use xfopen() in more places

xfopen()

 - provides error details
 - explains error on reading, or writing, or whatever operation
 - has l10n support
 - prints file name in the error

Some of these are missing in the places that are replaced with xfopen(),
which is a clear win. In some other places, it's just less code (not as
clearly a win as the previous case but still is).

The only slight regresssion is in remote-testsvn, where we don't report
the file class (marks files) in the error messages anymore. But since
this is a _test_ svn remote transport, I'm not too concerned.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

bisect.c

@@ -438,10 +438,7 @@ static void read_bisect_paths(struct argv_array *array)
 {
 	struct strbuf str = STRBUF_INIT;
 	const char *filename = git_path_bisect_names();
-	FILE *fp = fopen(filename, "r");
-
-	if (!fp)
-		die_errno(_("Could not open file '%s'"), filename);
+	FILE *fp = xfopen(filename, "r");
 
 	while (strbuf_getline_lf(&str, fp) != EOF) {
 		strbuf_trim(&str);

builtin/am.c

@@ -1275,12 +1275,8 @@ static int parse_mail(struct am_state *state, const char *mail)
 		die("BUG: invalid value for state->scissors");
 	}
 
-	mi.input = fopen(mail, "r");
-	if (!mi.input)
-		die("could not open input");
-	mi.output = fopen(am_path(state, "info"), "w");
-	if (!mi.output)
-		die("could not open output 'info'");
+	mi.input = xfopen(mail, "r");
+	mi.output = xfopen(am_path(state, "info"), "w");
 	if (mailinfo(&mi, am_path(state, "msg"), am_path(state, "patch")))
 		die("could not parse patch");
 

builtin/commit.c

@@ -1695,10 +1695,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 		if (!reflog_msg)
 			reflog_msg = "commit (merge)";
 		pptr = commit_list_append(current_head, pptr);
-		fp = fopen(git_path_merge_head(), "r");
-		if (fp == NULL)
-			die_errno(_("could not open '%s' for reading"),
-				  git_path_merge_head());
+		fp = xfopen(git_path_merge_head(), "r");
 		while (strbuf_getline_lf(&m, fp) != EOF) {
 			struct commit *parent;
 

builtin/fast-export.c

@@ -905,9 +905,7 @@ static void export_marks(char *file)
 static void import_marks(char *input_file)
 {
 	char line[512];
-	FILE *f = fopen(input_file, "r");
-	if (!f)
-		die_errno("cannot read '%s'", input_file);
+	FILE *f = xfopen(input_file, "r");
 
 	while (fgets(line, sizeof(line), f)) {
 		uint32_t mark;

builtin/fsck.c

@@ -280,8 +280,7 @@ static void check_unreachable_object(struct object *obj)
 				free(filename);
 				return;
 			}
-			if (!(f = fopen(filename, "w")))
-				die_errno("Could not open '%s'", filename);
+			f = xfopen(filename, "w");
 			if (obj->type == OBJ_BLOB) {
 				if (stream_blob_to_fd(fileno(f), &obj->oid, NULL, 1))
 					die_errno("Could not write '%s'", filename);

builtin/merge.c

@@ -839,9 +839,7 @@ static int suggest_conflicts(void)
 	struct strbuf msgbuf = STRBUF_INIT;
 
 	filename = git_path_merge_msg();
-	fp = fopen(filename, "a");
-	if (!fp)
-		die_errno(_("Could not open '%s' for writing"), filename);
+	fp = xfopen(filename, "a");
 
 	append_conflicts_hint(&msgbuf);
 	fputs(msgbuf.buf, fp);

builtin/pull.c

@@ -337,8 +337,7 @@ static void get_merge_heads(struct oid_array *merge_heads)
 	struct strbuf sb = STRBUF_INIT;
 	struct object_id oid;
 
-	if (!(fp = fopen(filename, "r")))
-		die_errno(_("could not open '%s' for reading"), filename);
+	fp = xfopen(filename, "r");
 	while (strbuf_getline_lf(&sb, fp) != EOF) {
 		if (get_oid_hex(sb.buf, &oid))
 			continue;  /* invalid line: does not start with SHA1 */

diff.c

@@ -4071,9 +4071,7 @@ int diff_opt_parse(struct diff_options *options,
 		DIFF_OPT_CLR(options, FUNCCONTEXT);
 	else if ((argcount = parse_long_opt("output", av, &optarg))) {
 		char *path = prefix_filename(prefix, optarg);
-		options->file = fopen(path, "w");
-		if (!options->file)
-			die_errno("Could not open '%s'", path);
+		options->file = xfopen(path, "w");
 		options->close_file = 1;
 		if (options->use_color != GIT_COLOR_ALWAYS)
 			options->use_color = GIT_COLOR_NEVER;
@@ -4807,9 +4805,7 @@ void diff_flush(struct diff_options *options)
 		 */
 		if (options->close_file)
 			fclose(options->file);
-		options->file = fopen("/dev/null", "w");
-		if (!options->file)
-			die_errno("Could not open /dev/null");
+		options->file = xfopen("/dev/null", "w");
 		options->close_file = 1;
 		for (i = 0; i < q->nr; i++) {
 			struct diff_filepair *p = q->queue[i];

fast-import.c

@@ -3274,9 +3274,7 @@ static void option_export_pack_edges(const char *edges)
 {
 	if (pack_edges)
 		fclose(pack_edges);
-	pack_edges = fopen(edges, "a");
-	if (!pack_edges)
-		die_errno("Cannot open '%s'", edges);
+	pack_edges = xfopen(edges, "a");
 }
 
 static int parse_one_option(const char *option)

remote-testsvn.c

@@ -124,10 +124,8 @@ static int note2mark_cb(const unsigned char *object_sha1,
 static void regenerate_marks(void)
 {
 	int ret;
-	FILE *marksfile = fopen(marksfilename, "w+");
+	FILE *marksfile = xfopen(marksfilename, "w+");
 
-	if (!marksfile)
-		die_errno("Couldn't create mark file %s.", marksfilename);
 	ret = for_each_note(NULL, 0, note2mark_cb, marksfile);
 	if (ret)
 		die("Regeneration of marks failed, returned %d.", ret);
@@ -148,9 +146,7 @@ static void check_or_regenerate_marks(int latestrev)
 	marksfile = fopen(marksfilename, "r");
 	if (!marksfile) {
 		regenerate_marks();
-		marksfile = fopen(marksfilename, "r");
-		if (!marksfile)
-			die_errno("cannot read marks file %s!", marksfilename);
+		marksfile = xfopen(marksfilename, "r");
 		fclose(marksfile);
 	} else {
 		strbuf_addf(&sb, ":%d ", latestrev);