Storing regex matching environment variables in the existing cmdine variable

atop.c

@@ -298,7 +298,7 @@
 #include "json.h"
 #include "gpucom.h"
 
-#define	allflags  "ab:cde:fghijklmnopqrstuvwxyz1ABCDEFGHIJ:KL:MNOP:QRSTUVWXYZ"
+#define	allflags  "ab:cde:fghijklmnopqrstuvwxyz:1ABCDEFGHIJ:KL:MNOP:QRSTUVWXYZ"
 #define	MAXFL		64      /* maximum number of command-line flags  */
 
 /*
@@ -324,6 +324,9 @@ char      	calcpss    = 0;  /* boolean: read/calculate process PSS  */
 char      	getwchan   = 0;  /* boolean: obtain wchan string         */
 char      	rmspaces   = 0;  /* boolean: remove spaces from command  */
 		                 /* name in case of parseable output     */
+char		prependenv = 0;  /* boolean: prepend selected            */
+				 /* environment variables to cmdline     */
+regex_t		envregex;
 
 unsigned short	hertz;
 unsigned int	pidwidth;
@@ -619,6 +622,14 @@ main(int argc, char *argv[])
 				rmspaces = 1;
 				break;
 
+			   case 'z':            /* prepend regex matching environment variables */
+				if (regcomp(&envregex, optarg, REG_NOSUB|REG_EXTENDED)) {
+					printf("Invalid environment regular expression!");
+					prusage(argv[0]);
+				}
+				prependenv = 1;
+				break;
+
 			   default:		/* gather other flags */
 				flaglist[i++] = c;
 			}
@@ -1102,6 +1113,8 @@ prusage(char *myname)
 			MRMSPACES);
 	printf("\t  -L  alternate line length (default 80) in case of "
 			"non-screen output\n");
+	printf("\t  -z  prepend regex matching environment variables to "
+                        "processes command line\n");
 
 	if (vis.show_usage)
 		(*vis.show_usage)();

man/atop.1

@@ -1599,7 +1599,10 @@ the total number of pages of the process/thread list are shown.
 .B COMMAND-LINE
 The full command line of the process (including arguments). If the length of
 the command line exceeds the length of the screen line, the arrow 
-keys -> and <- can be used for horizontal scroll.
+keys -> and <- can be used for horizontal scroll. The '-z <regex>' command
+line option can be used to prepend matching environment variables to the
+displayed command line. POSIX Extended Regular Expression syntax are used
+(see regex(3)).
 .br
 Behind the verb `COMMAND-LINE' in the header line, the current page number
 and the total number of pages of the process/thread list are shown.

photoproc.c

@@ -40,6 +40,7 @@
 #include <ctype.h>
 #include <time.h>
 #include <stdlib.h>
+#include <regex.h>
 
 #include "atop.h"
 #include "photoproc.h"
@@ -73,6 +74,9 @@ void		fillcgroupv2(struct cgroupv2vals *, char *, char *, int);
 int 		readcgroupv2(char *, char *, char *, int, long []);
 static void	wipecgroupv2(void);
 
+extern char	prependenv;
+extern regex_t  envregex;
+
 unsigned long
 photoproc(struct tstat *tasklist, int maxtask)
 {
@@ -711,21 +715,48 @@ procio(struct tstat *curtask)
 static void
 proccmd(struct tstat *curtask)
 {
-	FILE		*fp;
+	FILE		*fp, *fpe;
 	register int 	i, nr;
 
 	memset(curtask->gen.cmdline, 0, CMDLEN+1);
 
+	ssize_t env_len = 0;
+
+	if ( prependenv && (fpe = fopen("environ", "r")) != NULL) {
+		register char *p = curtask->gen.cmdline;
+		/* we let getdelim handle the allocation */
+		char *line = NULL;
+		ssize_t nread;
+		size_t len = 0;
+		while ((nread = getdelim(&line, &len, '\0', fpe)) != -1) {
+			if (nread > 0 && !regexec(&envregex, line, 0, NULL, 0)) {
+				env_len += nread;
+
+				if (env_len >= CMDLEN) {
+					env_len -= nread;
+					break;
+				}
+
+				strcpy(p, line);
+				p += nread;
+			}
+		}
+		/* line has been (re)allocated within the first call to getlim */
+                /* even if the call fails, see getline(3) */
+		free(line);
+		fclose(fpe);
+	}
+
 	if ( (fp = fopen("cmdline", "r")) != NULL)
 	{
 		register char *p = curtask->gen.cmdline;
 
-		nr = fread(p, 1, CMDLEN, fp);
+		nr = fread(p+env_len, 1, CMDLEN-env_len, fp);
 		fclose(fp);
 
 		if (nr >= 0)	/* anything read ? */
 		{
-			for (i=0; i < nr-1; i++, p++)
+			for (i=0; i < nr+env_len-1; i++, p++)
 			{
 				switch (*p)
 				{