maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Simplify and add comments. NFC. 

llvm-svn: 297686
This commit is contained in:
Rui Ueyama 2017-03-13 23:23:40 +00:00
parent 1899e8d9e8
commit f327999a45
1 changed files with 24 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

38
lld/ELF/Driver.cpp
View File

@ -799,15 +799,26 @@ static uint64_t getImageBase(opt::InputArgList &Args) {
return V;
}
static void ensureWritable(StringRef Path) {
if (Path.empty())
return;
// Returns true if a given file seems to be writable.
//
// Determining whether a file is writable or not is amazingly hard,
// and after all the only reliable way of doing that is to actually
// create a file. But we don't want to do that in this function
// because LLD shouldn't update any file if it will end in a failure.
// We also don't want to reimplement heuristics. So we'll let
// FileOutputBuffer do the work.
//
// FileOutputBuffer doesn't touch a desitnation file until commit()
// is called. We use that class without calling commit() to predict
// if the given file is writable.
static bool isWritable(StringRef Path) {
ErrorOr<std::unique_ptr<FileOutputBuffer>> Err =
FileOutputBuffer::create(Path, 1);
if (!Err)
error("cannot open output file " + Path + ": " +
Err.getError().message());
if (auto EC = Err.getError()) {
error("cannot open output file " + Path + ": " + EC.message());
return false;
}
return true;
}
// Do actual linking. Note that when this function is called,
@ -825,6 +836,12 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
if (Config->OutputFile.empty())
Config->OutputFile = "a.out";
// Fail early if the output file is not writable. If a user has a long link,
// e.g. due to a large LTO link, they do not wish to run it and find that it
// failed because there was a mistake in their command-line.
if (!isWritable(Config->OutputFile))
return;
// Use default entry point name if no name was given via the command
// line nor linker scripts. For some reason, MIPS entry point name is
// different from others.
@ -833,13 +850,6 @@ template <class ELFT> void LinkerDriver::link(opt::InputArgList &Args) {
if (Config->Entry.empty() && !Config->Relocatable)
Config->Entry = (Config->EMachine == EM_MIPS) ? "__start" : "_start";
// Fail early if the output file is not writable. If a user has a long link,
// e.g. due to a large LTO link, they do not wish to run it and find that it
// failed because there was a mistake in their command-line.
ensureWritable(Config->OutputFile);
if (ErrorCount)
return;
// Handle --trace-symbol.
for (auto *Arg : Args.filtered(OPT_trace_symbol))
Symtab.trace(Arg->getValue());