From fece189bdb9270b929820ecf890bacd81efeee56 Mon Sep 17 00:00:00 2001
From: Randy Heit <rheit@zdoom.fake>
Date: Sat, 22 Jun 2013 20:49:38 -0500
Subject: [PATCH] - Change updaterevision to use git instead of svnversion

---
 tools/updaterevision/updaterevision.c | 103 +++++++++++++++-----------
 1 file changed, 60 insertions(+), 43 deletions(-)

diff --git a/tools/updaterevision/updaterevision.c b/tools/updaterevision/updaterevision.c
index 55e81bc405..c1e3ccc8fa 100644
--- a/tools/updaterevision/updaterevision.c
+++ b/tools/updaterevision/updaterevision.c
@@ -1,8 +1,9 @@
 /* updaterevision.c
  *
- * Public domain. This program uses the svnversion command to get the
- * repository revision for a particular directory and writes it into
- * a header file so that it can be used as a project's build number.
+ * Public domain. This program uses git commands command to get
+ * various bits of repository status for a particular directory
+ * and writes it into a header file so that it can be used for a
+ * project's versioning.
  */
 
 #define _CRT_SECURE_NO_DEPRECATE
@@ -13,24 +14,41 @@
 #include <ctype.h>
 #include <errno.h>
 
+// Used to strip newline characters from lines read by fgets.
+void stripnl(char *str)
+{
+	if (*str != '\0')
+	{
+		size_t len = strlen(str);
+		if (str[len - 1] == '\n')
+		{
+			str[len - 1] = '\0';
+		}
+	}
+}
+
 int main(int argc, char **argv)
 {
 	char *name;
-	char currev[64], lastrev[64], run[256], *rev;
-	unsigned long urev;
+	char vertag[64], lastlog[64], lasthash[64], run[256], *hash = NULL;
 	FILE *stream = NULL;
 	int gotrev = 0, needupdate = 1;
 
+	vertag[0] = '\0';
+	lastlog[0] = '\0';
+
 	if (argc != 3)
 	{
-		fprintf (stderr, "Usage: %s <repository directory> <path to svnrevision.h>\n", argv[0]);
+		fprintf(stderr, "Usage: %s <repository directory> <path to gitinfo.h>\n", argv[0]);
 		return 1;
 	}
 
-	// Use svnversion to get the revision number. If that fails, pretend it's
-	// revision 0. Note that this requires you have the command-line svn tools installed.
-	sprintf (run, "svnversion -cn %s", argv[1]);
-	if ((name = tempnam(NULL, "svnout")) != NULL)
+	// Use git describe --tags to get a version string. If we are sitting directly
+	// on a tag, it returns that tag. Otherwise it returns <most recent tag>-<number of
+	// commits since the tag>-<short hash>.
+	// Use git log to get the time of the latest commit in ISO 8601 format and its full hash.
+	sprintf(run, "git describe --tags && git log -1 --format=%%ai*%%H", argv[1]);
+	if ((name = tempnam(NULL, "gitout")) != NULL)
 	{
 #ifdef __APPLE__
 		// tempnam will return errno of 2 even though it is successful for our purposes.
@@ -40,39 +58,41 @@ int main(int argc, char **argv)
 		   system(run) == 0 &&
 		   errno == 0 &&
 		   fseek(stream, 0, SEEK_SET) == 0 &&
-		   fgets(currev, sizeof currev, stream) == currev &&
-		   (isdigit(currev[0]) || (currev[0] == '-' && currev[1] == '1')))
+		   fgets(vertag, sizeof vertag, stream) == vertag &&
+		   fgets(lastlog, sizeof lastlog, stream) == lastlog)
 		{
+			stripnl(vertag);
+			stripnl(lastlog);
 			gotrev = 1;
 		}
 	}
 	if (stream != NULL)
 	{
-		fclose (stream);
-		remove (name);
+		fclose(stream);
+		remove(name);
 	}
 	if (name != NULL)
 	{
-		free (name);
+		free(name);
 	}
 
-	if (!gotrev)
+	if (gotrev)
 	{
-		fprintf (stderr, "Failed to get current revision: %s\n", strerror(errno));
-		strcpy (currev, "0");
-		rev = currev;
+		hash = strchr(lastlog, '*');
+		if (hash != NULL)
+		{
+			*hash = '\0';
+			hash++;
+		}
 	}
-	else
+	if (hash == NULL)
 	{
-		rev = strchr (currev, ':');
-		if (rev == NULL)
-		{
-			rev = currev;
-		}
-		else
-		{
-			rev += 1;
-		}
+		fprintf(stderr, "Failed to get commit info: %s\n", strerror(errno));
+		strcpy(vertag, "<unknown version>");
+		lastlog[0] = '\0';
+		lastlog[1] = '0';
+		lastlog[2] = '\0';
+		hash = lastlog + 1;
 	}
 
 	stream = fopen (argv[2], "r");
@@ -86,13 +106,10 @@ int main(int argc, char **argv)
 		// Read the revision that's in this file already. If it's the same as
 		// what we've got, then we don't need to modify it and can avoid rebuilding
 		// dependant files.
-		if (fgets(lastrev, sizeof lastrev, stream) == lastrev)
+		if (fgets(lasthash, sizeof lasthash, stream) == lasthash)
 		{
-			if (lastrev[0] != '\0')
-			{ // Strip trailing \n
-				lastrev[strlen(lastrev) - 1] = '\0';
-			}
-			if (strcmp(rev, lastrev + 3) == 0)
+			stripnl(lasthash);
+			if (strcmp(hash, lasthash + 3) == 0)
 			{
 				needupdate = 0;
 			}
@@ -107,22 +124,22 @@ int main(int argc, char **argv)
 		{
 			return 1;
 		}
-		urev = strtoul(rev, NULL, 10);
-		fprintf (stream,
+		fprintf(stream,
 "// %s\n"
 "//\n"
 "// This file was automatically generated by the\n"
 "// updaterevision tool. Do not edit by hand.\n"
 "\n"
-"#define SVN_REVISION_STRING \"%s\"\n"
-"#define SVN_REVISION_NUMBER %lu\n",
-			rev, rev, urev);
-		fclose (stream);
-		fprintf (stderr, "%s updated to revision %s.\n", argv[2], rev);
+"#define GIT_DESCRIPTION \"%s\"\n"
+"#define GIT_HASH \"%s\"\n"
+"#define GIT_TIME \"%s\"\n",
+			hash, vertag, hash, lastlog);
+		fclose(stream);
+		fprintf(stderr, "%s updated to commit %s.\n", argv[2], vertag);
 	}
 	else
 	{
-		fprintf (stderr, "%s is up to date at revision %s.\n", argv[2], rev);
+		fprintf (stderr, "%s is up to date at commit %s.\n", argv[2], vertag);
 	}
 
 	return 0;