Add support for redirecting file descriptors1.1

Signed-off-by: Mattias Andrée <maandree@kth.se>

2 files changed, 143 insertions, 6 deletions

diff --git a/sshexec.1 b/sshexec.1
index b734c5b..0dfe121 100644
--- a/sshexec.1
+++ b/sshexec.1
@@ -6,8 +6,9 @@ sshexec - run a command through ssh(1) with normal command syntax
 .SH SYNOPSIS
 .B sshexec
 .RB [ {
-.RI [\fBssh= ssh-command ]
-.RI [\fBdir= directory ]
+.RI [\fBssh=\fP ssh-command ]
+.RI [\fBdir=\fP directory ]
+.RB [[\fIfd\fP]{ > , >> , >| , < , <> }[ & ] = \fIfile\fP]
 .BR } ]
 [ssh-option] ...\,
 .I destination
@@ -97,6 +98,91 @@ In the remote, change working directory to
 .I directory
 before executing
 .IR command .
+.TP
+.IB \fR[\fPfd\fP]\fP >= file
+After changing working directory (assuming one is specified),
+create or truncate the specified
+.I file
+and open it for writing, using file descriptor number
+.IR fd .
+(Default
+.I fd
+is 1 (standard output).)
+.TP
+.IB \fR[\fPfd\fP]\fP >>= file
+After changing working directory (assuming one is specified),
+create the specified
+.I file
+if it does not exist and open it for writing in
+append-mode, using file descriptor number
+.IR fd .
+(Default
+.I fd
+is 1 (standard output).)
+.TP
+.IB \fR[\fPfd\fP]\fP >|= file
+After changing working directory (assuming one is specified),
+create the specified
+.IR file ,
+but fail if it already exists, and open it for writing,
+using file descriptor number
+.IR fd .
+(Default
+.I fd
+is 1 (standard output).)
+.TP
+.IB \fR[\fPfd\fP]\fP <= file
+After changing working directory (assuming one is specified),
+open the specified
+.IR file ,
+for reading, using file descriptor number
+.IR fd .
+(Default
+.I fd
+is 0 (standard input).)
+.TP
+.IB \fR[\fPfd\fP]\fP <>= file
+After changing working directory (assuming one is specified),
+open the specified
+.IR file ,
+for reading and writing, creating it if it does not
+already exist, using file descriptor number
+.IR fd .
+(Default
+.I fd
+is 0 (standard input).)
+.TP
+.IB \fR[\fPfd\fP]\fP \fR{\fP>\fP,\fP>>\fP,\fP>|\fP}\fP&= file
+Duplicate the file descriptor
+.I fd
+giving the new file descriptor the number
+.IR file .
+(Default
+.I fd
+is 1 (standard output).)
+.TP
+.IB \fR[\fPfd\fP]\fP \fR{\fP>\fP,\fP>>\fP,\fP>|\fP}\fP&=-
+Close the file descriptor
+.IR fd .
+(Default
+.I fd
+is 1 (standard output).)
+.TP
+.IB \fR[\fPfd\fP]\fP \fR{\fP<\fP,\fP<>\fP}\fP&= file
+Duplicate the file descriptor
+.I fd
+giving the new file descriptor the number
+.IR file .
+(Default
+.I fd
+is 0 (standard input).)
+.TP
+.IB \fR[\fPfd\fP]\fP \fR{\fP<\fP,\fP<>\fP}\fP&=-
+Close the file descriptor
+.IR fd .
+(Default
+.I fd
+is 0 (standard input).)
 
 .SH OPERANDS
 The following operands are supported:
diff --git a/sshexec.c b/sshexec.c
index f8eaed6..1ad2cf8 100644
--- a/sshexec.c
+++ b/sshexec.c
@@ -19,9 +19,16 @@ static void
 usage(void)
 {
 	exitf("usage: %s [{ %s }] [ssh-option] ... destination command [argument] ...\n",
-	      argv0, "[ssh=command] [dir=directory]");
+	      argv0, "[ssh=command] [dir=directory] [[fd]{>,>>,>|,<>}[&]=file]");
 }
 
+
+struct redirection {
+	const char *asis;
+	const char *escape;
+};
+
+
 static const enum optclass {
 	NO_RECOGNISED = 0,
 	NO_ARGUMENT,
@@ -54,7 +61,7 @@ static size_t command_len = 0;
 	} while (0)
 
 #define build_command_asis(S)\
-	build_command(S, sizeof(S) - 1)
+	build_command(S, strlen(S))
 
 #define finalise_command()\
 	build_command("", 1)
@@ -122,8 +129,10 @@ main(int argc_unused, char *argv[])
 {
 	const char *dir = NULL;
 	const char *ssh = NULL;
+	struct redirection *redirections = NULL;
+	size_t nredirections = 0;
 	const char *destination;
-	char **opts;
+	char **opts, *p;
 	size_t nopts;
 	enum optclass class;
 	const char *arg;
@@ -142,17 +151,51 @@ main(int argc_unused, char *argv[])
 			usage();\
 		continue;\
 	}
+
 	if (*argv && !strcmp(*argv, "{")) {
 		argv++;
 		for (; *argv && strcmp(*argv, "}"); argv++) {
 			STORE_OPT(&ssh, "ssh")
 			STORE_OPT(&dir, "dir")
-			usage();
+
+			p = *argv;
+			while (isdigit(*p))
+				p++;
+			if (p[0] == '>')
+				p = &p[1 + (p[1] == '>' || p[1] == '|')];
+			else if (p[0] == '<')
+				p = &p[1 + (p[1] == '>')];
+			else
+				usage();
+			if (p[p[0] == '&'] != '=')
+				usage(); 
+			redirections = realloc(redirections, (nredirections + 1U) * sizeof(*redirections));
+			if (!redirections)
+				exitf("%s: could not allocate enough memory\n", argv0);
+			if (*p == '&') {
+				p = &p[1];
+				memmove(p, &p[1], strlen(&p[1]) + 1U);
+				if (isdigit(*p)) {
+					p++;
+					while (isdigit(*p))
+						p++;
+				} else if (*p == '-') {
+					p++;
+				}
+				if (*p)
+					usage();
+				redirections[nredirections].escape = NULL;
+			} else {
+				*p++ = '\0';
+				redirections[nredirections].escape = p;
+			}
+			redirections[nredirections++].asis = *argv;
 		}
 		if (!*argv)
 			usage();
 		argv++;
 	}
+
 #undef STORE_OPT
 
 	if (!ssh)
@@ -202,6 +245,14 @@ main(int argc_unused, char *argv[])
 		build_command_asis(" ");
 		build_command_escape(*argv);
 	}
+	for (i = 0; i < nredirections; i++) {
+		build_command_asis(" ");
+		build_command_asis(redirections[i].asis);
+		if (redirections[i].escape) {
+			build_command_asis(" ");
+			build_command_escape(redirections[i].escape);
+		}
+	}
 	finalise_command();
 
 	i = 0;