thodg/libgit2

diff --git a/src/commit.c b/src/commit.c
index d39fc54..019cefe 100644
--- a/src/commit.c
+++ b/src/commit.c
@@ -26,11 +26,12 @@
 #include "git2/common.h"
 #include "git2/object.h"
 #include "git2/repository.h"
+#include "git2/signature.h"
 
 #include "common.h"
 #include "commit.h"
 #include "revwalk.h"
-#include "person.h"
+#include "signature.h"
 
 #define COMMIT_BASIC_PARSE 0x0
 #define COMMIT_FULL_PARSE 0x1
@@ -50,8 +51,8 @@ void git_commit__free(git_commit *commit)
 {
 	clear_parents(commit);
 
-	git_person__free(commit->author);
-	git_person__free(commit->committer);
+	git_signature_free(commit->author);
+	git_signature_free(commit->committer);
 
 	free(commit->message);
 	free(commit->message_short);
@@ -82,12 +83,12 @@ int git_commit__writeback(git_commit *commit, git_odb_source *src)
 	if (commit->author == NULL)
 		return GIT_EMISSINGOBJDATA;
 
-	git_person__write(src, "author", commit->author);
+	git_signature__write(src, "author", commit->author);
 
 	if (commit->committer == NULL)
 		return GIT_EMISSINGOBJDATA;
 
-	git_person__write(src, "committer", commit->committer);
+	git_signature__write(src, "committer", commit->committer);
 
 	if (commit->message != NULL)
 		git__source_printf(src, "\n%s", commit->message);
@@ -137,10 +138,10 @@ int commit_parse_buffer(git_commit *commit, void *data, size_t len, unsigned int
 
 	if (parse_flags & COMMIT_FULL_PARSE) {
 		if (commit->author)
-			git_person__free(commit->author);
+			git_signature_free(commit->author);
 
-		commit->author = git__malloc(sizeof(git_person));
-		if ((error = git_person__parse(commit->author, &buffer, buffer_end, "author ")) < GIT_SUCCESS)
+		commit->author = git__malloc(sizeof(git_signature));
+		if ((error = git_signature__parse(commit->author, &buffer, buffer_end, "author ")) < GIT_SUCCESS)
 			return error;
 
 	} else {
@@ -152,14 +153,12 @@ int commit_parse_buffer(git_commit *commit, void *data, size_t len, unsigned int
 
 	/* Always parse the committer; we need the commit time */
 	if (commit->committer)
-		git_person__free(commit->committer);
+		git_signature_free(commit->committer);
 
-	commit->committer = git__malloc(sizeof(git_person));
-	if ((error = git_person__parse(commit->committer, &buffer, buffer_end, "committer ")) < GIT_SUCCESS)
+	commit->committer = git__malloc(sizeof(git_signature));
+	if ((error = git_signature__parse(commit->committer, &buffer, buffer_end, "committer ")) < GIT_SUCCESS)
 		return error;
 
-	commit->commit_time = commit->committer->time;
-
 	/* parse commit message */
 	while (buffer <= buffer_end && *buffer == '\n')
 		buffer++;
@@ -231,22 +230,21 @@ int git_commit__parse_full(git_commit *commit)
 		git_commit__parse_full(commit); 
 
 GIT_COMMIT_GETTER(git_tree *, tree)
-GIT_COMMIT_GETTER(git_person *, author)
-GIT_COMMIT_GETTER(git_person *, committer)
+GIT_COMMIT_GETTER(git_signature *, author)
+GIT_COMMIT_GETTER(git_signature *, committer)
 GIT_COMMIT_GETTER(char *, message)
 GIT_COMMIT_GETTER(char *, message_short)
 
 time_t git_commit_time(git_commit *commit)
 {
-	assert(commit);
-
-	if (commit->commit_time)
-		return commit->commit_time;
-
-	if (!commit->object.in_memory)
-		git_commit__parse_full(commit);
+	assert(commit && commit->committer);
+	return commit->committer->when.time;
+}
 
-	return commit->commit_time;
+int git_commit_time_offset(git_commit *commit)
+{
+	assert(commit && commit->committer);
+	return commit->committer->when.offset;
 }
 
 unsigned int git_commit_parentcount(git_commit *commit)
@@ -269,25 +267,24 @@ void git_commit_set_tree(git_commit *commit, git_tree *tree)
 	commit->tree = tree;
 }
 
-void git_commit_set_author(git_commit *commit, const char *name, const char *email, time_t time)
+void git_commit_set_author(git_commit *commit, const git_signature *author_sig)
 {
-	assert(commit && name && email);
+	assert(commit && author_sig);
 	commit->object.modified = 1;
 	CHECK_FULL_PARSE();
 
-	git_person__free(commit->author);
-	commit->author = git_person__new(name, email, time);
+	git_signature_free(commit->author);
+	commit->author = git_signature_dup(author_sig);
 }
 
-void git_commit_set_committer(git_commit *commit, const char *name, const char *email, time_t time)
+void git_commit_set_committer(git_commit *commit, const git_signature *committer_sig)
 {
-	assert(commit && name && email);
+	assert(commit && committer_sig);
 	commit->object.modified = 1;
 	CHECK_FULL_PARSE();
 
