From cfb3c482a5c9235a9899e107f2f90873164f7049 Mon Sep 17 00:00:00 2001
From: Craig Small <csmall@dropbear.xyz>
Date: Tue, 13 Jun 2023 16:23:35 +1000
Subject: [PATCH] pgrep: Suppress warning if using regex

pgrep gives a warning if the match string is longer than
15 characters and there was no match. That often does not
make sense when using regex or at the very least difficult
to know when to warn users. e.g
"1234567890|123456789X" is a 21 character string but only
matching two 10 string words.

pgrep has a simple check for regex and will now suppress
that warning if that has been used.

References:
 https://bugs.debian.org/1037450

Signed-off-by: Craig Small <csmall@dropbear.xyz>
---
 NEWS        |  1 +
 src/pgrep.c | 23 ++++++++++++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index 1fa44899..59e51319 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ procps-ng-NEXT
     restore the proper main thread tics valuations         issue #280
   * free: -L one line output                               issue #156
   * pgrep: Use only --signal option for signal             Debian #1031765
+  * pgrep: suppress >15 warning if using regex             Debian #1037450
   * ps: fixed missing or corrupted fields with -m option   Debian #1036631, issue #279
   * tests: dont compare floats with ==                     issue #271
   * top: bad command line arguments yield EXIT_FAILURE     issue #273
diff --git a/src/pgrep.c b/src/pgrep.c
index 442dbfcc..838bb2d0 100644
--- a/src/pgrep.c
+++ b/src/pgrep.c
@@ -636,6 +636,27 @@ static size_t get_arg_max(void)
     return val;
 }
 
+/* 
+ * Check if we have a long simple (non-regex) match
+ * Returns true if the string:
+ *  1) is longer than 15 characters
+ *  2) Doesn't have | or [ which are used by regex
+ * This is not an exhaustive list but catches most instances
+ * It's only used to suppress the warning
+ */
+static bool is_long_match(const char *str)
+{
+    int i, len;
+
+    if (str == NULL)
+        return FALSE;
+    if (15 >= (len = strlen(str)))
+        return FALSE;
+    for (i=0; i<len; i++)
+        if (str[i] == '|' || str[i] == '[')
+            return FALSE;
+    return TRUE;
+}
 static struct el * select_procs (int *num)
 {
 #define PIDS_GETINT(e) PIDS_VAL(EU_ ## e, s_int, stack, info)
@@ -784,7 +805,7 @@ static struct el * select_procs (int *num)
 
     *num = matches;
 
-    if ((!matches) && (!opt_full) && opt_pattern && (strlen(opt_pattern) > 15))
+    if ((!matches) && (!opt_full) && is_long_match(opt_pattern))
         xwarnx(_("pattern that searches for process name longer than 15 characters will result in zero matches\n"
                  "Try `%s -f' option to match against the complete command line."),
                program_invocation_short_name);