all: assert that native errno numbers are positive

Use the NM_ERRNO_NATIVE() macro that asserts that these errno numbers are
indeed positive. Using the macro also serves as a documentation of what
the meaning of these numbers is.

That is often not obvious, whether we have an nm_errno(), an nm_errno_native()
(from <errno.h>), or another error number (e.g. WaitForNlResponseResult). This
situation already improved by merging netlink error codes (nle),
NMPlatformError enum and <errno.h> as nm_errno(). But we still must
always be careful about not to mix error codes from different
domains or transform them appropriately (like nm_errno_from_native()).

shared/nm-utils/nm-io-utils.c

@@ -29,6 +29,7 @@
 
 #include "nm-shared-utils.h"
 #include "nm-secret-utils.h"
+#include "nm-errno.h"
 
 /*****************************************************************************/
 
@@ -36,11 +37,7 @@ _nm_printf (3, 4)
 static int
 _get_contents_error (GError **error, int errsv, const char *format, ...)
 {
-	if (errsv < 0) {
+	nm_assert (NM_ERRNO_NATIVE (errsv));
-		errsv =   errsv == G_MININT
-		        ? G_MAXINT
-		        : -errsv;
-	}
 
 	if (error) {
 		char *msg;
@@ -306,7 +303,7 @@ nm_utils_file_get_contents (int dirfd,
 			             "Failed to open file \"%s\" with openat: %s",
 			             filename,
 			             g_strerror (errsv));
-			return -errsv;
+			return -NM_ERRNO_NATIVE (errsv);
 		}
 	} else {
 		fd = open (filename, O_RDONLY | O_CLOEXEC);
@@ -319,7 +316,7 @@ nm_utils_file_get_contents (int dirfd,
 			             "Failed to open file \"%s\": %s",
 			             filename,
 			             g_strerror (errsv));
-			return -errsv;
+			return -NM_ERRNO_NATIVE (errsv);
 		}
 	}
 	return nm_utils_fd_get_contents (fd,

shared/nm-utils/nm-shared-utils.c

@@ -28,6 +28,8 @@
 #include <fcntl.h>
 #include <sys/syscall.h>
 
+#include "nm-errno.h"
+
 /*****************************************************************************/
 
 const void *const _NM_PTRARRAY_EMPTY[1] = { NULL };
@@ -1742,7 +1744,7 @@ nm_utils_fd_wait_for_event (int fd, int event, gint64 timeout_ns)
 
 	r = ppoll (&pollfd, 1, pts, NULL);
 	if (r < 0)
-		return -errno;
+		return -NM_ERRNO_NATIVE (errno);
 	if (r == 0)
 		return 0;
 	return pollfd.revents;
@@ -1784,7 +1786,7 @@ nm_utils_fd_read_loop (int fd, void *buf, size_t nbytes, bool do_poll)
 				continue;
 			}
 
-			return n > 0 ? n : -errsv;
+			return n > 0 ? n : -NM_ERRNO_NATIVE (errsv);
 		}
 
 		if (k == 0)

src/ndisc/nm-lndp-ndisc.c

@@ -32,6 +32,7 @@
 #include "NetworkManagerUtils.h"
 #include "platform/nm-platform.h"
 #include "platform/nmp-netns.h"
+#include "nm-utils/nm-errno.h"
 
 #define _NMLOG_PREFIX_NAME                "ndisc-lndp"
 
@@ -72,7 +73,6 @@ send_rs (NMNDisc *ndisc, GError **error)
 
 	errsv = ndp_msg_new (&msg, NDP_MSG_RS);
 	if (errsv) {
-		errsv = errsv > 0 ? errsv : -errsv;
 		g_set_error_literal (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
 		                     "cannot create router solicitation");
 		return FALSE;
@@ -82,7 +82,7 @@ send_rs (NMNDisc *ndisc, GError **error)
 	errsv = ndp_msg_send (priv->ndp, msg);
 	ndp_msg_destroy (msg);
 	if (errsv) {
-		errsv = errsv > 0 ? errsv : -errsv;
+		errsv = nm_errno_native (errsv);
 		g_set_error (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
 		             "%s (%d)",
 		             g_strerror (errsv), errsv);
@@ -360,7 +360,6 @@ send_ra (NMNDisc *ndisc, GError **error)
 