-	git_person__free(commit->committer);
-	commit->committer = git_person__new(name, email, time);
-	commit->commit_time = time;
+	git_signature_free(commit->committer);
+	commit->committer = git_signature_dup(committer_sig);
 }
 
 void git_commit_set_message(git_commit *commit, const char *message)
diff --git a/src/commit.h b/src/commit.h
index eca566d..b53ee9b 100644
--- a/src/commit.h
+++ b/src/commit.h
@@ -11,12 +11,11 @@
 struct git_commit {
 	git_object object;
 
-	time_t commit_time;
 	git_vector parents;
 
 	git_tree *tree;
-	git_person *author;
-	git_person *committer;
+	git_signature *author;
+	git_signature *committer;
 
 	char *message;
 	char *message_short;
diff --git a/src/git2.h b/src/git2.h
index dbf5a99..9eb9294 100644
--- a/src/git2.h
+++ b/src/git2.h
@@ -33,6 +33,7 @@
 #include "git2/types.h"
 
 #include "git2/oid.h"
+#include "git2/signature.h"
 #include "git2/odb.h"
 
 #include "git2/repository.h"
diff --git a/src/git2/commit.h b/src/git2/commit.h
index 7286797..ccffec4 100644
--- a/src/git2/commit.h
+++ b/src/git2/commit.h
@@ -93,18 +93,25 @@ GIT_EXTERN(const char *) git_commit_message(git_commit *commit);
 GIT_EXTERN(time_t) git_commit_time(git_commit *commit);
 
 /**
+ * Get the commit timezone offset (i.e. committer's preferred timezone) of a commit.
+ * @param commit a previously loaded commit.
+ * @return positive or negative timezone offset, in minutes from UTC
+ */
+GIT_EXTERN(int) git_commit_timezone_offset(git_commit *commit);
+
+/**
  * Get the committer of a commit.
  * @param commit a previously loaded commit.
  * @return the committer of a commit
  */
-GIT_EXTERN(const git_person *) git_commit_committer(git_commit *commit);
+GIT_EXTERN(const git_signature *) git_commit_committer(git_commit *commit);
 
 /**
  * Get the author of a commit.
  * @param commit a previously loaded commit.
  * @return the author of a commit
  */
-GIT_EXTERN(const git_person *) git_commit_author(git_commit *commit);
+GIT_EXTERN(const git_signature *) git_commit_author(git_commit *commit);
 
 /**
  * Get the tree pointed to by a commit.
@@ -147,20 +154,16 @@ GIT_EXTERN(void) git_commit_set_message(git_commit *commit, const char *message)
 /**
  * Set the committer of a commit
  * @param commit the commit object
- * @param name name of the new committer
- * @param email email of the new committer
- * @param time time when the committer committed the commit
+ * @param author_sig signature of the committer
  */
-GIT_EXTERN(void) git_commit_set_committer(git_commit *commit, const char *name, const char *email, time_t time);
+GIT_EXTERN(void) git_commit_set_committer(git_commit *commit, const git_signature *committer_sig);
 
 /**
  * Set the author of a commit
  * @param commit the commit object
- * @param name name of the new author
- * @param email email of the new author
- * @param time time when the author created the commit
+ * @param author_sig signature of the author
  */
-GIT_EXTERN(void) git_commit_set_author(git_commit *commit, const char *name, const char *email, time_t time);
+GIT_EXTERN(void) git_commit_set_author(git_commit *commit, const git_signature *author_sig);
 
 /**
  * Set the tree which is pointed to by a commit
diff --git a/src/git2/common.h b/src/git2/common.h
index b819f05..9d014c0 100644
--- a/src/git2/common.h
+++ b/src/git2/common.h
@@ -134,16 +134,7 @@
 /** The index file is not backed up by an existing repository */
 #define GIT_EBAREINDEX (GIT_ERROR -14)
 
-
 GIT_BEGIN_DECL
-
-/** Parsed representation of a person */
-typedef struct git_person git_person;
-
-const char *git_person_name(git_person *person);
-const char *git_person_email(git_person *person);
-time_t git_person_time(git_person *person);
-
 /** @} */
 GIT_END_DECL
 #endif
diff --git a/src/git2/signature.h b/src/git2/signature.h
new file mode 100644
index 0000000..96275aa
--- /dev/null
+++ b/src/git2/signature.h
@@ -0,0 +1,70 @@
+/*
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2,
+ * as published by the Free Software Foundation.
+ *
+ * In addition to the permissions in the GNU General Public License,
+ * the authors give you unlimited permission to link the compiled
+ * version of this file into combinations with other programs,
+ * and to distribute those combinations without any restriction
+ * coming from the use of this file.  (The General Public License
+ * restrictions do apply in other respects; for example, they cover
+ * modification of the file, and distribution when not linked into
+ * a combined executable.)
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+#ifndef INCLUDE_git_signature_h__
+#define INCLUDE_git_signature_h__
+
+#include "common.h"
+#include "types.h"
+
+/**
+ * @file git2/signature.h
+ * @brief Git signature creation
+ * @defgroup git_signature Git signature creation
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Create a new action signature. The signature must be freed
+ * manually or using git_signature_free
+ *
+ * @name name of the person
+ * @email email of the person
+ * @time time when the action happened
+ * @offset timezone offset in minutes for the time
+ * @return the new sig, NULl on out of memory
+ */
+GIT_EXTERN(git_signature *) git_signature_new(const char *name, const char *email, time_t time, int offset);
+
+/**
+ * Create a copy of an existing signature.
+ *
+ * All internal strings are also duplicated.
+ * @sig signature to duplicated
+ * @return a copy of sig, NULL on out of memory
+ */
+GIT_EXTERN(git_signature *) git_signature_dup(const git_signature *sig);
+
+/**
+ * Free an existing signature
+ *
+ * @sig signature to free
+ */
+GIT_EXTERN(void) git_signature_free(git_signature *sig);
+
+/** @} */
+GIT_END_DECL
+#endif
diff --git a/src/git2/tag.h b/src/git2/tag.h
index 39b45ac..8e29bc1 100644
--- a/src/git2/tag.h
+++ b/src/git2/tag.h
@@ -96,7 +96,7 @@ GIT_EXTERN(const char *) git_tag_name(git_tag *t);
  * @param tag a previously loaded tag.
  * @return reference to the tag's author
  */
-GIT_EXTERN(const git_person *) git_tag_tagger(git_tag *t);
+GIT_EXTERN(const git_signature *) git_tag_tagger(git_tag *t);
 
