Add environment variables that lets the user override the option classes of ssh

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

5 files changed, 482 insertions, 42 deletions

diff --git a/LICENSE b/LICENSE
index 6ddac9a..73634bb 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 ISC License
 
-© 2023 Mattias Andrée <m@maandree.se>
+© 2023, 2024, 2025 Mattias Andrée <m@maandree.se>
 
 Permission to use, copy, modify, and/or distribute this software for any
 purpose with or without fee is hereby granted, provided that the above
diff --git a/README b/README
index d7cbe87..8476cee 100644
--- a/README
+++ b/README
@@ -148,6 +148,78 @@ OPERANDS
 		command must not contain an equals sign (=) or be just
 		a dash ("-").
 
+ENVIRONMENT VARIABLES
+	The following environment variables affects the execution of
+	sshexec:
+
+	PATH
+		Default. See to the Base Definitions volume of POSIX.1-2017,
+		Section 8.3, Other Environment Variables. This environment
+		variable affects where the sshexec utility can find the
+		ssh(1) utility or ssh-command.
+
+	SSHEXEC_OPTS_NO_ARG
+		List of options that sshexec shall interpret as ssh(1)
+		options that do not have any argument. (Default is
+		46AaCfGgKkMNnqsTtVvXxYy, meaning the options -4, -6, -A,
+		-a, -C, -f, -G, -g, -K, -k, -M, -N, -n, -q, -s, -T, -t,
+		-V, -v, -X, -x, -Y, and -y.)
+
+	SSHEXEC_OPTS_ARG
+		List of options that sshexec shall interpret as ssh(1)
+		options that have an argument. (Default is
+		BbcDEeFIiJLlmOoPpQRSWw, meaning the options -B, -b, -c,
+		-D, -E, -e, -F, -I, -i, -J, -L, -l, -m, -O, -o, -P, -p,
+		-Q, -R, -S, -W, and -w.)
+
+	SSHEXEC_OPTS_OPT_ATTACHED_ARG
+		List of options that sshexec shall interpret as ssh(1)
+		options that have an argument only if there are
+		additional characters after the option character in the
+		same command line argument. (Default is the empty
+		string, meaning no options.)
+
+	SSHEXEC_OPTS_OPT_ARG
+		List of options that sshexec shall interpret as ssh(1)
+		options that have an argument if there are additional
+		characters after the option character in the same
+		command line argument or if argument is followed
+		directly by another argument which does not start with
+		a dash (-). (Default is the empty string, meaning no
+		options.)
+
+	SSHEXEC_LONG_OPTS_NO_ARG
+		Space-separated list of long options that sshexec shall
+		interpret as ssh(1) options that do not have any
+		argument unless it is followed directly by an equals
+		sign (=) in the same command line argument. Options
+		that do not start with two dashes (--) are silently
+		ignored. (Default is the empty string, meaning no
+		options.)
+
+	SSHEXEC_LONG_OPTS_ARG
+		Space-separated list of long options that sshexec shall
+		interpret as ssh(1) options that have an argument that
+		must either be specified in the next command line
+		argument or after an equals sign (=) the shall directly
+		follow the option string in the same command line
+		argument. Options that do not start with two dashes
+		(--) are silently ignored. (Default is the empty string,
+		meaning no options.)
+
+	SSHEXEC_LONG_OPTS_OPT_ARG
+		Space-separated list of long options that sshexec shall
+		interpret as ssh(1) options that have an argument if
+		it is the option string is is directly followed by
+		equals sign (=) in the same command line argument or if
+		argument is followed directly by another argument which
+		does not start with a dash (-). Options that do not
+		start with two dashes (--) are silently ignored.
