split off buffer logic

1 files changed, 226 insertions, 0 deletions

diff --git a/src/util/buffer.c b/src/util/buffer.c
new file mode 100644
index 000000000..85762322a
--- /dev/null
+++ b/src/util/buffer.c
@@ -0,0 +1,226 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2019 GNUnet e.V.
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file util.c
+ * @brief Common buffer management functions; we might choose to move those to GNUnet at some point
+ * @author Florian Dold
+ */
+#include "platform.h"
+#include "taler_util.h"
+#include <gcrypt.h>
+
+/**
+ * Initialize a buffer with the given capacity.
+ *
+ * When a buffer is allocated with this function, a warning is logged
+ * when the buffer exceeds the initial capacity.
+ *
+ * @param buf the buffer to initialize
+ * @param capacity the capacity (in bytes) to allocate for @a buf
+ */
+void
+TALER_buffer_prealloc (struct TALER_Buffer *buf, size_t capacity)
+{
+  /* Buffer should be zero-initialized */
+  GNUNET_assert (0 == buf->mem);
+  GNUNET_assert (0 == buf->capacity);
+  GNUNET_assert (0 == buf->position);
+  buf->mem = GNUNET_malloc (capacity);
+  buf->capacity = capacity;
+  buf->warn_grow = GNUNET_YES;
+}
+
+
+/**
+ * Make sure that at least @a n bytes remaining in the buffer.
+ *
+ * @param buf buffer to potentially grow
+ * @param n number of bytes that should be available to write
+ */
+void
+TALER_buffer_ensure_remaining (struct TALER_Buffer *buf, size_t n)
+{
+  size_t new_capacity = buf->position + n;
+
+  if (new_capacity <= buf->capacity)
+    return;
+  /* warn if calculation of expected size was wrong */
+  GNUNET_break (GNUNET_YES != buf->warn_grow);
+  if (new_capacity < buf->capacity * 2)
+    new_capacity = buf->capacity * 2;
+  buf->capacity = new_capacity;
+  if (NULL != buf->mem)
+    buf->mem = GNUNET_realloc (buf->mem, new_capacity);
+  else
+    buf->mem = GNUNET_malloc (new_capacity);
+}
+
+
+/**
+ * Write bytes to the buffer.
+ *
+ * Grows the buffer if necessary.
+ *
+ * @param buf buffer to write to
+ * @param data data to read from
+ * @param len number of bytes to copy from @a data to @a buf
+ *
+ */
+void
+TALER_buffer_write (struct TALER_Buffer *buf, const char *data, size_t len)
+{
+  TALER_buffer_ensure_remaining (buf, len);
+  memcpy (buf->mem + buf->position, data, len);
+  buf->position += len;
+}
+
+
+/**
+ * Write a 0-terminated string to a buffer, excluding the 0-terminator.
+ *
+ * @param buf the buffer to write to
+ * @param str the string to write to @a buf
+ */
+void
+TALER_buffer_write_str (struct TALER_Buffer *buf, const char *str)
+{
+  size_t len = strlen (str);
+
+  TALER_buffer_write (buf, str, len);
+}
+
+
+/**
+ * Clear the buffer and return the string it contained.
+ * The caller is responsible to eventually #GNUNET_free
+ * the returned string.
+ *
+ * The returned string is always 0-terminated.
+ *
+ * @param buf the buffer to reap the string from
+ * @returns the buffer contained in the string
+ */
+char *
+TALER_buffer_reap_str (struct TALER_Buffer *buf)
+{
+  char *res;
+
+  /* ensure 0-termination */
+  if ( (0 == buf->position) || ('\0' != buf->mem[buf->position - 1]))
+  {
+    TALER_buffer_ensure_remaining (buf, 1);
+    buf->mem[buf->position++] = '\0';
+  }
+  res = buf->mem;
+  *buf = (struct TALER_Buffer) { 0 };
+  return res;
+}
+
+
+/**
+ * Free the backing memory of the given buffer.
+ * Does not free the memory of the buffer control structure,
+ * which is typically stack-allocated.
+ */
+void
+TALER_buffer_clear (struct TALER_Buffer *buf)
+{
+  GNUNET_free_non_null (buf->mem);
+  *buf = (struct TALER_Buffer) { 0 };
+}
+
+
+/**
+ * Write a path component to a buffer, ensuring that
+ * there is exactly one slash between the previous contents
+ * of the buffer and the new string.
+ *
+ * @param buf buffer to write to
+ * @param str string containing the new path component
+ */
+void
+TALER_buffer_write_path (struct TALER_Buffer *buf, const char *str)
+{
+  size_t len = strlen (str);
+
+  while ( (0 != len) && ('/' == str[0]) )
+  {
+    str++;
+    len--;
+  }
+  if ( (0 == buf->position) || ('/' != buf->mem[buf->position - 1]) )
+  {
+    TALER_buffer_ensure_remaining (buf, 1);
+    buf->mem[buf->position++] = '/';
+  }
+  TALER_buffer_write (buf, str, len);
+}
+
+
+/**
+ * Write a 0-terminated formatted string to a buffer, excluding the
+ * 0-terminator.
+ *
+ * Grows the buffer if necessary.
+ *
+ * @param buf the buffer to write to
+ * @param fmt format string
+ * @param ... format arguments
+ */
+void
+TALER_buffer_write_fstr (struct TALER_Buffer *buf, const char *fmt, ...)
+{
+  va_list args;
+
+  va_start (args, fmt);
+  TALER_buffer_write_vfstr (buf, fmt, args);
+  va_end (args);
+}
+
+
+/**
+ * Write a 0-terminated formatted string to a buffer, excluding the
+ * 0-terminator.
+ *
+ * Grows the buffer if necessary.
+ *
+ * @param buf the buffer to write to
+ * @param fmt format string
+ * @param args format argument list
+ */
+void
+TALER_buffer_write_vfstr (struct TALER_Buffer *buf,
+                          const char *fmt,
+                          va_list args)
+{
+  int res;
+  va_list args2;
+
+  va_copy (args2, args);
+  res = vsnprintf (NULL, 0, fmt, args2);
+  va_end (args2);
+
+  GNUNET_assert (res >= 0);
+  TALER_buffer_ensure_remaining (buf, res + 1);
+
+  va_copy (args2, args);
+  res = vsnprintf (buf->mem + buf->position, res + 1, fmt, args2);
+  va_end (args2);
+
+  GNUNET_assert (res >= 0);
+  buf->position += res;
+  GNUNET_assert (buf->position <= buf->capacity);
+}