 /**
  * Get the message of a tag
@@ -122,11 +122,9 @@ GIT_EXTERN(void) git_tag_set_name(git_tag *tag, const char *name);
 /**
  * Set the tagger of a tag
  * @param tag The tag to modify
- * @param name the name of the new tagger
- * @param email the email of the new tagger
- * @param time the time when the tag was created
+ * @param tagger_sig signature of the tagging action
  */
-GIT_EXTERN(void) git_tag_set_tagger(git_tag *tag, const char *name, const char *email, time_t time);
+GIT_EXTERN(void) git_tag_set_tagger(git_tag *tag, const git_signature *tagger_sig);
 
 /**
  * Set the message of a tag
diff --git a/src/git2/types.h b/src/git2/types.h
index 22fecef..99de332 100644
--- a/src/git2/types.h
+++ b/src/git2/types.h
@@ -82,6 +82,19 @@ typedef struct git_tree git_tree;
 /** Memory representation of an index file. */
 typedef struct git_index git_index;
 
+/** Time in a signature */
+typedef struct git_time {
+	time_t time; /** time in seconds from epoch */
+	int offset; /** timezone offset, in minutes */
+} git_time;
+
+/** An action signature (e.g. for committers, taggers, etc) */
+typedef struct git_signature {
+	char *name; /** full name of the author */
+	char *email; /** email of the author */
+	git_time when; /** time when the action happened */
+} git_signature;
+
 /** @} */
 GIT_END_DECL
 
