linux-kernel - [PATCH v9-resend 21/54] dyndbg: split multi-query strings with %

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Message-ID: <20240716185806.1572048-22-jim.cromie@gmail.com>
Date: Tue, 16 Jul 2024 12:57:33 -0600
From: Jim Cromie <jim.cromie@...il.com>
To: linux-kernel@...r.kernel.org,
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	Jim Cromie <jim.cromie@...il.com>
Subject: [PATCH v9-resend 21/54] dyndbg: split multi-query strings with %

Since commit
85f7f6c0edb8 ("dynamic_debug: process multiple debug-queries on a line")

Multi-query commands have been allowed:

  modprobe drm dyndbg="class DRM_UT_CORE +p; class DRM_UT_KMS +p"
  modprobe drm dyndbg=<<EOX
     class DRM_UT_CORE +p
     class DRM_UT_KMS +p
  EOX

More recently, the need for quoting was avoided by treating a comma
like a space/token-terminator:

  modprobe drm dyndbg=class,DRM_UT_CORE,+p\;class,DRM_UT_KMS,+p

That works, but it needs the escaped semicolon, which is a shell
special-char (one of the bash control operators), so it is brittle
when passed in/down/around scripts.  In particular, it fails when
passed to vng (virtme-ng).

So this patch adds '%' to the existing ';' and '\n' multi-command
separators, which is more shell-friendly, so you can more fully avoid
quoting and escaping hassles.

NOTE: it does break format matching on '%' patterns:

bash-5.2# ddcmd 'format "find-me: %foo" +p'
[  203.900581] dyndbg: read 26 bytes from userspace
[  203.900883] dyndbg: query 0: "format "find-me: " mod:*
[  203.901118] dyndbg: unclosed quote: find-me:
[  203.901355] dyndbg: tokenize failed
[  203.901529] dyndbg: query 1: "foo" +p" mod:*
[  203.901957] dyndbg: split into words: "foo"" "+p"
[  203.902243] dyndbg: op='+' flags=0x1 maskp=0xffffffff
[  203.902458] dyndbg: expecting pairs of match-spec <value>
[  203.902703] dyndbg: query parse failed
[  203.902871] dyndbg: processed 2 queries, with 0 matches, 2 errs
bash: echo: write error: Invalid argument

The '%' splits the input into 2 queries, and both fail.  Given the
limited utility of matching against the working parts of a format
string "foo: %d bar %s", nothing is actually lost here.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 lib/dynamic_debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 235d85765b63..dcec7b3657bb 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -596,7 +596,7 @@ static int ddebug_exec_queries(char *query, const char *modname)
 	int i, errs = 0, exitcode = 0, rc, nfound = 0;
 
 	for (i = 0; query; query = split) {
-		split = strpbrk(query, ";\n");
+		split = strpbrk(query, "%;\n");
 		if (split)
 			*split++ = '\0';
 
-- 
2.45.2