From b1de290eee2476737581409ae33121dfdbc8c5e4 Mon Sep 17 00:00:00 2001
From: James Blades <jwkblades+git@gmail.com>
Date: Sun, 13 Jan 2019 21:26:39 -0700
Subject: [PATCH] [Issue #23] Allow larger than 2GB files to be read.

`read` and `write` return a signed int, meaning that they can only read
up to 2 billion bytes (2GB) at a time. bsdiff and bspatch were expecting
the entire file to be read (or written, respectively) in a single call
to `read` or `write`, which is only possible if they are less than 2GB
in size. There are also other times in which a single function call
would be inadequate for IO, for instance in the case where a device is
busy. The fix for this was to place the functions in a loop and continue
as long as at least 1 byte was transferred (in or out). If an error, or 0
return value, comes back from the transfer, break out of the loop and
return the total number of bytes that had been transferred up to that
point.

Updated the .gitignore file to ignore vim swap files, as well as the
autoconf (generated) files and the executables.
---
 .gitignore | 18 ++++++++++++++++++
 bsdiff.c   | 23 +++++++++++++++++++++--
 bspatch.c  | 42 ++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/.gitignore b/.gitignore
index 4e13492..867f2bb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
+*.*.sw*
 .deps/*
 .libs/*
 *.lo
@@ -9,3 +10,20 @@ NEWS
 README
 ChangeLog
 COPYING
+INSTALL
+Makefile
+Makefile.in
+aclocal.m4
+autom4te.cache/
+compile
+config.h
+config.h.in
+config.log
+config.status
+configure
+depcomp
+install-sh
+missing
+stamp-h1
+/bsdiff
+/bspatch
diff --git a/bsdiff.c b/bsdiff.c
index 628f1c1..44f9a2b 100644
--- a/bsdiff.c
+++ b/bsdiff.c
@@ -373,6 +373,25 @@ static int bz2_write(struct bsdiff_stream* stream, const void* buffer, int size)
 	return 0;
 }
 
+static off_t readFileToBuffer(int fd, uint8_t* buffer, off_t bufferSize)
+{
+    off_t bytesRead = 0;
+    int ret;
+    while (bytesRead < bufferSize)
+    {
+        ret = read(fd, buffer + bytesRead, bufferSize - bytesRead);
+        if (ret > 0)
+        {
+            bytesRead += ret;
+        }
+        else
+        {
+            break;
+        }
+    }
+    return bytesRead;
+}
+
 int main(int argc,char *argv[])
 {
 	int fd;
@@ -397,7 +416,7 @@ int main(int argc,char *argv[])
 		((oldsize=lseek(fd,0,SEEK_END))==-1) ||
 		((old=malloc(oldsize+1))==NULL) ||
 		(lseek(fd,0,SEEK_SET)!=0) ||
-		(read(fd,old,oldsize)!=oldsize) ||
+		(readFileToBuffer(fd,old,oldsize)!=oldsize) ||
 		(close(fd)==-1)) err(1,"%s",argv[1]);
 
 
@@ -407,7 +426,7 @@ int main(int argc,char *argv[])
 		((newsize=lseek(fd,0,SEEK_END))==-1) ||
 		((new=malloc(newsize+1))==NULL) ||
 		(lseek(fd,0,SEEK_SET)!=0) ||
-		(read(fd,new,newsize)!=newsize) ||
+		(readFileToBuffer(fd,new,newsize)!=newsize) ||
 		(close(fd)==-1)) err(1,"%s",argv[2]);
 
 	/* Create the patch file */
diff --git a/bspatch.c b/bspatch.c
index b544914..1c9bd91 100644
--- a/bspatch.c
+++ b/bspatch.c
@@ -121,6 +121,44 @@ static int bz2_read(const struct bspatch_stream* stream, void* buffer, int lengt
 	return 0;
 }
 
+static off_t readFileToBuffer(int fd, uint8_t* buffer, off_t bufferSize)
+{
+    off_t bytesRead = 0;
+    int ret;
+    while (bytesRead < bufferSize)
+    {
+        ret = read(fd, buffer + bytesRead, bufferSize - bytesRead);
+        if (ret > 0)
+        {
+            bytesRead += ret;
+        }
+        else
+        {
+            break;
+        }
+    }
+    return bytesRead;
+}
+
+static off_t writeFileFromBuffer(int fd, uint8_t* buffer, off_t bufferSize)
+{
+    off_t bytesWritten = 0;
+    int ret;
+    while (bytesWritten < bufferSize)
+    {
+        ret = write(fd, buffer + bytesWritten, bufferSize - bytesWritten);
+        if (ret > 0)
+        {
+            bytesWritten += ret;
+        }
+        else
+        {
+            break;
+        }
+    }
+    return bytesWritten;
+}
+
 int main(int argc,char * argv[])
 {
 	FILE * f;
@@ -160,7 +198,7 @@ int main(int argc,char * argv[])
 		((oldsize=lseek(fd,0,SEEK_END))==-1) ||
 		((old=malloc(oldsize+1))==NULL) ||
 		(lseek(fd,0,SEEK_SET)!=0) ||
-		(read(fd,old,oldsize)!=oldsize) ||
+		(readFileToBuffer(fd,old,oldsize)!=oldsize) ||
 		(fstat(fd, &sb)) ||
 		(close(fd)==-1)) err(1,"%s",argv[1]);
 	if((new=malloc(newsize+1))==NULL) err(1,NULL);
@@ -179,7 +217,7 @@ int main(int argc,char * argv[])
 
 	/* Write the new file */
 	if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,sb.st_mode))<0) ||
-		(write(fd,new,newsize)!=newsize) || (close(fd)==-1))
+		(writeFileFromBuffer(fd,new,newsize)!=newsize) || (close(fd)==-1))
 		err(1,"%s",argv[2]);
 
 	free(new);