Move iTerm-server daemon to per-user namespace. Issue 4147 #381

pradorocchi · 2019-01-29T22:34:20Z

This PR fixes issue 4147

ooglek

Learned a bunch about macOS, thanks! Pointed out a few spelling/grammar changes. Woot

ooglek · 2019-01-30T04:47:27Z

sources/shell_launcher.c

+
+   Issue 4147 happens because the forked daemon is running in the Aqua session namespace. So
+   when the user logout or a GUI crash happens, the forked daemon remains isolated in a lost
+   per-session namespace. It partially looses it's IPC capabilities to comunicate with other


partially loses its ability ... to communicate ...

ooglek · 2019-01-30T04:48:46Z

sources/shell_launcher.c

+   namespace that already exists [the current one], or any new 'per-session' namespaces that
+   may in future be (re)created below it.
+
+   Important is to mention that it's availability is to serve just the same user (the same UID).


that its availability ...

ooglek · 2019-01-30T04:49:56Z

sources/shell_launcher.c

+   Important is to mention that it's availability is to serve just the same user (the same UID).
+   This is what we want, because all other BSD preparations here is done to create the
+   iTerm-Server to serve just that given user who started it. If another user is logged-in via
+   GUI via fast user switching, this other user will have it's own Per-User session, and will


have its own ...

ooglek · 2019-01-30T04:50:11Z

sources/shell_launcher.c

+   This is what we want, because all other BSD preparations here is done to create the
+   iTerm-Server to serve just that given user who started it. If another user is logged-in via
+   GUI via fast user switching, this other user will have it's own Per-User session, and will
+   have below it his Aqua per-session GUI belonging to it's UID, and his programs running there,


to its UID ...

ooglek · 2019-01-30T04:50:26Z

sources/shell_launcher.c

+   iTerm-Server to serve just that given user who started it. If another user is logged-in via
+   GUI via fast user switching, this other user will have it's own Per-User session, and will
+   have below it his Aqua per-session GUI belonging to it's UID, and his programs running there,
+   including his own iTerm-Server daemons forked just for it's UID use.


for its UID ...

ooglek · 2019-01-30T04:51:09Z

sources/shell_launcher.c

+   is never destroyed by GUI logout or crashes. And it will exist until there is at least one
+   daemon or service running on it, for that given user. [* from Apples documentation]
+
+   That's the exact namespace where Launchd places daemons for a given user.


👍 Great writeup and docs!

ooglek · 2019-01-30T04:52:05Z

sources/shell_launcher.c

+        return; /* All Done! now return, as we are ready to begin forking! */
+    }
+    // Never reach. Unless if we had failed to get the parent bootstrap port, which according
+    // to Apple's documentation never happens. But I already saw rare wierd system situations


saw weird system ...

Thank you very much for the spelling/grammar changes!
My natural language is Portuguese (I'm from Brazil), some (sometimes a lot of) mistakes happens, :)

ooglek · 2019-01-30T04:54:00Z

sources/shell_launcher.c

+    // to Apple's documentation never happens. But I already saw rare wierd system situations
+    // where it may happen.
+    // Almost impossible, but if it happens, for sure is a BUG. So log it just in case.
+    FDLog(LOG_ERR,"BUG: Error getting parent BS port! Please report this msg and code: '%x'", kr);


I'm a fan of defensive error logging

Me too, learned the importance of that on my last 9 years working as developer on the asterisk telephony platform. There are a lot of similar BUG situations on that code, and naturally I created this function the way I'm accustomed to do.

Thank you for your appreciation!

gnachman · 2019-01-30T06:11:55Z

This is a fantastic PR! Thank you!

pradorocchi · 2019-01-30T13:33:22Z

This is a fantastic PR! Thank you!

