make exec keep its argument list more reliably

Bits of exec code were putting the constructed commands into globals
PL_Argv and PL_Cmd, which could then be clobbered by reentrancy.
These are only global in order to manage their freeing, but that's
better managed by using the scope stack.  So replace them with automatic
variables, with ENTER/SAVEFREEPV/LEAVE to free the memory.  Also copy
the strings acquired from SVs, to avoid magic clobbering the buffers of
SVs already read.  Fixes [perl #129888].

1 files changed, 35 insertions, 31 deletions

diff --git a/amigaos4/amigaio.c b/amigaos4/amigaio.c
index b471220260..edc237a033 100644
--- a/amigaos4/amigaio.c
+++ b/amigaos4/amigaio.c
@@ -646,7 +646,7 @@ static void S_exec_failed(pTHX_ const char *cmd, int fd, int do_report)
 static I32 S_do_amigaos_exec3(pTHX_ const char *incmd, int fd, int do_report)
 {
 	dVAR;
-	const char **a;
+	const char **argv, **a;
 	char *s;
 	char *buf;
 	char *cmd;
@@ -656,7 +656,9 @@ static I32 S_do_amigaos_exec3(pTHX_ const char *incmd, int fd, int do_report)
 
 	PERL_ARGS_ASSERT_DO_EXEC3;
 
+	ENTER;
 	Newx(buf, cmdlen, char);
+	SAVEFREEPV(buf);
 	cmd = buf;
 	memcpy(cmd, incmd, cmdlen);
 
@@ -709,15 +711,16 @@ doshell:
 			PERL_FPU_POST_EXEC
 			S_exec_failed(aTHX_ PL_sh_path, fd, do_report);
 			amigaos_post_exec(fd, do_report);
-			Safefree(buf);
-			return result;
+			goto leave;
 		}
 	}
 
-	Newx(PL_Argv, (s - cmd) / 2 + 2, const char *);
-	PL_Cmd = savepvn(cmd, s - cmd);
-	a = PL_Argv;
-	for (s = PL_Cmd; *s;)
+	Newx(argv, (s - cmd) / 2 + 2, const char *);
+	SAVEFREEPV(argv);
+	cmd = savepvn(cmd, s - cmd);
+	SAVEFREEPV(cmd);
+	a = argv;
+	for (s = cmd; *s;)
 	{
 		while (isSPACE(*s))
 			s++;
@@ -729,22 +732,18 @@ doshell:
 			*s++ = '\0';
 	}
 	*a = NULL;
-	if (PL_Argv[0])
+	if (argv[0])
 	{
 		PERL_FPU_PRE_EXEC
-		result = myexecvp(FALSE, PL_Argv[0], EXEC_ARGV_CAST(PL_Argv));
+		result = myexecvp(FALSE, argv[0], EXEC_ARGV_CAST(argv));
 		PERL_FPU_POST_EXEC
-		if (errno == ENOEXEC)
-		{
-			/* for system V NIH syndrome */
-			do_execfree();
+		if (errno == ENOEXEC) /* for system V NIH syndrome */
 			goto doshell;
-		}
-		S_exec_failed(aTHX_ PL_Argv[0], fd, do_report);
+		S_exec_failed(aTHX_ argv[0], fd, do_report);
 		amigaos_post_exec(fd, do_report);
 	}
-	do_execfree();
-	Safefree(buf);
+leave:
+	LEAVE;
 	return result;
 }
 
@@ -754,42 +753,47 @@ I32 S_do_amigaos_aexec5(
 	dVAR;
 	I32 result = -1;
 	PERL_ARGS_ASSERT_DO_AEXEC5;
+	ENTER;
 	if (sp > mark)
 	{
-		const char **a;
+		const char **argv, **a;
 		const char *tmps = NULL;
-		Newx(PL_Argv, sp - mark + 1, const char *);
-		a = PL_Argv;
+		Newx(argv, sp - mark + 1, const char *);
+		SAVEFREEPV(argv);
+		a = argv;
 
 		while (++mark <= sp)
 		{
-			if (*mark)
-				*a++ = SvPV_nolen_const(*mark);
-			else
+			if (*mark) {
+				char *arg = savepv(SvPV_nolen_const(*mark));
+				SAVEFREEPV(arg);
+				*a++ = arg;
+			} else
 				*a++ = "";
 		}
 		*a = NULL;
-		if (really)
-			tmps = SvPV_nolen_const(really);
-		if ((!really && *PL_Argv[0] != '/') ||
+		if (really) {
+			tmps = savepv(SvPV_nolen_const(really));
+			SAVEFREEPV(tmps);
+		}
+		if ((!really && *argv[0] != '/') ||
 		        (really && *tmps != '/')) /* will execvp use PATH? */
 			TAINT_ENV(); /* testing IFS here is overkill, probably
                                         */
 		PERL_FPU_PRE_EXEC
 		if (really && *tmps)
 		{
-			result = myexecvp(FALSE, tmps, EXEC_ARGV_CAST(PL_Argv));
+			result = myexecvp(FALSE, tmps, EXEC_ARGV_CAST(argv));
 		}
 		else
 		{
-			result = myexecvp(FALSE, PL_Argv[0],
-			                  EXEC_ARGV_CAST(PL_Argv));
+			result = myexecvp(FALSE, argv[0], EXEC_ARGV_CAST(argv));
 		}
 		PERL_FPU_POST_EXEC
-		S_exec_failed(aTHX_(really ? tmps : PL_Argv[0]), fd, do_report);
+		S_exec_failed(aTHX_(really ? tmps : argv[0]), fd, do_report);
 	}
 	amigaos_post_exec(fd, do_report);
-	do_execfree();
+	LEAVE;
 	return result;
 }