From 352b41c12eec3297ca1cd40841002800737be5d6 Mon Sep 17 00:00:00 2001
From: Thierry Parmentelat <thierry.parmentelat@sophia.inria.fr>
Date: Tue, 20 Sep 2011 19:37:03 +0200
Subject: [PATCH] a few usability improvements (*) warn when getuid is not 0,
 suggests to use sudo (*) look for pipe files in /vsys/

---
 vsyssh/Makefile |   2 +-
 vsyssh/vsyssh.c | 156 ++++++++++++++++++++++++++----------------------
 2 files changed, 86 insertions(+), 72 deletions(-)

diff --git a/vsyssh/Makefile b/vsyssh/Makefile
index 9458790..425dca3 100644
--- a/vsyssh/Makefile
+++ b/vsyssh/Makefile
@@ -1,4 +1,4 @@
 all: vsyssh
 
 vsyssh: vsyssh.c
-	gcc -g vsyssh.c -o vsyssh
+	gcc -Wall -g vsyssh.c -o vsyssh
diff --git a/vsyssh/vsyssh.c b/vsyssh/vsyssh.c
index bfb68d7..fd5d62a 100644
--- a/vsyssh/vsyssh.c
+++ b/vsyssh/vsyssh.c
@@ -1,4 +1,4 @@
-/* gcc -Wall -O2 -g chpid.c -o chpid */
+/* gcc -Wall -O2 -g vsyssh.c -o vsyssh */
 #define _XOPEN_SOURCE
 #define _XOPEN_SOURCE_EXTENDED
 #define _SVID_SOURCE
@@ -17,6 +17,7 @@
 #include <sys/resource.h>
 #include <sys/mount.h>
 #include <sys/vfs.h>
+#include <sys/types.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <sched.h>
@@ -24,86 +25,99 @@
 #include <dirent.h>
 
 void pipe_handler (int sig) {
-	printf("SIGPIPE");
+  printf("SIGPIPE");
 }
 
-int main(int argc, char **argv, char **envp)
-{
-	if (argc<2) {
-		printf("Usage: vsyssh <vsys entry> [cmd]\n");
-		exit(1);
-	}
-	else {
-		int vfd0,vfd1;
-		char *inf,*outf;
-		struct timeval tv;
+#define FILELEN 256
+
+int main(int argc, char **argv, char **envp) {
 
-		signal(SIGPIPE,pipe_handler);
-		inf=(char *)malloc(strlen(argv[1])+3);
-		outf=(char *)malloc(strlen(argv[1])+4);
-		strcpy(inf,argv[1]);
-		strcpy(outf,argv[1]);
-		strcat(inf,".in");
-		strcat(outf,".out");
+  if ( (argc<2) || (strcmp(argv[1],"--help")==0) ) {
+    printf("Usage: vsyssh <vsys entry> [cmd]\n");
+    exit(1);
+  }
 
-		vfd0 = open(outf,O_RDONLY|O_NONBLOCK);
-		vfd1 = open(inf,O_WRONLY);
+  {
+    uid_t uid=getuid();
+    if (uid!=0) {
+      printf ("%s requires root privileges, please run under sudo\n",argv[0]);
+      exit(1);
+    }
+  }
 
-		if (vfd0==-1 || vfd1 == -1) {
-			printf("Error opening vsys entry %s (%s)\n", argv[1],strerror(errno));
-			exit(1);
-		}
+  {
+    int vfd0,vfd1;
+    char inf[FILELEN], outf[FILELEN];
+    int fatal=0;
 
-		if (fcntl(vfd0, F_SETFL, O_RDONLY) == -1) {
-			printf("Error making pipe blocking: %m\n");
-			exit(1);
-		}
+    signal(SIGPIPE,pipe_handler);
+    
+    sprintf(inf,"/vsys/%s.in",argv[1]);
+    sprintf(outf,"/vsys/%s.out",argv[1]);
+    vfd0 = open(outf,O_RDONLY|O_NONBLOCK);
+    if (vfd0<0) {
+      printf("Error opening vsys channel %s (%m)\n",outf);
+      fatal=1;
+    }
+    vfd1 = open(inf,O_WRONLY);
+    if (vfd1<0) {
+      printf("Error opening vsys channel %s (%m)\n",inf);
+      fatal=1;
+    }
 
-		if (argc<3) {
-			fd_set set;
-			char do_input = 1, do_output = 1;
+    if (fcntl(vfd0, F_SETFL, O_RDONLY) == -1) {
+      printf("Error making pipe blocking: %m\n");
+      fatal=1;
+    }
 
-			while (1)
-			{
-				int ret;
-				printf("vsys>");fflush(stdout);
-				FD_ZERO(&set);
-				if (do_input)
-					FD_SET(0, &set);
-				if (do_output)
-					FD_SET(vfd0, &set);
-				ret = select(vfd0+1, &set, NULL, NULL, NULL);
-				if (FD_ISSET(0,&set)) {
-					char lineread[2048];
-					int ret;
-					ret=read(0,lineread,2048);
-					if (ret == 0)
-						do_input = 0;
-					lineread[ret]='\0';
-					printf ("writing %s\n",lineread);
-					write(vfd1,lineread,ret);
-				}
-				if (FD_ISSET(vfd0,&set)) {
-					char lineread[2048];
-					int ret;
-					ret = read(vfd0,lineread,2048);
-					if (ret == 0)
-						break;
-					write(1,lineread,ret);
-				}
-			}
+    if (fatal) { exit(1);}
+
+    if (argc<3) {
+      /* interactive mode */
+      fd_set set;
+      char do_input = 1, do_output = 1;
+
+      while (1) {
+	  int ret;
+	  printf("vsys>");fflush(stdout);
+	  FD_ZERO(&set);
+	  if (do_input)
+	    FD_SET(0, &set);
+	  if (do_output)
+	    FD_SET(vfd0, &set);
+	  ret = select(vfd0+1, &set, NULL, NULL, NULL);
+	  if (FD_ISSET(0,&set)) {
+	    char lineread[2048];
+	    int ret;
+	    ret=read(0,lineread,2048);
+	    /*printf ("read=%d\n",ret);*/
+	    if (ret == 0)
+	      do_input = 0;
+	    lineread[ret]='\0';
+	    printf ("writing %s\n",lineread);
+	    write(vfd1,lineread,ret);
+	  }
+	  if (FD_ISSET(vfd0,&set)) {
+	    char lineread[2048];
+	    int ret;
+	    ret = read(vfd0,lineread,2048);
+	    if (ret == 0)
+	      break;
+	    write(1,lineread,ret);
+	  }
+	}
 
-		}
-		else {
-			close(0);
-			close(1);
+    } else {
+      /* line mode */
+      close(0);
+      close(1);
 
-			dup2(vfd0,0);
-			dup2(vfd1,1);
-			execve(argv[2],argv+2,envp);
-		}
-       }
+      dup2(vfd0,0);
+      dup2(vfd1,1);
+      execve(argv[2],argv+2,envp);
+    }
+  }
 
-       return -1;
+  return -1;
 
 }
-- 
2.43.0