diff --git a/src/person.c b/src/person.c
deleted file mode 100644
index e93e1b8..0000000
--- a/src/person.c
+++ /dev/null
@@ -1,140 +0,0 @@
-/*
- * This file is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License, version 2,
- * as published by the Free Software Foundation.
- *
- * In addition to the permissions in the GNU General Public License,
- * the authors give you unlimited permission to link the compiled
- * version of this file into combinations with other programs,
- * and to distribute those combinations without any restriction
- * coming from the use of this file.  (The General Public License
- * restrictions do apply in other respects; for example, they cover
- * modification of the file, and distribution when not linked into
- * a combined executable.)
- *
- * This file is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; see the file COPYING.  If not, write to
- * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
- * Boston, MA 02110-1301, USA.
- */
-
-#include "common.h"
-#include "person.h"
-#include "repository.h"
-#include "git2/common.h"
-
-void git_person__free(git_person *person)
-{
-	if (person == NULL)
-		return;
-
-	free(person->name);
-	free(person->email);
-	free(person);
-}
-
-git_person *git_person__new(const char *name, const char *email, time_t time)
-{
-	git_person *p;
-
-	if ((p = git__malloc(sizeof(git_person))) == NULL)
-		goto cleanup;
-
-	p->name = git__strdup(name);
-	p->email = git__strdup(email);
-	p->time = time;
-
-	if (p->name == NULL || p->email == NULL)
-		goto cleanup;
-
-	return p;
-
-cleanup:
-	git_person__free(p);
-	return NULL;
-}
-
-const char *git_person_name(git_person *person)
-{
-	return person->name;
-}
-
-const char *git_person_email(git_person *person)
-{
-	return person->email;
-}
-
-time_t git_person_time(git_person *person)
-{
-	return person->time;
-}
-
-int git_person__parse(git_person *person, char **buffer_out,
-		const char *buffer_end, const char *header)
-{
-	const size_t header_len = strlen(header);
-
-	int name_length, email_length;
-	char *buffer = *buffer_out;
-	char *line_end, *name_end, *email_end;
-
-	memset(person, 0x0, sizeof(git_person));
-
-	line_end = memchr(buffer, '\n', buffer_end - buffer);
-	if (!line_end)
-		return GIT_EOBJCORRUPTED;
-
-	if (buffer + (header_len + 1) > line_end)
-		return GIT_EOBJCORRUPTED;
-
-	if (memcmp(buffer, header, header_len) != 0)
-		return GIT_EOBJCORRUPTED;
-
-	buffer += header_len;
-
-	/* Parse name */
-	if ((name_end = memchr(buffer, '<', buffer_end - buffer)) == NULL)
-		return GIT_EOBJCORRUPTED;
-
-	name_length = name_end - buffer - 1;
-	person->name = git__malloc(name_length + 1);
-	memcpy(person->name, buffer, name_length);
-	person->name[name_length] = 0;
-	buffer = name_end + 1;
-
-	if (buffer >= line_end)
-		return GIT_EOBJCORRUPTED;
-
-	/* Parse email */
-	if ((email_end = memchr(buffer, '>', buffer_end - buffer)) == NULL)
-		return GIT_EOBJCORRUPTED;
-
-	email_length = email_end - buffer;
-	person->email = git__malloc(email_length + 1);
-	memcpy(person->email, buffer, email_length);
-	person->email[email_length] = 0;
-	buffer = email_end + 1;
-
-	if (buffer >= line_end)
-		return GIT_EOBJCORRUPTED;
-
-	person->time = strtol(buffer, &buffer, 10);
-
-	if (person->time == 0)
-		return GIT_EOBJCORRUPTED;
-
-	*buffer_out = (line_end + 1);
-	return GIT_SUCCESS;
-}
-
-int git_person__write(git_odb_source *src, const char *header, const git_person *person)
-{
-	return git__source_printf(src, "%s %s <%s> %u\n", header, person->name, person->email, person->time);
-}
-
-
diff --git a/src/person.h b/src/person.h
deleted file mode 100644
index 7a9fcb7..0000000
--- a/src/person.h
+++ /dev/null
@@ -1,20 +0,0 @@
-#ifndef INCLUDE_person_h__
-#define INCLUDE_person_h__
-
-#include "git2/common.h"
-#include "repository.h"
-#include <time.h>
-
-/** Parsed representation of a person */
-struct git_person {
-	char *name; /**< Full name */
-	char *email; /**< Email address */
-	time_t time; /**< Time when this person committed the change */
-};
-
-void git_person__free(git_person *person);
-git_person *git_person__new(const char *name, const char *email, time_t time);
-int git_person__parse(git_person *person, char **buffer_out, const char *buffer_end, const char *header);
-int git_person__write(git_odb_source *src, const char *header, const git_person *person);
-
-#endif
diff --git a/src/revwalk.c b/src/revwalk.c
index f2eaa71..df8f47a 100644
--- a/src/revwalk.c
+++ b/src/revwalk.c
@@ -400,8 +400,8 @@ void git_revwalk_list_timesort(git_revwalk_list *list)
 					e = q, q = q->next, q_size--;
 
 				else if (q_size == 0 || q == NULL ||
-						p->walk_commit->commit_object->commit_time >= 
-						q->walk_commit->commit_object->commit_time)
+						p->walk_commit->commit_object->committer->when.time >= 
+						q->walk_commit->commit_object->committer->when.time)
 					e = p, p = p->next, p_size--;
 
