main.c.diff   [plain text]

--- /SourceCache/flex/flex-19/flex/main.c	2006-02-14 10:55:42.000000000 -0800
+++ ./main.c	2007-07-06 10:23:00.000000000 -0700
@@ -36,7 +36,7 @@
 #include "version.h"
 #include "options.h"
 #include "tables.h"
-
+#include <sys/stat.h>
 static char flex_version[] = FLEX_VERSION;
 
 /* declare functions that have forward references */
@@ -359,8 +359,46 @@ void check_options ()
 
     /* Setup the filter chain. */
     output_chain = filter_create_int(NULL, filter_tee_header, headerfilename);
-    if ( !(m4 = getenv("M4")))
-        m4 = M4;
+    if ( !(m4 = getenv("M4"))) {
+	    char *slash;
+		m4 = M4;
+		if (slash = strrchr(M4, '/')) {
+			m4 = slash+1;
+			/* break up $PATH */
+			const char *path = getenv("PATH");
+			if (!path) {
+				m4 = M4;
+			} else {
+				do {
+					char m4_path[PATH_MAX];
+					int length = strlen(path);
+					struct stat sbuf;
+
+					const char *endOfDir = strchr(path, ':');
+					if (!endOfDir)
+						endOfDir = path+length;
+
+					if ((endOfDir-path+2) >= sizeof(m4_path)) {
+					    path = endOfDir+1;
+						continue;
+					}
+
+					strlcpy(m4_path, path, sizeof(m4_path));
+					m4_path[endOfDir-path] = '/';
+					m4_path[endOfDir-path+1] = '\0';
+					strlcat(m4_path, m4, sizeof(m4_path));
+					if (stat(m4_path, &sbuf) == 0 &&
+						(S_ISREG(sbuf.st_mode))) { /* check executable? */
+						m4 = strdup(m4_path);
+						break;
+					}
+					path = endOfDir+1;
+				} while (path[0]);
+				if (!path[0])
+				    m4 = M4;
+			}
+		}
+	}
     filter_create_ext(output_chain, m4, "-P", 0);
     filter_create_int(output_chain, filter_fix_linedirs, NULL);