ncd: modules: add substr

blog_channels.txt

@@ -134,3 +134,4 @@ ncd_file_open 4
 ncd_backtrack 4
 ncd_socket 4
 ncd_depend_scope 4
+ncd_substr 4

generated/blog_channel_ncd_substr.h

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

generated/blog_channels_defines.h

@@ -134,4 +134,5 @@
 #define BLOG_CHANNEL_ncd_backtrack 133
 #define BLOG_CHANNEL_ncd_socket 134
 #define BLOG_CHANNEL_ncd_depend_scope 135
-#define BLOG_NUM_CHANNELS 136
+#define BLOG_CHANNEL_ncd_substr 136
+#define BLOG_NUM_CHANNELS 137

generated/blog_channels_list.h

@@ -134,3 +134,4 @@
 {"ncd_backtrack", 4},
 {"ncd_socket", 4},
 {"ncd_depend_scope", 4},
+{"ncd_substr", 4},

ncd/CMakeLists.txt

@@ -171,6 +171,7 @@ add_library(ncdinterpreter
     modules/file_open.c
     modules/backtrack.c
     modules/depend_scope.c
+    modules/substr.c
     ${NCD_ADDITIONAL_SOURCES}
 )
 target_link_libraries(ncdinterpreter

ncd/modules/modules.h

@@ -77,6 +77,7 @@ extern const struct NCDModuleGroup ncdmodule_timer;
 extern const struct NCDModuleGroup ncdmodule_file_open;
 extern const struct NCDModuleGroup ncdmodule_backtrack;
 extern const struct NCDModuleGroup ncdmodule_depend_scope;
+extern const struct NCDModuleGroup ncdmodule_substr;
 #ifndef BADVPN_EMSCRIPTEN
 extern const struct NCDModuleGroup ncdmodule_regex_match;
 extern const struct NCDModuleGroup ncdmodule_run;
@@ -158,6 +159,7 @@ static const struct NCDModuleGroup *ncd_modules[] = {
     &ncdmodule_file_open,
     &ncdmodule_backtrack,
     &ncdmodule_depend_scope,
+    &ncdmodule_substr,
 #ifndef BADVPN_EMSCRIPTEN
     &ncdmodule_regex_match,
     &ncdmodule_run,

ncd/modules/substr.c

@@ -0,0 +1,160 @@
+/**
+ * @file substr.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
+ * 
+ * Synopsis:
+ *   substr(string str, string start [, string max])
+ * 
+ * Description:
+ *   Extracts a substring from a string. The result is the longest substring which
+ *   starts at the offset 'start' bytes into 'str', and is no longer than 'max' bytes.
+ *   If 'max' is not provided, the result is the substring from the offset 'start' to
+ *   the end. In any case, 'start' must not be greater than the length of 'str'.
+ */
+
+#include <stddef.h>
+#include <string.h>
+#include <limits.h>
+
+#include <ncd/NCDModule.h>
+#include <ncd/static_strings.h>
+#include <ncd/extra/value_utils.h>
+
+#include <generated/blog_channel_ncd_substr.h>
+
+#define ModuleLog(i, ...) NCDModuleInst_Backend_Log((i), BLOG_CURRENT_CHANNEL, __VA_ARGS__)
+
+struct substr_instance {
+    NCDModuleInst *i;
+    NCDRefTarget *ref_target;
+    const char *data;
+    size_t length;
+};
+
+static void substr_func_new_common (void *vo, NCDModuleInst *i, NCDRefTarget *ref_target, const char *data, size_t length)
+{
+    struct substr_instance *o = vo;
+    o->i = i;
+    
+    o->ref_target = ref_target;
+    o->data = data;
+    o->length = length;
+    
+    NCDModuleInst_Backend_Up(i);
+}
+
+static int substr_func_getvar (void *vo, NCD_string_id_t name, NCDValMem *mem, NCDValRef *out)
+{
+    struct substr_instance *o = vo;
+    
+    if (name == NCD_STRING_EMPTY) {
+        if (o->ref_target) {
+            *out = NCDVal_NewExternalString(mem, o->data, o->length, o->ref_target);
+        } else {
+            *out = NCDVal_NewStringBin(mem, (const uint8_t *)o->data, o->length);
+        }
+        if (NCDVal_IsInvalid(*out)) {
+            ModuleLog(o->i, BLOG_ERROR, "NCDVal_NewExternalString/NCDVal_NewStringBin failed");
+        }
+        return 1;
+    }
+    
+    return 0;
+}
+
+static void func_new_substr (void *vo, NCDModuleInst *i, const struct NCDModuleInst_new_params *params)
+{
+    NCDValRef str_arg;
+    NCDValRef start_arg;
+    NCDValRef max_arg = NCDVal_NewInvalid();
+    if (!NCDVal_ListRead(params->args, 2, &str_arg, &start_arg) &&
+        !NCDVal_ListRead(params->args, 3, &str_arg, &start_arg, &max_arg)
+    ) {
+        ModuleLog(i, BLOG_ERROR, "wrong arity");
+        goto fail0;
+    }
+    if (!NCDVal_IsString(str_arg) || !NCDVal_IsString(start_arg) ||
+        (!NCDVal_IsInvalid(max_arg) && !NCDVal_IsString(max_arg))
+    ) {
+        ModuleLog(i, BLOG_ERROR, "wrong type");
+        goto fail0;
+    }
+    
+    uintmax_t start;
+    if (!ncd_read_uintmax(start_arg, &start) || start > SIZE_MAX) {
+        ModuleLog(i, BLOG_ERROR, "wrong size");
+        goto fail0;
+    }
+    
+    uintmax_t max = SIZE_MAX;
+    if (!NCDVal_IsInvalid(max_arg)) {
+        if (!ncd_read_uintmax(max_arg, &max) || max > SIZE_MAX) {
+            ModuleLog(i, BLOG_ERROR, "wrong max");
+            goto fail0;
+        }
+    }
+    
+    const char *str_data = NCDVal_StringData(str_arg);
+    size_t str_length = NCDVal_StringLength(str_arg);
+    
+    if (start > str_length) {
+        ModuleLog(i, BLOG_ERROR, "start is beyond the end of the string");
+        goto fail0;
+    }
+    
+    const char *sub_data = str_data + start;
+    size_t sub_length = str_length - start;
+    if (sub_length > max) {
+        sub_length = max;
+    }
+    
+    NCDRefTarget *ref_target = (!NCDVal_IsExternalString(str_arg) ? NULL : NCDVal_ExternalStringTarget(str_arg));
+    
+    substr_func_new_common(vo, i, ref_target, sub_data, sub_length);
+    return;
+    
+fail0:
+    NCDModuleInst_Backend_SetError(i);
+    NCDModuleInst_Backend_Dead(i);
+}
+
+static struct NCDModule modules[] = {
+    {
+        .type = "substr",
+        .func_new2 = func_new_substr,
+        .func_getvar2 = substr_func_getvar,
+        .alloc_size = sizeof(struct substr_instance)
+    }, {
+        .type = NULL
+    }
+};
+
+const struct NCDModuleGroup ncdmodule_substr = {
+    .modules = modules
+};