 				else
diff --git a/src/signature.c b/src/signature.c
new file mode 100644
index 0000000..c5bfda8
--- /dev/null
+++ b/src/signature.c
@@ -0,0 +1,199 @@
+/*
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2,
+ * as published by the Free Software Foundation.
+ *
+ * In addition to the permissions in the GNU General Public License,
+ * the authors give you unlimited permission to link the compiled
+ * version of this file into combinations with other programs,
+ * and to distribute those combinations without any restriction
+ * coming from the use of this file.  (The General Public License
+ * restrictions do apply in other respects; for example, they cover
+ * modification of the file, and distribution when not linked into
+ * a combined executable.)
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "common.h"
+#include "signature.h"
+#include "repository.h"
+#include "git2/common.h"
+
+void git_signature_free(git_signature *sig)
+{
+	if (sig == NULL)
+		return;
+
+	free(sig->name);
+	free(sig->email);
+	free(sig);
+}
+
+git_signature *git_signature_new(const char *name, const char *email, time_t time, int offset)
+{
+	git_signature *p = NULL;
+
+	if ((p = git__malloc(sizeof(git_signature))) == NULL)
+		goto cleanup;
+
+	p->name = git__strdup(name);
+	if (p->name == NULL)
+		goto cleanup;
+
+	p->email = git__strdup(email);
+	if (p->email == NULL)
+		goto cleanup;
+
+	p->when.time = time;
+	p->when.offset = offset;
+
+	if (p->name == NULL || p->email == NULL)
+		goto cleanup;
+
+	return p;
+
+cleanup:
+	git_signature_free(p);
+	return NULL;
+}
+
+git_signature *git_signature_dup(const git_signature *sig)
+{
+	return git_signature_new(sig->name, sig->email, sig->when.time, sig->when.offset);
+}
+
+
+static int parse_timezone_offset(const char *buffer, int *offset_out)
+{
+	int offset, dec_offset;
+	int mins, hours;
+
+	const char* offset_start;
+	char* offset_end;
+
+	offset_start = buffer + 1;
+
+	if (*offset_start == '\n') {
+		*offset_out = 0;
+		return GIT_SUCCESS;
+	}
+
+	if (offset_start[0] != '-' && offset_start[0] != '+')
+		return GIT_EOBJCORRUPTED;
+
+	dec_offset = strtol(offset_start + 1, &offset_end, 10);
+
+	if (offset_end - offset_start != 5)
+		return GIT_EOBJCORRUPTED;
+
+	hours = dec_offset / 100;
+	mins = dec_offset % 100;
+
+	if (hours > 14)	// see http://www.worldtimezone.com/faq.html 
+		return GIT_EOBJCORRUPTED;
+
+	if (mins > 59)
+		return GIT_EOBJCORRUPTED;
+
+	offset = (hours * 60) + mins;
+
+	if (offset_start[0] == '-')
+		offset *= -1;
+	
+	*offset_out = offset;
+
+	return GIT_SUCCESS;
+}
+
+
+int git_signature__parse(git_signature *sig, char **buffer_out,
+		const char *buffer_end, const char *header)
+{
+	const size_t header_len = strlen(header);
+
+	int name_length, email_length;
+	char *buffer = *buffer_out;
+	char *line_end, *name_end, *email_end;
+	int offset = 0;
+
+	memset(sig, 0x0, sizeof(git_signature));
+
+	line_end = memchr(buffer, '\n', buffer_end - buffer);
+	if (!line_end)
+		return GIT_EOBJCORRUPTED;
+
+	if (buffer + (header_len + 1) > line_end)
+		return GIT_EOBJCORRUPTED;
+
+	if (memcmp(buffer, header, header_len) != 0)
+		return GIT_EOBJCORRUPTED;
+
+	buffer += header_len;
+
+	/* Parse name */
+	if ((name_end = memchr(buffer, '<', buffer_end - buffer)) == NULL)
+		return GIT_EOBJCORRUPTED;
+
+	name_length = name_end - buffer - 1;
+	sig->name = git__malloc(name_length + 1);
+	memcpy(sig->name, buffer, name_length);
+	sig->name[name_length] = 0;
+	buffer = name_end + 1;
+
+	if (buffer >= line_end)
+		return GIT_EOBJCORRUPTED;
+
+	/* Parse email */
+	if ((email_end = memchr(buffer, '>', buffer_end - buffer)) == NULL)
+		return GIT_EOBJCORRUPTED;
+
+	email_length = email_end - buffer;
+	sig->email = git__malloc(email_length + 1);
+	memcpy(sig->email, buffer, email_length);
+	sig->email[email_length] = 0;
+	buffer = email_end + 1;
+
+	if (buffer >= line_end)
+		return GIT_EOBJCORRUPTED;
+
+	sig->when.time = strtol(buffer, &buffer, 10);
+
+	if (sig->when.time == 0)
+		return GIT_EOBJCORRUPTED;
+
+	if (parse_timezone_offset(buffer, &offset) < GIT_SUCCESS)
+		return GIT_EOBJCORRUPTED;
+	
+	sig->when.offset = offset;
+
+	*buffer_out = (line_end + 1);
+	return GIT_SUCCESS;
+}
+
+int git_signature__write(git_odb_source *src, const char *header, const git_signature *sig)
+{
+	char sign;
+	int offset, hours, mins;
+
+	offset = sig->when.offset;
+	sign = (sig->when.offset < 0) ? '-' : '+';
+	
+	if (offset < 0)
+		offset = -offset;
+
+	hours = offset / 60;
+	mins = offset % 60;
+
+	return git__source_printf(src, "%s %s <%s> %u %c%02d%02d\n", header, sig->name, sig->email, sig->when.time, sign, hours, mins);
+}
+
+
diff --git a/src/signature.h b/src/signature.h
new file mode 100644
index 0000000..ee212c2
--- /dev/null
+++ b/src/signature.h
@@ -0,0 +1,12 @@
+#ifndef INCLUDE_signature_h__
+#define INCLUDE_signature_h__
+
+#include "git2/common.h"
+#include "git2/signature.h"
+#include "repository.h"
+#include <time.h>
+
+int git_signature__parse(git_signature *sig, char **buffer_out, const char *buffer_end, const char *header);
+int git_signature__write(git_odb_source *src, const char *header, const git_signature *sig);
+
+#endif
diff --git a/src/tag.c b/src/tag.c
index b5b8b9f..4c6cabf 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -26,14 +26,15 @@
 #include "common.h"
 #include "commit.h"
 #include "tag.h"
-#include "person.h"
+#include "signature.h"
 #include "revwalk.h"
 #include "git2/object.h"
 #include "git2/repository.h"
+#include "git2/signature.h"
 
 void git_tag__free(git_tag *tag)
 {
-	git_person__free(tag->tagger);
+	git_signature_free(tag->tagger);
 	free(tag->message);
 	free(tag->tag_name);
 	free(tag);
@@ -92,18 +93,18 @@ void git_tag_set_name(git_tag *tag, const char *name)
 	tag->tag_name = git__strdup(name);
 }
 
-const git_person *git_tag_tagger(git_tag *t)
+const git_signature *git_tag_tagger(git_tag *t)
 {
 	return t->tagger;
 }
 
