From 469074b4a59d26566d388680a1154c522d9395c7 Mon Sep 17 00:00:00 2001
From: Thomas Watson <twatson52@icloud.com>
Date: Sun, 10 Jul 2022 13:33:46 -0500
Subject: [PATCH] switch to chunk-wide read/write loops when loading and
 dumping in stdio mode

This fixes the high CPU usage and slow speeds observed when using
stdio mode and temporary files need to be spilled to disk.
---
 lrzip.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 54 insertions(+), 5 deletions(-)

diff --git a/lrzip.c b/lrzip.c
index bcc04ce..9ee2b27 100644
--- a/lrzip.c
+++ b/lrzip.c
@@ -56,6 +56,7 @@
 #include "stream.h"
 
 #define MAGIC_LEN (24)
+#define STDIO_TMPFILE_BUFFER_SIZE (65536) // used in read_tmpinfile and dump_tmpoutfile
 
 static void release_hashes(rzip_control *control);
 
@@ -412,7 +413,7 @@ static bool flush_tmpoutbuf(rzip_control *control)
 /* Dump temporary outputfile to perform stdout */
 static bool dump_tmpoutfile(rzip_control *control)
 {
-	int tmpchar, fd_out = control->fd_out;
+	int fd_out = control->fd_out;
 	FILE *tmpoutfp;
 
 	if (unlikely(fd_out == -1))
@@ -425,9 +426,35 @@ static bool dump_tmpoutfile(rzip_control *control)
 	rewind(tmpoutfp);
 
 	if (!TEST_ONLY) {
+		char* buf;
+
 		print_verbose("Dumping temporary file to control->outFILE.\n");
-		while ((tmpchar = fgetc(tmpoutfp)) != EOF)
-			putchar(tmpchar);
+		fflush(control->outFILE);
+
+		buf = malloc(STDIO_TMPFILE_BUFFER_SIZE);
+		if (unlikely(!buf))
+			fatal_return(("Failed to allocate buffer in dump_tmpoutfile\n"), false);
+
+		while (1) {
+			ssize_t num_read, num_written;
+			num_read = fread(buf, 1, STDIO_TMPFILE_BUFFER_SIZE, tmpoutfp);
+			if (unlikely(num_read == 0)) {
+				if (ferror(tmpoutfp)) {
+					dealloc(buf);
+					fatal_return(("Failed read in dump_tmpoutfile\n"), false);
+				} else {
+					break; // must be at EOF
+				}
+			}
+
+			num_written = fwrite(buf, 1, num_read, control->outFILE);
+			if (unlikely(num_written != num_read)) {
+				dealloc(buf);
+				fatal_return(("Failed write in dump_tmpoutfile\n"), false);
+			}
+		}
+
+		dealloc(buf);
 		fflush(control->outFILE);
 		rewind(tmpoutfp);
 	}
@@ -539,6 +566,7 @@ bool read_tmpinfile(rzip_control *control, int fd_in)
 {
 	FILE *tmpinfp;
 	int tmpchar;
+	char* buf;
 
 	if (fd_in == -1)
 		return false;
@@ -548,9 +576,30 @@ bool read_tmpinfile(rzip_control *control, int fd_in)
 	if (unlikely(tmpinfp == NULL))
 		fatal_return(("Failed to fdopen in tmpfile\n"), false);
 
-	while ((tmpchar = getchar()) != EOF)
-		fputc(tmpchar, tmpinfp);
+	buf = malloc(STDIO_TMPFILE_BUFFER_SIZE);
+	if (unlikely(!buf))
+		fatal_return(("Failed to allocate buffer in read_tmpinfile\n"), false);
 
+	while (1) {
+		ssize_t num_read, num_written;
+		num_read = fread(buf, 1, STDIO_TMPFILE_BUFFER_SIZE, stdin);
+		if (unlikely(num_read == 0)) {
+			if (ferror(stdin)) {
+				dealloc(buf);
+				fatal_return(("Failed read in read_tmpinfile\n"), false);
+			} else {
+				break; // must be at EOF
+			}
+		}
+
+		num_written = fwrite(buf, 1, num_read, tmpinfp);
+		if (unlikely(num_written != num_read)) {
+			dealloc(buf);
+			fatal_return(("Failed write in read_tmpinfile\n"), false);
+		}
+	}
+
+	dealloc(buf);
 	fflush(tmpinfp);
 	rewind(tmpinfp);
 	return true;