ash,hush: show 'c' in $- if run in "sh -c CMD"

function                                             old     new   delta
options                                              552     599     +47
expand_one_var                                      2375    2385     +10
optletters_optnames                                   60      64      +4
hush_main                                           1108    1111      +3
ash_main                                            1150    1152      +2
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 5/0 up/down: 66/0)               Total: 66 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 50 insertions, 25 deletions

diff --git a/shell/ash.c b/shell/ash.c
index c8857366c..e3bbac9a0 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -315,17 +315,18 @@ static const char *const optletters_optnames[] = {
 	"e"   "errexit",
 	"f"   "noglob",
 	"I"   "ignoreeof",
-/* The below allows this invocation:
+/* The below allowed this invocation:
  * ash -c 'set -i; echo $-; sleep 5; echo $-'
  * to be ^C-ed and get to interactive ash prompt.
- * bash does not support this "set -i". bash also has no
- * "set -o interactive".
+ * bash does not support such "set -i".
+ * In our code, this is denoted by empty long name:
  */
-	"i"   "interactive",
+	"i"   "",
 	"m"   "monitor",
 	"n"   "noexec",
-/* Ditto: bash has no "set -s" and "set -o stdin" */
-	"s"   "stdin",
+/* Ditto: bash has no "set -s" */
+	"s"   "",
+	"c"   "",
 	"x"   "xtrace",
 	"v"   "verbose",
 	"C"   "noclobber",
@@ -359,7 +360,6 @@ static const char *const optletters_optnames[] = {
 #define optletters(n)  optletters_optnames[n][0]
 #define optnames(n)   (optletters_optnames[n] + 1)
 
-
 enum { NOPTS = ARRAY_SIZE(optletters_optnames) };
 
 
@@ -419,21 +419,22 @@ struct globals_misc {
 #define mflag optlist[4]
 #define nflag optlist[5]
 #define sflag optlist[6]
-#define xflag optlist[7]
-#define vflag optlist[8]
-#define Cflag optlist[9]
-#define aflag optlist[10]
-#define bflag optlist[11]
-#define uflag optlist[12]
-#define viflag optlist[13]
+#define cflag optlist[7]
+#define xflag optlist[8]
+#define vflag optlist[9]
+#define Cflag optlist[10]
+#define aflag optlist[11]
+#define bflag optlist[12]
+#define uflag optlist[13]
+#define viflag optlist[14]
 #if BASH_PIPEFAIL
-# define pipefail optlist[14]
+# define pipefail optlist[15]
 #else
 # define pipefail 0
 #endif
 #if DEBUG
-# define nolog optlist[14 + BASH_PIPEFAIL]
-# define debug optlist[15 + BASH_PIPEFAIL]
+# define nolog optlist[15 + BASH_PIPEFAIL]
+# define debug optlist[16 + BASH_PIPEFAIL]
 #endif
 
 	/* trap handler commands */
@@ -11104,7 +11105,7 @@ setoption(int flag, int val)
 	int i;
 
