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authorJunio C Hamano <gitster@pobox.com>2017-01-31 13:15:00 -0800
committerJunio C Hamano <gitster@pobox.com>2017-01-31 13:15:00 -0800
commit6ad8b8e98faa5a301a98a2997da162dea060672e (patch)
tree99ca685d15df287c1f686c033157756d439c119c /compat
parent4e170adc8ad654bddb9421a4bf51bb4802656262 (diff)
parent83fc4d64fec779d73b18494461613ef911236daf (diff)
downloadgit-6ad8b8e98faa5a301a98a2997da162dea060672e.tar.gz
Merge branch 'rs/qsort-s'
A few codepaths had to rely on a global variable when sorting elements of an array because sort(3) API does not allow extra data to be passed to the comparison function. Use qsort_s() when natively available, and a fallback implementation of it when not, to eliminate the need, which is a prerequisite for making the codepath reentrant. * rs/qsort-s: ref-filter: use QSORT_S in ref_array_sort() string-list: use QSORT_S in string_list_sort() perf: add basic sort performance test add QSORT_S compat: add qsort_s()
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;
+}