[fedora-virt] [PATCH] Add pipe support to guestfish
Richard W.M. Jones
rjones at redhat.com
Sat Jun 27 13:32:33 UTC 2009
This patch adds support for pipes to guestfish, so you can pipe output
from a guestfish command through a command on the host. The canonical
example is:
><fs> hexdump /bin/ls | less
Another example, looking for root backdoors in the password file:
><fs> cat /etc/passwd | awk -F: '$3 == 0 { print }' | grep -v ^root:
Anything right of the first pipe symbol gets passed to the local
shell, thus expansion, redirection and so on work on that.
Rich.
>From 57de1f4b17aba957ac18b64fccef66d2f21241d9 Mon Sep 17 00:00:00 2001
From: Richard W.M. Jones <rjones at redhat.com>
Date: Sat, 27 Jun 2009 15:00:48 +0200
Subject: [PATCH] Guestfish pipes.
---
fish/fish.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++----------
fish/fish.h | 2 +-
fish/glob.c | 2 +-
guestfish.pod | 26 +++++++++++++++++
4 files changed, 99 insertions(+), 17 deletions(-)
diff --git a/fish/fish.c b/fish/fish.c
index 5e8a6e9..5b0a065 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -29,6 +29,8 @@
#include <signal.h>
#include <assert.h>
#include <ctype.h>
+#include <sys/types.h>
+#include <sys/wait.h>
#ifdef HAVE_LIBREADLINE
#include <readline/readline.h>
@@ -138,9 +140,15 @@ main (int argc, char *argv[])
struct mp *mp;
char *p, *file = NULL;
int c, inspector = 0;
+ struct sigaction sa;
initialize_readline ();
+ memset (&sa, 0, sizeof sa);
+ sa.sa_handler = SIG_IGN;
+ sa.sa_flags = SA_RESTART;
+ sigaction (SIGPIPE, &sa, NULL);
+
/* guestfs_create is meant to be a lightweight operation, so
* it's OK to do it early here.
*/
@@ -462,6 +470,8 @@ script (int prompt)
"\n"));
while (!quit) {
+ char *pipe = NULL;
+
exit_on_error = global_exit_on_error;
buf = rl_gets (prompt);
@@ -522,9 +532,8 @@ script (int prompt)
/* Get the parameters. */
while (*p && i < sizeof argv / sizeof argv[0]) {
- /* Parameters which start with quotes or square brackets
- * are treated specially. Bare parameters are delimited
- * by whitespace.
+ /* Parameters which start with quotes or pipes are treated
+ * specially. Bare parameters are delimited by whitespace.
*/
if (*p == '"') {
p++;
@@ -556,6 +565,10 @@ script (int prompt)
}
p[len] = '\0';
pend = p[len+1] ? &p[len+2] : &p[len+1];
+ } else if (*p == '|') {
+ *p = '\0';
+ pipe = p+1;
+ continue;
/*
} else if (*p == '[') {
int c = 1;
@@ -607,7 +620,7 @@ script (int prompt)
argv[i] = NULL;
got_command:
- if (issue_command (cmd, argv) == -1) {
+ if (issue_command (cmd, argv, pipe) == -1) {
if (exit_on_error) exit (1);
}
@@ -636,18 +649,51 @@ cmdline (char *argv[], int optind, int argc)
optind++;
if (optind == argc) {
- if (issue_command (cmd, params) == -1) exit (1);
+ if (issue_command (cmd, params, NULL) == -1) exit (1);
} else {
argv[optind] = NULL;
- if (issue_command (cmd, params) == -1) exit (1);
+ if (issue_command (cmd, params, NULL) == -1) exit (1);
cmdline (argv, optind+1, argc);
}
}
int
-issue_command (const char *cmd, char *argv[])
+issue_command (const char *cmd, char *argv[], const char *pipecmd)
{
int argc;
+ int stdout_saved_fd = -1;
+ int pid = 0;
+ int r;
+
+ /* For | ... commands. Annoyingly we can't use popen(3) here. */
+ if (pipecmd) {
+ int fd[2];
+
+ fflush (stdout);
+ pipe (fd);
+ pid = fork ();
+ if (pid == -1) {
+ perror ("fork");
+ return -1;
+ }
+
+ if (pid == 0) { /* Child process. */
+ close (fd[1]);
+ dup2 (fd[0], 0);
+
+ r = system (pipecmd);
+ if (r == -1) {
+ perror (pipecmd);
+ _exit (1);
+ }
+ _exit (WEXITSTATUS (r));
