✨ Allow extracted file to be output to file instead of stdout

src/errorAndExit.c

@@ -12,5 +12,6 @@ void errorAndExit() {
   fprintf(stderr, "  -s, --size: The stored size of the file we want to extract (= the compressed size). After inflation, the file will likely be bigger than this.\n");
   fprintf(stderr, "  -k, --keys: Optionally, the three decryption keys used to decrypt the file before inflation.\n");
   fprintf(stderr, "  -p, --previous: Optionally, the location of the previous version of this file, in case this disk only contains the xdelta3 differences and not an actual file.\n");
+  fprintf(stderr, "  -t, --target: The path where the extracted file is saved to. If not specified, the file is outputted to stdout.\n");
   exit(1);
 }

src/main.c

@@ -1,3 +1,4 @@
+#include <errno.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -84,6 +85,16 @@ int main(int argc, char *argv[]) {
     xdelta3Init(state.prevFile);
   }
 
+  //If a target path is specified, create a file write stream
+  FILE* targetFile;
+  if (state.target) {
+    targetFile = fopen(state.target, "wb");
+    if (!targetFile) {
+      fprintf(stderr, "Could not open the target file \"%s\" for writing: %s\n", state.target, strerror(errno));
+      errorAndExit();
+    }
+  }
+
   //-------------------------------------------------
 
   struct InflateOutput inflateResult;
@@ -116,9 +127,13 @@ int main(int argc, char *argv[]) {
 
     //Optionally perform xdelta3
     if (state.prevFile) {
-      xdelta3AddInput(uncompressedChunk + uncompressedPosition, inflateResult.numBytesWrittenToOutput, remainingBytes == 0 && hasReachedEnd);
-    } else { //otherwise write to stdout
-      write(1, uncompressedChunk + uncompressedPosition, inflateResult.numBytesWrittenToOutput);
+      xdelta3AddInput(uncompressedChunk + uncompressedPosition, inflateResult.numBytesWrittenToOutput, remainingBytes == 0 && hasReachedEnd, targetFile);
+    } else { //otherwise write to target file or stdout
+      if (state.target) {
+        fwrite(uncompressedChunk + uncompressedPosition, 1, inflateResult.numBytesWrittenToOutput, targetFile);
+      } else {
+        write(1, uncompressedChunk + uncompressedPosition, inflateResult.numBytesWrittenToOutput);
+      }
     }
 
     uncompressedPosition += inflateResult.numBytesWrittenToOutput;

src/parseArguments.c

@@ -15,6 +15,7 @@ static struct option long_options[] = {
   {"size", required_argument, 0, 's'},
   {"keys", required_argument, 0, 'k'},
   {"previous", required_argument, 0, 'p'},
+  {"target", required_argument, 0, 't'},
   {NULL, 0, 0, 0},
 };
 
@@ -31,7 +32,7 @@ struct arguments parseArguments(int argc, char *argv[]) {
     //In this variable, getopt_long stores the current long option that was found. Unused since we don't use flags in our long options
     int optionIndex = 0;
 
-    int curOption = getopt_long_only(argc, argv, "d:o:s:k:p:", long_options, &optionIndex);
+    int curOption = getopt_long_only(argc, argv, "d:o:s:k:p:t:", long_options, &optionIndex);
 
     //end of command line arguments reached
     if (curOption == -1) {
@@ -77,6 +78,9 @@ struct arguments parseArguments(int argc, char *argv[]) {
       case 'p': //previous file for xdelta3
         state.prevFile = optarg;
         break;
+      case 't': //target file path where extracted file is saved to
+        state.target = optarg;
+        break;
       case '?':
         errorAndExit();
         break;

src/parseArguments.h

@@ -15,6 +15,8 @@ struct arguments {
   bool isEncrypted;
   //For xdelta3, the location of the old file
   char* prevFile;
+  //Target file location where the extracted file is saved to
+  char* target;
 };
 
 

src/xdelta3.c

@@ -9,6 +9,7 @@ typedef unsigned long long xoff_t;
 #include "../lib/xdelta3/xdelta3.c"
 
 //Include other libraries
+#include <errno.h>
 #include <stdbool.h>
 #include <unistd.h>
 
@@ -29,7 +30,7 @@ unsigned long totalOut = 0UL;
 void xdelta3Init(char* prevFile) {
   srcFile = fopen(prevFile, "rb");
   if (srcFile == NULL) {
-    fprintf(stderr, "Could not open previous file %s for reading during xdelta3.\n", prevFile);
+    fprintf(stderr, "Could not open previous file %s for reading during xdelta3: %s\n", prevFile, strerror(errno));
     errorAndExit();
   }
 
@@ -54,7 +55,7 @@ void xdelta3Init(char* prevFile) {
 
 
 /** Supplies the given input buffer to xdelta3 and undiffs the data. */
-void xdelta3AddInput(unsigned char* inputBuffer, unsigned int inputLength, bool isLastPart) {
+void xdelta3AddInput(unsigned char* inputBuffer, unsigned int inputLength, bool isLastPart, FILE* targetFile) {
   xd3_avail_input(&stream, inputBuffer, inputLength);
 
   int returnValue;
@@ -69,7 +70,11 @@ process:
     case XD3_OUTPUT: {
       //fprintf(stderr, "XD3_OUTPUT\n");
       totalOut += stream.avail_out;
-      write(1, stream.next_out, stream.avail_out);
+      if (targetFile) {
+        fwrite(stream.next_out, 1, stream.avail_out, targetFile);
+      } else {
+        write(1, stream.next_out, stream.avail_out);
+      }
       xd3_consume_output(&stream);
       goto process;
     }

src/xdelta3.h

@@ -4,4 +4,4 @@
 void xdelta3Init(char* prevFile);
 
 /** Supplies the given input buffer to xdelta3 and undiffs the data. */
-void xdelta3AddInput(unsigned char* inputBuffer, unsigned int inputLength, bool isLastPart);
+void xdelta3AddInput(unsigned char* inputBuffer, unsigned int inputLength, bool isLastPart, FILE* targetFile);