Code clarity and test working with musl

Made changes according to feedback from @Mic92 such as moving the
`rewriteSections` inline into every method.

Improved `replace-add-needed.sh` to work with musl libc

Author: fzakaria

src/patchelf.cc

@@ -1311,6 +1311,7 @@ void ElfFile<ElfFileParamNames>::modifySoname(sonameMode op, const std::string &
     }
 
     changed = true;
+    this->rewriteSections();
 }
 
 template<ElfFileParams>
@@ -1319,6 +1320,7 @@ void ElfFile<ElfFileParamNames>::setInterpreter(const std::string & newInterpret
     std::string & section = replaceSection(".interp", newInterpreter.size() + 1);
     setSubstr(section, 0, newInterpreter + '\0');
     changed = true;
+    this->rewriteSections();
 }
 
 
@@ -1395,6 +1397,7 @@ void ElfFile<ElfFileParamNames>::removeRPath(Elf_Shdr & shdrDynamic) {
         }
     }
     memset(last, 0, sizeof(Elf_Dyn) * (dyn - last));
+    this->rewriteSections();
 }
 
 template<ElfFileParams>
@@ -1541,6 +1544,7 @@ void ElfFile<ElfFileParamNames>::modifyRPath(RPathOp op,
         newDyn.d_un.d_val = shdrDynStr.sh_size;
         setSubstr(newDynamic, 0, std::string((char *) &newDyn, sizeof(Elf_Dyn)));
     }
+    this->rewriteSections();
 }
 
 
@@ -1570,6 +1574,8 @@ void ElfFile<ElfFileParamNames>::removeNeeded(const std::set<std::string> & libs
     }
 
     memset(last, 0, sizeof(Elf_Dyn) * (dyn - last));
+
+    this->rewriteSections();
 }
 
 template<ElfFileParams>
@@ -1693,6 +1699,8 @@ void ElfFile<ElfFileParamNames>::replaceNeeded(const std::map<std::string, std::
             --verNeedNum;
         }
     }
+
+    this->rewriteSections();
 }
 
 template<ElfFileParams>
@@ -1743,6 +1751,8 @@ void ElfFile<ElfFileParamNames>::addNeeded(const std::set<std::string> & libs)
     }
 
     changed = true;
+
+    this->rewriteSections();
 }
 
 template<ElfFileParams>
@@ -1799,6 +1809,7 @@ void ElfFile<ElfFileParamNames>::noDefaultLib()
         setSubstr(newDynamic, 0, std::string((char *) &newDyn, sizeof(Elf_Dyn)));
     }
 
+    this->rewriteSections();
     changed = true;
 }
 
@@ -1828,6 +1839,7 @@ void ElfFile<ElfFileParamNames>::clearSymbolVersions(const std::set<std::string>
         }
     }
     changed = true;
+    this->rewriteSections();
 }
 
 static bool printInterpreter = false;
@@ -1878,28 +1890,15 @@ static void patchElf2(ElfFile && elfFile, const FileContents & fileContents, con
 
     if (printNeeded) elfFile.printNeededLibs();
 
-    if (!neededLibsToRemove.empty()) {
-        elfFile.removeNeeded(neededLibsToRemove);
-        elfFile.rewriteSections();
-    }
-    if (!neededLibsToReplace.empty()) {
-        elfFile.replaceNeeded(neededLibsToReplace);
-        elfFile.rewriteSections();
-    }
-    if (!neededLibsToAdd.empty()) {
-        elfFile.addNeeded(neededLibsToAdd);
-        elfFile.rewriteSections();
-    }
-    if (!symbolsToClearVersion.empty()) {
-        elfFile.clearSymbolVersions(symbolsToClearVersion);
-        elfFile.rewriteSections();
-    }
+    elfFile.removeNeeded(neededLibsToRemove);
+    elfFile.replaceNeeded(neededLibsToReplace);
+    elfFile.addNeeded(neededLibsToAdd);
+    elfFile.clearSymbolVersions(symbolsToClearVersion);
 
     if (noDefaultLib)
         elfFile.noDefaultLib();
 
     if (elfFile.isChanged()){
-        elfFile.rewriteSections();
         writeFile(fileName, elfFile.fileContents);
     } else if (alwaysWrite) {
         debug("not modified, but alwaysWrite=true\n");

tests/replace-add-needed.sh

@@ -12,7 +12,8 @@ cp libbar.so ${SCRATCH}/
 
 cd ${SCRATCH}
 
-libcldd=$(ldd ./simple | grep -oP "(?<=libc.so.6 => )[^ ]+")
+# This grep is necessary to catch either glibc or libc.so for musl
+libcldd=$(ldd ./simple | awk '/ => / { print $3 }' | grep libc.so)
 
 # We have to set the soname on these libraries
 ${PATCHELF} --set-soname libbar.so ./libbar.so