Changes to allow examples/*.c to compile and link. This required on

change to the signature of an API function (git_signature_new).
Also, the examples/general.c had a lot of unchecked return values
which were addresed with a couple of macros. The resulting example
still does not work correctly but at least now it fails with an
error message rather than not compiling or dumping core. Example
runtime issues may be addressed in a later commit.

examples/general.c

@@ -28,6 +28,19 @@
 #include <git2.h>
 #include <stdio.h>
 
+// It's not necessarily recommended that you use macros like this in a real application
+// but they're handy for a simple demo.
+#define CHK_INT(fcn) \
+  if ((fcn) != GIT_SUCCESS) { \
+    fprintf(stderr, "%s: Error: %s at %s:%d\n", argv[0], git_lasterror(), __FILE__, __LINE__); \
+    exit(2); \
+  }
+#define CHK_PTR(fcn) \
+  if ((fcn) == NULL) { \
+    fprintf(stderr, "%s: Error: %s at %s:%d\n", argv[0], git_lasterror(), __FILE__, __LINE__); \
+    exit(2); \
+  }
+
 int main (int argc, char** argv)
 {
   // ### Opening the Repository
@@ -38,7 +51,11 @@ int main (int argc, char** argv)
   //
   // [me]: http://libgit2.github.com/libgit2/#HEAD/group/repository
   git_repository *repo;
-  git_repository_open(&repo, "/opt/libgit2-test/.git");
+  if (argc > 1) {
+    CHK_INT(git_repository_open(&repo, argv[1]));
+  } else {
+    CHK_INT(git_repository_open(&repo, "/opt/libgit2-test/.git"));
+  }
 
   // ### SHA-1 Value Conversions
 
@@ -49,10 +66,10 @@ int main (int argc, char** argv)
   // The `git_oid` is the structure that keeps the SHA value. We will use this throughout the example
   // for storing the value of the current SHA key we're working with.
   git_oid oid;
-  git_oid_fromstr(&oid, hex);
+  CHK_INT(git_oid_fromstr(&oid, hex));
 
   // Once we've converted the string into the oid value, we can get the raw value of the SHA.
-  printf("Raw 20 bytes: [%s]\n", (&oid)->id);
+  printf("Raw 20 bytes: [%.20s]\n", (&oid)->id);
 
   // Next we will convert the 20 byte raw SHA1 value to a human readable 40 char hex value.
   printf("\n*Raw to Hex*\n");
@@ -70,7 +87,7 @@ int main (int argc, char** argv)
   // repository.
   // [odb]: http://libgit2.github.com/libgit2/#HEAD/group/odb
   git_odb *odb;
-  odb = git_repository_database(repo);
+  CHK_PTR(odb = git_repository_database(repo));
 
   // #### Raw Object Reading
 
@@ -79,12 +96,11 @@ int main (int argc, char** argv)
   git_otype otype;
   const unsigned char *data;
   const char *str_type;
-  int error;
 
   // We can read raw objects directly from the object database if we have the oid (SHA)
   // of the object.  This allows us to access objects without knowing thier type and inspect
   // the raw bytes unparsed.
-  error = git_odb_read(&obj, odb, &oid);
+  CHK_INT(git_odb_read(&obj, odb, &oid));
 
   // A raw object only has three properties - the type (commit, blob, tree or tag), the size
   // of the raw data and the raw, unparsed data itself.  For a commit or tag, that raw data
@@ -113,7 +129,7 @@ int main (int argc, char** argv)
   // direct access to the key/value properties of Git.  Here we'll write a new blob object
   // that just contains a simple string.  Notice that we have to specify the object type as
   // the `git_otype` enum.
-  git_odb_write(&oid, odb, "test data", sizeof("test data") - 1, GIT_OBJ_BLOB);
+  CHK_INT(git_odb_write(&oid, odb, "test data", sizeof("test data") - 1, GIT_OBJ_BLOB));
 
