Add helper to create string parts and combine them

src/helpers.c

@@ -18,6 +18,93 @@
 
 // Standard library includes.
 #include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+int c_simple_http_internal_get_string_part_full_size(void *data, void *ud) {
+  C_SIMPLE_HTTP_String_Part *part = data;
+  size_t *count = ud;
+
+  *count += part->size - 1;
+
+  return 0;
+}
+
+int c_simple_http_internal_combine_string_parts_from_list(void *data, void *ud) {
+  C_SIMPLE_HTTP_String_Part *part = data;
+  void **ptrs = ud;
+  char *buf = ptrs[0];
+  size_t *current_count = ptrs[1];
+  const size_t *total_count = ptrs[2];
+
+  if (*current_count + part->size - 1 > *total_count) {
+    fprintf(stderr, "ERROR Invalid state combining string parts!\n");
+    return 1;
+  }
+
+  memcpy(buf + *current_count, part->buf, part->size - 1);
+
+  *current_count += part->size - 1;
+
+  return 0;
+}
+
+void c_simple_http_cleanup_string_part(void *data) {
+  C_SIMPLE_HTTP_String_Part *part = data;
+  if (part) {
+    if (part->buf) {
+      free(part->buf);
+      part->buf = NULL;
+    }
+    free(part);
+  }
+}
+
+void c_simple_http_add_string_part(
+    SDArchiverLinkedList *list, const char *c_string, size_t extra) {
+  C_SIMPLE_HTTP_String_Part *string_part =
+    malloc(sizeof(C_SIMPLE_HTTP_String_Part));
+
+  string_part->size = strlen(c_string) + 1;
+  string_part->buf = malloc(string_part->size);
+  memcpy(string_part->buf, c_string, string_part->size);
+
+  string_part->extra = extra;
+
+  simple_archiver_list_add(
+    list, string_part, c_simple_http_cleanup_string_part);
+}
+
+char *c_simple_http_combine_string_parts(const SDArchiverLinkedList *list) {
+  if (!list || list->count == 0) {
+    return NULL;
+  }
+
+  size_t count = 0;
+
+  simple_archiver_list_get(
+    list, c_simple_http_internal_get_string_part_full_size, &count);
+
+  char *buf = malloc(count + 1);
+  size_t current_count = 0;
+
+  void **ptrs = malloc(sizeof(void*) * 3);
+  ptrs[0] = buf;
+  ptrs[1] = &current_count;
+  ptrs[2] = &count;
+
+  if (simple_archiver_list_get(
+      list, c_simple_http_internal_combine_string_parts_from_list, ptrs)) {
+    free(buf);
+    return NULL;
+  }
+
+  free(ptrs);
+
+  buf[count] = 0;
+
+  return buf;
+}
 
 void c_simple_http_helper_to_lowercase_in_place(char *buf, size_t size) {
   for (size_t idx = 0; idx < size; ++idx) {

src/helpers.h

@@ -20,6 +20,27 @@
 // Standard library includes.
 #include <stddef.h>
 
+// Third-party includes.
+#include <SimpleArchiver/src/data_structures/linked_list.h>
+
+typedef struct C_SIMPLE_HTTP_String_Part {
+  char *buf;
+  size_t size;
+  size_t extra;
+} C_SIMPLE_HTTP_String_Part;
+
+/// Assumes "data" is a C_SIMPLE_HTTP_String_Part, "data" was malloced, and
+/// "data->buf" was malloced.
+void c_simple_http_cleanup_string_part(void *data);
+
+/// Puts a malloced instance of String_Part into the list.
+/// The given c_string will be copied into a newly malloced buffer.
+void c_simple_http_add_string_part(
+  SDArchiverLinkedList *list, const char *c_string, size_t extra);
+
+/// Combines all String_Parts in the list and returns it as a single buffer.
+char *c_simple_http_combine_string_parts(const SDArchiverLinkedList *list);
+
 /// Modifies "buf" in-place to change all uppercase to lowercase alpha chars.
 void c_simple_http_helper_to_lowercase_in_place(char *buf, size_t size);
 

src/test.c

@@ -5,14 +5,15 @@
 #include <stdint.h>
 
 // Local includes.
-#include "SimpleArchiver/src/data_structures/linked_list.h"
 #include "config.h"
+#include "helpers.h"
 #include "http_template.h"
 #include "http.h"
 
 // Third party includes.
 #include <SimpleArchiver/src/helpers.h>
 #include <SimpleArchiver/src/data_structures/hash_map.h>
+#include <SimpleArchiver/src/data_structures/linked_list.h>
 
 static int32_t checks_checked = 0;
 static int32_t checks_passed = 0;
@@ -542,6 +543,21 @@ int main(void) {
     free(stripped_path_buf);
   }
 
+  // Test helpers.
+  {
+    __attribute__((cleanup(simple_archiver_list_free)))
+    SDArchiverLinkedList *list = simple_archiver_list_init();
+
+    c_simple_http_add_string_part(list, "one\n", 0);
+    c_simple_http_add_string_part(list, "two\n", 0);
+    c_simple_http_add_string_part(list, "three\n", 0);
+
+    __attribute__((cleanup(simple_archiver_helper_cleanup_c_string)))
+    char *buf = c_simple_http_combine_string_parts(list);
+    ASSERT_TRUE(buf);
+    ASSERT_TRUE(strcmp(buf, "one\ntwo\nthree\n") == 0);
+  }
+
   RETURN()
 }