);
- return call_sock_from_fd(fake_pair[0]);
+ return;
}
static void make_executor_argv(const char *const *argv) {
- switch (laundering) {
- case 'U': break;
+ switch (mediation) {
+ case MEDIATION_UNLAUNDERED: break;
default: die("need -U (specifying unlaundered argument handling)");
}
EACH_NEW_ARG( *out++ = arg; );
*out++ = 0;
-}
+}
int main(int argc_unused, const char *const *argv) {
process_opts(&argv);
assert(strlen(socket_path) <= sizeof(sockaddr_sun.sun_path));
strncpy(sockaddr_sun.sun_path, socket_path, sizeof(sockaddr_sun.sun_path));
- FILE *call_sock = connect_or_spawn();
+ connect_or_spawn();
+
+ // We're committed now, send the request (or bail out)
+ send_request();
+
uint32_t status;
- ssize_t sr = fread(&status, sizeof(status), 1, call_sock);
- if (sr != 1) {
- if (was_eof(call_sock)) die("per-call server monitor process quit");
- diee("read status from call socket");
- }
+ protocol_read(&status, sizeof(status));
status = ntohl(status);
if (status > INT_MAX) die("status 0x%lx does not fit in an int",
~ian / chiark-utils.git / blobdiff