gbranden pushed a commit to branch master
in repository groff.
commit cde7dc97696a494510e06f1315756b524cb846d7
Author: G. Branden Robinson <[email protected]>
AuthorDate: Sat Jun 20 05:09:33 2026 -0500
[libgroff]: Improve `string` reallocations. (1/2)
* src/libs/libgroff/string.cpp (srealloc): Avoid unnecessary memset(3)
if the new string's `length` is equal to the old string's `sz`
(capacity), because it is already (invariantly) null-terminated.
Simplify condition for performing memcpy(3) of old contents to new: do
it only if the old length is not zero. Unconditionally memset(3) the
memory from the end of the new string to the end of string's capacity.
---
ChangeLog | 10 ++++++++++
src/libs/libgroff/string.cpp | 9 ++++-----
2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/ChangeLog b/ChangeLog
index bbd0598ff..a7c784034 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2026-06-20 G. Branden Robinson <[email protected]>
+
+ * src/libs/libgroff/string.cpp (srealloc): Avoid unnecessary
+ memset(3) if the new string's `length` is equal to the old
+ string's `sz` (capacity), because it is already (invariantly)
+ null-terminated. Simplify condition for performing memcpy(3) of
+ old contents to new: do it only if the old length is not zero.
+ Unconditionally memset(3) the memory from the end of the new
+ string to the end of string's capacity.
+
2026-06-19 G. Branden Robinson <[email protected]>
* src/libs/libgroff/string.cpp (string::string): Drop redundant
diff --git a/src/libs/libgroff/string.cpp b/src/libs/libgroff/string.cpp
index 731aa4887..227357b26 100644
--- a/src/libs/libgroff/string.cpp
+++ b/src/libs/libgroff/string.cpp
@@ -99,7 +99,8 @@ static char *srealloc(char *ptr, size_t oldsz, size_t oldlen,
{
if (oldsz >= newlen) {
*sizep = oldsz;
- memset((ptr + oldlen), 0, (newlen - oldsz));
+ if (oldsz > newlen)
+ memset((ptr + newlen), 0, (oldsz - newlen));
return ptr;
}
size_t amount = newlen;
@@ -117,11 +118,9 @@ static char *srealloc(char *ptr, size_t oldsz, size_t
oldlen,
catch (const std::bad_alloc &exc) {
fatal("cannot allocate %1 bytes for string reallocation", amount);
}
- if ((oldlen < newlen) && (oldlen != 0)) {
- assert(amount > 0);
- memset(p, 0, amount);
+ if (oldlen != 0)
memcpy(p, ptr, oldlen);
- }
+ memset((p + oldlen), 0, (amount - oldlen));
delete[] ptr;
return p;
}
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