X-Git-Url: http://git.archive.openwrt.org/?p=project%2Fuci.git;a=blobdiff_plain;f=file.c;h=5360ef764a15cb9b9d3bbd5e17c64135fac26c45;hp=c6ea7b485343923fda69324b2f124e308c4294aa;hb=d4bab379481c8ef0d5710a616660f1d7144d768f;hpb=6042bb553c8660cc649a3f0eed0d932878b10cac

diff --git a/file.c b/file.c
index c6ea7b4..5360ef7 100644
--- a/file.c
+++ b/file.c
@@ -2,9 +2,9 @@
  * libuci - Library for the Unified Configuration Interface
  * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
  *
- * this program is free software; you can redistribute it and/or modify
- * it under the terms of the gnu lesser general public license version 2.1
- * as published by the free software foundation
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -16,246 +16,16 @@
  * This file contains the code for parsing uci config files
  */
 
+#define _GNU_SOURCE
 #include <sys/types.h>
-#include <sys/stat.h>
+#include <sys/file.h>
 #include <stdbool.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <ctype.h>
 
-#define LINEBUF	32
-#define LINEBUF_MAX	4096
-
-static void uci_parse_error(struct uci_context *ctx, char *pos, char *reason)
-{
-	struct uci_parse_context *pctx = ctx->pctx;
-
-	pctx->reason = reason;
-	pctx->byte = pos - pctx->buf;
-	UCI_THROW(ctx, UCI_ERR_PARSE);
-}
-
-/*
- * Fetch a new line from the input stream and resize buffer if necessary
- */
-static void uci_getln(struct uci_context *ctx, int offset)
-{
-	struct uci_parse_context *pctx = ctx->pctx;
-	char *p;
-	int ofs;
-
-	if (pctx->buf == NULL) {
-		pctx->buf = uci_malloc(ctx, LINEBUF);
-		pctx->bufsz = LINEBUF;
-	}
-
-	ofs = offset;
-	do {
-		p = &pctx->buf[ofs];
-		p[ofs] = 0;
-
-		p = fgets(p, pctx->bufsz - ofs, pctx->file);
-		if (!p || !*p)
-			return;
-
-		ofs += strlen(p);
-		if (pctx->buf[ofs - 1] == '\n') {
-			pctx->line++;
-			pctx->buf[ofs - 1] = 0;
-			return;
-		}
-
-		if (pctx->bufsz > LINEBUF_MAX/2)
-			uci_parse_error(ctx, p, "line too long");
-
-		pctx->bufsz *= 2;
-		pctx->buf = uci_realloc(ctx, pctx->buf, pctx->bufsz);
-	} while (1);
-}
-
-/*
- * Clean up all extra memory used by the parser and exporter
- */
-static void uci_file_cleanup(struct uci_context *ctx)
-{
-	struct uci_parse_context *pctx;
-
-	if (ctx->buf) {
-		free(ctx->buf);
-		ctx->buf = NULL;
-		ctx->bufsz = 0;
-	}
-
-	pctx = ctx->pctx;
-	if (!pctx)
-		return;
-
-	ctx->pctx = NULL;
-	if (pctx->package)
-		uci_free_package(&pctx->package);
-
-	if (pctx->buf)
-		free(pctx->buf);
-
-	free(pctx);
-}
-
-/* 
- * parse a character escaped by '\'
- * returns true if the escaped character is to be parsed
- * returns false if the escaped character is to be ignored
- */
-static inline bool parse_backslash(struct uci_context *ctx, char **str)
-{
-	/* skip backslash */
-	*str += 1;
-
-	/* undecoded backslash at the end of line, fetch the next line */
-	if (!**str) {
-		*str += 1;
-		uci_getln(ctx, *str - ctx->pctx->buf);
-		return false;
-	}
-
-	/* FIXME: decode escaped char, necessary? */
-	return true;
-}
-
-/*
- * move the string pointer forward until a non-whitespace character or
- * EOL is reached
- */
-static void skip_whitespace(struct uci_context *ctx, char **str)
-{
-restart:
-	while (**str && isspace(**str))
-		*str += 1;
-
-	if (**str == '\\') {
-		if (!parse_backslash(ctx, str))
-			goto restart;
-	}
-}
-
-static inline void addc(char **dest, char **src)
-{
-	**dest = **src;
-	*dest += 1;
-	*src += 1;
-}
-
-/*
- * parse a double quoted string argument from the command line
- */
-static void parse_double_quote(struct uci_context *ctx, char **str, char **target)
-{
-	char c;
-
-	/* skip quote character */
-	*str += 1;
-
-	while ((c = **str)) {
-		switch(c) {
-		case '"':
-			**target = 0;
-			*str += 1;
-			return;
-		case '\\':
-			if (!parse_backslash(ctx, str))
-				continue;
-			/* fall through */
-		default:
-			addc(target, str);
-			break;
-		}
-	}
-	uci_parse_error(ctx, *str, "unterminated \"");
-}
-
-/*
- * parse a single quoted string argument from the command line
- */
-static void parse_single_quote(struct uci_context *ctx, char **str, char **target)
-{
-	char c;
-	/* skip quote character */
-	*str += 1;
-
-	while ((c = **str)) {
-		switch(c) {
-		case '\'':
-			**target = 0;
-			*str += 1;
-			return;
-		default:
-			addc(target, str);
-		}
-	}
-	uci_parse_error(ctx, *str, "unterminated '");
-}
-
-/*
- * parse a string from the command line and detect the quoting style
- */
-static void parse_str(struct uci_context *ctx, char **str, char **target)
-{
-	do {
-		switch(**str) {
-		case '\'':
-			parse_single_quote(ctx, str, target);
-			break;
-		case '"':
-			parse_double_quote(ctx, str, target);
-			break;
-		case 0:
-			goto done;
-		case '\\':
-			if (!parse_backslash(ctx, str))
-				continue;
-			/* fall through */
-		default:
-			addc(target, str);
-			break;
-		}
-	} while (**str && !isspace(**str));
-done:
-
-	/* 
-	 * if the string was unquoted and we've stopped at a whitespace
-	 * character, skip to the next one, because the whitespace will
-	 * be overwritten by a null byte here
-	 */
-	if (**str)
-		*str += 1;
-
-	/* terminate the parsed string */
-	**target = 0;
-}
-
-/*
- * extract the next argument from the command line
- */
-static char *next_arg(struct uci_context *ctx, char **str, bool required, bool name)
-{
-	char *val;
-	char *ptr;
-
-	val = ptr = *str;
-	skip_whitespace(ctx, str);
-	parse_str(ctx, str, &ptr);
-	if (!*val) {
-		if (required)
-			uci_parse_error(ctx, *str, "insufficient arguments");
-		goto done;
-	}
-
-	if (name && !uci_validate_name(val))
-		uci_parse_error(ctx, val, "invalid character in field");
-
-done:
-	return val;
-}
+static struct uci_backend uci_file_backend;
 
