From f0dea66749bb599f65762991f4fded229c3df5a3 Mon Sep 17 00:00:00 2001
From: Ron Yorston <rmy@pobox.com>
Date: Sun, 20 Oct 2024 14:23:43 +0100
Subject: make: enforce restrictions on prerequisites/commands

POSIX mentions some restrictions on whether rules may or may not
have prerequisites or commands:

- most special targets shouldn't have commnds;

- inference/.DEFAULT rules shouldn't have prerequisites.

Enforce these restrictions in POSIX mode.

Generally, implementations are happy to accept prerequisites or
commands even if they're subsequently ignored.  Allow this as an
extension.

Adds 216-256 bytes.
---
 miscutils/make.c | 54 +++++++++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 45 insertions(+), 9 deletions(-)

(limited to 'miscutils')

diff --git a/miscutils/make.c b/miscutils/make.c
index df810677f..bf1cfe226 100644
--- a/miscutils/make.c
+++ b/miscutils/make.c
@@ -385,6 +385,12 @@ error_in_inference_rule(const char *s)
 	error("%s in inference rule", s);
 }
 
+static void
+error_not_allowed(const char *s, const char *t)
+{
+	error("%s not allowed for %s", s, t);
+}
+
 static void
 warning(const char *msg, ...)
 {
@@ -1803,9 +1809,14 @@ is_suffix(const char *s)
 	return FALSE;
 }
 
-#define T_NORMAL 0
-#define T_SPECIAL 1
-#define T_INFERENCE 2
+enum {
+	T_NORMAL    =  0,
+	T_SPECIAL   = (1 << 0),
+	T_INFERENCE = (1 << 1), // Inference rule
+	T_NOPREREQ  = (1 << 2), // If set must not have prerequisites
+	T_COMMAND   = (1 << 3), // If set must have commands, if unset must not
+};
+
 /*
  * Determine if the argument is a special target and return a set
  * of flags indicating its properties.
@@ -1830,24 +1841,38 @@ target_type(char *s)
 #endif
 	;
 
+	static const uint8_t s_type[] = {
+		T_SPECIAL | T_NOPREREQ | T_COMMAND,
+		T_SPECIAL | T_NOPREREQ,
+		T_SPECIAL,
+		T_SPECIAL,
+		T_SPECIAL,
+		T_SPECIAL,
+		T_SPECIAL,
+		T_SPECIAL | T_NOPREREQ,
+		T_SPECIAL,
+		T_SPECIAL,
+	};
+
 	if (*s != '.')
 		return T_NORMAL;
 
 	// Check for one of the known special targets
-	if (index_in_strings(s_name, s) >= 0)
-		return T_SPECIAL;
+	ret = index_in_strings(s_name, s);
+	if (ret >= 0)
+		return s_type[ret];
 
 	// Check for an inference rule
 	ret = T_NORMAL;
 	sfx = suffix(s);
 	if (is_suffix(sfx)) {
 		if (s == sfx) {	// Single suffix rule
-			ret = T_INFERENCE;
+			ret = T_INFERENCE | T_NOPREREQ | T_COMMAND;
 		} else {
 			// Suffix is valid, check that prefix is too
 			*sfx = '\0';
 			if (is_suffix(s))
-				ret = T_INFERENCE;
+				ret = T_INFERENCE | T_NOPREREQ | T_COMMAND;
 			*sfx = '.';
 		}
 	}
@@ -2347,12 +2372,23 @@ input(FILE *fd, int ilevel)
 
 				np = newname(files[i]);
 				if (ttype != T_NORMAL) {
-					if (ttype == T_INFERENCE) {
-						if (posix) {
+					// Enforce prerequisites/commands in POSIX mode
+					if (posix) {
+						if ((ttype & T_NOPREREQ) && dp)
+							error_not_allowed("prerequisites", p);
+						if ((ttype & T_INFERENCE)) {
 							if (semicolon_cmd)
 								error_in_inference_rule("'; command'");
 							seen_inference = TRUE;
 						}
+						if ((ttype & T_COMMAND) && !cp &&
+								!((ttype & T_INFERENCE) && !semicolon_cmd))
+							error("commands required for %s", p);
+						if (!(ttype & T_COMMAND) && cp)
+							error_not_allowed("commands", p);
+					}
+
+					if ((ttype & T_INFERENCE)) {
 						np->n_flag |= N_INFERENCE;
 					} else if (strcmp(p, ".DEFAULT") == 0) {
 						// .DEFAULT rule is a special case
-- 
cgit v1.2.3-55-g6feb