Add SBOX_MAP_PATH_ALLOW_NONEXISTENT flag to sbox_map_path().

This flag allows path resolution to succeed even if non-final
components in the pathname refer to nonexistent directories.

This is needed for emulating bindtextdomain() function
which can accept pathname refering to nonexistent directory
without returning an error.

Signed-off-by: Oleg Girko <[email protected]>

Author: Oleg Girko

scratchbox2/include/mapping.h

@@ -74,6 +74,7 @@ extern void free_mapping_results(mapping_results_t *res);
 extern void force_path_to_mapping_result(mapping_results_t *res, const char *path);
 
 #define SBOX_MAP_PATH_DONT_RESOLVE_FINAL_SYMLINK 0x01
+#define SBOX_MAP_PATH_ALLOW_NONEXISTENT          0x02
 
 extern void sbox_map_path(const char *func_name, const char *path,
 	uint32_t flags, mapping_results_t *res, uint32_t classmask);

scratchbox2/pathmapping/pathmapping.h

@@ -88,6 +88,7 @@ typedef struct path_mapping_context_s {
 	int			pmc_dont_resolve_final_symlink;
 	int			pmc_file_must_exist;
 	int			pmc_must_be_directory;
+	int			pmc_allow_nonexistent;
 	struct sb2context	*pmc_sb2ctx;
 
 	/* for paths_ruletree_mapping.c: */

scratchbox2/pathmapping/pathresolution.c

@@ -668,6 +668,14 @@ static ruletree_object_offset_t sb_path_resolution(
 				SB_LOG(SB_LOGLEVEL_NOISE2,
 					"Last component doesn't exist [%d] '%s'",
 					component_index, virtual_path_work_ptr->pe_path_component);
+			} else if (errno == ENOENT &&
+			    ctx->pmc_allow_nonexistent) {
+				/* this is not last component,
+				 * but it's still not required to exist.
+				*/
+				SB_LOG(SB_LOGLEVEL_NOISE3,
+					"Component doesn't exist [%d] '%s'",
+					component_index, virtual_path_work_ptr->pe_path_component);
 			} else {
 				/* any other errno valus is error */
 				resolved_virtual_path_res->mres_errno = errno;
@@ -1244,6 +1252,7 @@ void sbox_map_path_internal__c_engine(
 	ctx.pmc_virtual_orig_path = virtual_orig_path;
 	ctx.pmc_dont_resolve_final_symlink =
 		flags & SBOX_MAP_PATH_DONT_RESOLVE_FINAL_SYMLINK;
+	ctx.pmc_allow_nonexistent = flags & SBOX_MAP_PATH_ALLOW_NONEXISTENT;
 	ctx.pmc_sb2ctx = sb2ctx;
 #if 0 /* see comment at pathmapping_interf.c/custom_map_path() */
 	ctx.pmc_rule_list_offset = rule_list_offset;

scratchbox2/preload/gen-interface.pl

@@ -63,6 +63,14 @@
 #     NOTE: THIS MUST BE USED BEFORE THE map() OR map_at() MODIFIERS!
 #   - "resolve_final_symlink" is the opposite of "dont_resolve_final_symlink"
 #     (and it is on by default)
+#   - "allow_nonexistent" is used to prefix "map" modifiers where the
+#     whole pathname (not just the last component) is allowed to refer
+#     to nonexistent file in nonexistent directory.
+#     NOTE: THIS MUST BE USED BEFORE THE map() OR map_at() MODIFIERS!
+#   - "allow_nonexistent_if(condition)" conditionally
+#     allows the pathname to refer to nonexistent file in nonexistent directory
+#     (see "allow_nonexistent")
+#     NOTE: THIS MUST BE USED BEFORE THE map() OR map_at() MODIFIERS!
 #   - "postprocess(varname)" can be used to call  postprocessor functions for
 #     mapped variables.
 #   - "return(expr)" can be used to alter the return value.
@@ -493,6 +501,22 @@ sub expr_to_flagexpr {
 	return "$expr ? $flag : 0";
 }
 
+sub flagexpr_join {
+	my $result = "0";
+	foreach my $flagexpr (@_) {
+		if ($flagexpr eq "0") {
+			# zero flag, leave result as is
+		} elsif ($result eq "0") {
+			# zero result, replace with flag
+			$result = $flagexpr;
+		} else {
+			# non-zero result and flag, join with |
+			$result .= " | $flagexpr";
+		}
+	}
+	return $result;
+}
+
 # Process the modifier section coming from the original input line.
 # This returns undef if failed, or a structure containing code fragments
 # and other information for the actual code generation phase.
@@ -521,6 +545,7 @@ sub process_wrap_or_gate_modifiers {
 		'mapped_params_by_orig_name' => {},
 		'mapping_results_by_orig_name' => {},
 		'dont_resolve_final_symlink' => 0,
+		'allow_nonexistent' => 0,
 