 /*
  * verify that the end of the line or command is reached.
@@ -265,8 +35,9 @@ static void assert_eol(struct uci_context *ctx, char **str)
 {
 	char *tmp;
 
+	skip_whitespace(ctx, str);
 	tmp = next_arg(ctx, str, false, false);
-	if (tmp && *tmp)
+	if (*tmp && (ctx->flags & UCI_FLAG_STRICT))
 		uci_parse_error(ctx, *str, "too many arguments");
 }
 
@@ -285,6 +56,7 @@ static void uci_switch_config(struct uci_context *ctx)
 
 	/* add the last config to main config file list */
 	if (pctx->package) {
+		pctx->package->backend = ctx->backend;
 		uci_list_add(&ctx->root, &pctx->package->e.list);
 
 		pctx->package = NULL;
@@ -298,7 +70,7 @@ static void uci_switch_config(struct uci_context *ctx)
 	 * if an older config under the same name exists, unload it
 	 * ignore errors here, e.g. if the config was not found
 	 */
-	e = uci_lookup_list(ctx, &ctx->root, name);
+	e = uci_lookup_list(&ctx->root, name);
 	if (e)
 		UCI_THROW(ctx, UCI_ERR_DUPLICATE);
 	pctx->package = uci_alloc_package(ctx, name);
@@ -323,56 +95,12 @@ static void uci_parse_package(struct uci_context *ctx, char **str, bool single)
 	uci_switch_config(ctx);
 }
 