 	errsv = ndp_msg_new (&msg, NDP_MSG_RA);
 	if (errsv) {
-		errsv = errsv > 0 ? errsv : -errsv;
 		g_set_error_literal (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
 		                     "cannot create a router advertisement");
 		return FALSE;
@@ -468,7 +467,7 @@ send_ra (NMNDisc *ndisc, GError **error)
 
 	ndp_msg_destroy (msg);
 	if (errsv) {
-		errsv = errsv > 0 ? errsv : -errsv;
+		errsv = nm_errno_native (errsv);
 		g_set_error (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
 		             "%s (%d)",
 		             g_strerror (errsv), errsv);
@@ -599,7 +598,7 @@ nm_lndp_ndisc_new (NMPlatform *platform,
 	errsv = ndp_open (&priv->ndp);
 
 	if (errsv != 0) {
-		errsv = errsv > 0 ? errsv : -errsv;
+		errsv = nm_errno_native (errsv);
 		g_set_error (error, NM_UTILS_ERROR, NM_UTILS_ERROR_UNKNOWN,
 		             "failure creating libndp socket: %s (%d)",
 		             g_strerror (errsv), errsv);

src/platform/nm-linux-platform.c

@@ -327,7 +327,7 @@ typedef enum {
 typedef enum {
 	/* Negative values are errors from kernel. Add dummy member to
 	 * make enum signed. */
-	_WAIT_FOR_NL_RESPONSE_RESULT_SYSTEM_ERROR = -1,
+	_WAIT_FOR_NL_RESPONSE_RESULT_SYSTEM_ERROR = G_MININT,
 
 	WAIT_FOR_NL_RESPONSE_RESULT_UNKNOWN = 0,
 	WAIT_FOR_NL_RESPONSE_RESULT_RESPONSE_OK,
@@ -7825,7 +7825,7 @@ continue_reading:
 				err = -NME_NL_MSG_TRUNC;
 				abort_parsing = TRUE;
 			} else if (e->error) {
-				int errsv = e->error > 0 ? e->error : -e->error;
+				int errsv = nm_errno_native (e->error);
 
 				if (   NM_FLAGS_HAS (hdr->nlmsg_flags, NLM_F_ACK_TLVS)
 				    && hdr->nlmsg_len >= sizeof (*e) + e->msg.nlmsg_len) {
@@ -7850,7 +7850,7 @@ continue_reading:
 				       errsv,
 				       NM_PRINT_FMT_QUOTED (extack_msg, " \"", extack_msg, "\"", ""),
 				       nlmsg_hdr (msg)->nlmsg_seq);
-				seq_result = -errsv;
+				seq_result = -NM_ERRNO_NATIVE (errsv);
 			} else
 				seq_result = WAIT_FOR_NL_RESPONSE_RESULT_RESPONSE_OK;
 		} else

src/platform/nm-platform-utils.c

@@ -84,7 +84,7 @@ socket_handle_init (SocketHandle *shandle, int ifindex)
 	shandle->fd = socket (PF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
 	if (shandle->fd < 0) {
 		shandle->ifindex = 0;
-		return -errno;
+		return -NM_ERRNO_NATIVE (errno);
 	}
 
 	shandle->ifindex = ifindex;
@@ -158,7 +158,7 @@ ethtool_call_handle (SocketHandle *shandle, gpointer edata)
 		              _ethtool_data_to_string (edata, sbuf, sizeof (sbuf)),
 		              shandle->ifname,
 		              strerror (errsv));
-		return -errsv;
+		return -NM_ERRNO_NATIVE (errsv);
 	}
 
 	nm_log_trace (LOGD_PLATFORM, "ethtool[%d]: %s, %s: success",