libpcp, pcp-xsos: finer grained string output control in pmPrintValue

Implement a mechanism in pmPrintValue for producing single-line value
output, giving shell scripts a chance to operate sensibly with whacky
command lines.

Resolves Red Hat bugs RHEL-67164 and RHEL-67148.

man/man3/pmprintvalue.3

@@ -80,6 +80,15 @@ and
 pairs for each requested metric), based upon the
 metrics type as returned from
 .BR pmLookupDesc (3).
+.SH ENVIRONMENT
+Output of string metric values can be further controlled using
+.BR PCP_SQUASH_NEWLINES .
+When set in the environment of the calling process, and the
+.I type
+is set to PM_TYPE_STRING or PM_TYPE_AGGREGATE, then the output
+value is guaranteed to be free of embedded newline characters.
+If the given value contained such characters, they will have been
+replaced by a space before being printed.
 .SH SEE ALSO
 .BR PMAPI (3),
 .BR pmAtomStr (3),

qa/1564

@@ -117,5 +117,33 @@ pcp -a $archive xsos -x -n | _filter_net
 echo === Archive pcp xsos -N
 pcp -a $archive xsos -x -N | _filter_netstat
 
+echo === Special case: eval command issues | tee -a $seq.full
+test -f /eperm && $sudo rm -f /eperm
+(./src/args \$\(touch /eperm\) )&
+argspid=$!
+$PCP_BINADM_DIR/pmsleep 0.25  # start args
+$sudo pcp xsos -x --ps >> $seq.full
+echo $? exit status
+test -f /eperm && echo file exists && $sudo rm -f /eperm
+$PCP_BINADM_DIR/pmsignal $argspid
+wait $argspid
+
+echo === Special case: multiline ps issues | tee -a $seq.full
+(./src/args '
+multi
+line
+args
+')&
+argspid=$!
+$PCP_BINADM_DIR/pmsleep 0.25  # start args
+pcp xsos -x --ps >> $seq.full
+echo $? exit status
+$PCP_BINADM_DIR/pmsignal $argspid
+wait $argspid
+
+echo === Special case: command line errors | tee -a $seq.full
+pcp xsos unknown_arg >> $seq.full 2>&1
+echo $? exit status
+
 # success, all done
 exit

qa/1564.out

@@ -111,3 +111,9 @@ NET STATS
   Ip.InAddrErrors: XXX
   Ip6.InAddrErrors: XXX
 
+=== Special case: eval command issues
+0 exit status
+=== Special case: multiline ps issues
+0 exit status
+=== Special case: command line errors
+1 exit status

qa/src/.gitignore

@@ -13,6 +13,7 @@ archend
 archfetch
 archinst
 arch_maxfd
+args
 atomstr
 badUnitsStr_r
 badloglabel

qa/src/GNUlocaldefs

@@ -48,7 +48,7 @@ CFILES = disk_test.c exercise.c context_test.c chkoptfetch.c \
 	archctl_segfault.c debug.c int2pmid.c int2indom.c exectest.c \
 	unpickargs.c hanoi.c progname.c countmark.c check_attribute.c \
 	indom2int.c pmid2int.c scanmeta.c traverse_return_codes.c \
-	timeshift.c checkstructs.c bcc_profile.c sha1int2ext.c \
+	timeshift.c checkstructs.c bcc_profile.c args.c sha1int2ext.c \
 	getdomainname.c profilecrash.c store_and_fetch.c test_service_notify.c \
 	ctx_derive.c pmstrn.c pmfstring.c pmfg-derived.c mmv_help.c sizeof.c \
 	stampconv.c time_stamp.c archend.c scandata.c wait_for_values.c \

qa/src/args.c

@@ -0,0 +1,18 @@
+/*
+ * Copyright (c) 2024 Red Hat.
+ *
+ * QA helper that waits for stdin input then exits, useful for
+ * shell escape testing as it allows arbitrary args (ignored).
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+int
+main(int argc, char **argv)
+{
+    while (1)
+	sleep(1);
+    exit(EXIT_SUCCESS);
+}

src/libpcp/src/check-statics

@@ -581,6 +581,8 @@ util.o
     msgbuf			# guarded by util_lock mutex
     msgbuflen			# guarded by util_lock mutex
     msgsize			# guarded by util_lock mutex
+    squashed			# guarded by __pmLock_extcall mutex when set
+    				# in a one-trip initialization
     filename			# guarded by __pmLock_extcall mutex when set
     				# in a one-trip initialization
     ?base			# no unsafe side-effects, see notes in util.c

src/libpcp/src/util.c

@@ -984,6 +984,18 @@ print_event_summary(FILE *f, const pmValue *val, int highres)
     fputc(']', f);
 }
 
+static void
+squash_string(char *s, unsigned int len)
+{
+    unsigned int i;
+
+    /* replace end-of-line characters */
+    for (i = 0; i < len; i++) {
+	if (isspace(s[i]))
+	    s[i] = ' ';
+    }
+}
+
 /* Print single pmValue. */
 void
 pmPrintValue(FILE *f,			/* output stream */
@@ -997,6 +1009,16 @@ pmPrintValue(FILE *f,			/* output stream */
     int         n;
     char        *p;
     int		sts;
+    static int	squashed = -1;
+
+    if (squashed == -1) {
+	/* one-trip initialization */
+	PM_LOCK(__pmLock_extcall);
+	squashed = 0;
+	if (getenv("PCP_SQUASH_NEWLINES") != NULL)	/* THREADSAFE */
+	    squashed = 1;
+	PM_UNLOCK(__pmLock_extcall);
+    }
 
     if (type != PM_TYPE_UNKNOWN &&
 	type != PM_TYPE_EVENT &&
@@ -1032,7 +1054,10 @@ pmPrintValue(FILE *f,			/* output stream */
         break;
 
     case PM_TYPE_STRING:
-	n = (int)strlen(a.cp) + 2;
+	n = (int)strlen(a.cp);
+	if (squashed)
+	    squash_string(a.cp, n);
+	n += 2;
 	while (n < minwidth) {
 	    fputc(' ', f);
 	    n++;
@@ -1123,6 +1148,8 @@ pmPrintValue(FILE *f,			/* output stream */
 			n++;
 		    }
 		    n = (int)val->value.pval->vlen - PM_VAL_HDR_SIZE;
+		    if (squashed)
+	    	        squash_string(val->value.pval->vbuf, n);
 		    fprintf(f, "\"%*.*s\"", n, n, val->value.pval->vbuf);
 		    done = 1;
 		}