Thread

Re: [PATCH]Remove the redundant assignment

Heikki Linnakangas <hlinnaka@iki.fi> — 2025-12-16T14:02:53Z

On 16/12/2025 13:16, Dagfinn Ilmari Mannsåker wrote:
> 
> A quick grep reveals a bunch of strncpy() calls followed by a '\0'
> assignment that could be replaced with strlcpy():
> 
> $ rg -A1 strncpy|rg -B1 "= '\\\\0';"
> src/interfaces/libpq/fe-secure-openssl.c:		strncpy(buf, conn->sslpassword, size);
> src/interfaces/libpq/fe-secure-openssl.c-		buf[size - 1] = '\0';

I'm not sure what exactly this code does, but it seems prudent to zero 
the unused bytes since we're dealing with a password.

> --
> src/bin/pgbench/pgbench.c:		strncpy(*script, option, namelen);
> src/bin/pgbench/pgbench.c-		(*script)[namelen] = '\0';

Yeah, this one could use strlcpy(). Or memcpy(). Or pstrndup().

> --
> doc/src/sgml/ecpg.sgml:            strncpy(name_buf, v.sqlname.data, v.sqlname.length);
> doc/src/sgml/ecpg.sgml-            name_buf[v.sqlname.length] = '\0';
> --
> doc/src/sgml/ecpg.sgml:                strncpy(name_buf, v.sqlname.data, v.sqlname.length);
> doc/src/sgml/ecpg.sgml-                name_buf[v.sqlname.length] = '\0';
> --
> src/interfaces/ecpg/ecpglib/execute.c:					strncpy(newcopy, (char *) var->value, slen);
> src/interfaces/ecpg/ecpglib/execute.c-					newcopy[slen] = '\0';
> --
> src/interfaces/ecpg/ecpglib/execute.c:					strncpy(mallocedval, (char *) var->value, slen);
> src/interfaces/ecpg/ecpglib/execute.c-					mallocedval[slen] = '\0';
> --
> src/interfaces/ecpg/ecpglib/execute.c:					strncpy(newcopy, variable->arr, variable->len);
> src/interfaces/ecpg/ecpglib/execute.c-					newcopy[variable->len] = '\0';

I don't know if these depend on the zero-padding...

> --
> src/backend/utils/adt/name.c:	strncpy(NameStr(*name), str, NAMEDATALEN);
> src/backend/utils/adt/name.c-	NameStr(*name)[NAMEDATALEN - 1] = '\0';

This one *does* require the zero-padding, there's a comment that says so:

> void
> namestrcpy(Name name, const char *str)
> {
> 	/* NB: We need to zero-pad the destination. */
> 	strncpy(NameStr(*name), str, NAMEDATALEN);
> 	NameStr(*name)[NAMEDATALEN - 1] = '\0';
> }

- Heikki