-/* Based on an efficient hash function published by D. J. Bernstein */
-static unsigned int djbhash(unsigned int hash, char *str)
-{
-	int len = strlen(str);
-	int i;
-
-	/* initial value */
-	if (hash == ~0)
-		hash = 5381;
-
-	for(i = 0; i < len; i++) {
-		hash = ((hash << 5) + hash) + str[i];
-	}
-	return (hash & 0x7FFFFFFF);
-}
-
-/* fix up an unnamed section */
-static void uci_fixup_section(struct uci_context *ctx, struct uci_section *s)
-{
-	unsigned int hash = ~0;
-	struct uci_element *e;
-	char buf[16];
-
-	if (!s || s->e.name)
-		return;
-
-	/*
-	 * Generate a name for unnamed sections. This is used as reference
-	 * when locating or updating the section from apps/scripts.
-	 * To make multiple concurrent versions somewhat safe for updating,
-	 * the name is generated from a hash of its type and name/value
-	 * pairs of its option, and it is prefixed by a counter value.
-	 * If the order of the unnamed sections changes for some reason,
-	 * updates to them will be rejected.
-	 */
-	hash = djbhash(hash, s->type);
-	uci_foreach_element(&s->options, e) {
-		hash = djbhash(hash, e->name);
-		hash = djbhash(hash, uci_to_option(e)->value);
-	}
-	sprintf(buf, "cfg%02x%04x", ++s->package->n_section, hash % (1 << 16));
-	s->e.name = uci_strdup(ctx, buf);
-}
-
 /*
  * parse the 'config' uci command (open a section)
  */
 static void uci_parse_config(struct uci_context *ctx, char **str)
 {
-	struct uci_section *s;
+	struct uci_parse_context *pctx = ctx->pctx;
 	char *name = NULL;
 	char *type = NULL;
 
@@ -387,10 +115,22 @@ static void uci_parse_config(struct uci_context *ctx, char **str)
 	/* command string null-terminated by strtok */
 	*str += strlen(*str) + 1;
 
-	type = next_arg(ctx, str, true, true);
+	type = next_arg(ctx, str, true, false);
+	if (!uci_validate_str(type, false))
+		uci_parse_error(ctx, type, "invalid character in field");
 	name = next_arg(ctx, str, false, true);
 	assert_eol(ctx, str);
-	ctx->pctx->section = uci_alloc_section(ctx->pctx->package, type, name);
+
+	if (pctx->merge) {
+		UCI_TRAP_SAVE(ctx, error);
+		if (uci_set(ctx, pctx->package, name, NULL, type, NULL) != UCI_OK)
+			goto error;
+		UCI_TRAP_RESTORE(ctx);
+		return;
+error:
+		UCI_THROW(ctx, ctx->errno);
+	} else
+		pctx->section = uci_alloc_section(pctx->package, type, name);
 }
 
 /*
@@ -398,19 +138,29 @@ static void uci_parse_config(struct uci_context *ctx, char **str)
  */
 static void uci_parse_option(struct uci_context *ctx, char **str)
 {
+	struct uci_parse_context *pctx = ctx->pctx;
 	char *name = NULL;
 	char *value = NULL;
 
-	if (!ctx->pctx->section)
+	if (!pctx->section)
 		uci_parse_error(ctx, *str, "option command found before the first section");
 
 	/* command string null-terminated by strtok */
 	*str += strlen(*str) + 1;
 
 	name = next_arg(ctx, str, true, true);
-	value = next_arg(ctx, str, true, false);
+	value = next_arg(ctx, str, false, false);
 	assert_eol(ctx, str);
-	uci_alloc_option(ctx->pctx->section, name, value);
+
+	if (pctx->merge) {
+		UCI_TRAP_SAVE(ctx, error);
+		uci_set(ctx, pctx->package, pctx->section->e.name, name, value, NULL);
+		UCI_TRAP_RESTORE(ctx);
+		return;
+error:
+		UCI_THROW(ctx, ctx->errno);
+	} else
+		uci_alloc_option(pctx->section, name, value);
 }
 
 
@@ -420,16 +170,19 @@ static void uci_parse_option(struct uci_context *ctx, char **str)
 static void uci_parse_line(struct uci_context *ctx, bool single)
 {
 	struct uci_parse_context *pctx = ctx->pctx;
-	char *word, *brk = NULL;
+	char *word, *brk;
 