+		(Default is the empty string, meaning no options.)
+
+	Other environment variables may affect the execution of the
+	ssh(1) utility.
+
 BUGS
 	The remote shell must be sufficiently similar to sh(1posix).
 	Namely, it must support the cd builtin command and the commands
diff --git a/sshcd.1 b/sshcd.1
index ba08414..7b5ede4 100644
--- a/sshcd.1
+++ b/sshcd.1
@@ -123,7 +123,7 @@ None.
 The following environment variables affects the execution of
 .BR sshcd :
 .TP
-.SH PATH
+.I PATH
 Default. See to the Base Definitions volume of POSIX.1-2017, Section 8.3, Other Environment Variables.
 This environment variable affects where the
 .B sshcd
@@ -132,13 +132,156 @@ utility can find the
 utility or
 .IR ssh-command .
 .TP
-.B SSHCD_PTY_ALLOC_FLAG
+.I SSHCD_PTY_ALLOC_FLAG
 Specifies the option to pass to
 .BR ssh (1)
 to tell SSH to allocate a pseudo terminal. If unset
 .B -t
 will be used. If set but empty, no flag will be passed to
 .BR ssh (1).
+.TP
+.I SSHEXEC_OPTS_NO_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that do not have any argument.
+(Default is
+.BR 46AaCfGgKkMNnqsTtVvXxYy ,
+meaning the options
+.BR -4 ,
+.BR -6 ,
+.BR -A ,
+.BR -a ,
+.BR -C ,
+.BR -f ,
+.BR -G ,
+.BR -g ,
+.BR -K ,
+.BR -k ,
+.BR -M ,
+.BR -N ,
+.BR -n ,
+.BR -q ,
+.BR -s ,
+.BR -T ,
+.BR -t ,
+.BR -V ,
+.BR -v ,
+.BR -X ,
+.BR -x ,
+.BR -Y ,
+and
+.BR -y .)
+.TP
+.I SSHEXEC_OPTS_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument.
+(Default is
+.BR BbcDEeFIiJLlmOoPpQRSWw ,
+meaning the options
+.BR -B ,
+.BR -b ,
+.BR -c ,
+.BR -D ,
+.BR -E ,
+.BR -e ,
+.BR -F ,
+.BR -I ,
+.BR -i ,
+.BR -J ,
+.BR -L ,
+.BR -l ,
+.BR -m ,
+.BR -O ,
+.BR -o ,
+.BR -P ,
+.BR -p ,
+.BR -Q ,
+.BR -R ,
+.BR -S ,
+.BR -W ,
+and
+.BR -w .)
+.TP
+.I SSHEXEC_OPTS_OPT_ATTACHED_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument only if
+there are additional characters after
+the option character in the same
+command line argument. (Default is
+the empty string, meaning no options.)
+.TP
+.I SSHEXEC_OPTS_OPT_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument if there
+are additional characters after
+the option character in the same
+command line argument or if argument is
+followed directly by another argument
+which does not start with a dash
+.RB ( - ).
+(Default is
+the empty string, meaning no options.)
+.TP
+.I SSHEXEC_LONG_OPTS_NO_ARG
+Space-separated list of long options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that do not have any argument
+unless it is followed directly by an
+equals sign
+.RB ( = )
+in the same command line argument.
+Options that do not start with two dashes
+.RB ( -- )
+are silently ignored. (Default is the
+empty string, meaning no options.)
+.TP
+.I SSHEXEC_LONG_OPTS_ARG
+Space-separated list of long options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument that must
+either be specified in the next command
+line argument or after an
+equals sign
+.RB ( = )
+the shall directly follow the option
+string in the same command line argument.
+Options that do not start with two dashes
+.RB ( -- )
+are silently ignored. (Default is the
+empty string, meaning no options.)
+.TP
+.I SSHEXEC_LONG_OPTS_OPT_ARG
+Space-separated list of long options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument if it is
+the option string is is directly followed
+by equals sign
+.RB ( = )
+in the same command line argument or if
+argument is followed directly by another
+argument which does not start with a dash
+.RB ( - ).
+Options that do not start with two dashes
+.RB ( -- )