   // Now that we've written the object, we can check out what SHA1 was generated when the
   // object was written to our database.
@@ -133,20 +149,19 @@ int main (int argc, char** argv)
   printf("\n*Commit Parsing*\n");
 
   git_commit *commit;
-  git_oid_fromstr(&oid, "f0877d0b841d75172ec404fc9370173dfffc20d1");
+  CHK_INT(git_oid_fromstr(&oid, "f0877d0b841d75172ec404fc9370173dfffc20d1"));
 
-  error = git_commit_lookup(&commit, repo, &oid);
+  CHK_INT(git_commit_lookup(&commit, repo, &oid));
 
   const git_signature *author, *cmtter;
-  const char *message, *message_short;
+  const char *message;
   time_t ctime;
   unsigned int parents, p;
 
   // Each of the properties of the commit object are accessible via methods, including commonly
-  // needed variations, such as `git_commit_time` which returns the author time and `_message_short`
-  // which gives you just the first line of the commit message.
+  // needed variations, such as `git_commit_time` which returns the author time and `_message`
+  // which gives you the commit message.
   message  = git_commit_message(commit);
-  message_short = git_commit_message_short(commit);
   author   = git_commit_author(commit);
   cmtter   = git_commit_committer(commit);
   ctime    = git_commit_time(commit);
@@ -161,7 +176,7 @@ int main (int argc, char** argv)
   parents  = git_commit_parentcount(commit);
   for (p = 0;p < parents;p++) {
     git_commit *parent;
-    git_commit_parent(&parent, commit, p);
+    CHK_INT(git_commit_parent(&parent, commit, p));
     git_oid_fmt(out, git_commit_id(parent));
     printf("Parent: %s\n", out);
     git_commit_close(parent);
@@ -187,17 +202,17 @@ int main (int argc, char** argv)
   // this to create a commit in order to specify who created it and when.  Default values for the name
   // and email should be found in the `user.name` and `user.email` configuration options.  See the `config`
   // section of this example file to see how to access config values.
-  author = git_signature_new("Scott Chacon", "schacon@gmail.com",
-      123456789, 60);
-  cmtter = git_signature_new("Scott A Chacon", "scott@github.com",
-      987654321, 90);
+  CHK_INT(git_signature_new(&author, "Scott Chacon", "schacon@gmail.com",
+      123456789, 60));
+  CHK_INT(git_signature_new(&cmtter, "Scott A Chacon", "scott@github.com",
+      987654321, 90));
 
   // Commit objects need a tree to point to and optionally one or more parents.  Here we're creating oid
   // objects to create the commit with, but you can also use
-  git_oid_fromstr(&tree_id, "28873d96b4e8f4e33ea30f4c682fd325f7ba56ac");
-  git_tree_lookup(&tree, repo, &tree_id);
-  git_oid_fromstr(&parent_id, "f0877d0b841d75172ec404fc9370173dfffc20d1");
-  git_commit_lookup(&parent, repo, &parent_id);
+  CHK_INT(git_oid_fromstr(&tree_id, "28873d96b4e8f4e33ea30f4c682fd325f7ba56ac"));
+  CHK_INT(git_tree_lookup(&tree, repo, &tree_id));
+  CHK_INT(git_oid_fromstr(&parent_id, "f0877d0b841d75172ec404fc9370173dfffc20d1"));
+  CHK_INT(git_commit_lookup(&parent, repo, &parent_id));
 
   // Here we actually create the commit object with a single call with all the values we need to create
   // the commit.  The SHA key is written to the `commit_id` variable here.
@@ -207,6 +222,7 @@ int main (int argc, char** argv)
     NULL, /* do not update the HEAD */
     author,
     cmtter,
+    NULL, /* use default message encoding */
     "example commit",
     tree,
     1, parent);
@@ -226,14 +242,14 @@ int main (int argc, char** argv)
 
   // We create an oid for the tag object if we know the SHA and look it up in the repository the same
   // way that we would a commit (or any other) object.
-  git_oid_fromstr(&oid, "bc422d45275aca289c51d79830b45cecebff7c3a");
+  CHK_INT(git_oid_fromstr(&oid, "bc422d45275aca289c51d79830b45cecebff7c3a"));
 