-void git_tag_set_tagger(git_tag *tag, const char *name, const char *email, time_t time)
+void git_tag_set_tagger(git_tag *tag, const git_signature *tagger_sig)
 {
-	assert(tag && name && email);
+	assert(tag && tagger_sig);
 	tag->object.modified = 1;
 
-	git_person__free(tag->tagger);
-	tag->tagger = git_person__new(name, email, time);
+	git_signature_free(tag->tagger);
+	tag->tagger = git_signature_dup(tagger_sig);
 }
 
 const char *git_tag_message(git_tag *t)
@@ -190,11 +191,11 @@ static int parse_tag_buffer(git_tag *tag, char *buffer, const char *buffer_end)
 	buffer = search + 1;
 
 	if (tag->tagger != NULL)
-		git_person__free(tag->tagger);
+		git_signature_free(tag->tagger);
 
-	tag->tagger = git__malloc(sizeof(git_person));
+	tag->tagger = git__malloc(sizeof(git_signature));
 
-	if ((error = git_person__parse(tag->tagger, &buffer, buffer_end, "tagger ")) != 0)
+	if ((error = git_signature__parse(tag->tagger, &buffer, buffer_end, "tagger ")) != 0)
 		return error;
 
 	text_len = buffer_end - ++buffer;
@@ -217,7 +218,7 @@ int git_tag__writeback(git_tag *tag, git_odb_source *src)
 	git__write_oid(src, "object", git_object_id(tag->target));
 	git__source_printf(src, "type %s\n", git_object_type2string(tag->type));
 	git__source_printf(src, "tag %s\n", tag->tag_name);
-	git_person__write(src, "tagger", tag->tagger);
+	git_signature__write(src, "tagger", tag->tagger);
 
 	if (tag->message != NULL)
 		git__source_printf(src, "\n%s", tag->message);
diff --git a/src/tag.h b/src/tag.h
index dd84ff6..624fcc6 100644
--- a/src/tag.h
+++ b/src/tag.h
@@ -10,7 +10,7 @@ struct git_tag {
 	git_object *target;
 	git_otype type;
 	char *tag_name;
-	git_person *tagger;
+	git_signature *tagger;
 	char *message;
 };
 
diff --git a/tests/t0401-parse.c b/tests/t0401-parse.c
index b82a9b1..d734e5d 100644
--- a/tests/t0401-parse.c
+++ b/tests/t0401-parse.c
@@ -1,7 +1,7 @@
 #include "test_lib.h"
 #include "test_helpers.h"
 #include "commit.h"
-#include "person.h"
+#include "signature.h"
 #include <git2/odb.h>
 #include <git2/commit.h>
 #include <git2/revwalk.h>
@@ -129,96 +129,134 @@ BEGIN_TEST(parse_oid_test)
 
 END_TEST
 
-BEGIN_TEST(parse_person_test)
+BEGIN_TEST(parse_sig_test)
 
-#define TEST_PERSON_PASS(_string, _header, _name, _email, _time) { \
+#define TEST_SIGNATURE_PASS(_string, _header, _name, _email, _time, _offset) { \
 	char *ptr = _string; \
 	size_t len = strlen(_string);\
-	git_person person = {NULL, NULL, 0}; \
-	must_pass(git_person__parse(&person, &ptr, ptr + len, _header));\
+	git_signature person = {NULL, NULL, {0, 0}}; \
+	must_pass(git_signature__parse(&person, &ptr, ptr + len, _header));\
 	must_be_true(strcmp(_name, person.name) == 0);\
 	must_be_true(strcmp(_email, person.email) == 0);\
-	must_be_true(_time == person.time);\
+	must_be_true(_time == person.when.time);\
+	must_be_true(_offset == person.when.offset);\
 	free(person.name); free(person.email);\
 }
 
-#define TEST_PERSON_FAIL(_string, _header) { \
+#define TEST_SIGNATURE_FAIL(_string, _header) { \
 	char *ptr = _string; \
 	size_t len = strlen(_string);\
-	git_person person = {NULL, NULL, 0}; \
-	must_fail(git_person__parse(&person, &ptr, ptr + len, _header));\
+	git_signature person = {NULL, NULL, {0, 0}}; \
+	must_fail(git_signature__parse(&person, &ptr, ptr + len, _header));\
 	free(person.name); free(person.email);\
 }
 
-	TEST_PERSON_PASS(
-			"author Vicent Marti <tanoku@gmail.com> 12345 \n",
-			"author ",
-			"Vicent Marti",
-			"tanoku@gmail.com",
-			12345);
+	TEST_SIGNATURE_PASS(
+		"author Vicent Marti <tanoku@gmail.com> 12345 \n",
+		"author ",
+		"Vicent Marti",
+		"tanoku@gmail.com",
+		12345,
+		0);
 
-	TEST_PERSON_PASS(
+	TEST_SIGNATURE_PASS(
 		"author Vicent Marti <> 12345 \n",
 		"author ",
 		"Vicent Marti",
 		"",
-		12345);
+		12345,
+		0);
 
-	TEST_PERSON_PASS(
-		"author Vicent Marti <tanoku@gmail.com> 231301 +2020\n",
+	TEST_SIGNATURE_PASS(
+		"author Vicent Marti <tanoku@gmail.com> 231301 +1020\n",
 		"author ",
 		"Vicent Marti",
 		"tanoku@gmail.com",
-		231301);
+		231301,
+		620);
 