-	for (word = strtok_r(pctx->buf, ";", &brk);
-		 word;
-		 word = strtok_r(NULL, ";", &brk)) {
-
-		char *pbrk = NULL;
-		word = strtok_r(word, " \t", &pbrk);
+	word = pctx->buf;
+	do {
+		brk = NULL;
+		word = strtok_r(word, " \t", &brk);
+		if (!word)
+			return;
 
 		switch(word[0]) {
+			case 0:
+			case '#':
+				return;
 			case 'p':
 				if ((word[1] == 0) || !strcmp(word + 1, "ackage"))
 					uci_parse_package(ctx, &word, single);
@@ -446,7 +199,7 @@ static void uci_parse_line(struct uci_context *ctx, bool single)
 				uci_parse_error(ctx, word, "unterminated command");
 				break;
 		}
-	}
+	} while (1);
 }
 
 /* max number of characters that escaping adds to the string */
@@ -504,7 +257,7 @@ static void uci_export_package(struct uci_package *p, FILE *stream, bool header)
 	uci_foreach_element(&p->sections, s) {
 		struct uci_section *sec = uci_to_section(s);
 		fprintf(stream, "\nconfig '%s'", uci_escape(ctx, sec->type));
-		if (!sec->anonymous)
+		if (!sec->anonymous || (ctx->flags & UCI_FLAG_EXPORT_NAME))
 			fprintf(stream, " '%s'", uci_escape(ctx, sec->e.name));
 		fprintf(stream, "\n");
 		uci_foreach_element(&sec->options, o) {
@@ -537,21 +290,28 @@ int uci_export(struct uci_context *ctx, FILE *stream, struct uci_package *packag
 int uci_import(struct uci_context *ctx, FILE *stream, const char *name, struct uci_package **package, bool single)
 {
 	struct uci_parse_context *pctx;
+	UCI_HANDLE_ERR(ctx);
 
 	/* make sure no memory from previous parse attempts is leaked */
-	uci_file_cleanup(ctx);
+	uci_cleanup(ctx);
 
-	pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
-	ctx->pctx = pctx;
+	uci_alloc_parse_context(ctx);
+	pctx = ctx->pctx;
 	pctx->file = stream;
+	if (*package && single) {
+		pctx->package = *package;
+		pctx->merge = true;
+	}
 
 	/*
 	 * If 'name' was supplied, assume that the supplied stream does not contain
 	 * the appropriate 'package <name>' string to specify the config name
 	 * NB: the config file can still override the package name
 	 */
-	if (name)
+	if (name) {
+		UCI_ASSERT(ctx, uci_validate_name(name));
 		pctx->name = name;
+	}
 
 	while (!feof(pctx->file)) {
 		uci_getln(ctx, 0);
@@ -569,305 +329,84 @@ error:
 	}
 
 	uci_fixup_section(ctx, ctx->pctx->section);
+	if (!pctx->package && name)
+		uci_switch_config(ctx);
 	if (package)
 		*package = pctx->package;
+	if (pctx->merge)
+		pctx->package = NULL;
 
 	pctx->name = NULL;
 	uci_switch_config(ctx);
 
 	/* no error happened, we can get rid of the parser context now */
-	uci_file_cleanup(ctx);
+	uci_cleanup(ctx);
 
 	return 0;
 }
 
-/*
- * open a stream and go to the right position
- *
- * note: when opening for write and seeking to the beginning of
- * the stream, truncate the file
- */
-static FILE *uci_open_stream(struct uci_context *ctx, const char *filename, int pos, bool write, bool create)
-{
-	struct stat statbuf;
-	FILE *file = NULL;
-	int fd, ret;
-	int mode = (write ? O_RDWR : O_RDONLY);
-
-	if (create)
-		mode |= O_CREAT;
 