Thank you for creating iTerm2 @gnachman, you deserve the best congratulations!

pradorocchi · 2019-01-30T14:29:27Z

If you want to TEST what kind of session you are, I wrote this simple code that will show the current session you are. I needed to do it during the validation/debug phase of my PR. Here is a simplified version of it.

compile using:
gcc which_namespace.c -o which_namespace

CODE: which_namespace.c

#include <stdio.h>
#include <unistd.h>
#include <vproc.h>

typedef void * vproc_err_t;
typedef struct vproc_s * vproc_t;
typedef enum {
    VPROC_GSK_ZERO,
    VPROC_GSK_LAST_EXIT_STATUS,
    VPROC_GSK_GLOBAL_ON_DEMAND,
    VPROC_GSK_MGR_UID,
    VPROC_GSK_MGR_PID,
    VPROC_GSK_IS_MANAGED,
    VPROC_GSK_MGR_NAME,
    VPROC_GSK_BASIC_KEEPALIVE,
} vproc_gsk_t;

vproc_err_t vproc_swap_integer(vproc_t vp, vproc_gsk_t key, int64_t *inval, int64_t *outval);
vproc_err_t vproc_swap_string(vproc_t vp, vproc_gsk_t key, const char *instr, char **outstr);

int main() {
    int64_t lduid;
    char *manager_name = NULL;

    if (vproc_swap_integer(NULL, VPROC_GSK_MGR_UID, 0, &lduid) != 0) {
        printf("err: vproc_swap_integer -> UID \n"); }

    if (vproc_swap_string(NULL, VPROC_GSK_MGR_NAME, NULL, &manager_name) != 0) {
        printf("err: vproc_swap_string -> SessionName \n"); }

    printf("========================================================\n");
    printf("The Current Boostrap Session Namespace I am running is: \n" );
    printf("--------------------------------------------------------\n");
    printf("  * ManagerSessionUserID: ........ '%lld'\n",lduid);
    printf("  * ManagerSessionName: .......... '%s'\n", manager_name);
    printf("--------------------------------------------------------\n");

    return 0;
}

.

You can use it to test iTerm2 before and after this PR patch.

This is the output before:

prado@MacPro ~/testwork    
> $ ./which_namespace
========================================================
The Current Boostrap Session Namespace I am running is:
--------------------------------------------------------
  * ManagerSessionUserID: ........ '501'
  * ManagerSessionName: .......... 'Aqua'
--------------------------------------------------------

This is the output after this PR patch.

prado@MacPro ~/testwork    
> $ ./which_namespace
========================================================
The Current Boostrap Session Namespace I am running is:
--------------------------------------------------------
  * ManagerSessionUserID: ........ '501'
  * ManagerSessionName: .......... 'Background'
--------------------------------------------------------

gnachman · 2019-01-30T19:37:06Z

Awesome! How did you figure this out?

pradorocchi · 2019-02-01T12:51:03Z

Here is all the information sources I used to achieve this PR

.

Apple Excellent technical note about the intrinsic mechanism of BSD + Mach kernel portions
https://developer.apple.com/library/archive/technotes/tn2083/_index.html

Apple Libc source code
https://opensource.apple.com/source/Libc/Libc-1272.200.26/

MacOS launchctl source code
https://github.com/PureDarwin/XPC/blob/master/src/launchctl/launchctl.c

MacOS 10.14 kernel fork() source code
http://newosxbook.com/src.jl?tree=xnu&file=/bsd/kern/kern_fork.c

Additional researches looking for use cases at :

MacOS 10.14.0 Kernel source code
http://newosxbook.com/src.jl?tree=xnu-4903.221.2

Various system packages source code for Mojave 10.14.1 that deals with process execution
https://opensource.apple.com/release/macos-10141.html

Move iTerm-server daemon to per-user namespace. Issue 4147

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ooglek approved these changes Jan 30, 2019

View reviewed changes

Update shell_launcher.c

78caa62

gnachman merged commit 85cf962 into gnachman:master Jan 30, 2019

gnachman pushed a commit that referenced this pull request Feb 6, 2019

Move iTerm-server daemon to per-user namespace. Issue 4147 (#381)

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Move iTerm-server daemon to per-user namespace. Issue 4147 #381

Move iTerm-server daemon to per-user namespace. Issue 4147 #381

pradorocchi commented Jan 29, 2019

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edited

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pradorocchi commented Feb 1, 2019

Move iTerm-server daemon to per-user namespace. Issue 4147 #381

Move iTerm-server daemon to per-user namespace. Issue 4147 #381

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gnachman commented Jan 30, 2019

pradorocchi commented Jan 30, 2019

pradorocchi commented Jan 30, 2019

gnachman commented Jan 30, 2019

pradorocchi commented Feb 1, 2019

ooglek Jan 30, 2019 •

edited