-	TEST_PERSON_PASS(
+	TEST_SIGNATURE_PASS(
 		"author Vicent Marti with an outrageously long name \
 		which will probably overflow the buffer <tanoku@gmail.com> 12345 \n",
 		"author ",
 		"Vicent Marti with an outrageously long name \
 		which will probably overflow the buffer",
 		"tanoku@gmail.com",
-		12345);
+		12345,
+		0);
 
-	TEST_PERSON_PASS(
+	TEST_SIGNATURE_PASS(
 		"author Vicent Marti <tanokuwithaveryveryverylongemail\
 		whichwillprobablyvoverflowtheemailbuffer@gmail.com> 12345 \n",
 		"author ",
 		"Vicent Marti",
 		"tanokuwithaveryveryverylongemail\
 		whichwillprobablyvoverflowtheemailbuffer@gmail.com",
-		12345);
+		12345,
+		0);
+
+	TEST_SIGNATURE_PASS(
+		"committer Vicent Marti <tanoku@gmail.com> 123456 +0000 \n",
+		"committer ",
+		"Vicent Marti",
+		"tanoku@gmail.com",
+		123456,
+		0);
+
+	TEST_SIGNATURE_PASS(
+		"committer Vicent Marti <tanoku@gmail.com> 123456 +0100 \n",
+		"committer ",
+		"Vicent Marti",
+		"tanoku@gmail.com",
+		123456,
+		60);
+
+	TEST_SIGNATURE_PASS(
+		"committer Vicent Marti <tanoku@gmail.com> 123456 -0100 \n",
+		"committer ",
+		"Vicent Marti",
+		"tanoku@gmail.com",
+		123456,
+		-60);
+
+	TEST_SIGNATURE_FAIL(
+		"committer Vicent Marti <tanoku@gmail.com> 123456 -1500 \n",
+		"committer ");
+
+	TEST_SIGNATURE_FAIL(
+		"committer Vicent Marti <tanoku@gmail.com> 123456 +0163 \n",
+		"committer ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author Vicent Marti <tanoku@gmail.com> 12345 \n",
 		"author  ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author Vicent Marti <tanoku@gmail.com> 12345 \n",
 		"committer ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author Vicent Marti 12345 \n",
 		"author ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author Vicent Marti <broken@email 12345 \n",
 		"author ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author Vicent Marti <tanoku@gmail.com> notime \n",
 		"author ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author Vicent Marti <tanoku@gmail.com>\n",
 		"author ");
 
-	TEST_PERSON_FAIL(
+	TEST_SIGNATURE_FAIL(
 		"author ",
 		"author ");
 
-#undef TEST_PERSON_PASS
-#undef TEST_PERSON_FAIL
+#undef TEST_SIGNATURE_PASS
+#undef TEST_SIGNATURE_FAIL
 
 END_TEST
 
diff --git a/tests/t0402-details.c b/tests/t0402-details.c
index 489b3ff..0b2fe22 100644
--- a/tests/t0402-details.c
+++ b/tests/t0402-details.c
@@ -1,7 +1,7 @@
 #include "test_lib.h"
 #include "test_helpers.h"
 #include "commit.h"
-#include "person.h"
+#include "signature.h"
 
 #include <git2/odb.h>
 #include <git2/commit.h>
@@ -28,7 +28,7 @@ BEGIN_TEST(query_details_test)
 		git_oid id;
 		git_commit *commit;
 
-		const git_person *author, *committer;
+		const git_signature *author, *committer;
 		const char *message, *message_short;
 		time_t commit_time;
 		unsigned int parents, p;
diff --git a/tests/t0403-write.c b/tests/t0403-write.c
index 8b29b05..c8e72da 100644
--- a/tests/t0403-write.c
+++ b/tests/t0403-write.c
@@ -1,11 +1,12 @@
 #include "test_lib.h"
 #include "test_helpers.h"
 #include "commit.h"
-#include "person.h"
+#include "signature.h"
 
 #include <git2/odb.h>
 #include <git2/commit.h>
 #include <git2/revwalk.h>
+#include <git2/signature.h>
 
 static const char *commit_ids[] = {
 	"a4a7dce85cf63874e984719f4fdd239f5145052f", /* 0 */
@@ -27,7 +28,7 @@ BEGIN_TEST(writenew_test)
 	git_commit *commit, *parent;
 	git_tree *tree;
 	git_oid id;
-	const git_person *author, *committer;
+	const git_signature *author, *committer;
 	/* char hex_oid[41]; */
 
 	must_pass(git_repository_open(&repo, REPOSITORY_FOLDER));
@@ -42,23 +43,33 @@ BEGIN_TEST(writenew_test)
 	git_commit_add_parent(commit, parent);
 