+are silently ignored. (Default is the
+empty string, meaning no options.)
 .PP
 Other environment variables may affect the execution of the
 .BR ssh (1)
diff --git a/sshexec.1 b/sshexec.1
index d4ace81..9f37962 100644
--- a/sshexec.1
+++ b/sshexec.1
@@ -287,7 +287,7 @@ None.
 The following environment variables affects the execution of
 .BR sshexec :
 .TP
-.SH PATH
+.I PATH
 Default. See to the Base Definitions volume of POSIX.1-2017, Section 8.3, Other Environment Variables.
 This environment variable affects where the
 .B sshexec
@@ -295,6 +295,149 @@ utility can find the
 .BR ssh (1)
 utility or
 .IR ssh-command .
+.TP
+.I SSHEXEC_OPTS_NO_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that do not have any argument.
+(Default is
+.BR 46AaCfGgKkMNnqsTtVvXxYy ,
+meaning the options
+.BR -4 ,
+.BR -6 ,
+.BR -A ,
+.BR -a ,
+.BR -C ,
+.BR -f ,
+.BR -G ,
+.BR -g ,
+.BR -K ,
+.BR -k ,
+.BR -M ,
+.BR -N ,
+.BR -n ,
+.BR -q ,
+.BR -s ,
+.BR -T ,
+.BR -t ,
+.BR -V ,
+.BR -v ,
+.BR -X ,
+.BR -x ,
+.BR -Y ,
+and
+.BR -y .)
+.TP
+.I SSHEXEC_OPTS_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument.
+(Default is
+.BR BbcDEeFIiJLlmOoPpQRSWw ,
+meaning the options
+.BR -B ,
+.BR -b ,
+.BR -c ,
+.BR -D ,
+.BR -E ,
+.BR -e ,
+.BR -F ,
+.BR -I ,
+.BR -i ,
+.BR -J ,
+.BR -L ,
+.BR -l ,
+.BR -m ,
+.BR -O ,
+.BR -o ,
+.BR -P ,
+.BR -p ,
+.BR -Q ,
+.BR -R ,
+.BR -S ,
+.BR -W ,
+and
+.BR -w .)
+.TP
+.I SSHEXEC_OPTS_OPT_ATTACHED_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument only if
+there are additional characters after
+the option character in the same
+command line argument. (Default is
+the empty string, meaning no options.)
+.TP
+.I SSHEXEC_OPTS_OPT_ARG
+List of options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument if there
+are additional characters after
+the option character in the same
+command line argument or if argument is
+followed directly by another argument
+which does not start with a dash
+.RB ( - ).
+(Default is
+the empty string, meaning no options.)
+.TP
+.I SSHEXEC_LONG_OPTS_NO_ARG
+Space-separated list of long options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that do not have any argument
+unless it is followed directly by an
+equals sign
+.RB ( = )
+in the same command line argument.
+Options that do not start with two dashes
+.RB ( -- )
+are silently ignored. (Default is the
+empty string, meaning no options.)
+.TP
+.I SSHEXEC_LONG_OPTS_ARG
+Space-separated list of long options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument that must
+either be specified in the next command
+line argument or after an
+equals sign
+.RB ( = )
+the shall directly follow the option
+string in the same command line argument.
+Options that do not start with two dashes
+.RB ( -- )
+are silently ignored. (Default is the
+empty string, meaning no options.)
+.TP
+.I SSHEXEC_LONG_OPTS_OPT_ARG
+Space-separated list of long options that
+.B sshexec
+shall interpret as
+.BR ssh (1)
+options that have an argument if it is
+the option string is is directly followed
+by equals sign
+.RB ( = )
+in the same command line argument or if
+argument is followed directly by another
+argument which does not start with a dash
+.RB ( - ).
+Options that do not start with two dashes
+.RB ( -- )
+are silently ignored. (Default is the
+empty string, meaning no options.)
 .PP
 Other environment variables may affect the execution of the
 .BR ssh (1)
diff --git a/sshexec.c b/sshexec.c
index e8089a6..7ed551a 100644
--- a/sshexec.c
+++ b/sshexec.c
@@ -60,26 +60,6 @@ struct redirection {
 };
 
