Sort an empty list without handing qsort a null

Every list sorted here is null until its first entry, and C leaves a
null base undefined even with nothing to sort. glibc declares it nonnull
and its UBSan build aborted the stats page of a repository with no
commits in the window, which the Linux matrix caught.

5 files changed, 21 insertions, 9 deletions

diff --git a/source/cgit.c b/source/cgit.cindex 8a3d8c1..6d663fe 100644--- a/source/cgit.c+++ b/source/cgit.c@@ -335,7 +335,7 @@ static void parse_args(int argc, const char **argv) 		} 	} 	if (scanned) {-		qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), cmp_repos);+		cgit_qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), cmp_repos); 		print_repolist(stdout, &cgit_repolist, 0); 		exit(0); 	}
diff --git a/source/cgit.c b/source/cgit.c
index 8a3d8c1..6d663fe 100644
--- a/source/cgit.c
+++ b/source/cgit.c
@@ -335,7 +335,7 @@ static void parse_args(int argc, const char **argv)
 		}
 	}
 	if (scanned) {
-		qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), cmp_repos);
+		cgit_qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), cmp_repos);
 		print_repolist(stdout, &cgit_repolist, 0);
 		exit(0);
 	}
diff --git a/source/shared.h b/source/shared.hindex e22eb57..2bf305d 100644--- a/source/shared.h+++ b/source/shared.h@@ -140,4 +140,16 @@ extern int cgit_valid_rev(const char *rev);  */ extern int cgit_notes_ref_usable(const char *notes_ref); +/*+ * qsort for a list that may be empty. C leaves a null base undefined even+ * with nothing to sort, and glibc declares it nonnull, while the lists here+ * stay null until their first entry.+ */+static inline void cgit_qsort(void *base, size_t n, size_t size,+	int (*cmp)(const void *, const void *))+{+	if (n)+		qsort(base, n, size, cmp);+}+ #endif // CGIT_SHARED_H
diff --git a/source/shared.h b/source/shared.h
index e22eb57..2bf305d 100644
--- a/source/shared.h
+++ b/source/shared.h
@@ -140,4 +140,16 @@ extern int cgit_valid_rev(const char *rev);
  */
 extern int cgit_notes_ref_usable(const char *notes_ref);
 
+/*
+ * qsort for a list that may be empty. C leaves a null base undefined even
+ * with nothing to sort, and glibc declares it nonnull, while the lists here
+ * stay null until their first entry.
+ */
+static inline void cgit_qsort(void *base, size_t n, size_t size,
+	int (*cmp)(const void *, const void *))
+{
+	if (n)
+		qsort(base, n, size, cmp);
+}
+
 #endif // CGIT_SHARED_H
diff --git a/source/ui-refs.c b/source/ui-refs.cindex 890a959..38a5773 100644--- a/source/ui-refs.c+++ b/source/ui-refs.c@@ -246,9 +246,9 @@ static void print_branches_page(int pagesize) 	print_branch_header(); 	collect_branches(&list); -	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date); 	if (ctx.repo->branch_sort == 0)-		qsort(list.refs, list.count, sizeof(*list.refs), cmp_name);+		cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_name);  	page = page_bounds(pagesize, list.count); @@ -271,7 +271,7 @@ static void print_tags_page(int pagesize) 	collect_tags(&list); 	if (list.count == 0) 		return;-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);  	page = page_bounds(pagesize, list.count); @@ -300,9 +300,9 @@ void cgit_print_branches(int maxcount) 	// The date sort covers the list, the name sort only the rows about to 	// be shown, so the section holds the newest branches rather than the 	// first ones by name.-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date); 	if (ctx.repo->branch_sort == 0)-		qsort(list.refs, maxcount, sizeof(*list.refs), cmp_name);+		cgit_qsort(list.refs, maxcount, sizeof(*list.refs), cmp_name);  	for (i = 0; i < maxcount; i++) 		print_branch(list.refs[i]);@@ -322,7 +322,7 @@ void cgit_print_tags(int maxcount) 	collect_tags(&list); 	if (list.count == 0) 		return;-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date); 	if (maxcount <= 0 || maxcount > list.count) 		maxcount = list.count; 	print_tag_header();
diff --git a/source/ui-refs.c b/source/ui-refs.c
index 890a959..38a5773 100644
--- a/source/ui-refs.c
+++ b/source/ui-refs.c
@@ -246,9 +246,9 @@ static void print_branches_page(int pagesize)
 	print_branch_header();
 	collect_branches(&list);
 