 		'postprocess_vars' => [],
 		'return_expr' => undef,
@@ -573,6 +598,9 @@ sub process_wrap_or_gate_modifiers {
 			my $new_name = "mapped__".$param_to_be_mapped;
 			my $no_symlink_resolve =
 				expr_to_flagexpr($mods->{'dont_resolve_final_symlink'}, "SBOX_MAP_PATH_DONT_RESOLVE_FINAL_SYMLINK");
+			my $allow_nonexistent =
+				expr_to_flagexpr($mods->{'allow_nonexistent'}, "SBOX_MAP_PATH_ALLOW_NONEXISTENT");
+			my $flags = flagexpr_join($no_symlink_resolve, $allow_nonexistent);
 
 			$mods->{'mapped_params_by_orig_name'}->{$param_to_be_mapped} = "res_$new_name.mres_result_path";
 			$mods->{'mapping_results_by_orig_name'}->{$param_to_be_mapped} = "res_$new_name";
@@ -583,7 +611,7 @@ sub process_wrap_or_gate_modifiers {
 				"\tclear_mapping_results_struct(&res_$new_name);\n".
 				"\tsbox_map_path(__func__, ".
 					"$param_to_be_mapped, ".
-					"$no_symlink_resolve, ".
+					"$flags, ".
 					"&res_$new_name, classmask);\n".
 				"\tif (res_$new_name.mres_errno) {\n".
 				"\t\tSB_LOG(SB_LOGLEVEL_DEBUG, \"mapping failed, errno %d\",".
@@ -626,6 +654,9 @@ sub process_wrap_or_gate_modifiers {
 			my $ro_flag = $param_to_be_mapped."_is_readonly";
 			my $no_symlink_resolve =
 				expr_to_flagexpr($mods->{'dont_resolve_final_symlink'}, "SBOX_MAP_PATH_DONT_RESOLVE_FINAL_SYMLINK");
+			my $allow_nonexistent =
+				expr_to_flagexpr($mods->{'allow_nonexistent'}, "SBOX_MAP_PATH_ALLOW_NONEXISTENT");
+			my $flags = flagexpr_join($no_symlink_resolve, $allow_nonexistent);
 
 			$mods->{'mapped_params_by_orig_name'}->{$param_to_be_mapped} = "res_$new_name.mres_result_path";
 			$mods->{'mapping_results_by_orig_name'}->{$param_to_be_mapped} = "res_$new_name";
@@ -636,7 +667,7 @@ sub process_wrap_or_gate_modifiers {
 				"\tsbox_map_path_at(__func__, ".
 					"$fd_param, ".
 					"$param_to_be_mapped, ".
-					"$no_symlink_resolve, ".
+					"$flags, ".
 					"&res_$new_name, classmask);\n".
 				"\tif (res_$new_name.mres_errno) {\n".
 				"\t\terrno = res_$new_name.mres_errno;\n".
@@ -692,6 +723,11 @@ sub process_wrap_or_gate_modifiers {
 		} elsif($modifiers[$i] =~ m/^dont_resolve_final_symlink_if\((.*)\)$/) {
 			my $condition = $1;
 			$mods->{'dont_resolve_final_symlink'} = "($condition)";
+		} elsif($modifiers[$i] eq 'allow_nonexistent') {
+			$mods->{'allow_nonexistent'} = 1;
+		} elsif($modifiers[$i] =~ m/^allow_nonexistent_if\((.*)\)$/) {
+			my $condition = $1;
+			$mods->{'allow_nonexistent'} = "($condition)";
 		} elsif(($modifiers[$i] =~ m/^optional_arg_is_create_mode\((.*)\)$/) &&
 			($fn->{'has_varargs'})) {
 			my $va_list_condition = $1;

scratchbox2/preload/sb_l10n.c

@@ -37,7 +37,9 @@ char *bindtextdomain_gate(int *result_errno_ptr,
 	clear_mapping_results_struct(&res);
 
 	if (dirname != NULL) { 
-		sbox_map_path(realfn_name, dirname, 0, &res, SB2_INTERFACE_CLASS_L10N);
+		sbox_map_path(realfn_name, dirname,
+		     SBOX_MAP_PATH_ALLOW_NONEXISTENT, &res,
+		     SB2_INTERFACE_CLASS_L10N);
 		assert(res.mres_result_path != NULL);
 
 		mapped_dirname = res.mres_result_path;