-  error = git_tag_lookup(&tag, repo, &oid);
+  CHK_INT(git_tag_lookup(&tag, repo, &oid));
 
   // Now that we have the tag object, we can extract the information it generally contains: the target
   // (usually a commit object), the type of the target object (usually 'commit'), the name ('v1.0'),
   // the tagger (a git_signature - name, email, timestamp), and the tag message.
-  git_tag_target((git_object **)&commit, tag);
+  CHK_INT(git_tag_target((git_object **)&commit, tag));
   tname = git_tag_name(tag);    // "test"
   ttype = git_tag_type(tag);    // GIT_OBJ_COMMIT (otype enum)
   tmessage = git_tag_message(tag); // "tag message\n"
@@ -253,18 +269,18 @@ int main (int argc, char** argv)
   git_object *objt;
 
   // Create the oid and lookup the tree object just like the other objects.
-  git_oid_fromstr(&oid, "2a741c18ac5ff082a7caaec6e74db3075a1906b5");
-  git_tree_lookup(&tree, repo, &oid);
+  CHK_INT(git_oid_fromstr(&oid, "2a741c18ac5ff082a7caaec6e74db3075a1906b5"));
+  CHK_INT(git_tree_lookup(&tree, repo, &oid));
 
   // Getting the count of entries in the tree so you can iterate over them if you want to.
   int cnt = git_tree_entrycount(tree); // 3
   printf("tree entries: %d\n", cnt);
 
-  entry = git_tree_entry_byindex(tree, 0);
+  CHK_PTR(entry = git_tree_entry_byindex(tree, 0));
   printf("Entry name: %s\n", git_tree_entry_name(entry)); // "hello.c"
 
   // You can also access tree entries by name if you know the name of the entry you're looking for.
-  entry = git_tree_entry_byname(tree, "hello.c");
+  CHK_PTR(entry = git_tree_entry_byname(tree, "hello.c"));
   git_tree_entry_name(entry); // "hello.c"
 
   // Once you have the entry object, you can access the content or subtree (or commit, in the case
@@ -287,15 +303,15 @@ int main (int argc, char** argv)
   printf("\n*Blob Parsing*\n");
   git_blob *blob;
 
-  git_oid_fromstr(&oid, "af7574ea73f7b166f869ef1a39be126d9a186ae0");
-  git_blob_lookup(&blob, repo, &oid);
+  CHK_INT(git_oid_fromstr(&oid, "af7574ea73f7b166f869ef1a39be126d9a186ae0"));
+  CHK_INT(git_blob_lookup(&blob, repo, &oid));
 
   // You can access a buffer with the raw contents of the blob directly.
   // Note that this buffer may not be contain ASCII data for certain blobs (e.g. binary files):
   // do not consider the buffer a NULL-terminated string, and use the `git_blob_rawsize` attribute to
   // find out its exact size in bytes
   printf("Blob Size: %d\n", git_blob_rawsize(blob)); // 8
-  git_blob_rawcontent(blob); // "content"
+  CHK_PTR(git_blob_rawcontent(blob)); // "content"
 
   // ### Revwalking
   //
@@ -311,17 +327,17 @@ int main (int argc, char** argv)
   git_revwalk *walk;
   git_commit *wcommit;
 
-  git_oid_fromstr(&oid, "f0877d0b841d75172ec404fc9370173dfffc20d1");
+  CHK_INT(git_oid_fromstr(&oid, "f0877d0b841d75172ec404fc9370173dfffc20d1"));
 
