From ab4755240a76d9bf57809d53c87548345cf326df Mon Sep 17 00:00:00 2001
From: Jordan Bancino <jordan@bancino.net>
Date: Wed, 15 Mar 2023 17:14:16 +0000
Subject: [PATCH] Add IoCopy() and StreamCopy()

Both do buffered reads and writes, but IoCopy() uses IoRead() and
IoWrite() directly, whereas StreamCopy() relies on StreamGetc() and
StreamPutc(), which manipulate the stream buffers.
---
 src/Io.c             | 44 +++++++++++++++++++++++---
 src/Stream.c         | 75 +++++++++++++++++++++++++++++++++++++++++---
 src/include/Io.h     |  3 ++
 src/include/Stream.h |  3 ++
 4 files changed, 115 insertions(+), 10 deletions(-)

diff --git a/src/Io.c b/src/Io.c
index c261e5e..7f1038a 100644
--- a/src/Io.c
+++ b/src/Io.c
@@ -5,8 +5,8 @@
 #include <errno.h>
 #include <stdio.h>
 
-#ifndef IO_PRINTF_BUFFER
-#define IO_PRINTF_BUFFER 1024
+#ifndef IO_BUFFER
+#define IO_BUFFER 4096
 #endif
 
 struct Io
@@ -177,13 +177,13 @@ IoVprintf(Io *io, const char *fmt, va_list ap)
         return -1;
     }
 
-    buf = Malloc(IO_PRINTF_BUFFER);
+    buf = Malloc(IO_BUFFER);
     if (!buf)
     {
         return -1;
     }
 
-    write = vsnprintf(buf, IO_PRINTF_BUFFER, fmt, ap);
+    write = vsnprintf(buf, IO_BUFFER, fmt, ap);
 
     if (write < 0)
     {
@@ -195,7 +195,7 @@ IoVprintf(Io *io, const char *fmt, va_list ap)
      * be rare, but may occasionally happen. If it does, realloc to
      * the correct size and try again.
      */
-    if (write >= IO_PRINTF_BUFFER)
+    if (write >= IO_BUFFER)
     {
         char *new = Realloc(buf, write + 1);
         if (!new)
@@ -228,3 +228,37 @@ IoPrintf(Io *io, const char *fmt, ...)
 
     return ret;
 }
+
+ssize_t
+IoCopy(Io *in, Io *out)
+{
+    ssize_t nBytes = 0;
+    char buf[IO_BUFFER];
+    ssize_t rRes;
+    ssize_t wRes;
+
+    if (!in || !out)
+    {
+        errno = EBADF;
+        return -1;
+    }
+
+    while ((rRes = IoRead(in, &buf, IO_BUFFER)) != 0)
+    {
+        if (rRes == -1)
+        {
+            return -1;
+        }
+
+        wRes = IoWrite(out, &buf, rRes);
+
+        if (wRes == -1)
+        {
+            return -1;
+        }
+
+        nBytes += wRes;
+    }
+
+    return nBytes;
+}
diff --git a/src/Stream.c b/src/Stream.c
index 491f21e..19801b9 100644
--- a/src/Stream.c
+++ b/src/Stream.c
@@ -4,11 +4,20 @@
 #define STREAM_BUFFER 4096
 #endif
 
+#ifndef STREAM_RETRIES
+#define STREAM_RETRIES 10
+#endif
+
+#ifndef STREAM_DELAY
+#define STREAM_DELAY 2
+#endif
+
 #define STREAM_EOF (1 << 0)
 #define STREAM_ERR (1 << 1)
 
 #include <Io.h>
 #include <Memory.h>
+#include <Util.h>
 
 #include <stdio.h>
 #include <errno.h>
@@ -29,7 +38,7 @@ struct Stream
     size_t ugSize;
     size_t ugLen;
 
-    int flags : 2;
+    int flags:2;
 };
 
 Stream *
@@ -55,7 +64,7 @@ StreamOpen(Io * io)
 }
 
 int
-StreamClose(Stream *stream)
+StreamClose(Stream * stream)
 {
     int ret = 0;
 
@@ -73,6 +82,7 @@ StreamClose(Stream *stream)
     if (stream->wBuf)
     {
         ssize_t writeRes = IoWrite(stream->io, stream->wBuf, stream->wLen);
+
         Free(stream->wBuf);
 
         if (writeRes == -1)
@@ -100,12 +110,12 @@ StreamVprintf(Stream * stream, const char *fmt, va_list ap)
         return -1;
     }
 
-    StreamFlush(stream); /* Flush the buffer out before doing the printf */
+    StreamFlush(stream);           /* Flush the buffer out before doing
+                                    * the printf */
 
     /* Defer printf to underlying Io. We probably should buffer the
      * printf operation just like StreamPutc() so we don't have to
-     * flush the buffer.
-     */
+     * flush the buffer. */
     return IoVprintf(stream->io, fmt, ap);
 }
 
@@ -317,3 +327,58 @@ StreamFlush(Stream * stream)
 
     return 0;
 }
+
+ssize_t
+StreamCopy(Stream * in, Stream * out)
+{
+    ssize_t nBytes = 0;
+    int c;
+    int tries = 0;
+    int readFlg = 0;
+
+    while (1)
+    {
+        c = StreamGetc(in);
+
+        if (StreamEof(in))
+        {
+            break;
+        }
+
+        if (StreamError(in))
+        {
+            if (errno == EAGAIN)
+            {
+                StreamClearError(in);
+                tries++;
+
+                if (tries >= STREAM_RETRIES || readFlg)
+                {
+                    break;
+                }
+                else
+                {
+                    UtilSleepMillis(STREAM_DELAY);
+                    continue;
+                }
+            }
+            else
+            {
+                break;
+            }
+        }
+
+        /* As soon as we've successfully read a byte, treat future
+         * EAGAINs as EOF, because somebody might have forgotten to
+         * close their stream. */
+
+        readFlg = 1;
+        tries = 0;
+
+        StreamPutc(out, c);
+        nBytes++;
+    }
+
+    StreamFlush(out);
+    return nBytes;
+}
diff --git a/src/include/Io.h b/src/include/Io.h
index 7d822a4..ff86675 100644
--- a/src/include/Io.h
+++ b/src/include/Io.h
@@ -43,4 +43,7 @@ IoVprintf(Io *, const char *, va_list);
 extern int
 IoPrintf(Io *, const char *, ...);
 
+extern ssize_t
+IoCopy(Io *, Io *);
+
 #endif /* TELODENDRIA_IO_H */
diff --git a/src/include/Stream.h b/src/include/Stream.h
index d3cfbac..ef94f52 100644
--- a/src/include/Stream.h
+++ b/src/include/Stream.h
@@ -40,4 +40,7 @@ StreamClearError(Stream *);
 extern int
 StreamFlush(Stream *);
 
+extern ssize_t
+StreamCopy(Stream *, Stream *);
+
 #endif /* TELODENDRIA_STREAM_H */