Implement dynstr_new_from_cstring and dynstr_memcpy.

3 files changed, 39 insertions, 1 deletions

diff --git a/dynstr.c b/dynstr.c
index bd025f4..f593df7 100644
--- a/dynstr.c
+++ b/dynstr.c
@@ -87,6 +87,11 @@ Dynstr *dynstr_new_empty(void)
     return new(NULL, 0, true);
 }
 
+Dynstr *dynstr_new_from_cstring(const char *cstring)
+{
+    return new(cstring, strlen(cstring), true);
+}
+
 size_t dynstr_len(Dynstr *dynstr)
 {
     return dynstr->size;
@@ -96,3 +101,17 @@ bool dynstr_is_empty(Dynstr *dynstr)
 {
     return dynstr_len(dynstr) == 0;
 }
+
+size_t dynstr_memcpy(void *mem, Dynstr *dynstr, size_t offset, size_t size)
+{
+    size_t len;
+    
+    len = dynstr_len(dynstr);
+    if (offset >= len)
+        return 0;
+    if (size > len - offset)
+        size = len - offset;
+    memcpy(mem, dynstr->mem + offset, size);
+    return size;
+}
+
diff --git a/dynstr.h b/dynstr.h
index b668026..39d2a61 100644
--- a/dynstr.h
+++ b/dynstr.h
@@ -107,7 +107,7 @@ int dynstr_byte_at(Dynstr *dynstr, size_t offset);
 
 /* Copy contents of a dynamic string into a memory area. If the dynamic
  * string is not long enough, or the offset is past the end of the string,
- * the copy is silently truncated. */
+ * the copy is truncated. Return number of bytes copied. */
 size_t dynstr_memcpy(void *mem, Dynstr *dynstr, size_t offset, size_t size);
 
 /* Search for first or last byte with a given value in a string, 
diff --git a/unittests.c b/unittests.c
index adb8e32..0e0285c 100644
--- a/unittests.c
+++ b/unittests.c
@@ -5,6 +5,7 @@
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "dynstr.h"
 
@@ -100,6 +101,23 @@ static int test_empty_string_is_empty(void)
 }
 
 
+static int test_creates_from_cstring(void)
+{
+    const char bytes[] = "asdfasdfafdasdfasdfqw4tb";
+    char newbytes[sizeof(bytes)];
+    Dynstr *dynstr;
+    size_t size;
+    
+    dynstr = dynstr_new_from_cstring(bytes);
+    FAIL_UNLESS_EQUAL(dynstr_len(dynstr), strlen(bytes));
+
+    size = dynstr_memcpy(newbytes, dynstr, 0, strlen(bytes));
+    FAIL_UNLESS_EQUAL(size, strlen(bytes));
+    FAIL_UNLESS_EQUAL(memcmp(bytes, newbytes, sizeof(bytes)), 0);
+    return true;
+}
+
+
 struct test {
     const char *name;
     int (*test)(void);
@@ -114,6 +132,7 @@ static const struct test tests[] = {
     TEST(test_init_resets_error_handler),
     TEST(test_abort_handler_calls_abort),
     TEST(test_empty_string_is_empty),
+    TEST(test_creates_from_cstring),
 };
 static const int num_tests = sizeof(tests) / sizeof(tests[0]);