   // To use the revwalker, create a new walker, tell it how you want to sort the output and then push
   // one or more starting points onto the walker.  If you want to emulate the output of `git log` you
   // would push the SHA of the commit that HEAD points to into the walker and then start traversing them.
   // You can also 'hide' commits that you want to stop at or not see any of their ancestors.  So if you
   // want to emulate `git log branch1..branch2`, you would push the oid of `branch2` and hide the oid
   // of `branch1`.
-  git_revwalk_new(&walk, repo);
+  CHK_INT(git_revwalk_new(&walk, repo));
   git_revwalk_sorting(walk, GIT_SORT_TOPOLOGICAL | GIT_SORT_REVERSE);
-  git_revwalk_push(walk, &oid);
+  CHK_INT(git_revwalk_push(walk, &oid));
 
   const git_signature *cauth;
   const char *cmsg;
@@ -332,8 +348,8 @@ int main (int argc, char** argv)
   // note that this operation is specially fast since the raw contents of the commit object will
   // be cached in memory
   while ((git_revwalk_next(&oid, walk)) == GIT_SUCCESS) {
-    error = git_commit_lookup(&wcommit, repo, &oid);
-    cmsg  = git_commit_message_short(wcommit);
+    CHK_INT(git_commit_lookup(&wcommit, repo, &oid));
+    cmsg  = git_commit_message(wcommit);
     cauth = git_commit_author(wcommit);
     printf("%s (%s)\n", cmsg, cauth->email);
     git_commit_close(wcommit);
@@ -359,7 +375,7 @@ int main (int argc, char** argv)
   // You can either open the index from the standard location in an open repository, as we're doing
   // here, or you can open and manipulate any index file with `git_index_open_bare()`. The index
   // for the repository will be located and loaded from disk.
-  git_repository_index(&index, repo);
+  CHK_INT(git_repository_index(&index, repo));
 
   // For each entry in the index, you can get a bunch of information including the SHA (oid), path
   // and mode which map to the tree objects that are written out.  It also has filesystem properties
@@ -388,7 +404,7 @@ int main (int argc, char** argv)
   // Here we will implement something like `git for-each-ref` simply listing out all available
   // references and the object SHA they resolve to.
   git_strarray ref_list;
-  git_reference_listall(&ref_list, repo, GIT_REF_LISTALL);
+  CHK_INT(git_reference_listall(&ref_list, repo, GIT_REF_LISTALL));
 
   const char *refname;
   git_reference *ref;
@@ -397,7 +413,7 @@ int main (int argc, char** argv)
   // resolve them to the SHA, then print both values out.
   for (i = 0; i < ref_list.count; ++i) {
     refname = ref_list.strings[i];
-    git_reference_lookup(&ref, repo, refname);
+    CHK_INT(git_reference_lookup(&ref, repo, refname));
 
     switch (git_reference_type(ref)) {
     case GIT_REF_OID:
@@ -431,7 +447,7 @@ int main (int argc, char** argv)
   git_config *cfg;
 
   // Open a config object so we can read global values from it.
-  git_config_open_ondisk(&cfg, "~/.gitconfig");
+  CHK_INT(git_config_open_ondisk(&cfg, "~/.gitconfig"));
 
   git_config_get_int(cfg, "help.autocorrect", &j);
   printf("Autocorrect: %d\n", j);

include/git2/signature.h

@@ -48,7 +48,7 @@ GIT_BEGIN_DECL
  * @param offset timezone offset in minutes for the time
  * @return 0 on success; error code otherwise
  */
-GIT_EXTERN(int) git_signature_new(git_signature **sig_out, const char *name, const char *email, git_time_t time, int offset);
+GIT_EXTERN(int) git_signature_new(const git_signature **sig_out, const char *name, const char *email, git_time_t time, int offset);
 
 /**
  * Create a new action signature with a timestamp of 'now'. The

src/signature.c

@@ -81,7 +81,7 @@ static int process_trimming(const char *input, char **storage, const char *input
 	return GIT_SUCCESS;
 }
 
-int git_signature_new(git_signature **sig_out, const char *name, const char *email, git_time_t time, int offset)
+int git_signature_new(const git_signature **sig_out, const char *name, const char *email, git_time_t time, int offset)
 {
 	int error;
 	git_signature *p = NULL;