 	for (i = 0; i < NOPTS; i++) {
-		if (optletters(i) == flag) {
+		if (optletters(i) == flag && optnames(i)[0] != '\0') {
 			optlist[i] = val;
 			return;
 		}
@@ -11150,6 +11151,15 @@ options(int *login_sh)
 				/* bash 3.2 indeed handles -c CMD and +c CMD the same */
 				if (c == 'c') {
 					minusc = p; /* command is after shell args */
+					cflag = 1;
+					continue;
+				}
+				if (c == 's') { /* -s, +s */
+					sflag = 1;
+					continue;
+				}
+				if (c == 'i') { /* -i, +i */
+					iflag = 1;
 					continue;
 				}
 				if (c == 'l') {
@@ -14170,8 +14180,13 @@ procargs(char **argv)
 			ash_msg_and_raise_error(bb_msg_requires_arg, "-c");
 		sflag = 1;
 	}
-	if (iflag == 2 && sflag == 1 && isatty(0) && isatty(1))
+	if (iflag == 2 /* no explicit -i given */
+	 && sflag == 1 /* -s given (or implied) */
+	 && !minusc /* bash compat: ash -sc 'echo $-' is not interactive (dash is) */
+	 && isatty(0) && isatty(1) /* we are on tty */
+	) {
 		iflag = 1;
+	}
 	if (mflag == 2)
 		mflag = iflag;
 	for (i = 0; i < NOPTS; i++)
@@ -14359,10 +14374,17 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
 		 * Ensure we don't falsely claim that 0 (stdin)
 		 * is one of stacked source fds.
 		 * Testcase: ash -c 'exec 1>&0' must not complain. */
+
 		// if (!sflag) g_parsefile->pf_fd = -1;
 		// ^^ not necessary since now we special-case fd 0
 		// in save_fd_on_redirect()
-		evalstring(minusc, sflag ? 0 : EV_EXIT);
+
+		// dash: evalstring(minusc, sflag ? 0 : EV_EXIT);
+		// The above makes
+		//  ash -sc 'echo $-'
+		// continue reading input from stdin after running 'echo'.
+		// bash does not do this: it prints "hBcs" and exits.
+		evalstring(minusc, EV_EXIT);
 	}
 
 	if (sflag || minusc == NULL) {
diff --git a/shell/hush.c b/shell/hush.c
index 4b08232a4..f82747f74 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -903,6 +903,7 @@ struct globals {
 # define G_x_mode 0
 #endif
 	char opt_s;
+	char opt_c;
 #if ENABLE_HUSH_INTERACTIVE
 	smallint promptmode; /* 0: PS1, 1: PS2 */
 #endif
@@ -1009,7 +1010,7 @@ struct globals {
 	int debug_indent;
 #endif
 	struct sigaction sa;
-	char optstring_buf[sizeof("eixs")];
+	char optstring_buf[sizeof("eixcs")];
 #if BASH_EPOCH_VARS
 	char epoch_buf[sizeof("%lu.nnnnnn") + sizeof(long)*3];
 #endif
@@ -6414,9 +6415,10 @@ static NOINLINE int expand_one_var(o_string *output, int n,
 			 * commands read but are not executed,
 			 * so $- can not execute too, 'n' is never seen in $-.
 			 */
+			if (G.opt_c)
+				*cp++ = 'c';
 			if (G.opt_s)
 				*cp++ = 's';
-//TODO: show 'c' if executed via "hush -c 'CMDS'" (bash only, not ash)
 			*cp = '\0';
 			break;
 		}
@@ -9859,7 +9861,6 @@ int hush_main(int argc, char **argv)
 {
 	enum {
 		OPT_login = (1 << 0),
-		OPT_s     = (1 << 1),
 	};
 	unsigned flags;
 	unsigned builtin_argc;
@@ -10029,6 +10030,7 @@ int hush_main(int argc, char **argv)
 				}
 				goto final_return;
 			}
+			G.opt_c = 1;
 			if (!G.global_argv[0]) {
 				/* -c 'script' (no params): prevent empty $0 */
 				G.global_argv--; /* points to argv[i] of 'script' */
@@ -10044,7 +10046,7 @@ int hush_main(int argc, char **argv)
 			/* G_interactive_fd++; */
 			break;
 		case 's':
-			flags |= OPT_s;
+			G.opt_s = 1;
 			break;
 		case 'l':
 			flags |= OPT_login;
@@ -10154,7 +10156,7 @@ int hush_main(int argc, char **argv)
 	}
 
 	/* -s is: hush -s ARGV1 ARGV2 (no SCRIPT) */
-	if (!(flags & OPT_s) && G.global_argv[1]) {
+	if (!G.opt_s && G.global_argv[1]) {
 		HFILE *input;
 		/*
 		 * "bash <script>" (which is never interactive (unless -i?))
@@ -10178,6 +10180,7 @@ int hush_main(int argc, char **argv)
 #endif
 		goto final_return;
 	}
+	/* "implicit" -s: bare interactive hush shows 's' in $- */
 	G.opt_s = 1;
 
 	/* Up to here, shell was non-interactive. Now it may become one.