[PATCH 4/5] perf symbol: Shrink the demangled Rust buffer to fit

[Michal Pluta <michalpl2003@gmail.com>]

The buffer a demangled Rust name is returned in is sized to whatever
attempt succeeded, which is usually larger than the string it holds.
Shrink it to the string's exact length before returning it.

Signed-off-by: Michal Pluta <michalpl2003@gmail.com>
---
 tools/perf/util/symbol.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 1a52bc2980a0..858a14a91f79 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -2772,8 +2772,10 @@ char *dso__demangle_sym(struct dso *dso, int kmodule, const char *elf_name)
 				break;
 			demangled = tmp;
 			if (rust_demangle_display_demangle(&rust_demangle, demangled, buf_len,
-							   /*alternate=*/true) == OverflowOk)
-				return demangled;
+							   /*alternate=*/true) == OverflowOk) {
+				tmp = realloc(demangled, strlen(demangled) + 1);
+				return tmp ?: demangled;
+			}
 		}
 		/* Failure to grow output buffer or buffer exceeded sensible bounds. */
 		free(demangled);
-- 
2.43.0