-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
 	if (ctx.repo->branch_sort == 0)
-		qsort(list.refs, list.count, sizeof(*list.refs), cmp_name);
+		cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_name);
 
 	page = page_bounds(pagesize, list.count);
 
@@ -271,7 +271,7 @@ static void print_tags_page(int pagesize)
 	collect_tags(&list);
 	if (list.count == 0)
 		return;
-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
 
 	page = page_bounds(pagesize, list.count);
 
@@ -300,9 +300,9 @@ void cgit_print_branches(int maxcount)
 	// The date sort covers the list, the name sort only the rows about to
 	// be shown, so the section holds the newest branches rather than the
 	// first ones by name.
-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
 	if (ctx.repo->branch_sort == 0)
-		qsort(list.refs, maxcount, sizeof(*list.refs), cmp_name);
+		cgit_qsort(list.refs, maxcount, sizeof(*list.refs), cmp_name);
 
 	for (i = 0; i < maxcount; i++)
 		print_branch(list.refs[i]);
@@ -322,7 +322,7 @@ void cgit_print_tags(int maxcount)
 	collect_tags(&list);
 	if (list.count == 0)
 		return;
-	qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
+	cgit_qsort(list.refs, list.count, sizeof(*list.refs), cmp_date);
 	if (maxcount <= 0 || maxcount > list.count)
 		maxcount = list.count;
 	print_tag_header();
diff --git a/source/ui-repolist.c b/source/ui-repolist.cindex 58e31ed..6df70e4 100644--- a/source/ui-repolist.c+++ b/source/ui-repolist.c@@ -402,7 +402,7 @@ static int sort_repolist(const char *field) 			continue; 		if (column->cmp == cmp_idle || column->cmp == cmp_section) 			resolve_modtimes();-		qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), column->cmp);+		cgit_qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), column->cmp); 		return 1; 	} 	return 0;
diff --git a/source/ui-repolist.c b/source/ui-repolist.c
index 58e31ed..6df70e4 100644
--- a/source/ui-repolist.c
+++ b/source/ui-repolist.c
@@ -402,7 +402,7 @@ static int sort_repolist(const char *field)
 			continue;
 		if (column->cmp == cmp_idle || column->cmp == cmp_section)
 			resolve_modtimes();
-		qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), column->cmp);
+		cgit_qsort(cgit_repolist.repos, cgit_repolist.count, sizeof(struct cgit_repo), column->cmp);
 		return 1;
 	}
 	return 0;
diff --git a/source/ui-stats.c b/source/ui-stats.cindex f200b63..a332335 100644--- a/source/ui-stats.c+++ b/source/ui-stats.c@@ -450,7 +450,7 @@ void cgit_show_stats(void) 	} 	if (collect_stats(period, &authors)) 		return;-	qsort(authors.items, authors.nr, sizeof(struct string_list_item), cmp_total_commits);+	cgit_qsort(authors.items, authors.nr, sizeof(struct string_list_item), cmp_total_commits);  	top = ctx.qry.ofs; 	if (!top)
diff --git a/source/ui-stats.c b/source/ui-stats.c
index f200b63..a332335 100644
--- a/source/ui-stats.c
+++ b/source/ui-stats.c
@@ -450,7 +450,7 @@ void cgit_show_stats(void)
 	}
 	if (collect_stats(period, &authors))
 		return;
-	qsort(authors.items, authors.nr, sizeof(struct string_list_item), cmp_total_commits);
+	cgit_qsort(authors.items, authors.nr, sizeof(struct string_list_item), cmp_total_commits);
 
 	top = ctx.qry.ofs;
 	if (!top)