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// file : build2/version/snapshot-git.cxx -*- C++ -*-
// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
// license : MIT; see accompanying LICENSE file
#include <libbutl/sha1.mxx>
#include <build2/version/snapshot.hxx>
using namespace std;
using namespace butl;
namespace build2
{
namespace version
{
snapshot
extract_snapshot_git (const dir_path& src_root)
{
snapshot r;
const char* d (src_root.string ().c_str ());
// First check whether the working directory is clean. There doesn't
// seem to be a way to do everything in a single invocation (the
// porcelain v2 gives us the commit id but not timestamp).
//
// If git status --porcelain returns anything, then the working
// directory is not clean.
//
{
const char* args[] {"git", "-C", d, "status", "--porcelain", nullptr};
if (!run<string> (3, args, [](string& s) {return move (s);}).empty ())
return r;
}
// Now extract the commit id and date. One might think that would be
// easy... Commit id is a SHA1 hash of the commit object. And commit
// object looks like this:
//
// commit <len>\0
// <data>
//
// Where <len> is the size of <data> and <data> is the output of:
//
// git cat-file commit ...
//
string data;
const char* args[] {
"git", "-C", d, "cat-file", "commit", "HEAD", nullptr};
process pr (run_start (3 /* verbosity */, args, -1 /* stdout */));
try
{
ifdstream is (move (pr.in_ofd), ifdstream::badbit);
for (string l; !eof (getline (is, l)); )
{
data += l;
data += '\n'; // We assume there is always a newline.
if (r.sn == 0 && l.compare (0, 10, "committer ") == 0)
try
{
// The line format is:
//
// committer <noise> <timestamp> <timezone>
//
// For example:
//
// committer John Doe <john@example.org> 1493117819 +0200
//
// The timestamp is in seconds since UNIX epoch. The timezone
// appears to be always numeric (+0000 for UTC).
//
size_t p1 (l.rfind (' ')); // Can't be npos.
string tz (l, p1 + 1);
size_t p2 (l.rfind (' ', p1 - 1));
if (p2 == string::npos)
throw invalid_argument ("missing timestamp");
string ts (l, p2 + 1, p1 - p2 - 1);
r.sn = stoull (ts);
if (tz.size () != 5)
throw invalid_argument ("invalid timezone");
unsigned long h (stoul (string (tz, 1, 2)));
unsigned long m (stoul (string (tz, 3, 2)));
unsigned long s (h * 3600 + m * 60);
// The timezone indicates where the timestamp was generated so to
// convert to UTC we need to invert the sign.
//
switch (tz[0])
{
case '+': r.sn -= s; break;
case '-': r.sn += s; break;
default: throw invalid_argument ("invalid timezone sign");
}
}
catch (const invalid_argument& e)
{
fail << "unable to extract git commit date from '" << l << "': "
<< e;
}
}
is.close ();
}
catch (const io_error&)
{
// Presumably the child process failed. Let run_finish() deal with
// that.
}
run_finish (args, pr);
if (r.sn == 0)
fail << "unable to extract git commit id/date for " << src_root;
sha1 cs;
cs.append ("commit " + to_string (data.size ())); // Includes '\0'.
cs.append (data.c_str (), data.size ());
r.id.assign (cs.string (), 16); // 16-characters abbreviated commit id.
return r;
}
}
}
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