[PATCH v2 2/3] strbuf: set errno to 0 after strbuf_getcwd

From: Kyle Lippincott via GitGitGadget <gitgitgadget@gmail.com>
Date: Aug 2, 2024, 20:58 UTC
Message-ID: <0ed09e9abb85e73a80d044c1ddaed303517752ac.1722632287.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1756.v2.git.git.1722632287.gitgitgadget@gmail.com>

From: Kyle Lippincott <spectral@google.com>

If the loop executes more than once due to cwd being longer than 128 bytes, then `errno = ERANGE` might persist outside of this function. This technically shouldn't be a problem, as all locations where the value in `errno` is tested should either (a) call a function that's guaranteed to set `errno` to 0 on success, or (b) set `errno` to 0 prior to calling the function that only conditionally sets errno, such as the `strtod` function. In the case of functions in category (b), it's easy to forget to do that.

Set `errno = 0;` prior to exiting from `strbuf_getcwd` successfully. This matches the behavior in functions like `run_transaction_hook` (refs.c:2176) and `read_ref_internal` (refs/files-backend.c:564).

Signed-off-by: Kyle Lippincott <spectral@google.com>
---
 strbuf.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/strbuf.c b/strbuf.c
index 3d2189a7f64..b94ef040ab0 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -601,6 +601,7 @@ int strbuf_getcwd(struct strbuf *sb)
 		strbuf_grow(sb, guessed_len);
 		if (getcwd(sb->buf, sb->alloc)) {
 			strbuf_setlen(sb, strlen(sb->buf));
+			errno = 0;
 			return 0;
 		}

-- 
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