 
-static const enum optclass {
-	NO_RECOGNISED = 0,
-	NO_ARGUMENT,
-	MANDATORY_ARGUMENT
-} sshopts[(size_t)1 << CHAR_BIT] = {
-#define X(F) [F] = NO_ARGUMENT
-	X('4'), X('6'), X('A'), X('a'), X('C'), X('f'), X('G'),
-	X('g'), X('K'), X('k'), X('M'), X('N'), X('n'), X('q'),
-	X('s'), X('T'), X('t'), X('V'), X('v'), X('X'), X('x'),
-	X('Y'), X('y'),
-#undef X
-#define X(F) [F] = MANDATORY_ARGUMENT
-	X('B'), X('b'), X('c'), X('D'), X('E'), X('e'), X('F'),
-	X('I'), X('i'), X('J'), X('L'), X('l'), X('m'), X('O'),
-	X('o'), X('P'), X('p'), X('Q'), X('R'), X('S'), X('W'),
-	X('w')
-#undef X
-};
-
-
 /**
  * Command being constructor for ssh(1)
  */
@@ -375,6 +355,45 @@ extract_directory_from_destination(void)
 
 
 /**
+ * Get an environment variable or a default value
+ * 
+ * @param   var  The name of the environment variable
+ * @param   def  The default value to return if the environment variable is not set
+ * @return       The value of the environment variable, or the default value if unset
+ */
+static const char *
+get(const char *var, const char *def)
+{
+	const char *ret = getenv(var);
+	return ret ? ret : def;
+}
+
+
+/**
+ * Check if a string appears as a word in another string
+ * 
+ * @param   set     The string to search in; words are separated by spaces
+ * @param   sought  The string to search for
+ * @return          1 if the string is found, 0 otherwise
+ */
+#if defined(__GNUC__)
+__attribute__((__pure__))
+#endif
+static int
+contains(const char *set, const char *sought)
+{
+	size_t m, n = strlen(sought);
+	const char *p, *q;
+	for (p = set; (q = strchr(p, ' ')); p = &q[1]) {
+		m = (size_t)(q - p);
+		if (m == n && !strncmp(p, sought, n))
+			return 1;
+	}
+	return !strcmp(p, sought);
+}
+
+
+/**
  * Read and parse the sshexec options
  *
  * @param   argv  The arguments from the command line after
@@ -495,42 +514,107 @@ end_of_options:
  *                     arguments, this includes all arguments the
  *                     return value offsets `argv` except the "--"
  *                     (if there is one), so this includes both
- *                     the options themselves and their arguments
+ *                     the options themselves and their arguments,
+ *                     and joined options countas one
  * @return             `argv` offset to skip pass any ssh(1) options,
  *                     and any "--" immediately after them
  */
 static char **
 parse_ssh_options(char *argv[], size_t *nopts_out)
 {
-	enum optclass class;
+	const char *unarged_opts;
+	const char *arged_opts;
+	const char *optatarged_opts;
+	const char *optarged_opts;
+	const char *unarged_longopts;
+	const char *arged_longopts;
+	const char *optarged_longopts;
 	const char *arg;
-	char opt;
 	size_t nopts = 0;
 
