From bb0236cbf76db82e5520a17ce4ea952b3e2c6d28 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Sat, 16 Jul 2022 23:14:39 +0200
Subject: [PATCH] ego uses fork/exec too, so factor out the new system() code
 from ack and use it there.

---
 modules/src/system/build.lua   |  1 +
 modules/src/system/syssystem.c | 42 ++++++++++++++++++++++++++++
 modules/src/system/system.h    |  2 ++
 util/ack/build.lua             |  1 +
 util/ack/run.c                 | 39 ++------------------------
 util/ego/em_ego/em_ego.c       | 51 +++++++++++++---------------------
 6 files changed, 67 insertions(+), 69 deletions(-)
 create mode 100644 modules/src/system/syssystem.c

diff --git a/modules/src/system/build.lua b/modules/src/system/build.lua
index b409f697d..81d28d3af 100644
--- a/modules/src/system/build.lua
+++ b/modules/src/system/build.lua
@@ -8,6 +8,7 @@ clibrary {
 		"./rename.c", "./seek.c", "./stop.c", "./system.c",
 		--"./unlock.c”,”./tmpdir.c”,
 		"./write.c",
+		"./syssystem.c",
 	},
 	hdrs = { "./system.h" },
 }
diff --git a/modules/src/system/syssystem.c b/modules/src/system/syssystem.c
new file mode 100644
index 000000000..c86b0be65
--- /dev/null
+++ b/modules/src/system/syssystem.c
@@ -0,0 +1,42 @@
+#include <stdlib.h>
+#include <string.h>
+#include "system.h"
+
+int sys_system(const char* prog, const char* const* arglist)
+{
+	/* Calculate the maximum length of the command line. */
+
+	int len = strlen(prog);
+	for (const char* const* arg = arglist+1; *arg; arg++)
+		len += strlen(*arg) * 2 + 1;
+
+	/* Now actually build the command line. */
+
+	char* cmdline = malloc(len + 1);
+	strcpy(cmdline, prog);
+	char* p = cmdline + strlen(prog);
+
+	for (const char* const* arg = arglist+1; *arg; arg++)
+	{
+		const char* word = *arg;
+		*p++ = ' ';
+
+		for (;;)
+		{
+			char c = *word++;
+			if (!c)
+				break;
+			if ((c == ' ') || (c == '\"') || (c == '\''))
+				*p++ = '\\';
+			*p++ = c;
+		}
+	}
+
+	*p = 0;
+
+	int status = system(cmdline);
+
+	free(cmdline);
+	return status;
+}
+
diff --git a/modules/src/system/system.h b/modules/src/system/system.h
index 598ceb03f..12c27916b 100644
--- a/modules/src/system/system.h
+++ b/modules/src/system/system.h
@@ -48,6 +48,8 @@ off_t sys_filesize(char *);
 int sys_chmode(char *, int);
 /* Return the temporary directory location */
 char* sys_gettmpdir(void);
+/* Call another program. */
+int sys_system(const char* prog, const char* const* argv);
 #if 0
 int sys_lock(char *);
 int sys_unlock(char *);
diff --git a/util/ack/build.lua b/util/ack/build.lua
index cb9b66fd4..cf4dc9035 100644
--- a/util/ack/build.lua
+++ b/util/ack/build.lua
@@ -34,6 +34,7 @@ cprogram {
 	deps = {
 		"h+emheaders",
 		"h+local",
+		"modules/src/system+lib",
 		"./ack.h",
 		"./data.h",
 		"./dmach.h",
diff --git a/util/ack/run.c b/util/ack/run.c
index d1c4fe730..71eea0592 100644
--- a/util/ack/run.c
+++ b/util/ack/run.c
@@ -15,6 +15,7 @@
 #include "grows.h"
 #include "data.h"
 #include <signal.h>
+#include "system.h"
 
 #ifndef NORCSID
 static char rcs_id[] = "$Id$";
@@ -84,40 +85,6 @@ int runphase(trf* phase)
 	return result;
 }
 
-static char* build_command_line(const char* prog)
-{
-	/* Calculate the maximum length of the command line. */
-
-	int len = strlen(prog);
-	for (int i = 1; i < (argcount - 1); i++)
-		len += strlen(arglist[i]) * 2 + 1;
-
-	/* Now actually build the command line. */
-
-	char* cmdline = malloc(len + 1);
-	strcpy(cmdline, prog);
-	char* p = cmdline + strlen(prog);
-
-	for (int i = 1; i < (argcount - 1); i++)
-	{
-		const char* word = arglist[i];
-		*p++ = ' ';
-
-		for (;;)
-		{
-			char c = *word++;
-			if (!c)
-				break;
-			if ((c == ' ') || (c == '\"') || (c == '\''))
-				*p++ = '\\';
-			*p++ = c;
-		}
-	}
-
-	*p = 0;
-	return cmdline;
-}
-
 static int run_exec(trf* phase, const char* prog)
 {
 	int status, child, waitchild;
@@ -159,9 +126,7 @@ static int run_exec(trf* phase, const char* prog)
 		}
 	}
 
-	char* cmdline = build_command_line(prog);
-	status = system(cmdline);
-	free(cmdline);
+	status = sys_system(prog, arglist);
 
 	if (oldstdin != -1)
 	{
diff --git a/util/ego/em_ego/em_ego.c b/util/ego/em_ego/em_ego.c
index e9f9eb9f8..74ca2c83a 100644
--- a/util/ego/em_ego/em_ego.c
+++ b/util/ego/em_ego/em_ego.c
@@ -11,7 +11,6 @@
 #include <unistd.h>
 #include <signal.h>
 #include <sys/types.h>
-#include <sys/wait.h>
 #include <string.h>
 #include <limits.h>
 #include "em_path.h"
@@ -281,7 +280,7 @@ static void
 			if (descr_file)
 			{
 				phargs[argc++] = "-M";
-				phargs[argc++] = descr_file;
+				phargs[argc++] = (char*) descr_file;
 			}
 
 			for (i=0; i<nphase_args; i++)
@@ -291,40 +290,28 @@ static void
 			break;
 		}
 	}
-	if ((pid = fork()) < 0)
-	{
-		fatal("Could not fork");
-	}
-	else if (pid == 0)
-	{
-		if (v_flag)
-		{
-			register int i = 0;
 
-			while (phargs[i])
-			{
-				fprint(STDERR, "%s ", phargs[i]);
-				i++;
-			}
-			fprint(STDERR, "\n");
-		}
-		(void)execv(phargs[0], phargs);
-		fatal("Could not exec %s", phargs[0]);
-		sys_stop(S_EXIT);
-	}
-	else
+	if (v_flag)
 	{
-		while (wait(&status) != pid) /* nothing */
-			;
-		if ((status & 0177) != 0)
+		register int i = 0;
+
+		while (phargs[i])
 		{
-			fatal("%s got a unix signal", phargs[0]);
-		}
-		if (((status >> 8) & 0377) != 0)
-		{
-			cleanup();
-			sys_stop(S_EXIT);
+			fprint(STDERR, "%s ", phargs[i]);
+			i++;
 		}
+		fprint(STDERR, "\n");
+	}
+
+	status = sys_system(phargs[0], (const char* const*) phargs);
+	if ((status & 0177) != 0)
+	{
+		fatal("%s got a unix signal", phargs[0]);
+	}
+	if (((status >> 8) & 0377) != 0)
+	{
+		cleanup();
+		sys_stop(S_EXIT);
 	}
 }