-	if (!write && ((stat(filename, &statbuf) < 0) ||
-		((statbuf.st_mode &  S_IFMT) != S_IFREG))) {
-		UCI_THROW(ctx, UCI_ERR_NOTFOUND);
-	}
-
-	fd = open(filename, mode, UCI_FILEMODE);
-	if (fd <= 0)
-		goto error;
-
-	if (flock(fd, (write ? LOCK_EX : LOCK_SH)) < 0)
-		goto error;
-
-	ret = lseek(fd, 0, pos);
-
-	if (ret < 0)
-		goto error;
-
-	file = fdopen(fd, (write ? "w+" : "r"));
-	if (file)
-		goto done;
-
-error:
-	UCI_THROW(ctx, UCI_ERR_IO);
-done:
-	return file;
-}
-
-static void uci_close_stream(FILE *stream)
-{
-	int fd;
-
-	if (!stream)
-		return;
-
-	fd = fileno(stream);
-	flock(fd, LOCK_UN);
-	fclose(stream);
-}
-
-static void uci_parse_history_line(struct uci_context *ctx, struct uci_package *p, char *buf)
-{
-	bool delete = false;
-	char *package = NULL;
-	char *section = NULL;
-	char *option = NULL;
-	char *value = NULL;
-
-	if (buf[0] == '-') {
-		delete = true;
-		buf++;
-	}
-
-	UCI_INTERNAL(uci_parse_tuple, ctx, buf, &package, &section, &option, &value);
-	if (!package || !section || (!delete && !value))
-		goto error;
-	if (strcmp(package, p->e.name) != 0)
-		goto error;
-	if (!uci_validate_name(section))
-		goto error;
-	if (option && !uci_validate_name(option))
-		goto error;
-
-	if (delete)
-		UCI_INTERNAL(uci_del, ctx, p, section, option);
-	else
-		UCI_INTERNAL(uci_set, ctx, p, section, option, value);
-
-	return;
-error:
-	UCI_THROW(ctx, UCI_ERR_PARSE);
-}
-
-static void uci_parse_history(struct uci_context *ctx, FILE *stream, struct uci_package *p)
-{
-	struct uci_parse_context *pctx;
-
-	/* make sure no memory from previous parse attempts is leaked */
-	uci_file_cleanup(ctx);
-
-	pctx = (struct uci_parse_context *) uci_malloc(ctx, sizeof(struct uci_parse_context));
-	ctx->pctx = pctx;
-	pctx->file = stream;
-
-	while (!feof(pctx->file)) {
-		uci_getln(ctx, 0);
-		if (!pctx->buf[0])
-			continue;
-
-		/*
-		 * ignore parse errors in single lines, we want to preserve as much
-		 * history as possible
-		 */
-		UCI_TRAP_SAVE(ctx, error);
-		uci_parse_history_line(ctx, p, pctx->buf);
-		UCI_TRAP_RESTORE(ctx);
-error:
-		continue;
-	}
-
-	/* no error happened, we can get rid of the parser context now */
-	uci_file_cleanup(ctx);
-}
-
-static void uci_load_history(struct uci_context *ctx, struct uci_package *p, bool flush)
-{
-	char *filename = NULL;
-	FILE *f = NULL;
-
-	if (!p->confdir)
-		return;
-	if ((asprintf(&filename, "%s/%s", UCI_SAVEDIR, p->e.name) < 0) || !filename)
-		UCI_THROW(ctx, UCI_ERR_MEM);
-
-	UCI_TRAP_SAVE(ctx, done);
-	f = uci_open_stream(ctx, filename, SEEK_SET, flush, false);
-	uci_parse_history(ctx, f, p);
-	UCI_TRAP_RESTORE(ctx);
-
-done:
-	if (flush && f) {
-		rewind(f);
-		ftruncate(fileno(f), 0);
-	}
-	if (filename)
-		free(filename);
-	uci_close_stream(f);
-	ctx->errno = 0;
-}
-
-
-int uci_load(struct uci_context *ctx, const char *name, struct uci_package **package)
+static char *uci_config_path(struct uci_context *ctx, const char *name)
 {
 	char *filename;
-	bool confdir;
-	FILE *file = NULL;
 
-	UCI_HANDLE_ERR(ctx);
-	UCI_ASSERT(ctx, name != NULL);
+	UCI_ASSERT(ctx, uci_validate_name(name));
+	filename = uci_malloc(ctx, strlen(name) + strlen(ctx->confdir) + 2);
+	sprintf(filename, "%s/%s", ctx->confdir, name);
 
