dirent: Implement

3 files changed, 189 insertions, 0 deletions

diff --git a/src/dirent.c b/src/dirent.c
new file mode 100644
index 0000000..52e8f84
--- /dev/null
+++ b/src/dirent.c
@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2023  Patrick McDermott
+ *
+ * This file is part of opkg-opk.
+ *
+ * opkg-opk is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opkg-opk is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opkg-opk.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "defs.h"
+#include "dirent.h"
+
+static int
+_opkg_opk_dirent_name_prefix(struct opkg_opk_dirent *dirent, char **name_buf,
+		size_t *name_buf_len, char **pref_buf, size_t *pref_buf_len,
+		size_t *name_len, size_t *pref_len)
+{
+	size_t   len;
+	char   **buf;
+
+	len = strlen(dirent->name) + 1;
+	if (*name_len + len <= *name_buf_len) {
+		*name_buf_len -= len;
+		buf = name_buf;
+	} else if (*pref_len + len <= *pref_buf_len) {
+		*pref_buf_len -= len;
+		buf = pref_buf;
+	} else {
+		return OPKG_OPK_ERROR;
+	}
+
+	if (dirent->parent != NULL &&
+			_opkg_opk_dirent_name_prefix(dirent->parent,
+				name_buf, name_buf_len, pref_buf, pref_buf_len,
+				name_len, pref_len) == OPKG_OPK_ERROR) {
+		return OPKG_OPK_ERROR;
+	}
+
+	**buf = '/';
+	*buf += 1;
+	memcpy(*buf, dirent->name, len - 1);
+	*buf += len - 1;
+
+	return OPKG_OPK_OK;
+}
+
+int
+opkg_opk_dirent_name_prefix(struct opkg_opk_dirent *dirent, char *name_buf,
+		size_t name_buf_len, char *pref_buf, size_t pref_buf_len)
+{
+	size_t name_len = 0;
+	size_t pref_len = 0;
+
+	if (_opkg_opk_dirent_name_prefix(dirent, &name_buf, &name_buf_len,
+				&pref_buf, &pref_buf_len, &name_len, &pref_len)
+			== OPKG_OPK_ERROR) {
+		return OPKG_OPK_ERROR;
+	}
+	name_buf[name_len] = '\0';
+	pref_buf[pref_len] = '\0';
+	return OPKG_OPK_OK;
+}
+
+static char *
+_opkg_opk_dirent_full_name(struct opkg_opk_dirent *dirent, char **cur,
+		size_t *buf_len)
+{
+	size_t  len;
+	char   *buf;
+
+	len = strlen(dirent->name) + 1;
+	*buf_len += len;
+
+	if (dirent->parent == NULL) {
+		buf = malloc(*buf_len);
+		if (buf == NULL) {
+			return NULL;
+		}
+		*cur = buf;
+	} else if ((buf = _opkg_opk_dirent_full_name(dirent->parent, cur,
+					buf_len)) == NULL) {
+		return NULL;
+	}
+
+	**cur = '/';
+	*cur += 1;
+	memcpy(*cur, dirent->name, len - 1);
+	*cur += len - 1;
+
+	return buf;
+}
+
+char *
+opkg_opk_dirent_full_name(struct opkg_opk_dirent *dirent)
+{
+	char   *name;
+	char   *cur     = NULL;
+	size_t  buf_len = 1;     /* 1 for NUL */
+
+	if ((name = _opkg_opk_dirent_full_name(dirent, &cur, &buf_len)) == NULL)
+	{
+		return NULL;
+	}
+	*cur = '\0';
+	return name;
+}
+
+int
+main()
+{
+	struct opkg_opk_dirent foo = {
+		.name   = "foo",
+		.parent = NULL,
+	};
+	struct opkg_opk_dirent bar = {
+		.name   = "bar",
+		.parent = &foo,
+	};
+	char *full_name;
+	char  name[5];
+	char  pref[5];
+
+	full_name = opkg_opk_dirent_full_name(&bar);
+	if (full_name == NULL) {
+		puts("Error building full name");
+		return EXIT_FAILURE;
+	}
+	puts(full_name);
+	free(full_name);
+
+	if (opkg_opk_dirent_name_prefix(&bar, name, 5, pref, 5) != OPKG_OPK_OK)
+	{
+		puts("Error building name parts");
+		return EXIT_FAILURE;
+	}
+	puts(name);
+	puts(pref);
+
+	return EXIT_SUCCESS;
+}
diff --git a/src/dirent.h b/src/dirent.h
new file mode 100644
index 0000000..44d33ea
--- /dev/null
+++ b/src/dirent.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2023  Patrick McDermott
+ *
+ * This file is part of opkg-opk.
+ *
+ * opkg-opk is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * opkg-opk is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with opkg-opk.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef OPKG_OPK_DIRENT_H_
+#define OPKG_OPK_DIRENT_H_
+
+struct opkg_opk_dirent {
+	const char             *name;
+	struct opkg_opk_dirent *parent;
+};
+
+int
+opkg_opk_dirent_name_prefix(struct opkg_opk_dirent *dirent, char *name_buf,
+		size_t name_len, char *pref_buf, size_t pref_len);
+
+char *
+opkg_opk_dirent_full_name(struct opkg_opk_dirent *dirent);
+
+#endif  /* OPKG_OPK_DIRENT_H_ */
diff --git a/src/local.mk b/src/local.mk
index 429aba3..e6d77cc 100644
--- a/src/local.mk
+++ b/src/local.mk
@@ -1,5 +1,7 @@
 opkg_opk_SOURCES += \
 	%reldir%/defs.h \
+	%reldir%/dirent.c \
+	%reldir%/dirent.h \
 	%reldir%/gzip.c \
 	%reldir%/gzip.h \
 	%reldir%/i18n.h \