X-Git-Url: https://git.lyx.org/gitweb/?a=blobdiff_plain;f=src%2Fsupport%2Fos.cpp;h=ab9d4159a6cc8180864e760f330af3fc95bbb5d7;hb=9234516731fac37651f5dacfc0942dc40775b96e;hp=4d2c55ed378e3862c0d4ce7c520f07e13a1bdcd4;hpb=9d0ea8aeff32833a90b3fe64df0c5518a9e241be;p=lyx.git

diff --git a/src/support/os.cpp b/src/support/os.cpp
index 4d2c55ed37..ab9d4159a6 100644
--- a/src/support/os.cpp
+++ b/src/support/os.cpp
@@ -4,13 +4,22 @@
  * Licence details can be found in the file COPYING.
  *
  * \author Ruurd A. Reitsma
+ * \author Enrico Forestieri
  *
  * Full author contact details are available in file CREDITS.
  */
 
 #include <config.h>
 
-#if defined(__CYGWIN__) || defined(__CYGWIN32__)
+#include "support/convert.h"
+#include "support/debug.h"
+#include "support/filetools.h"
+#include "support/qstring_helpers.h"
+#include "support/regex.h"
+
+#include <QDir>
+
+#if defined(__CYGWIN__)
 #include "support/os_cygwin.cpp"
 #elif defined(_WIN32)
 #include "support/os_win32.cpp"
@@ -18,18 +27,133 @@
 #include "support/os_unix.cpp"
 #endif
 
+// Static assert to break compilation on platforms where
+// int/unsigned int is not 4 bytes. Added to make sure that
+// e.g., the author hash is always 32-bit.
+template<bool Condition> struct static_assert_helper;
+template <> struct static_assert_helper<true> {};
+enum {
+	dummy = sizeof(static_assert_helper<sizeof(int) == 4>)
+};
+
 namespace lyx {
 namespace support {
 namespace os {
 
-std::string const python()
+int timeout_min()
 {
-	// Use the -tt switch so that mixed tab/whitespace indentation is
-	// an error
-	static std::string const command("python -tt");
-	return command;
+	return 3;
 }
 
+
+static string const python23_call(string const & binary, bool verbose = false)
+{
+	const string version_info = " -c 'from __future__ import print_function;import sys; print(sys.version_info[:2], end=\"\")'";
+	// Default to "python" if no binary is given.
+	if (binary.empty())
+		return "python -tt";
+
+	if (verbose)
+		lyxerr << "Examining " << binary << "\n";
+	// Check whether this is a python 2 or 3 binary.
+	cmd_ret const out = runCommand(binary + version_info);
+
+	smatch sm;
+	try {
+		static regex const python_reg("\\((\\d*), (\\d*)\\)");
+		if (out.first < 0 || !regex_match(out.second, sm, python_reg))
+			return string();
+	} catch(regex_error const & /*e*/) {
+		LYXERR0("Regex error! This should not happen.");
+		return string();
+	}
+
+	int major = convert<int>(sm.str(1));
+	int minor = convert<int>(sm.str(2));
+	if((major == 2 && minor < 7) || (major == 3 && minor < 5))
+		return string();
+
+	if (verbose)
+		lyxerr << "Found Python " << out.second << "\n";
+	// Add the -tt switch so that mixed tab/whitespace
+	// indentation is an error
+	return binary + " -tt";
 }
+
+
+static string const find_python_binary()
+{
+	// This function takes inspiration from PEP 394 and PEP 397
+	// PEP 394 -- The "python" Command on Unix-Like Systems
+	// https://www.python.org/dev/peps/pep-0394/
+	// PEP 397 -- Python launcher for Windows
+	// https://www.python.org/dev/peps/pep-0397/
+
+	// Check whether python3 in PATH is the right one.
+	string command = python23_call("python3");
+	if (!command.empty())
+		return command;
+
+	// python3 does not exists, let us try to find python3.x in PATH
+	// the search is probably broader than required
+	// but we are trying hard to find a valid python binary
+	vector<string> const path = getEnvPath("PATH");
+	lyxerr << "Looking for python 3.x ...\n";
+	for (auto bin: path) {
+		QString const dir = toqstr(bin);
+		string const localdir = dir.toLocal8Bit().constData();
+		QDir qdir(dir);
+		qdir.setFilter(QDir::Files | QDir::Executable);
+		QStringList list = qdir.entryList(QStringList("python3*"));
+		for (auto bin: list) {
+			string const binary = addName(localdir,
+				bin.toLocal8Bit().constData());
+			command = python23_call(binary, true);
+			if (!command.empty())
+				return command;
+		}
+	}
+
+	// python 3 was not found let us look for python 2
+	command = python23_call("python2");
+	if (!command.empty())
+		return command;
+
+	// python2 does not exists, let us try to find python2.x in PATH
+	// the search is probably broader than required
+	// but we are trying hard to find a valid python binary
+	lyxerr << "Looking for python 2.x ...\n";
+	for (auto bin: path) {
+		QString const dir = toqstr(bin);
+		string const localdir = dir.toLocal8Bit().constData();
+		QDir qdir(dir);
+		qdir.setFilter(QDir::Files | QDir::Executable);
+		QStringList list = qdir.entryList(QStringList("python2*"));
+		for (auto bin: list) {
+			string const binary = addName(localdir,
+				bin.toLocal8Bit().constData());
+			command = python23_call(binary, true);
+			if (!command.empty())
+				return command;
+		}
+	}
+
+	// If this happens all hope is lost that this is a sane system
+	lyxerr << "Warning: No python v2.x or 3.x binary found.\n";
+	return python23_call("");
 }
+
+
+string const python(bool reset)
+{
+	static string command = find_python_binary();
+	// FIXME THREAD
+	if (reset) {
+		command = find_python_binary();
+	}
+	return command;
 }
+
+} // namespace os
+} // namespace support
+} // namespace lyx