-	switch (name[0]) {
-	case '.':
-		/* relative path outside of /etc/config */
-		if (name[1] != '/')
-			UCI_THROW(ctx, UCI_ERR_NOTFOUND);
-		/* fall through */
-	case '/':
-		/* absolute path outside of /etc/config */
-		filename = uci_strdup(ctx, name);
-		name = strrchr(name, '/') + 1;
-		confdir = false;
-		break;
-	default:
-		/* config in /etc/config */
-		if (strchr(name, '/'))
-			UCI_THROW(ctx, UCI_ERR_INVAL);
-		filename = uci_malloc(ctx, strlen(name) + sizeof(UCI_CONFDIR) + 2);
-		sprintf(filename, UCI_CONFDIR "/%s", name);
-		confdir = true;
-		break;
-	}
-
-	file = uci_open_stream(ctx, filename, SEEK_SET, false, false);
-	ctx->errno = 0;
-	UCI_TRAP_SAVE(ctx, done);
-	uci_import(ctx, file, name, package, true);
-	UCI_TRAP_RESTORE(ctx);
-
-	if (*package) {
-		(*package)->path = filename;
-		(*package)->confdir = confdir;
-		uci_load_history(ctx, *package, false);
-	}
-
-done:
-	uci_close_stream(file);
-	return ctx->errno;
+	return filename;
 }
 
-int uci_save(struct uci_context *ctx, struct uci_package *p)
+void uci_file_commit(struct uci_context *ctx, struct uci_package **package, bool overwrite)
 {
-	FILE *f = NULL;
-	char *filename = NULL;
-	struct uci_element *e, *tmp;
-
-	UCI_HANDLE_ERR(ctx);
-	UCI_ASSERT(ctx, p != NULL);
-
-	/* 
-	 * if the config file was outside of the /etc/config path,
-	 * don't save the history to a file, update the real file
-	 * directly.
-	 * does not modify the uci_package pointer
-	 */
-	if (!p->confdir)
-		return uci_commit(ctx, &p);
-
-	if (uci_list_empty(&p->history))
-		return 0;
-
-	if ((asprintf(&filename, "%s/%s", UCI_SAVEDIR, p->e.name) < 0) || !filename)
-		UCI_THROW(ctx, UCI_ERR_MEM);
-
-	ctx->errno = 0;
-	UCI_TRAP_SAVE(ctx, done);
-	f = uci_open_stream(ctx, filename, SEEK_END, true, true);
-	UCI_TRAP_RESTORE(ctx);
-
-	uci_foreach_element_safe(&p->history, tmp, e) {
-		struct uci_history *h = uci_to_history(e);
-
-		if (h->cmd == UCI_CMD_REMOVE)
-			fprintf(f, "-");
-
-		fprintf(f, "%s.%s", p->e.name, h->section);
-		if (e->name)
-			fprintf(f, ".%s", e->name);
-
-		if (h->cmd == UCI_CMD_REMOVE)
-			fprintf(f, "\n");
-		else
-			fprintf(f, "=%s\n", h->value);
-		uci_free_history(h);
-	}
-
-done:
-	uci_close_stream(f);
-	if (filename)
-		free(filename);
-	if (ctx->errno)
-		UCI_THROW(ctx, ctx->errno);
-
-	return 0;
-}
-
-int uci_commit(struct uci_context *ctx, struct uci_package **package)
-{
-	struct uci_package *p;
+	struct uci_package *p = *package;
 	FILE *f = NULL;
 	char *name = NULL;
 	char *path = NULL;
 
-	UCI_HANDLE_ERR(ctx);
-	UCI_ASSERT(ctx, package != NULL);
-	p = *package;
-
-	UCI_ASSERT(ctx, p != NULL);
-	UCI_ASSERT(ctx, p->path != NULL);
+	if (!p->path) {
+		if (overwrite)
+			p->path = uci_config_path(ctx, p->e.name);
+		else
+			UCI_THROW(ctx, UCI_ERR_INVAL);
+	}
 
 	/* open the config file for writing now, so that it is locked */
 	f = uci_open_stream(ctx, p->path, SEEK_SET, true, true);
 
