Backport upstream patch to also match on 16 char TASK_COMM_LEN

At some point before the buster release, killall changed its COMM_LEN to
64 to cope with an (expected?) similar change in the kernel. But this
change is not present in buster's kernel and in fact, in none of the
other newer kernels AFAIK (likely due to the kernel "no-user-space
breakage" rule). And due to this mismatch, killall is not able to
identify process with names bigger than 15 characters.

Newer versions of killall thus learned to handle both possible lenghts
and this commit just backports the corresponding patch to fix this
regression in Debian 10.

debian/changelog

+psmisc (23.2-1+deb10u1) buster; urgency=medium
+
+  * Team upload.
+  * Fix regression in killall not matching process with names bigger than 15
+    characters by backporting the upstream patch that restores the check
+    that works on kernels that have TASK_COMM_LEN set to 16. Closes: #912748
+
+ -- Raphaël Hertzog <raphael@freexian.com>  Mon, 16 Aug 2021 11:17:53 +0200
+
 psmisc (23.2-1) unstable; urgency=medium
 
   * New upstream release

debian/patches/match-on-16-char-commlen

+From 1188315cd037d73bf946a0003b70c6423cc330d2 Mon Sep 17 00:00:00 2001
+From: Craig Small <csmall@enc.com.au>
+Date: Wed, 7 Nov 2018 20:13:09 +1100
+Subject: [PATCH] killall: match on 16 character commlen too
+
+The comm length increase meant killall could accommodate the
+larger comm name given out by newer kernels but it meant that
+if a user relied on the previous 16 character truncation then
+processes that used to match would fail.
+
+killall now checks to see if the comm is the old COMM_LEN
+length and the given name is longer than old COMM_LEN and does
+a truncated match as well.
+
+Bug-Debian: https://bugs.debian.org/912748
+Origin: upstream, https://gitlab.com/psmisc/psmisc/-/commit/1188315cd037d73bf946a0003b70c6423cc330d2 https://gitlab.com/psmisc/psmisc/-/commit/e2cf9f3e83e0fc0278ff39a4dfc8e3f2730eebca
+---
+diff --git a/src/killall.c b/src/killall.c
+index 2715515..09212a4 100644
+--- a/src/killall.c
++++ b/src/killall.c
+@@ -492,6 +492,49 @@ create_pid_table(int *max_pids, int *pids)
+     return pid_table;
+ }
+ 
++#define strcmp2(A,B,I) (I? strcasecmp((A),(B)):strcmp((A),(B)))
++#define strncmp2(A,B,L,I) (I? strncasecmp((A),(B),(L)):strncmp((A),(B),(L)))
++static int match_process_name(
++    const char *proc_comm,
++    const int comm_len,
++    const char *proc_cmdline,
++    const char *match_name,
++    const int match_len,
++    const int got_long
++                         )
++{
++    /* process is old length but matching longer */
++    if (comm_len == OLD_COMM_LEN - 1 && match_len >= OLD_COMM_LEN - 1)
++    {
++        if (got_long)
++        {
++            return (0 == strncmp2 (match_name, proc_cmdline, OLD_COMM_LEN - 1,
++                                   ignore_case));
++        } else {
++            return (0 == strncmp2 (match_name, proc_comm, OLD_COMM_LEN - 1,
++                                   ignore_case));
++        }
++    }
++
++    if (comm_len == COMM_LEN - 1 && match_len >= COMM_LEN - 1)
++    {
++        if (got_long)
++        {
++            return (0 == strncmp2 (match_name, proc_cmdline, COMM_LEN - 1,
++                                   ignore_case));
++        } else {
++            return (0 == strncmp2 (match_name, proc_comm, COMM_LEN - 1,
++                                   ignore_case));
++        }
++    }
++    /* Not old new COMM_LEN so we match all of it */
++    if (got_long)
++    {
++        return (0 == strcmp2 (match_name, proc_cmdline, ignore_case));
++    }
++    return (0 == strcmp2 (match_name, proc_comm, ignore_case));
++}
++
+ #ifdef WITH_SELINUX
+ static int
+ kill_all(int signal, int name_count, char **namelist, struct passwd *pwent, 
+@@ -599,28 +642,10 @@ kill_all (int signal, int name_count, char **namelist, struct passwd *pwent)
+             {
+                 if (!name_info[j].st.st_dev)
+                 {
+-                    if (length != COMM_LEN - 1 || name_info[j].name_length < COMM_LEN - 1)
+-                    {
+-                        if (ignore_case == 1)
+-                        {
+-                            if (strcasecmp (namelist[j], comm))
+-                                continue;
+-                        } else {
+-                            if (strcmp(namelist[j], comm))
+-                                continue;
+-                        }
+-                    } else {
+-                        if (ignore_case == 1)
+-                        {
+-                            if (got_long ? strcasecmp (namelist[j], command) :
+-                                strncasecmp (namelist[j], comm, COMM_LEN - 1))
+-                                continue;
+-                        } else {
+-                            if (got_long ? strcmp (namelist[j], command) :
+-                                strncmp (namelist[j], comm, COMM_LEN - 1))
+-                                continue;
+-                        }
+-                    }
++                    if (!match_process_name(comm, length, command, namelist[j],
++                                            name_info[j].name_length, got_long))
++                        continue;
++
+                 } else {
+                     int ok = 1; 
+                     if (asprintf (&path, PROC_BASE "/%d/exe", pid_table[i]) < 0)
+diff --git a/src/comm.h b/src/comm.h
+index b54b998..b10eb36 100644
+--- a/src/comm.h
++++ b/src/comm.h
+@@ -33,4 +33,10 @@
+  */
+ #define COMM_LEN 64
+ 
++/*
++ * Older kernels had only 16 characters, which means we may have to check this
++ * too
++ */
++#define OLD_COMM_LEN 16
++
+ #endif
+-- 
+GitLab
+

debian/patches/series

 manpage-fixes
+match-on-16-char-commlen