 	/* Set other attributes */
-	git_commit_set_committer(commit, COMMITTER_NAME, COMMITTER_EMAIL, 123456789);
-	git_commit_set_author(commit, COMMITTER_NAME, COMMITTER_EMAIL, 987654321);
+	committer = git_signature_new(COMMITTER_NAME, COMMITTER_EMAIL, 123456789, 60);
+	must_be_true(committer != NULL);
+
+	author = git_signature_new(COMMITTER_NAME, COMMITTER_EMAIL, 987654321, 90);
+	must_be_true(author != NULL);
+
+	git_commit_set_committer(commit, committer);
+	git_commit_set_author(commit, author);
 	git_commit_set_message(commit, COMMIT_MESSAGE);
 
+	git_signature_free((git_signature *)committer);
+	git_signature_free((git_signature *)author);
+
 	/* Check attributes were set correctly */
 	author = git_commit_author(commit);
 	must_be_true(author != NULL);
 	must_be_true(strcmp(author->name, COMMITTER_NAME) == 0);
 	must_be_true(strcmp(author->email, COMMITTER_EMAIL) == 0);
-	must_be_true(author->time == 987654321);
+	must_be_true(author->when.time == 987654321);
+	must_be_true(author->when.offset == 90);
 
 	committer = git_commit_committer(commit);
 	must_be_true(committer != NULL);
 	must_be_true(strcmp(committer->name, COMMITTER_NAME) == 0);
 	must_be_true(strcmp(committer->email, COMMITTER_EMAIL) == 0);
-	must_be_true(committer->time == 123456789);
-	must_be_true(git_commit_time(commit) == 123456789);
+	must_be_true(committer->when.time == 123456789);
+	must_be_true(committer->when.offset == 60);
 
 	must_be_true(strcmp(git_commit_message(commit), COMMIT_MESSAGE) == 0);
 
@@ -74,18 +85,8 @@ BEGIN_TEST(writenew_test)
 	/* Write to disk */
 	must_pass(git_object_write((git_object *)commit));
 
-	/* Show new SHA1 */
-/*
-	git_oid_fmt(hex_oid, git_commit_id(commit));
-	hex_oid[40] = 0;
-	printf("Written new commit, SHA1: %s\n", hex_oid);
-*/
-
 	must_pass(remove_loose_object(REPOSITORY_FOLDER, (git_object *)commit));
 
-	//git_person_free(&author);
-	//git_person_free(&committer);
-
 	git_repository_free(repo);
 END_TEST
 
@@ -104,12 +105,6 @@ BEGIN_TEST(writeback_test)
 
 	message = git_commit_message(commit);
 
-/*
-	git_oid_fmt(hex_oid, git_commit_id(commit));
-	hex_oid[40] = 0;
-	printf("Old SHA1: %s\n", hex_oid);
-*/
-
 	git_commit_set_message(commit, "This is a new test message. Cool!\n");
 
 	git_oid_mkstr(&id, commit_ids[4]);
@@ -119,12 +114,6 @@ BEGIN_TEST(writeback_test)
 
 	must_pass(git_object_write((git_object *)commit));
 
-/*
-	git_oid_fmt(hex_oid, git_commit_id(commit));
-	hex_oid[40] = 0;
-	printf("New SHA1: %s\n", hex_oid);
-*/
-
 	must_pass(remove_loose_object(REPOSITORY_FOLDER, (git_object *)commit));
 
 	git_repository_free(repo);
diff --git a/tests/t0502-list.c b/tests/t0502-list.c
index 04427f5..119f15f 100644
--- a/tests/t0502-list.c
+++ b/tests/t0502-list.c
@@ -4,6 +4,7 @@
 #include "revwalk.h"
 #include <git2/odb.h>
 #include <git2/commit.h>
+#include <git2/signature.h>
 
 BEGIN_TEST(list_timesort_test)
 
@@ -15,12 +16,13 @@ BEGIN_TEST(list_timesort_test)
 #define TEST_SORTED() \
 		previous_time = INT_MAX;\
 	for (n = list.head; n != NULL; n = n->next) {\
-		must_be_true(n->walk_commit->commit_object->commit_time <= previous_time);\
-		previous_time = n->walk_commit->commit_object->commit_time;\
+		must_be_true(n->walk_commit->commit_object->committer->when.time <= previous_time);\
+		previous_time = n->walk_commit->commit_object->committer->when.time;\
 	}
 
 #define CLEAR_LIST() \
 	for (n = list.head; n != NULL; n = n->next) {\
+		git_signature_free(n->walk_commit->commit_object->committer);\
 		free(n->walk_commit->commit_object);\
 		free(n->walk_commit);\
 	}\
@@ -37,7 +39,7 @@ BEGIN_TEST(list_timesort_test)
 			git_commit *c = git__malloc(sizeof(git_commit));
 			git_revwalk_commit *rc = git__malloc(sizeof(git_revwalk_commit));
 
-			c->commit_time = (time_t)rand();
+			c->committer = git_signature_new("", "", (time_t)rand(), 0);
 			rc->commit_object = c;
 
 			git_revwalk_list_push_back(&list, rc);
@@ -53,7 +55,7 @@ BEGIN_TEST(list_timesort_test)
 		git_commit *c = git__malloc(sizeof(git_commit));
 		git_revwalk_commit *rc = git__malloc(sizeof(git_revwalk_commit));
 
-		c->commit_time = 0;
+		c->committer = git_signature_new("", "", 0, 0);
 		rc->commit_object = c;
 
 		git_revwalk_list_push_back(&list, rc);