ncd: modules: add file

blog_channels.txt

@@ -116,3 +116,4 @@ ncd_getargs 4
 ncd_arithmetic 4
 ncd_parse 4
 ncd_valuemetic 4
+ncd_file 4

generated/blog_channel_ncd_file.h

@@ -0,0 +1,4 @@
+#ifdef BLOG_CURRENT_CHANNEL
+#undef BLOG_CURRENT_CHANNEL
+#endif
+#define BLOG_CURRENT_CHANNEL BLOG_CHANNEL_ncd_file

generated/blog_channels_defines.h

@@ -116,4 +116,5 @@
 #define BLOG_CHANNEL_ncd_arithmetic 115
 #define BLOG_CHANNEL_ncd_parse 116
 #define BLOG_CHANNEL_ncd_valuemetic 117
-#define BLOG_NUM_CHANNELS 118
+#define BLOG_CHANNEL_ncd_file 118
+#define BLOG_NUM_CHANNELS 119

generated/blog_channels_list.h

@@ -116,3 +116,4 @@
 {.name = "ncd_arithmetic", .loglevel = 4},
 {.name = "ncd_parse", .loglevel = 4},
 {.name = "ncd_valuemetic", .loglevel = 4},
+{.name = "ncd_file", .loglevel = 4},

ncd/CMakeLists.txt

@@ -108,6 +108,7 @@ add_executable(badvpn-ncd
     modules/arithmetic.c
     modules/parse.c
     modules/valuemetic.c
+    modules/file.c
     ${NCD_ADDITIONAL_SOURCES}
 )
 target_link_libraries(badvpn-ncd system flow flowextra dhcpclient arpprobe ncdconfig ncdvalue udevmonitor ncdinterfacemonitor ncdrequest)

