Feature: Added buffer_push_printf() and buffer_push_vprintf()

src/buffer.c

@@ -10,8 +10,10 @@
 #include <config.h>
 #endif
 
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stdarg.h>
 
 #include "buffer.h"
 #include "refobject.h"
@@ -195,6 +197,73 @@ int         buffer_push_string(buffer_t *buffer, const char *string)
     return buffer_push_data(buffer, string, strlen(string));
 }
 
+
+int         buffer_push_printf(buffer_t *buffer, const char *format, ...)
+{
+    int ret;
+    va_list ap;
+
+    if (!buffer || !format)
+        return -1;
+
+    if (!*format)
+        return 0;
+
+    va_start(ap, format);
+    ret = buffer_push_vprintf(buffer, format, ap);
+    va_end(ap);
+
+    return ret;
+}
+
+int         buffer_push_vprintf(buffer_t *buffer, const char *format, va_list ap)
+{
+    void *buf;
+    int ret;
+    size_t length = 1024;
+
+    if (!buffer || !format)
+        return -1;
+
+    if (!*format)
+        return 0;
+
+    ret = buffer_zerocopy_push_request(buffer, &buf, length);
+    if (ret != 0)
+        return ret;
+
+    ret = vsnprintf(buf, length, format, ap);
+    if (ret >= 0 && (size_t)ret < length) {
+        return buffer_zerocopy_push_complete(buffer, ret);
+    } else if (ret < 0) {
+        /* This vsnprintf() likely does not follow POSIX.
+         * We don't know what length we need to asume. So asume a big one and hope for the best. */
+        length = 8192;
+    } else {
+        /* Reallocate the buffer to the size reported plus one for '\0'-termination */
+        length = ret + 1;
+    }
+
+    /* We have not written any data yet. */
+    ret = buffer_zerocopy_push_complete(buffer, 0);
+    if (ret != 0)
+        return ret;
+
+    /* Now let's try again. */
+    ret = buffer_zerocopy_push_request(buffer, &buf, length);
+    if (ret != 0)
+        return ret;
+
+    ret = vsnprintf(buf, length, format, ap);
+    if (ret < 0 || (size_t)ret >= length) {
+        /* This still didn't work. Giving up. */
+        buffer_zerocopy_push_complete(buffer, 0);
+        return -1;
+    }
+
+    return buffer_zerocopy_push_complete(buffer, ret);
+}
+
 int         buffer_zerocopy_push_request(buffer_t *buffer, void **data, size_t request)
 {
     if (!buffer || !data)

src/buffer.h

@@ -18,6 +18,8 @@
 #include <config.h>
 #endif
 
+#include <stdarg.h>
+
 #include "icecasttypes.h"
 #include "compat.h"
 #include "refobject.h"
@@ -127,6 +129,30 @@ int         buffer_push_data(buffer_t *buffer, const void *data, size_t length);
  */
 int         buffer_push_string(buffer_t *buffer, const char *string);
 
+/* This pushes a formated string to the end of the buffer.
+ * Parameters:
+ *  buffer
+ *      The buffer to operate on.
+ *  format
+ *      The format string as for printf() family functions.
+ *  ...
+ *      The parameters according to the format string.
+ */
+int         buffer_push_printf(buffer_t *buffer, const char *format, ...);
+
+/* This pushes a formated string to the end of the buffer using a va_list.
+ * Parameters:
+ *  buffer
+ *      The buffer to operate on.
+ *  format
+ *      The format string as for printf() family functions.
+ *  ap
+ *      The parameters according to the format string as va_list.
+ * See also:
+ *  vprintf(3).
+ */
+int         buffer_push_vprintf(buffer_t *buffer, const char *format, va_list ap);
+
 /* This requests for a memory buffer that can be pushed to without the need for copy.
  * Parameters:
  *  buffer

src/tests/ctest_buffer.c

@@ -281,6 +281,28 @@ static void test_length(void)
     ctest_test("un-referenced", refobject_unref(a) == 0);
 }
 
+static void test_printf(void)
+{
+    buffer_t *a;
+    const char *str = "Hello World!";
+    const int num = -127;
+    const char *match_a = ":Hello World!:";
+    const char *match_b = ":Hello World!:<-127 >";
+    const char *match_c = ":Hello World!:<-127 >? +127?";
+
+    a = buffer_new_simple();
+    ctest_test("buffer created", a != NULL);
+
+    ctest_test("Set length to match pattern a", buffer_push_printf(a, ":%s:", str) == 0);
+    test__compare_to_string(a, "string matches pattern a", match_a);
+    ctest_test("Set length to match pattern a", buffer_push_printf(a, "<%-5i>", num) == 0);
+    test__compare_to_string(a, "string matches pattern b", match_b);
+    ctest_test("Set length to match pattern a", buffer_push_printf(a, "?%+5i?", -num) == 0);
+    test__compare_to_string(a, "string matches pattern c", match_c);
+
+    ctest_test("un-referenced", refobject_unref(a) == 0);
+}
+
 int main (void)
 {
     ctest_init();
@@ -299,6 +321,8 @@ int main (void)
     test_shift();
     test_length();
 
+    test_printf();
+
     ctest_fin();
 
     return 0;