Added --output flag

patchelf.1

@@ -83,6 +83,9 @@ option can be given multiple times.
 Marks the object that the search for dependencies of this object will ignore any
 default library search paths.
 
+.IP "--output FILE"
+Set the output file name.  If not specified, the input will be modified in place.
+
 .IP --debug
 Prints details of the changes made to the input file.
 

src/patchelf.cc

@@ -46,6 +46,8 @@ static bool debugMode = false;
 static bool forceRPath = false;
 
 static std::vector<std::string> fileNames;
+static std::string outputFileName;
+static bool alwaysWrite = false;
 static int pageSize = PAGESIZE;
 
 typedef std::shared_ptr<std::vector<unsigned char>> FileContents;
@@ -497,7 +499,9 @@ void ElfFile<ElfFileParamNames>::sortShdrs()
 
 static void writeFile(std::string fileName, FileContents contents)
 {
-    int fd = open(fileName.c_str(), O_TRUNC | O_WRONLY);
+    debug("writing %s\n", fileName.c_str());
+
+    int fd = open(fileName.c_str(), O_CREAT | O_TRUNC | O_WRONLY, 0777);
     if (fd == -1)
         error("open");
 
@@ -1567,7 +1571,7 @@ static bool printNeeded = false;
 static bool noDefaultLib = false;
 
 template<class ElfFile>
-static void patchElf2(ElfFile && elfFile, std::string fileName)
+static void patchElf2(ElfFile && elfFile, const FileContents & fileContents, std::string fileName)
 {
     if (printInterpreter)
         printf("%s\n", elfFile.getInterpreter().c_str());
@@ -1603,6 +1607,9 @@ static void patchElf2(ElfFile && elfFile, std::string fileName)
     if (elfFile.isChanged()){
         elfFile.rewriteSections();
         writeFile(fileName, elfFile.fileContents);
+    } else if (alwaysWrite) {
+        debug("not modified, but alwaysWrite=true\n");
+        writeFile(fileName, fileContents);
     }
 }
 
@@ -1616,11 +1623,12 @@ static void patchElf()
         debug("Kernel page size is %u bytes\n", getPageSize());
 
         auto fileContents = readFile(fileName);
+        std::string outputFileName2 = outputFileName.empty() ? fileName : outputFileName;
 
         if (getElfType(fileContents).is32Bit)
-            patchElf2(ElfFile<Elf32_Ehdr, Elf32_Phdr, Elf32_Shdr, Elf32_Addr, Elf32_Off, Elf32_Dyn, Elf32_Sym, Elf32_Verneed>(fileContents), fileName);
+            patchElf2(ElfFile<Elf32_Ehdr, Elf32_Phdr, Elf32_Shdr, Elf32_Addr, Elf32_Off, Elf32_Dyn, Elf32_Sym, Elf32_Verneed>(fileContents), fileContents, outputFileName2);
         else
-            patchElf2(ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, Elf64_Addr, Elf64_Off, Elf64_Dyn, Elf64_Sym, Elf64_Verneed>(fileContents), fileName);
+            patchElf2(ElfFile<Elf64_Ehdr, Elf64_Phdr, Elf64_Shdr, Elf64_Addr, Elf64_Off, Elf64_Dyn, Elf64_Sym, Elf64_Verneed>(fileContents), fileContents, outputFileName2);
     }
 }
 
@@ -1644,6 +1652,7 @@ void showHelp(const std::string & progName)
   [--replace-needed LIBRARY NEW_LIBRARY]\n\
   [--print-needed]\n\
   [--no-default-lib]\n\
+  [--output FILE]\n\
   [--debug]\n\
   [--version]\n\
   FILENAME...\n", progName.c_str());
@@ -1730,6 +1739,11 @@ int mainWrapped(int argc, char * * argv)
             neededLibsToReplace[ argv[i+1] ] = argv[i+2];
             i += 2;
         }
+        else if (arg == "--output") {
+            if (++i == argc) error("missing argument");
+            outputFileName = argv[i];
+            alwaysWrite = true;
+        }
         else if (arg == "--debug") {
             debugMode = true;
         }
@@ -1751,6 +1765,9 @@ int mainWrapped(int argc, char * * argv)
 
     if (fileNames.empty()) error("missing filename");
 
+    if (!outputFileName.empty() && fileNames.size() != 1)
+        error("--output option only allowed with single input file");
+
     patchElf();
 
     return 0;

tests/Makefile.am

@@ -21,7 +21,8 @@ no_rpath_arch_TESTS = \
 src_TESTS = \
   plain-fail.sh plain-run.sh shrink-rpath.sh set-interpreter-short.sh \
   set-interpreter-long.sh set-rpath.sh no-rpath.sh big-dynstr.sh \
-  set-rpath-library.sh soname.sh shrink-rpath-with-allowed-prefixes.sh
+  set-rpath-library.sh soname.sh shrink-rpath-with-allowed-prefixes.sh \
+  output-flag.sh
 
 build_TESTS = \
   $(no_rpath_arch_TESTS)

tests/output-flag.sh

@@ -0,0 +1,38 @@
+#! /bin/sh -e
+SCRATCH=scratch/$(basename $0 .sh)
+
+rm -rf ${SCRATCH}
+mkdir -p ${SCRATCH}
+mkdir -p ${SCRATCH}/libsA
+mkdir -p ${SCRATCH}/libsB
+
+cp main ${SCRATCH}/
+cp libfoo.so ${SCRATCH}/libsA/
+cp libbar.so ${SCRATCH}/libsB/
+
+oldRPath=$(../src/patchelf --print-rpath ${SCRATCH}/main)
+if test -z "$oldRPath"; then oldRPath="/oops"; fi
+
+../src/patchelf --force-rpath --set-rpath $oldRPath:$(pwd)/${SCRATCH}/libsA:$(pwd)/${SCRATCH}/libsB ${SCRATCH}/main --output ${SCRATCH}/main2
+# make sure it copies even when there is nothing to do (because rpath is already set)
+../src/patchelf --force-rpath --set-rpath $oldRPath:$(pwd)/${SCRATCH}/libsA:$(pwd)/${SCRATCH}/libsB ${SCRATCH}/main2 --output ${SCRATCH}/main3
+
+if test "$(uname)" = FreeBSD; then
+    export LD_LIBRARY_PATH=$(pwd)/${SCRATCH}/libsB
+fi
+
+exitCode=0
+(cd ${SCRATCH} && ./main2) || exitCode=$?
+
+if test "$exitCode" != 46; then
+    echo "bad exit code!"
+    exit 1
+fi
+
+exitCode=0
+(cd ${SCRATCH} && ./main3) || exitCode=$?
+
+if test "$exitCode" != 46; then
+    echo "bad exit code!"
+    exit 1
+fi