1 files changed, 50 insertions, 6 deletions

diff --git a/src/io.c b/src/io.c
index 9199d03..b9041e0 100644
--- a/src/io.c
+++ b/src/io.c
@@ -351,12 +351,17 @@ EXPORT_SYMBOL int HX_readlink(hxmc_t **target, const char *path)
 	size_t linkbuf_size;
 
 	if (allocate) {
-		linkbuf_size = 32;
-		*target = HXmc_meminit(NULL, 32);
+		linkbuf_size = 128;
+		*target = HXmc_meminit(nullptr, 128);
 		if (*target == NULL)
 			return -errno;
 	} else {
 		linkbuf_size = HXmc_length(*target);
+		if (linkbuf_size < 128) {
+			linkbuf_size = 128;
+			if (HXmc_setlen(target, 128) == nullptr)
+				return -errno;
+		}
 	}
 	while (true) {
 		ssize_t ret = readlink(path, *target, linkbuf_size);
@@ -453,6 +458,45 @@ HX_realpath_symres(struct HX_realpath_state *state, const char *path)
 	return 1;
 }
 
+EXPORT_SYMBOL int HX_getcwd(hxmc_t **target)
+{
+	bool allocate = *target == nullptr;
+	size_t linkbuf_size;
+
+	if (allocate) {
+		linkbuf_size = 128;
+		*target = HXmc_meminit(nullptr, linkbuf_size);
+		if (*target == nullptr)
+			return -errno;
+	} else {
+		linkbuf_size = HXmc_length(*target);
+		if (linkbuf_size < 128) {
+			linkbuf_size = 128;
+			if (HXmc_setlen(target, linkbuf_size) == nullptr)
+				return -errno;
+		}
+	}
+	while (true) {
+		const char *ret = getcwd(*target, linkbuf_size);
+		if (ret != nullptr) {
+			HXmc_setlen(target, strlen(ret)); /* shrink to fit */
+			return 1;
+		}
+		if (errno == ERANGE) {
+			if (HXmc_setlen(target, linkbuf_size *= 2) != nullptr)
+				continue;
+			/* errno already set by realloc, fall into next if block */
+		}
+		int saved_errno = errno;
+		if (allocate) {
+			HXmc_free(*target);
+			*target = nullptr;
+		}
+		return -(errno = saved_errno);
+	}
+	return -EINVAL;
+}
+
 EXPORT_SYMBOL int HX_realpath(hxmc_t **dest_pptr, const char *path,
     unsigned int flags)
 {
@@ -462,7 +506,7 @@ EXPORT_SYMBOL int HX_realpath(hxmc_t **dest_pptr, const char *path,
 	int ret = 0;
 
 	if (dnull) {
-		state.dest = HXmc_meminit(NULL, PATH_MAX);
+		state.dest = HXmc_meminit(NULL, 256);
 		if (state.dest == NULL)
 			goto err;
 	}
@@ -470,11 +514,9 @@ EXPORT_SYMBOL int HX_realpath(hxmc_t **dest_pptr, const char *path,
 	if (*path == '/') {
 		rq_slash = true;
 	} else if (flags & HX_REALPATH_ABSOLUTE) {
-		if (getcwd(state.dest, PATH_MAX) == NULL)
+		if (HX_getcwd(&state.dest) < 0)
 			goto err;
 		rq_slash = true;
-		if (HXmc_setlen(&state.dest, strlen(state.dest)) == NULL)
-			goto err;
 	}
 
 	while (*path != '\0') {
@@ -541,6 +583,8 @@ EXPORT_SYMBOL int HX_realpath(hxmc_t **dest_pptr, const char *path,
 		/* If caller supplied a buffer, do not take it away. */
 		HXmc_free(state.dest);
 		*dest_pptr = NULL;
+	} else {
+		*dest_pptr = state.dest;
 	}
 	HXmc_free(state.link_target);
 	HXmc_free(state.new_path);