1 files changed, 193 insertions, 0 deletions
diff --git a/utils/bufchain.c b/utils/bufchain.c
new file mode 100644
index 00000000..9b02c65f
--- /dev/null
+++ b/utils/bufchain.c
@@ -0,0 +1,193 @@
+/*
+ * Generic routines to deal with send buffers: a linked list of
+ * smallish blocks, with the operations
+ *
+ *  - add an arbitrary amount of data to the end of the list
+ *  - remove the first N bytes from the list
+ *  - return a (pointer,length) pair giving some initial data in
+ *    the list, suitable for passing to a send or write system
+ *    call
+ *  - retrieve a larger amount of initial data from the list
+ *  - return the current size of the buffer chain in bytes
+ */
+
+#include "defs.h"
+#include "misc.h"
+
+#define BUFFER_MIN_GRANULE  512
+
+struct bufchain_granule {
+    struct bufchain_granule *next;
+    char *bufpos, *bufend, *bufmax;
+};
+
+static void uninitialised_queue_idempotent_callback(IdempotentCallback *ic)
+{
+    unreachable("bufchain callback used while uninitialised");
+}
+
+void bufchain_init(bufchain *ch)
+{
+    ch->head = ch->tail = NULL;
+    ch->buffersize = 0;
+    ch->ic = NULL;
+    ch->queue_idempotent_callback = uninitialised_queue_idempotent_callback;
+}
+
+void bufchain_clear(bufchain *ch)
+{
+    struct bufchain_granule *b;
+    while (ch->head) {
+        b = ch->head;
+        ch->head = ch->head->next;
+        smemclr(b, sizeof(*b));
+        sfree(b);
+    }
+    ch->tail = NULL;
+    ch->buffersize = 0;
+}
+
+size_t bufchain_size(bufchain *ch)
+{
+    return ch->buffersize;
+}
+
+void bufchain_set_callback_inner(
+    bufchain *ch, IdempotentCallback *ic,
+    void (*queue_idempotent_callback)(IdempotentCallback *ic))
+{
+    ch->queue_idempotent_callback = queue_idempotent_callback;
+    ch->ic = ic;
+}
+
+void bufchain_add(bufchain *ch, const void *data, size_t len)
+{
+    const char *buf = (const char *)data;
+
+    if (len == 0) return;
+
+    ch->buffersize += len;
+
+    while (len > 0) {
+        if (ch->tail && ch->tail->bufend < ch->tail->bufmax) {
+            size_t copylen = min(len, ch->tail->bufmax - ch->tail->bufend);
+            memcpy(ch->tail->bufend, buf, copylen);
+            buf += copylen;
+            len -= copylen;
+            ch->tail->bufend += copylen;
+        }
+        if (len > 0) {
+            size_t grainlen =
+                max(sizeof(struct bufchain_granule) + len, BUFFER_MIN_GRANULE);
+            struct bufchain_granule *newbuf;
+            newbuf = smalloc(grainlen);
+            newbuf->bufpos = newbuf->bufend =
+                (char *)newbuf + sizeof(struct bufchain_granule);
+            newbuf->bufmax = (char *)newbuf + grainlen;
+            newbuf->next = NULL;
+            if (ch->tail)
+                ch->tail->next = newbuf;
+            else
+                ch->head = newbuf;
+            ch->tail = newbuf;
+        }
+    }
+
+    if (ch->ic)
+        ch->queue_idempotent_callback(ch->ic);
+}
+
+void bufchain_consume(bufchain *ch, size_t len)
+{
+    struct bufchain_granule *tmp;
+
+    assert(ch->buffersize >= len);
+    while (len > 0) {
+        int remlen = len;
+        assert(ch->head != NULL);
+        if (remlen >= ch->head->bufend - ch->head->bufpos) {
+            remlen = ch->head->bufend - ch->head->bufpos;
+            tmp = ch->head;
+            ch->head = tmp->next;
+            if (!ch->head)
+                ch->tail = NULL;
+            smemclr(tmp, sizeof(*tmp));
+            sfree(tmp);
+        } else
+            ch->head->bufpos += remlen;
+        ch->buffersize -= remlen;
+        len -= remlen;
+    }
+}
+
+ptrlen bufchain_prefix(bufchain *ch)
+{
+    return make_ptrlen(ch->head->bufpos, ch->head->bufend - ch->head->bufpos);
+}
+
+void bufchain_fetch(bufchain *ch, void *data, size_t len)
+{
+    struct bufchain_granule *tmp;
+    char *data_c = (char *)data;
+
+    tmp = ch->head;
+
+    assert(ch->buffersize >= len);
+    while (len > 0) {
+        int remlen = len;
+
+        assert(tmp != NULL);
+        if (remlen >= tmp->bufend - tmp->bufpos)
+            remlen = tmp->bufend - tmp->bufpos;
+        memcpy(data_c, tmp->bufpos, remlen);
+
+        tmp = tmp->next;
+        len -= remlen;
+        data_c += remlen;
+    }
+}
+
+void bufchain_fetch_consume(bufchain *ch, void *data, size_t len)
+{
+    bufchain_fetch(ch, data, len);
+    bufchain_consume(ch, len);
+}
+
+bool bufchain_try_fetch(bufchain *ch, void *data, size_t len)
+{
+    if (ch->buffersize >= len) {
+        bufchain_fetch(ch, data, len);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+bool bufchain_try_consume(bufchain *ch, size_t len)
+{
+    if (ch->buffersize >= len) {
+        bufchain_consume(ch, len);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+bool bufchain_try_fetch_consume(bufchain *ch, void *data, size_t len)
+{
+    if (ch->buffersize >= len) {
+        bufchain_fetch_consume(ch, data, len);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+size_t bufchain_fetch_consume_up_to(bufchain *ch, void *data, size_t len)
+{
+    if (len > ch->buffersize)
+        len = ch->buffersize;
+    if (len)
+        bufchain_fetch_consume(ch, data, len);
+    return len;
+}