[cfe-dev] How to redirect outs() to file?

[Anton Smirnov]

Hi.

I'm using some LLVM tools (like llvm-nm) as static libraries. I.e. i copied
source llvm-nm.cpp, renamed main(..) to llvm_nm(..) and compiled it as
static library. I'd like to forward standard output to my file.

I've tried to use the next approach:

  int    out_fd, err_fd;
  fpos_t out_pos, err_pos;

  // redirect out
  fflush(stdout);
  fgetpos(stdout, &out_pos);
  out_fd = dup(fileno(stdout));
  freopen(outFilename, "w", stdout);

  // execute
  int ret = llvm_nm(argc_, argv_);

  // restore output
  fflush(stdout);
  dup2(out_fd, fileno(stdout));
  close(out_fd);
  clearerr(stdout);
  fsetpos(stdout, &out_pos);

The problem is that it's not forwarded (it works if i add printf() in nm
source code but not for nm output). I've looked to the source code and i
can see output is done using llvm::outs() stream:

outs() << "Archive map" << "\n";

And it's implemented
<http://llvm.org/docs/doxygen/html/raw__ostream_8cpp_source.html> the next
way:

/// outs() - This returns a reference to a raw_ostream for standard
output.00702 /// Use it like: outs() << "foo" << "bar";00703
raw_ostream &llvm::outs() {00704   // Set buffer settings to model
stdout behavior.00705   // Delete the file descriptor when the program
exits, forcing error00706   // detection. If you don't want this
behavior, don't use outs().00707   static raw_fd_ostream
S(STDOUT_FILENO, true);00708   return S;00709 }

How can i redirect that output to my file?
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