+ }
+
+ stdout_saved_fd = dup (1);
+ close (fd[0]);
+ dup2 (fd[1], 1);
+ close (fd[1]);
+ }
for (argc = 0; argv[argc] != NULL; ++argc)
;
@@ -657,29 +703,39 @@ issue_command (const char *cmd, char *argv[])
list_commands ();
else
display_command (argv[0]);
- return 0;
+ r = 0;
}
else if (strcasecmp (cmd, "quit") == 0 ||
strcasecmp (cmd, "exit") == 0 ||
strcasecmp (cmd, "q") == 0) {
quit = 1;
- return 0;
+ r = 0;
}
else if (strcasecmp (cmd, "alloc") == 0 ||
strcasecmp (cmd, "allocate") == 0)
- return do_alloc (cmd, argc, argv);
+ r = do_alloc (cmd, argc, argv);
else if (strcasecmp (cmd, "echo") == 0)
- return do_echo (cmd, argc, argv);
+ r = do_echo (cmd, argc, argv);
else if (strcasecmp (cmd, "edit") == 0 ||
strcasecmp (cmd, "vi") == 0 ||
strcasecmp (cmd, "emacs") == 0)
- return do_edit (cmd, argc, argv);
+ r = do_edit (cmd, argc, argv);
else if (strcasecmp (cmd, "lcd") == 0)
- return do_lcd (cmd, argc, argv);
+ r = do_lcd (cmd, argc, argv);
else if (strcasecmp (cmd, "glob") == 0)
- return do_glob (cmd, argc, argv);
+ r = do_glob (cmd, argc, argv);
else
- return run_action (cmd, argc, argv);
+ r = run_action (cmd, argc, argv);
+
+ if (pipecmd) {
+ fflush (stdout);
+ close (1);
+ dup2 (stdout_saved_fd, 1);
+ close (stdout_saved_fd);
+ waitpid (pid, NULL, 0);
+ }
+
+ return r;
}
void
diff --git a/fish/fish.h b/fish/fish.h
index 8815807..8f57595 100644
--- a/fish/fish.h
+++ b/fish/fish.h
@@ -34,7 +34,7 @@
extern guestfs_h *g;
extern int quit;
extern int verbose;
-extern int issue_command (const char *cmd, char *argv[]);
+extern int issue_command (const char *cmd, char *argv[], const char *pipe);
extern void pod2text (const char *heading, const char *body);
extern void list_builtin_commands (void);
extern void display_builtin_command (const char *cmd);
diff --git a/fish/glob.c b/fish/glob.c
index f20da84..a8ac58a 100644
--- a/fish/glob.c
+++ b/fish/glob.c
@@ -147,7 +147,7 @@ glob_issue (char *cmd, int argc,
}
printf ("\n");
- if (issue_command (argv[0], &argv[1]) == -1)
+ if (issue_command (argv[0], &argv[1], NULL) == -1)
*r = -1; /* ... but don't exit */
for (i = argc-1; i >= 1; --i) {
diff --git a/guestfish.pod b/guestfish.pod
index 0870b9e..26312fe 100644
--- a/guestfish.pod
+++ b/guestfish.pod
@@ -282,6 +282,32 @@ will create a directory C<local> on the host, and then export
the contents of C</remote> on the mounted filesystem to
C<local/remote-data.tar.gz>. (See C<tgz-out>).
+=head1 PIPES
+
+Use C<command E<lt>spaceE<gt> | command> to pipe the output of the
+first command (a guestfish command) to the second command (any host
+command). For example:
+
+ cat /etc/passwd | awk -F: '$3 == 0 { print }'
+
+(where C<cat> is the guestfish cat command, but C<awk> is the host awk
+program). The above command would list all accounts in the guest
+filesystem which have UID 0, ie. root accounts including backdoors.
+Other examples:
+
+ hexdump /bin/ls | head
+ list-devices | tail -1
+
+The space before the pipe symbol is required, any space after the pipe
+symbol is optional. Everything after the pipe symbol is just passed
+straight to the host shell, so it can contain redirections, globs and
+anything else that makes sense on the host side.
+
+To use a literal argument which begins with a pipe symbol, you have
+to quote it, eg:
+
+ echo "|"
+
=head1 EXIT ON ERROR BEHAVIOUR
By default, guestfish will ignore any errors when in interactive mode
--
1.6.2.2
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/
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