thodg/libgit2

diff --git a/src/signature.c b/src/signature.c
index e801462..62bd28b 100644
--- a/src/signature.c
+++ b/src/signature.c
@@ -115,22 +115,22 @@ static int parse_timezone_offset(const char *buffer, long *offset_out)
 	}
 
 	if (offset_start[0] != '-' && offset_start[0] != '+')
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse TZ offset. It doesn't start with '+' or '-'");
 
 	if (git__strtol32(&dec_offset, offset_start + 1, &offset_end, 10) < GIT_SUCCESS)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse TZ offset. It isn't a number");
 
 	if (offset_end - offset_start != 5)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse TZ offset. Invalid length");
 
 	hours = dec_offset / 100;
 	mins = dec_offset % 100;
 
 	if (hours > 14)	// see http://www.worldtimezone.com/faq.html 
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse TZ offset. Hour value too large");;
 
 	if (mins > 59)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse TZ offset. Minute value too large");
 
 	offset = (hours * 60) + mins;
 
@@ -157,19 +157,19 @@ int git_signature__parse(git_signature *sig, const char **buffer_out,
 
 	line_end = memchr(buffer, '\n', buffer_end - buffer);
 	if (!line_end)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. No newline found");;
 
 	if (buffer + (header_len + 1) > line_end)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Signature too short");
 
 	if (memcmp(buffer, header, header_len) != 0)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Expected prefix '%s' doesn't match actual", header);
 
 	buffer += header_len;
 
 	/* Parse name */
 	if ((name_end = memchr(buffer, '<', buffer_end - buffer)) == NULL)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Can't find e-mail start");
 
 	name_length = name_end - buffer - 1;
 	sig->name = git__malloc(name_length + 1);
@@ -181,11 +181,11 @@ int git_signature__parse(git_signature *sig, const char **buffer_out,
 	buffer = name_end + 1;
 
 	if (buffer >= line_end)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Ended unexpectedly");
 
 	/* Parse email */
 	if ((email_end = memchr(buffer, '>', buffer_end - buffer)) == NULL)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Can't find e-mail end");
 
 	email_length = email_end - buffer;
 	sig->email = git__malloc(email_length + 1);
@@ -197,10 +197,10 @@ int git_signature__parse(git_signature *sig, const char **buffer_out,
 	buffer = email_end + 1;
 
 	if (buffer >= line_end)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Ended unexpectedly");
 
 	if (git__strtol32(&time, buffer, &buffer, 10) < GIT_SUCCESS)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse signature. Timestamp isn't a number");
 
 	sig->when.time = (time_t)time;
 
diff --git a/src/tag.c b/src/tag.c
index 148eb28..849429b 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -90,13 +90,13 @@ static int parse_tag_buffer(git_tag *tag, const char *buffer, const char *buffer
 	int error;
 
 	if ((error = git__parse_oid(&tag->target, &buffer, buffer_end, "object ")) < 0)
-		return error;
+		return git__rethrow(error, "Failed to parse tag. Object field invalid");
 
 	if (buffer + 5 >= buffer_end)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Object too short");
 
 	if (memcmp(buffer, "type ", 5) != 0)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Type field not found");
 	buffer += 5;
 
 	tag->type = GIT_OBJ_BAD;
@@ -105,7 +105,7 @@ static int parse_tag_buffer(git_tag *tag, const char *buffer, const char *buffer
 		size_t type_length = strlen(tag_types[i]);
 
 		if (buffer + type_length >= buffer_end)
-			return GIT_EOBJCORRUPTED;
+			return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Object too short");
 
 		if (memcmp(buffer, tag_types[i], type_length) == 0) {
 			tag->type = i;
@@ -115,18 +115,19 @@ static int parse_tag_buffer(git_tag *tag, const char *buffer, const char *buffer
 	}
 
 	if (tag->type == GIT_OBJ_BAD)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Invalid object type");
 
 	if (buffer + 4 >= buffer_end)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Object too short");
 
 	if (memcmp(buffer, "tag ", 4) != 0)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Tag field not found");
+
 	buffer += 4;
 
 	search = memchr(buffer, '\n', buffer_end - buffer);
 	if (search == NULL)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tag. Object too short");
 
 	text_len = search - buffer;
 
@@ -218,7 +219,7 @@ static int tag_create(
 	}
 
 	if (!git_odb_exists(repo->db, target))
-		return GIT_ENOTFOUND;
+		return git__throw(GIT_ENOTFOUND, "Failed to create tag. Object to tag doesn't exist");
 
 	/* Try to find out what the type is */
 	if (target_type == GIT_OBJ_ANY) {