Introduce NUT_IGNORE_CHECKPROCNAME=true support to skip PID process n…

…ame validation if it causes problems [networkupstools#2463]

Signed-off-by: Jim Klimov <[email protected]>

NEWS.adoc

@@ -139,7 +139,13 @@ https://github.com/networkupstools/nut/milestone/11
      that if they can resolve the program name of a running process with
      this identifier, that such name matches the current program (avoid
      failures to start NUT daemons if PID files are on persistent storage,
-     and some unrelated program got that PID after a reboot). [#2463]
+     and some unrelated program got that PID after a reboot).  This might
+     introduce regressions for heavily customized NUT builds (e.g. those
+     embedded in NAS or similar devices) where binary file names differ
+     significantly from a `progname` string defined in the respective NUT
+     source file, so a boolean `NUT_IGNORE_CHECKPROCNAME` environment
+     variable support was added to optionally disable this verification.
+     [issue #2463]
 
  - various recipe, documentation and source files were revised to address
    respective warnings issued by the new generations of analysis tools.

UPGRADING.adoc

@@ -44,7 +44,9 @@ Changes from 2.8.2 to 2.8.3
   determine one). This might introduce regressions for heavily customized
   NUT builds (e.g. embedded in NAS or similar devices) whose binary file
   names differ significantly from a `progname` defined in the respective
-  NUT source file. [issue #2463]
+  NUT source file, so a boolean `NUT_IGNORE_CHECKPROCNAME` environment
+  variable support was added to optionally disable this verification.
+  [issue #2463]
 
 
 Changes from 2.8.1 to 2.8.2

common/common.c

@@ -924,6 +924,7 @@ int checkprocname(pid_t pid, const char *progname)
 	/* If we can determine the binary path name of the specified "pid",
 	 * check if it matches the assumed name of the current program.
 	 * Returns:
+	 *	-3	Skipped because NUT_IGNORE_CHECKPROCNAME is set
 	 *	-2	Could not parse a program name (ok to proceed,
 	 *		risky - but matches legacy behavior)
 	 *	-1	Could not identify a program name (ok to proceed,
@@ -933,7 +934,7 @@ int checkprocname(pid_t pid, const char *progname)
 	 *		varying precision
 	 * Generally speaking, if (checkprocname(...)) then ok to proceed
 	 */
-	char	*procname = getprocname(pid);
+	char	*procname = NULL, *s;
 	int	ret = -127;
 	size_t	procbasenamelen = 0, progbasenamelen = 0;
 	/* Track where the last dot is in the basename; 0 means none */
@@ -944,6 +945,16 @@ int checkprocname(pid_t pid, const char *progname)
 	char	procbasename[PATH_MAX], progbasename[PATH_MAX];
 #endif
 
+	if ((s = getenv("NUT_IGNORE_CHECKPROCNAME"))) {
+		/* FIXME: Make server/conf.c::parse_boolean() reusable */
+		if ( (!strcasecmp(s, "true")) || (!strcasecmp(s, "on")) || (!strcasecmp(s, "yes")) || (!strcasecmp(s, "1"))) {
+			upsdebugx(1, "%s: skipping because caller set NUT_IGNORE_CHECKPROCNAME", __func__);
+			ret = -3;
+			goto finish;
+		}
+	}
+
+	procname = getprocname(pid);
 	if (!procname || !progname) {
 		ret = -1;
 		goto finish;
@@ -1064,6 +1075,10 @@ int checkprocname(pid_t pid, const char *progname)
 				__func__);
 			break;
 
+		case -3:
+			/* skipped due to envvar, logged above */
+			break;
+
 		default:
 			upsdebugx(1,
 				"%s: unexpected result looking for process name "

conf/nut.conf.sample

@@ -101,3 +101,12 @@ MODE=none
 #  `none`    Disabled and background() detaches stderr as usual
 #  `default`/unset/other   Not disabled
 #NUT_DEBUG_SYSLOG=stderr
+
+# Normally NUT can (attempt to) verify that the program file name matches the
+# name associated with a running process, when using PID files to send signals.
+# The `NUT_IGNORE_CHECKPROCNAME` boolean toggle allows to quickly skip such
+# verification, in case it causes problems (e.g. NUT programs were renamed and
+# do not match built-in expectations). This environment variable can also be
+# optionally set in init-scripts or service methods for `upsd`, `upsmon` and
+# NUT drivers/`upsdrvctl`.
+#NUT_IGNORE_CHECKPROCNAME=true

docs/man/nut.conf.txt

@@ -134,6 +134,18 @@ the same journal). Recognized values:
 | unset/other | Not disabled
 |===========================================================================
 
+*NUT_IGNORE_CHECKPROCNAME*::
+Optional, defaults to `false`.  Normally NUT can (attempt to) verify that
+the program file name matches the name associated with a running process,
+when using PID files to send signals.
++
+The `NUT_IGNORE_CHECKPROCNAME` boolean toggle allows to quickly skip such
+verification, in case it causes problems (e.g. NUT programs were renamed
+and do not match built-in expectations).
++
+This environment variable can also be optionally set in init-scripts or
+service methods for `upsd`, `upsmon` and NUT drivers/`upsdrvctl`.
+
 EXAMPLE
 -------
 

docs/nut.dict

@@ -1,4 +1,4 @@
-personal_ws-1.1 en 3168 utf-8
+personal_ws-1.1 en 3169 utf-8
 AAC
 AAS
 ABI
@@ -154,6 +154,7 @@ CERTIDENT
 CERTREQUEST
 CERTVERIF
 CEST
+CHECKPROCNAME
 CHOST
 CHRG
 CL

include/common.h

@@ -246,6 +246,7 @@ size_t parseprogbasename(char *buf, size_t buflen, const char *progname, size_t
 /* If we can determine the binary path name of the specified "pid",
  * check if it matches the assumed name of the current program.
  * Returns:
+ *	-3	Skipped because NUT_IGNORE_CHECKPROCNAME is set
  *	-2	Could not parse a program name (ok to proceed,
  *		risky - but matches legacy behavior)
  *	-1	Could not identify a program name (ok to proceed,