Migrate ODB files to new error handling

This migrates odb.c, odb_loose.c, odb_pack.c and pack.c to
the new style of error handling.  Also got the unix and win32
versions of map.c.  There are some minor changes to other
files but no others were completely converted.

This also contains an update to filebuf so that a zeroed out
filebuf will not think that the fd (== 0) is actually open
(and inadvertently call close() on fd 0 if cleaned up).

Lastly, this was built and tested on win32 and contains a
bunch of fixes for the win32 build which was pretty broken.

1 files changed, 24 insertions, 4 deletions

diff --git a/src/errors.c b/src/errors.c
index 6fb7777f0..19bc7b77b 100644
--- a/src/errors.c
+++ b/src/errors.c
@@ -40,7 +40,7 @@ static struct {
 	{GIT_EEXISTS, "A reference with this name already exists"},
 	{GIT_EOVERFLOW, "The given integer literal is too large to be parsed"},
 	{GIT_ENOTNUM, "The given literal is not a valid number"},
-	{GIT_EAMBIGUOUSOIDPREFIX, "The given oid prefix is ambiguous"},
+	{GIT_EAMBIGUOUS, "The given oid prefix is ambiguous"},
 };
 
 const char *git_strerror(int num)
@@ -129,9 +129,29 @@ void giterr_set(int error_class, const char *string, ...)
 
 	/* automatically suffix strerror(errno) for GITERR_OS errors */
 	if (error_class == GITERR_OS) {
-		strncat(error_str, ": ", sizeof(error_str));
-		strncat(error_str, strerror(errno), sizeof(error_str));
-		errno = 0;
+		if (errno != 0) {
+			strncat(error_str, ": ", sizeof(error_str));
+			strncat(error_str, strerror(errno), sizeof(error_str));
+			errno = 0;
+		}
+#ifdef GIT_WIN32
+		else {
+			LPVOID lpMsgBuf;
+			DWORD dw = GetLastError();
+
+			FormatMessage(
+				FORMAT_MESSAGE_ALLOCATE_BUFFER | 
+				FORMAT_MESSAGE_FROM_SYSTEM |
+				FORMAT_MESSAGE_IGNORE_INSERTS,
+				NULL, dw, 0, (LPTSTR) &lpMsgBuf, 0, NULL);
+
+			if (lpMsgBuf) {
+				strncat(error_str, ": ", sizeof(error_str));
+				strncat(error_str, (const char *)lpMsgBuf, sizeof(error_str));
+				LocalFree(lpMsgBuf);
+			}
+		}
+#endif
 	}
 
 	giterr_set_str(error_class, error_str);