emulation on host: fix UDP seek&peek (#8827)

Author: d-a-v

tests/host/common/UdpContextSocket.cpp

@@ -166,14 +166,14 @@ size_t mockUDPFillInBuf(int sock, char* ccinbuf, size_t& ccinbufsize, uint8_t& a
     return ccinbufsize += ret;
 }
 
-size_t mockUDPPeekBytes(int sock, char* dst, size_t usersize, int timeout_ms, char* ccinbuf,
-                        size_t& ccinbufsize)
+size_t mockUDPPeekBytes(int sock, char* dst, size_t offset, size_t usersize, int timeout_ms,
+                        char* ccinbuf, size_t& ccinbufsize)
 {
     (void)sock;
     (void)timeout_ms;
-    if (usersize > CCBUFSIZE)
+    if (offset + usersize > CCBUFSIZE)
         fprintf(stderr, MOCK "CCBUFSIZE(%d) should be increased by %zd bytes (-> %zd)\n", CCBUFSIZE,
-                usersize - CCBUFSIZE, usersize);
+                offset + usersize - CCBUFSIZE, offset + usersize);
 
     size_t retsize = 0;
     if (ccinbufsize)
@@ -183,25 +183,10 @@ size_t mockUDPPeekBytes(int sock, char* dst, size_t usersize, int timeout_ms, ch
         if (retsize > ccinbufsize)
             retsize = ccinbufsize;
     }
-    memcpy(dst, ccinbuf, retsize);
+    memcpy(dst, ccinbuf + offset, retsize);
     return retsize;
 }
 
-void mockUDPSwallow(size_t copied, char* ccinbuf, size_t& ccinbufsize)
-{
-    // poor man buffer
-    memmove(ccinbuf, ccinbuf + copied, ccinbufsize - copied);
-    ccinbufsize -= copied;
-}
-
-size_t mockUDPRead(int sock, char* dst, size_t size, int timeout_ms, char* ccinbuf,
-                   size_t& ccinbufsize)
-{
-    size_t copied = mockUDPPeekBytes(sock, dst, size, timeout_ms, ccinbuf, ccinbufsize);
-    mockUDPSwallow(copied, ccinbuf, ccinbufsize);
-    return copied;
-}
-
 size_t mockUDPWrite(int sock, const uint8_t* data, size_t size, int timeout_ms, uint32_t ipv4,
                     uint16_t port)
 {

tests/host/common/include/UdpContext.h

@@ -117,12 +117,12 @@ class UdpContext
 
     size_t getSize()
     {
-        return _inbufsize;
+        return _inbufsize - _inoffset;
     }
 
     size_t tell() const
     {
-        return 0;
+        return _inoffset;
     }
 
     void seek(const size_t pos)
@@ -132,7 +132,7 @@ class UdpContext
             mockverbose("UDPContext::seek too far (%zd >= %zd)\n", pos, _inbufsize);
             exit(EXIT_FAILURE);
         }
-        mockUDPSwallow(pos, _inbuf, _inbufsize);
+        _inoffset = pos;
     }
 
     bool isValidOffset(const size_t pos) const
@@ -165,6 +165,7 @@ class UdpContext
     bool next()
     {
         _inbufsize = 0;
+        _inoffset  = 0;
         mockUDPFillInBuf(_sock, _inbuf, _inbufsize, addrsize, addr, _dstport);
         if (_inbufsize > 0)
         {
@@ -182,13 +183,16 @@ class UdpContext
 
     size_t read(char* dst, size_t size)
     {
-        return mockUDPRead(_sock, dst, size, _timeout_ms, _inbuf, _inbufsize);
+        //return mockUDPRead(_sock, dst, size, _timeout_ms, _inbuf, _inbufsize);
+        auto ret = mockUDPPeekBytes(_sock, dst, _inoffset, size, _timeout_ms, _inbuf, _inbufsize);
+        _inoffset += ret;
+        return ret;
     }
 
     int peek()
     {
         char c;
-        return mockUDPPeekBytes(_sock, &c, 1, _timeout_ms, _inbuf, _inbufsize) ?: -1;
+        return mockUDPPeekBytes(_sock, &c, _inoffset, 1, _timeout_ms, _inbuf, _inbufsize) ?: -1;
     }
 
     void flush()
@@ -280,6 +284,7 @@ class UdpContext
 
     char   _inbuf[CCBUFSIZE];
     size_t _inbufsize = 0;
+    size_t _inoffset  = 0;
     char   _outbuf[CCBUFSIZE];
     size_t _outbufsize = 0;
 

tests/host/common/mock.h

@@ -160,13 +160,10 @@ int    mockUDPSocket();
 bool   mockUDPListen(int sock, uint32_t dstaddr, uint16_t port, uint32_t mcast = 0);
 size_t mockUDPFillInBuf(int sock, char* ccinbuf, size_t& ccinbufsize, uint8_t& addrsize,
                         uint8_t addr[16], uint16_t& port);
-size_t mockUDPPeekBytes(int sock, char* dst, size_t usersize, int timeout_ms, char* ccinbuf,
-                        size_t& ccinbufsize);
-size_t mockUDPRead(int sock, char* dst, size_t size, int timeout_ms, char* ccinbuf,
-                   size_t& ccinbufsize);
+size_t mockUDPPeekBytes(int sock, char* dst, size_t offset, size_t usersize, int timeout_ms,
+                        char* ccinbuf, size_t& ccinbufsize);
 size_t mockUDPWrite(int sock, const uint8_t* data, size_t size, int timeout_ms, uint32_t ipv4,
                     uint16_t port);
-void   mockUDPSwallow(size_t copied, char* ccinbuf, size_t& ccinbufsize);
 
 class UdpContext;
 void register_udp(int sock, UdpContext* udp = nullptr);