[PATCH v5 2/2] patch-id: replace `atoi()` with `strtoi_with_tail`

From: Mohit Marathe via GitGitGadget <gitgitgadget@gmail.com>
Date: Jan 28, 2024, 04:42 UTC
Message-ID: <ee8f4ae991d71d399a9c07086f56a38f7531b6cf.1706416952.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.1646.v5.git.1706416952.gitgitgadget@gmail.com>

From: Mohit Marathe <mohitmarathe23@gmail.com>

The change is made to improve the error-handling capabilities during the conversion of string to integers. The `strtoi_with_tail` function offers a more robust mechanism for converting strings to integers by providing enhanced error detection. Unlike `atoi`, `strtoi_with_tail` allows the code to differentiate between a valid conversion and an invalid one, offering better resilience against potential issues such as reading hunk header of a corrupted patch.

Signed-off-by: Mohit Marathe <mohitmarathe@proton.me>
---
 builtin/patch-id.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/builtin/patch-id.c b/builtin/patch-id.c
index 3894d2b9706..4e9a301e9fb 100644
--- a/builtin/patch-id.c
+++ b/builtin/patch-id.c
@@ -1,3 +1,4 @@
+#include "git-compat-util.h"
 #include "builtin.h"
 #include "config.h"
 #include "diff.h"
@@ -29,14 +30,16 @@ static int scan_hunk_header(const char *p, int *p_before, int *p_after)
 {
 	static const char digits[] = "0123456789";
 	const char *q, *r;
+	char *endp;
 	int n;
 
 	q = p + 4;
 	n = strspn(q, digits);
 	if (q[n] == ',') {
 		q += n + 1;
-		*p_before = atoi(q);
-		n = strspn(q, digits);
+		if (strtoi_with_tail(q, 10, p_before, &endp) != 0)
+			return 0;
+		n = endp - q;
 	} else {
 		*p_before = 1;
 	}
@@ -48,8 +51,9 @@ static int scan_hunk_header(const char *p, int *p_before, int *p_after)
 	n = strspn(r, digits);
 	if (r[n] == ',') {
 		r += n + 1;
-		*p_after = atoi(r);
-		n = strspn(r, digits);
+		if (strtoi_with_tail(r, 10, p_after, &endp) != 0)
+			return 0;
+		n = endp - r;
 	} else {
 		*p_after = 1;
 	}

-- 
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