pututxline: Don't set errno=0 in subfunctions.

The functions utx_active_add(), utx_active_remove(), utx_lastlogin_add() and
utx_log_add() set errno to 0 if they are successful. This not only violates
POSIX if pututxline() is successful, but may also overwrite a valid error
with 0 if, for example, utx_lastlogin_add() fails while utx_log_add()
succeeds.

Reviewed by:	ed

1 files changed, 8 insertions, 4 deletions

diff --git a/lib/libc/gen/pututxline.c b/lib/libc/gen/pututxline.c
index 555386c..4982c02 100644
--- a/lib/libc/gen/pututxline.c
+++ b/lib/libc/gen/pututxline.c
@@ -131,7 +131,8 @@ exact:
 	else
 		error = 0;
 	fclose(fp);
-	errno = error;
+	if (error != 0)
+		errno = error;
 	return (error == 0 ? 0 : 1);
 }
 
@@ -169,7 +170,8 @@ utx_active_remove(struct futx *fu)
 		}
 
 	fclose(fp);
-	errno = error;
+	if (ret != 0)
+		errno = error;
 	return (ret);
 }
 
@@ -225,7 +227,8 @@ utx_lastlogin_add(const struct futx *fu)
 		ret = -1;
 	}
 	fclose(fp);
-	errno = error;
+	if (ret == -1)
+		errno = error;
 	return (ret);
 }
 
@@ -277,7 +280,8 @@ utx_log_add(const struct futx *fu)
 	else
 		error = 0;
 	_close(fd);
-	errno = error;
+	if (error != 0)
+		errno = error;
 	return (error == 0 ? 0 : 1);
 }