+	/* Get option syntax from the environment */
+	unarged_opts = get("SSHEXEC_OPTS_NO_ARG", "46AaCfGgKkMNnqsTtVvXxYy");
+	arged_opts = get("SSHEXEC_OPTS_ARG", "BbcDEeFIiJLlmOoPpQRSWw");
+	optatarged_opts = get("SSHEXEC_OPTS_OPT_ATTACHED_ARG", "");
+	optarged_opts = get("SSHEXEC_OPTS_OPT_ARG", "");
+	unarged_longopts = get("SSHEXEC_LONG_OPTS_NO_ARG", "");
+	arged_longopts = get("SSHEXEC_LONG_OPTS_ARG", "");
+	optarged_longopts = get("SSHEXEC_LONG_OPTS_OPT_ARG", "");
+
+	/* Count option arguments from the command line */
 	while (*argv) {
+		/* Break at the first non-option */
 		if (!strcmp(*argv, "--")) {
 			argv++;
 			break;
 		} else if ((*argv)[0] != '-' || !(*argv)[1]) {
 			break;
 		}
-		arg = &(*argv++)[1];
+
+		arg = *argv++;
 		nopts++;
-		while (*arg) {
-			opt = *arg++;
-			class = sshopts[(unsigned char)opt];
-			if (class == MANDATORY_ARGUMENT) {
-				if (*arg) {
-					break;
-				} else if (*argv) {
+		if (arg[1] == '-') {
+			/* Long option */
+			if (strchr(arg, '=')) {
+				/* Option has attach argument */
+			} else if (contains(unarged_longopts, arg)) {
+				/* Option cannot have an argument */
+			} else if (contains(arged_longopts, arg)) {
+				/* Option has detached argument  */
+				if (!*argv)
+					exitf("%s: argument missing for option %s\n", argv0, arg);
+				argv++;
+				nopts++;
+			} else if (contains(optarged_longopts, arg)) {
+				/* Long option with either detached argument or no argument */
+				if (*argv && **argv != '-') {
+					/* The option has a detached argument */
 					argv++;
 					nopts++;
+				}
+			} else {
+				exitf("%s: unrecognised option %s\n", argv0, arg);
+			}
+		} else {
+			/* Short option */
+			arg++;
+			while (*arg) {
+				if (strchr(unarged_opts, *arg)) {
+					/* Option cannot have an argument */
+				} else if (strchr(arged_opts, *arg)) {
+					/* Option must have an argument */
+					if (arg[1]) {
+						/* Argument is attached to option */
+						break;
+					} else if (argv[1]) {
+						/* Argument is detached from option */
+						argv++;
+						nopts++;
+						break;
+					} else {
+						exitf("%s: argument missing for option -%c\n", argv0, *arg);
+					}
+				} else if (strchr(optatarged_opts, *arg)) {
+					/* Option may have an attached argument, but it cannot have a detached argument */
 					break;
+				} else if (strchr(optarged_opts, *arg)) {
+					/* Option may have an attached or detached argument */
+					if (arg[1]) {
+						/* Argument is attached to option */
+					} else {
+						/* Either there is no argument, or it is detached from the option */
+						if (argv[1] && argv[1][0] != '-') {
+							/* Argument exist and is detached. We assume that if the next
+							 * argument in the command line is the option's argument unless
+							 * it starts with '-'. */
+							argv++;
+							nopts++;
+							break;
+						}
+					}
 				} else {
-					exitf("%s: argument missing for option -%c\n", argv0, opt);
+					exitf("%s: unrecognised option -%c\n", argv0, *arg);
 				}
-			} else if (class == NO_RECOGNISED) {
-				exitf("%s: unrecognised option -%c\n", argv0, opt);
 			}
 		}
 	}
@@ -582,10 +666,8 @@ main(int argc_unused, char *argv[])
 		exitf("%s: could not allocate enough memory\n", argv0);
 	args[i++] = ssh;
 	if (is_sshcd) {
-		const char *pty_alloc_flag = getenv("SSHCD_PTY_ALLOC_FLAG");
-		if (!pty_alloc_flag)
-			args[i++] = "-t";
-		else if (*pty_alloc_flag)
+		const char *pty_alloc_flag = get("SSHCD_PTY_ALLOC_FLAG", "-t");
+		if (*pty_alloc_flag)
 			args[i++] = pty_alloc_flag;
 	}
 	memcpy(&args[i], opts, nopts * sizeof(*opts));