ncd/modules/file.c

@@ -0,0 +1,194 @@
+/**
+ * @file file.c
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the author nor the
+ *    names of its contributors may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ * @section DESCRIPTION
+ * 
+ * File I/O module.
+ * 
+ * Synopsis:
+ *   file_read(string filename)
+ * 
+ * Variables:
+ *   string (empty) - file contents
+ * 
+ * Description:
+ *   Reads the contents of a file. Reports an error if something goes wrong.
+ *   WARNING: this uses fopen/fread/fclose, blocking the entire interpreter while
+ *            the file is being read. For this reason, you should only use this
+ *            to read small local files which will be read quickly, and especially
+ *            not files on network mounts.
+ * 
+ * Synopsis:
+ *   file_write(string filename, string contents)
+ * 
+ * Description:
+ *   Writes a file, possibly overwriting an existing one. Reports an error if something
+ *   goes wrong.
+ *   WARNING: this is not an atomic operation; other programs may see the file in an
+ *            inconsistent state while it is being written. Similarly, if writing
+ *            fails, the file may remain in an inconsistent state indefinitely.
+ *            If this is a problem, you should write the new contents to a temporary
+ *            file and rename this temporary file to the live file.
+ *   WARNING: this uses fopen/fwrite/fclose, blocking the entire interpreter while
+ *            the file is being written. For this reason, you should only use this
+ *            to write small local files which will be written quickly, and especially
+ *            not files on network mounts.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+
+#include <misc/read_file.h>
+#include <misc/write_file.h>
+#include <ncd/NCDModule.h>
+
+#include <generated/blog_channel_ncd_file.h>
+
+#define ModuleLog(i, ...) NCDModuleInst_Backend_Log((i), BLOG_CURRENT_CHANNEL, __VA_ARGS__)
+
+struct read_instance {
+    NCDModuleInst *i;
+    uint8_t *file_data;
+    size_t file_len;
+};
+
+static void read_func_new (NCDModuleInst *i)
+{
+    // allocate instance
+    struct read_instance *o = malloc(sizeof(*o));
+    if (!o) {
+        ModuleLog(i, BLOG_ERROR, "failed to allocate instance");
+        goto fail0;
+    }
+    o->i = i;
+    NCDModuleInst_Backend_SetUser(i, o);
+    
+    // read arguments
+    NCDValue *filename_arg;
+    if (!NCDValue_ListRead(i->args, 1, &filename_arg)) {
+        ModuleLog(i, BLOG_ERROR, "wrong arity");
+        goto fail1;
+    }
+    if (!NCDValue_IsStringNoNulls(filename_arg)) {
+        ModuleLog(i, BLOG_ERROR, "wrong type");
+        goto fail1;
+    }
+    
+    // read file
+    if (!read_file(NCDValue_StringValue(filename_arg), &o->file_data, &o->file_len)) {
+        ModuleLog(i, BLOG_ERROR, "failed to read file");
+        goto fail1;
+    }
+    
+    // signal up
+    NCDModuleInst_Backend_Up(i);
+    return;
+    
+fail1:
+    free(o);
+fail0:
+    NCDModuleInst_Backend_SetError(i);
+    NCDModuleInst_Backend_Dead(i);
+}
+
+static void read_func_die (void *vo)
+{
+    struct read_instance *o = vo;
+    NCDModuleInst *i = o->i;
+    
+    // free data
+    free(o->file_data);
+    
+    // free instance
+    free(o);
+    
+    NCDModuleInst_Backend_Dead(i);
+}
+
+static int read_func_getvar (void *vo, const char *name, NCDValue *out_value)
+{
+    struct read_instance *o = vo;
+    
+    if (!strcmp(name, "")) {
+        if (!NCDValue_InitStringBin(out_value, o->file_data, o->file_len)) {
+            ModuleLog(o->i, BLOG_ERROR, "NCDValue_InitStringBin failed");
+            return 0;
+        }
+        return 1;
+    }
+    
+    return 0;
+}
+
+static void write_func_new (NCDModuleInst *i)
+{
+    // read arguments
+    NCDValue *filename_arg;
+    NCDValue *contents_arg;
+    if (!NCDValue_ListRead(i->args, 2, &filename_arg, &contents_arg)) {
+        ModuleLog(i, BLOG_ERROR, "wrong arity");
+        goto fail0;
+    }
+    if (!NCDValue_IsStringNoNulls(filename_arg) || !NCDValue_IsString(contents_arg)) {
+        ModuleLog(i, BLOG_ERROR, "wrong type");
+        goto fail0;
+    }
+    
+    // write file
+    if (!write_file(NCDValue_StringValue(filename_arg), NCDValue_StringValue(contents_arg), NCDValue_StringLength(contents_arg))) {
+        ModuleLog(i, BLOG_ERROR, "failed to write file");
+        goto fail0;
+    }
+    
+    // signal up
+    NCDModuleInst_Backend_Up(i);
+    return;
+    
+fail0:
+    NCDModuleInst_Backend_SetError(i);
+    NCDModuleInst_Backend_Dead(i);
+}
+
+static const struct NCDModule modules[] = {
+    {
+        .type = "file_read",
+        .func_new = read_func_new,
+        .func_die = read_func_die,
+        .func_getvar = read_func_getvar
+    }, {
+        .type = "file_write",
+        .func_new = write_func_new
+    }, {
+        .type = NULL
+    }
+};
+
+const struct NCDModuleGroup ncdmodule_file = {
+    .modules = modules
+};

ncd/modules/modules.h

@@ -97,6 +97,7 @@ extern const struct NCDModuleGroup ncdmodule_getargs;
 extern const struct NCDModuleGroup ncdmodule_arithmetic;
 extern const struct NCDModuleGroup ncdmodule_parse;
 extern const struct NCDModuleGroup ncdmodule_valuemetic;
+extern const struct NCDModuleGroup ncdmodule_file;
 
 static const struct NCDModuleGroup *ncd_modules[] = {
     &ncdmodule_var,
@@ -162,6 +163,7 @@ static const struct NCDModuleGroup *ncd_modules[] = {
     &ncdmodule_arithmetic,
     &ncdmodule_parse,
     &ncdmodule_valuemetic,
+    &ncdmodule_file,
     NULL
 };