ps: Match on truncated 16 char for -C

The referenced commit the comm length was increased from 16 to 64
characters to handle the larger command names for things like kernel
threads.

However most user processes are limited to 15 characters which means
if you try something like ps -C myprogramisbiggerthansixteen this would
fail to match because /proc/<PID>/comm would only be myprogramisbigg

ps now checks the comm length and if it is 15 and if the given match
is 15 or more, it will only match the first 15 characters.

This is also how killall has worked for about a year.

Thanks to Jean Delvare <jdelvare@suse.de> for the note.

References:
 commit 14005a371e5c14289e96a4927ffd1a827d3c9d85
 commit psmisc/psmisc@1188315cd037d73bf946a0003b70c6423cc330d2

Signed-off-by: Craig Small <csmall@dropbear.xyz>

diff --git a/NEWS b/NEWS
index 514f8efc1b3d5ebfe5d89dceb48975229a73bc71..9dfd42f4bd331cd0e0353bc0f891db66e8985d4c 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@ procps-ng NEXT
   * pgrep: Add older than selection                        merge #79
   * pidof: show worker threads                             Redhat #1803640
   * ps.1: Mention stime alias                              issue #164
+  * ps: check also match on truncated 16 char comm names
   * sysctl: Match systemd directory order
   * sysctl: Document directory order                       Debian #951550
   * top: ensure config file backward compatibility         Debian #951335

diff --git a/ps/select.c b/ps/select.c
index f58ca25318c8639272b95bb5e0f18e4e08379978..e26f2f19b0537409a5676e8f59d9564d73cc3c49 100644 (file)
--- a/ps/select.c
+++ b/ps/select.c
@@ -116,11 +116,15 @@ static int proc_was_listed(proc_t *buf){
     break; case SEL_TTY : return_if_match(tty,tty);
     break; case SEL_SESS: return_if_match(session,pid);
 
-    break; case SEL_COMM: i=sn->n; while(i--)
-    if(!strncmp( buf->cmd, (*(sn->u+i)).cmd, 63 )) return 1;
-
-
-
+    break;
+    case SEL_COMM:
+       i=sn->n;
+       while(i--) {
+           /* special case, comm is 16 characters but match is longer */
+           if (strlen(buf->cmd) == 15 && strlen((*(sn->u+i)).cmd) >= 15)
+               if(!strncmp( buf->cmd, (*(sn->u+i)).cmd, 15 )) return 1;
+           if(!strncmp( buf->cmd, (*(sn->u+i)).cmd, 63 )) return 1;
+       }
 #undef return_if_match
 
     }