[RFC PATCH 4/6] libutil: Remove usage of PATH_MAX from has_symlinkloop

Update has_symlinkloop to no longer use PATH_MAX. The change relies on
the behaviour of realpath to return an allocated buffer when passed a
NULL second argument.

Ensure that the buffer is freed(not leaked) before returning from the
function.
---
 libutil/find.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/libutil/find.c b/libutil/find.c
index a009538..1863df4 100644
--- a/libutil/find.c
+++ b/libutil/find.c
@@ -506,12 +506,12 @@ static int
 has_symlinkloop(const char *dir)
 {
 	struct stack_entry *sp;
-	char real[PATH_MAX], *p;
-	int i;
+	char *real, *p;
+	int i, ret = 0;
 
 	if (!strcmp(dir, "./"))
 		return 0;
-	if (realpath(dir, real) == NULL)
+	if ((real = realpath(dir, NULL)) == NULL)
 		die("cannot get real path of '%s'.", trimpath(dir));
 #ifdef SLOOPDEBUG
 	fprintf(stderr, "======== has_symlinkloop ======\n");
@@ -520,8 +520,10 @@ has_symlinkloop(const char *dir)
 	fprintf(stderr, "\tcheck '%s' < '%s'\n", real, rootdir);
 #endif
 	p = locatestring(rootdir, real, MATCH_AT_FIRST);
-	if (p && (*p == '/' || *p == '\0' || !strcmp(real, "/")))
-		return 1;
+	if (p && (*p == '/' || *p == '\0' || !strcmp(real, "/"))) {
+		ret = 1;
+		goto out;
+	}
 	sp = varray_assign(stack, 0, 0);
 #ifdef SLOOPDEBUG
 	fprintf(stderr, "TEST-2\n");
@@ -530,13 +532,17 @@ has_symlinkloop(const char *dir)
 #ifdef SLOOPDEBUG
 		fprintf(stderr, "%d:\tcheck '%s' == '%s'\n", i, real, sp[i].real);
 #endif
-		if (!strcmp(sp[i].real, real))
-			return 1;
+		if (!strcmp(sp[i].real, real)) {
+			ret = 1;
+			goto out;
+		}
 	}
 #ifdef SLOOPDEBUG
 	fprintf(stderr, "===============================\n");
 #endif
-	return 0;
+out:
+	free(real);
+	return ret;
 }
 
 /**
-- 
2.11.0