[PATCH v3 1/9] am: stop ignoring errors reported by log_tree_diff()

[Johannes Schindelin <johannes.schindelin@gmx.de>]

It is never a good idea to ignore errors, so let's handle them.

While at it, handle fopen() errors more gently (i.e. give the caller a
chance to do something about it rather than die()ing).

Note: there are more places in the builtin am code that ignore
errors returned from library functions. Fixing those is outside the
purview of the current patch series, though.

Cc: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 builtin/am.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index 3dfe70b..0e28a62 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1433,12 +1433,15 @@ static void get_commit_info(struct am_state *state, struct commit *commit)
 /**
  * Writes `commit` as a patch to the state directory's "patch" file.
  */
-static void write_commit_patch(const struct am_state *state, struct commit *commit)
+static int write_commit_patch(const struct am_state *state, struct commit *commit)
 {
 	struct rev_info rev_info;
 	FILE *fp;
 
-	fp = xfopen(am_path(state, "patch"), "w");
+	fp = fopen(am_path(state, "patch"), "w");
+	if (!fp)
+		return error(_("Could not open %s for writing"),
+			am_path(state, "patch"));
 	init_revisions(&rev_info, NULL);
 	rev_info.diff = 1;
 	rev_info.abbrev = 0;
@@ -1453,7 +1456,7 @@ static void write_commit_patch(const struct am_state *state, struct commit *comm
 	rev_info.diffopt.close_file = 1;
 	add_pending_object(&rev_info, &commit->object, "");
 	diff_setup_done(&rev_info.diffopt);
-	log_tree_commit(&rev_info, commit);
+	return log_tree_commit(&rev_info, commit);
 }
 
 /**
@@ -1501,13 +1504,14 @@ static int parse_mail_rebase(struct am_state *state, const char *mail)
 	unsigned char commit_sha1[GIT_SHA1_RAWSZ];
 
 	if (get_mail_commit_sha1(commit_sha1, mail) < 0)
-		die(_("could not parse %s"), mail);
+		return error(_("could not parse %s"), mail);
 
 	commit = lookup_commit_or_die(commit_sha1, mail);
 
 	get_commit_info(state, commit);
 
-	write_commit_patch(state, commit);
+	if (write_commit_patch(state, commit) < 0)
+		return -1;
 
 	hashcpy(state->orig_commit, commit_sha1);
 	write_state_text(state, "original-commit", sha1_to_hex(commit_sha1));
-- 
2.9.0.118.g0e1a633