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authorRené Scharfe <l.s.r@web.de>2017-01-22 18:51:11 +0100
committerJunio C Hamano <gitster@pobox.com>2017-01-23 11:02:34 -0800
commit04ee8b875b96c096c479132adca02fa734c3fa96 (patch)
treec9a761273a585248192544fd8dca35d0e678aada /compat
parentad36dc8b4b165bf9eb3576b42a241164e312d48c (diff)
downloadgit-04ee8b875b96c096c479132adca02fa734c3fa96.tar.gz
compat: add qsort_s()
The function qsort_s() was introduced with C11 Annex K; it provides the ability to pass a context pointer to the comparison function, supports the convention of using a NULL pointer for an empty array and performs a few safety checks. Add an implementation based on compat/qsort.c for platforms that lack a native standards-compliant qsort_s() (i.e. basically everyone). It doesn't perform the full range of possible checks: It uses size_t instead of rsize_t and doesn't check nmemb and size against RSIZE_MAX because we probably don't have the restricted size type defined. For the same reason it returns int instead of errno_t. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'compat')
-rw-r--r--compat/qsort_s.c69
1 files changed, 69 insertions, 0 deletions
diff --git a/compat/qsort_s.c b/compat/qsort_s.c
new file mode 100644
index 0000000000..52d1f0a73d
--- /dev/null
+++ b/compat/qsort_s.c
@@ -0,0 +1,69 @@
+#include "../git-compat-util.h"
+
+/*
+ * A merge sort implementation, simplified from the qsort implementation
+ * by Mike Haertel, which is a part of the GNU C Library.
+ * Added context pointer, safety checks and return value.
+ */
+
+static void msort_with_tmp(void *b, size_t n, size_t s,
+ int (*cmp)(const void *, const void *, void *),
+ char *t, void *ctx)
+{
+ char *tmp;
+ char *b1, *b2;
+ size_t n1, n2;
+
+ if (n <= 1)
+ return;
+
+ n1 = n / 2;
+ n2 = n - n1;
+ b1 = b;
+ b2 = (char *)b + (n1 * s);
+
+ msort_with_tmp(b1, n1, s, cmp, t, ctx);
+ msort_with_tmp(b2, n2, s, cmp, t, ctx);
+
+ tmp = t;
+
+ while (n1 > 0 && n2 > 0) {
+ if (cmp(b1, b2, ctx) <= 0) {
+ memcpy(tmp, b1, s);
+ tmp += s;
+ b1 += s;
+ --n1;
+ } else {
+ memcpy(tmp, b2, s);
+ tmp += s;
+ b2 += s;
+ --n2;
+ }
+ }
+ if (n1 > 0)
+ memcpy(tmp, b1, n1 * s);
+ memcpy(b, t, (n - n2) * s);
+}
+
+int git_qsort_s(void *b, size_t n, size_t s,
+ int (*cmp)(const void *, const void *, void *), void *ctx)
+{
+ const size_t size = st_mult(n, s);
+ char buf[1024];
+
+ if (!n)
+ return 0;
+ if (!b || !cmp)
+ return -1;
+
+ if (size < sizeof(buf)) {
+ /* The temporary array fits on the small on-stack buffer. */
+ msort_with_tmp(b, n, s, cmp, buf, ctx);
+ } else {
+ /* It's somewhat large, so malloc it. */
+ char *tmp = xmalloc(size);
+ msort_with_tmp(b, n, s, cmp, tmp, ctx);
+ free(tmp);
+ }
+ return 0;
+}