Implement source debugging for interpreter and AOT (#769)

Implement source debugging feature for classic interpreter and AOT:
- use `cmake -DWAMR_BUILD_DEBUG_INTERP=1` to enable interpreter debugging
- use `cmake -DWAMR_BUILD_DEBUG_AOT=1` to enable AOT debugging

See doc/source_debugging.md for more details.

core/iwasm/libraries/debug-engine/packets.c

@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2021 Ant Group.  All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+ */
+
+#include "packets.h"
+
+#include <stdbool.h>
+
+#include "bh_log.h"
+#include "gdbserver.h"
+
+void
+pktbuf_insert(WASMGDBServer *gdbserver, const uint8_t *buf, ssize_t len)
+{
+    WasmDebugPacket *pkt = &gdbserver->pkt;
+
+    if ((unsigned long)(pkt->end + len) >= sizeof(pkt->buf)) {
+        LOG_ERROR("Packet buffer overflow");
+        exit(-2);
+    }
+    memcpy(pkt->buf + pkt->end, buf, len);
+    pkt->end += len;
+}
+
+void
+pktbuf_erase_head(WASMGDBServer *gdbserver, ssize_t end)
+{
+    WasmDebugPacket *pkt = &gdbserver->pkt;
+    memmove(pkt->buf, pkt->buf + end, pkt->end - end);
+    pkt->end -= end;
+}
+
+void
+inbuf_erase_head(WASMGDBServer *gdbserver, ssize_t end)
+{
+    pktbuf_erase_head(gdbserver, end);
+}
+
+void
+pktbuf_clear(WASMGDBServer *gdbserver)
+{
+    WasmDebugPacket *pkt = &gdbserver->pkt;
+    pkt->end = 0;
+}
+
+int
+read_data_once(WASMGDBServer *gdbserver)
+{
+    ssize_t nread;
+    uint8_t buf[4096];
+
+    nread = read(gdbserver->socket_fd, buf, sizeof(buf));
+    if (nread <= 0) {
+        LOG_ERROR("Connection closed");
+        return -1;
+    }
+    pktbuf_insert(gdbserver, buf, nread);
+    return nread;
+}
+
+void
+write_data_raw(WASMGDBServer *gdbserver, const uint8_t *data, ssize_t len)
+{
+    ssize_t nwritten;
+
+    nwritten = write(gdbserver->socket_fd, data, len);
+    if (nwritten < 0) {
+        LOG_ERROR("Write error\n");
+        exit(-2);
+    }
+}
+
+void
+write_hex(WASMGDBServer *gdbserver, unsigned long hex)
+{
+    char buf[32];
+    size_t len;
+
+    len = snprintf(buf, sizeof(buf) - 1, "%02lx", hex);
+    write_data_raw(gdbserver, (uint8_t *)buf, len);
+}
+
+void
+write_packet_bytes(WASMGDBServer *gdbserver,
+                   const uint8_t *data,
+                   size_t num_bytes)
+{
+    uint8_t checksum;
+    size_t i;
+
+    write_data_raw(gdbserver, (uint8_t *)"$", 1);
+    for (i = 0, checksum = 0; i < num_bytes; ++i)
+        checksum += data[i];
+    write_data_raw(gdbserver, (uint8_t *)data, num_bytes);
+    write_data_raw(gdbserver, (uint8_t *)"#", 1);
+    write_hex(gdbserver, checksum);
+}
+
+void
+write_packet(WASMGDBServer *gdbserver, const char *data)
+{
+    LOG_VERBOSE("send replay:%s", data);
+    write_packet_bytes(gdbserver, (const uint8_t *)data, strlen(data));
+}
+
+void
+write_binary_packet(WASMGDBServer *gdbserver,
+                    const char *pfx,
+                    const uint8_t *data,
+                    ssize_t num_bytes)
+{
+    uint8_t *buf;
+    ssize_t pfx_num_chars = strlen(pfx);
+    ssize_t buf_num_bytes = 0;
+    int i;
+
+    buf = malloc(2 * num_bytes + pfx_num_chars);
+    memcpy(buf, pfx, pfx_num_chars);
+    buf_num_bytes += pfx_num_chars;
+
+    for (i = 0; i < num_bytes; ++i) {
+        uint8_t b = data[i];
+        switch (b) {
+            case '#':
+            case '$':
+            case '}':
+            case '*':
+                buf[buf_num_bytes++] = '}';
+                buf[buf_num_bytes++] = b ^ 0x20;
+                break;
+            default:
+                buf[buf_num_bytes++] = b;
+                break;
+        }
+    }
+    write_packet_bytes(gdbserver, buf, buf_num_bytes);
+    free(buf);
+}
+
+bool
+skip_to_packet_start(WASMGDBServer *gdbserver)
+{
+    ssize_t end = -1;
+
+    for (size_t i = 0; i < gdbserver->pkt.end; ++i)
+        if (gdbserver->pkt.buf[i] == '$') {
+            end = i;
+            break;
+        }
+
+    if (end < 0) {
+        pktbuf_clear(gdbserver);
+        return false;
+    }
+
+    pktbuf_erase_head(gdbserver, end);
+    bh_assert(1 <= gdbserver->pkt.end);
+    bh_assert('$' == gdbserver->pkt.buf[0]);
+    return true;
+}
+
+bool
+read_packet(WASMGDBServer *gdbserver)
+{
+    while (!skip_to_packet_start(gdbserver)) {
+        if(read_data_once(gdbserver) < 0)
+            return false;
+    }
+    if (!gdbserver->noack)
+        write_data_raw(gdbserver, (uint8_t *)"+", 1);
+    return true;
+}