 	/* flush unsaved changes and reload from history file */
 	UCI_TRAP_SAVE(ctx, done);
-	if (p->confdir) {
-		name = uci_strdup(ctx, p->e.name);
-		path = uci_strdup(ctx, p->path);
-		if (!uci_list_empty(&p->history))
-			UCI_INTERNAL(uci_save, ctx, p);
-		uci_free_package(&p);
-		uci_file_cleanup(ctx);
-		UCI_INTERNAL(uci_import, ctx, f, name, &p, true);
-
-		p->path = path;
-		p->confdir = true;
-		*package = p;
-
-		/* freed together with the uci_package */
-		path = NULL;
-
-		/* check for updated history, just in case */
-		uci_load_history(ctx, p, true);
+	if (p->has_history) {
+		if (!overwrite) {
+			name = uci_strdup(ctx, p->e.name);
+			path = uci_strdup(ctx, p->path);
+			/* dump our own changes to the history file */
+			if (!uci_list_empty(&p->history))
+				UCI_INTERNAL(uci_save, ctx, p);
+
+			/* 
+			 * other processes might have modified the config 
+			 * as well. dump and reload 
+			 */
+			uci_free_package(&p);
+			uci_cleanup(ctx);
+			UCI_INTERNAL(uci_import, ctx, f, name, &p, true);
+
+			p->path = path;
+			p->has_history = true;
+			*package = p;
+
+			/* freed together with the uci_package */
+			path = NULL;
+
+			/* check for updated history, flush */
+			if (!uci_load_history(ctx, p, true))
+				goto done;
+		} else {
+			/* flush history */
+			if (!uci_load_history(ctx, NULL, true))
+				goto done;
+		}
 	}
 
 	rewind(f);
@@ -884,8 +423,6 @@ done:
 	uci_close_stream(f);
 	if (ctx->errno)
 		UCI_THROW(ctx, ctx->errno);
-
-	return 0;
 }
 
 
@@ -906,16 +443,17 @@ static inline char *get_filename(char *path)
 	return p;
 }
 
-int uci_list_configs(struct uci_context *ctx, char ***list)
+static char **uci_list_config_files(struct uci_context *ctx)
 {
 	char **configs;
 	glob_t globbuf;
 	int size, i;
 	char *buf;
+	char *dir;
 
-	UCI_HANDLE_ERR(ctx);
-
-	if (glob(UCI_CONFDIR "/*", GLOB_MARK, NULL, &globbuf) != 0)
+	dir = uci_malloc(ctx, strlen(ctx->confdir) + 1 + sizeof("/*"));
+	sprintf(dir, "%s/*", ctx->confdir);
+	if (glob(dir, GLOB_MARK, NULL, &globbuf) != 0)
 		UCI_THROW(ctx, UCI_ERR_NOTFOUND);
 
 	size = sizeof(char *) * (globbuf.gl_pathc + 1);
@@ -942,8 +480,57 @@ int uci_list_configs(struct uci_context *ctx, char ***list)
 		strcpy(buf, p);
 		buf += strlen(buf) + 1;
 	}
-	*list = configs;
+	free(dir);
+	return configs;
+}
 
-	return 0;
+static struct uci_package *uci_file_load(struct uci_context *ctx, const char *name)
+{
+	struct uci_package *package = NULL;
+	char *filename;
+	bool confdir;
+	FILE *file = NULL;
+
+	switch (name[0]) {
+	case '.':
+		/* relative path outside of /etc/config */
+		if (name[1] != '/')
+			UCI_THROW(ctx, UCI_ERR_NOTFOUND);
+		/* fall through */
+	case '/':
+		/* absolute path outside of /etc/config */
+		filename = uci_strdup(ctx, name);
+		name = strrchr(name, '/') + 1;
+		confdir = false;
+		break;
+	default:
+		/* config in /etc/config */
+		filename = uci_config_path(ctx, name);
+		confdir = true;
+		break;
+	}
+
+	file = uci_open_stream(ctx, filename, SEEK_SET, false, false);
+	ctx->errno = 0;
+	UCI_TRAP_SAVE(ctx, done);
+	UCI_INTERNAL(uci_import, ctx, file, name, &package, true);
+	UCI_TRAP_RESTORE(ctx);
+
+	if (package) {
+		package->path = filename;
+		package->has_history = confdir;
+		uci_load_history(ctx, package, false);
+	}
+
+done:
+	uci_close_stream(file);
+	if (ctx->errno)
+		UCI_THROW(ctx, ctx->errno);
+	return package;
 }
 
+static UCI_BACKEND(uci_file_backend, "file",
+	.load = uci_file_load,
+	.commit = uci_file_commit,
+	.list_configs = uci_list_config_files,
+);