parse: replace atoi() with strtoul_ui() and strtol_i()

Replace unsafe uses of atoi() with strtoul_ui() for unsigned integers
and strtol_i() for signed integers across multiple files. This change
improves error handling and prevents potential integer overflow issues.

The following files were updated:
- daemon.c: Update parsing of --timeout, --init-timeout, and
  --max-connections
- imap-send.c: Improve parsing of UIDVALIDITY, UIDNEXT, APPENDUID, and
  tags
- merge-ll.c: Enhance parsing of marker size in ll_merge and
  ll_merge_marker_size

This change allows for better error detection when parsing integer
values from command-line arguments and IMAP responses, making the code
more robust and secure.

This is a #leftoverbit discussed here:
 https://public-inbox.org/git/CAC4O8c-nuOTS=a0sVp1603KaM2bZjs+yNZzdAaa5CGTNGFE7hQ@mail.gmail.com/

Signed-off-by: Usman Akinyemi <[email protected]>

Cc: [email protected]
Cc: Patrick Steinhardt <[email protected]>
Cc: [email protected]
Cc: Christian Couder <[email protected]>
Cc: Eric Sunshine <[email protected]>
Cc: Taylor Blau <[email protected]>
Signed-off-by: Taylor Blau <[email protected]>

daemon.c

@@ -1308,17 +1308,21 @@ int cmd_main(int argc, const char **argv)
 			continue;
 		}
 		if (skip_prefix(arg, "--timeout=", &v)) {
-			timeout = atoi(v);
+			if (strtoul_ui(v, 10, &timeout) < 0) {
+				die("'%s': not a valid integer for --timeout", v);
+			}
 			continue;
 		}
 		if (skip_prefix(arg, "--init-timeout=", &v)) {
-			init_timeout = atoi(v);
+			if (strtoul_ui(v, 10, &init_timeout) < 0) {
+				die("'%s': not a valid integer for --init-timeout", v);
+			}
 			continue;
 		}
 		if (skip_prefix(arg, "--max-connections=", &v)) {
-			max_connections = atoi(v);
-			if (max_connections < 0)
-				max_connections = 0;	        /* unlimited */
+			if (strtol_i(v, 10, &max_connections) != 0 || max_connections < 0) {
+				max_connections = 0;  /* unlimited */
+			}
 			continue;
 		}
 		if (!strcmp(arg, "--strict-paths")) {

imap-send.c

@@ -668,12 +668,12 @@ static int parse_response_code(struct imap_store *ctx, struct imap_cmd_cb *cb,
 		return RESP_BAD;
 	}
 	if (!strcmp("UIDVALIDITY", arg)) {
-		if (!(arg = next_arg(&s)) || !(ctx->uidvalidity = atoi(arg))) {
+		if (!(arg = next_arg(&s)) || strtol_i(arg, 10, &ctx->uidvalidity) != 0) {
 			fprintf(stderr, "IMAP error: malformed UIDVALIDITY status\n");
 			return RESP_BAD;
 		}
 	} else if (!strcmp("UIDNEXT", arg)) {
-		if (!(arg = next_arg(&s)) || !(imap->uidnext = atoi(arg))) {
+		if (!(arg = next_arg(&s)) || strtol_i(arg, 10, &imap->uidnext) != 0) {
 			fprintf(stderr, "IMAP error: malformed NEXTUID status\n");
 			return RESP_BAD;
 		}
@@ -686,8 +686,8 @@ static int parse_response_code(struct imap_store *ctx, struct imap_cmd_cb *cb,
 		for (; isspace((unsigned char)*p); p++);
 		fprintf(stderr, "*** IMAP ALERT *** %s\n", p);
 	} else if (cb && cb->ctx && !strcmp("APPENDUID", arg)) {
-		if (!(arg = next_arg(&s)) || !(ctx->uidvalidity = atoi(arg)) ||
-		    !(arg = next_arg(&s)) || !(*(int *)cb->ctx = atoi(arg))) {
+		if (!(arg = next_arg(&s)) || (strtol_i(arg, 10, &ctx->uidvalidity) != 0) ||
+			!(arg = next_arg(&s)) || (strtol_i(arg, 10, (int *)cb->ctx) != 0)) {
 			fprintf(stderr, "IMAP error: malformed APPENDUID status\n");
 			return RESP_BAD;
 		}
@@ -773,7 +773,10 @@ static int get_cmd_result(struct imap_store *ctx, struct imap_cmd *tcmd)
 			if (!tcmd)
 				return DRV_OK;
 		} else {
-			tag = atoi(arg);
+			if (strtol_i(arg, 10, &tag) != 0) {
+				fprintf(stderr, "IMAP error: malformed tag %s\n", arg);
+				return RESP_BAD;
+			}
 			for (pcmdp = &imap->in_progress; (cmdp = *pcmdp); pcmdp = &cmdp->next)
 				if (cmdp->tag == tag)
 					goto gottag;

merge-ll.c

@@ -427,8 +427,7 @@ enum ll_merge_result ll_merge(mmbuffer_t *result_buf,
 	git_check_attr(istate, path, check);
 	ll_driver_name = check->items[0].value;
 	if (check->items[1].value) {
-		marker_size = atoi(check->items[1].value);
-		if (marker_size <= 0)
+		if (strtol_i(check->items[1].value, 10, &marker_size) != 0 || marker_size <= 0)
 			marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 	}
 	driver = find_ll_merge_driver(ll_driver_name);
@@ -454,8 +453,7 @@ int ll_merge_marker_size(struct index_state *istate, const char *path)
 		check = attr_check_initl("conflict-marker-size", NULL);
 	git_check_attr(istate, path, check);
 	if (check->items[0].value) {
-		marker_size = atoi(check->items[0].value);
-		if (marker_size <= 0)
+		if (strtol_i(check->items[0].value, 10, &marker_size) != 0 || marker_size <= 0)
 			marker_size = DEFAULT_CONFLICT_MARKER_SIZE;
 	}
 	return marker_size;