Merge argument substitution into rdline

Signed-off-by: David Oberhollenzer <david.oberhollenzer@tele2.at>

lib/Makemodule.am

@@ -2,7 +2,7 @@ HEADRS = lib/include/util.h lib/include/service.h lib/include/telinit.h
 
 libinit_a_SOURCES = lib/src/delsvc.c lib/src/rdline.c lib/src/svcmap.c
 libinit_a_SOURCES += lib/src/splitkv.c lib/src/enum_by_name.c
-libinit_a_SOURCES += lib/src/strexpand.c lib/src/rdsvc.c lib/src/svcscan.c
+libinit_a_SOURCES += lib/src/rdsvc.c lib/src/svcscan.c
 libinit_a_SOURCES += lib/src/del_svc_list.c lib/src/svc_tsort.c
 libinit_a_SOURCES += lib/src/opensock.c lib/src/enum_to_name.c $(HEADRS)
 libinit_a_CPPFLAGS = $(AM_CPPFLAGS)

lib/include/util.h

@@ -55,8 +55,17 @@ typedef struct {
 	   it with a backslash.
 	 - If a second, coresponding '"' is not found, processing fails with
 	   errno set to EILSEQ.
+	 - If a '%' character is encountered, the next character is expected
+	   to be a single digit index into argv. If it is not a digit or
+	   outside the bounds set by argc, processing fails and sets errno
+	   to EINVAL. On success, the argv value is inserted and processed
+	   as described above.
+	 - A '%' character can be escaped by writing '%%' or, if inside
+	   a double quite string, by writing \%.
+	 - An attempt to use such an indexed argument inside an argument
+	   expansion, results in failure with errno set to ELOOP.
 */
-char *rdline(int fd);
+char *rdline(int fd, int argc, const char *const *argv);
 
 /*
 	Split a line of the shape "key = value" into key and value part.
@@ -88,12 +97,5 @@ const enum_map_t *enum_by_name(const enum_map_t *map, const char *name);
 */
 const char *enum_to_name(const enum_map_t *map, int value);
 
-/*
-	Create a copy of the input string inp, but replace all occourances
-	of %<number> with argv[number] if the number is within the bounds
-	specified by argc.
-*/
-char *strexpand(const char *inp, size_t argc, const char *const *argv);
-
 #endif /* UTIL_H */
 

lib/src/rdline.c

@@ -27,33 +27,45 @@ enum {
 	STATE_STRING = 1,
 	STATE_STRING_ESC = 2,
 	STATE_COMMENT = 3,
+	STATE_ARG = 4,
 };
 
-char *rdline(int fd)
+char *rdline(int fd, int argc, const char *const *argv)
 {
 	size_t i = 0, bufsiz = 0, newsz;
 	int ret, state = STATE_INITIAL;
 	char c, *new, *buffer = NULL;
+	const char *argstr = NULL;
 
 	for (;;) {
-		switch (read(fd, &c, 1)) {
-		case 0:
-			if (i == 0) {
-				errno = 0;
-				return NULL;
-			}
-			c = '\0';
-			break;
-		case 1:
-			if (c == '\n')
+		if (argstr == NULL) {
+			switch (read(fd, &c, 1)) {
+			case 0:
+				if (i == 0) {
+					errno = 0;
+					return NULL;
+				}
 				c = '\0';
-			break;
-		default:
-			if (errno == EINTR)
+				break;
+			case 1:
+				break;
+			default:
+				if (errno == EINTR)
+					continue;
+				goto fail;
+			}
+		} else {
+			c = *(argstr++);
+
+			if (c == '\0') {
+				argstr = NULL;
 				continue;
-			goto fail;
+			}
 		}
 
+		if (c == '\n')
+			c = '\0';
+
 		switch (state) {
 		case STATE_STRING:
 			if (c == '\\')
@@ -68,6 +80,20 @@ char *rdline(int fd)
 			if (c != '\0')
 				continue;
 			break;
+		case STATE_ARG:
+			state = STATE_INITIAL;
+			if (c == '%')
+				break;
+			if (!isdigit(c) || (c - '0') >= argc) {
+				errno = EINVAL;
+				goto fail;
+			}
+			if (argstr != NULL) {
+				errno = ELOOP;
+				goto fail;
+			}
+			argstr = argv[c - '0'];
+			continue;
 		default:
 			if (isspace(c))
 				c = ' ';
@@ -77,6 +103,10 @@ char *rdline(int fd)
 				state = STATE_COMMENT;
 				continue;
 			}
+			if (c == '%') {
+				state = STATE_ARG;
+				continue;
+			}
 			if (c == '"')
 				state = STATE_STRING;
 			break;

lib/src/rdsvc.c

@@ -171,7 +171,7 @@ static const struct {
 
 service_t *rdsvc(int dirfd, const char *filename)
 {
-	const char *arg, *args[1];
+	const char *arg, *args[1], *error;
 	char *line, *key, *value;
 	size_t i, argc, lineno;
 	service_t *svc;
@@ -213,15 +213,30 @@ service_t *rdsvc(int dirfd, const char *filename)
 
 	for (lineno = 1; ; ++lineno) {
 		errno = 0;
-		line = rdline(fd);
+		line = rdline(fd, argc, args);
 
 		if (line == NULL) {
-			if (errno != 0) {
-				fprintf(stderr, "read: %s: %zu: %s\n",
-					filename, lineno, strerror(errno));
-				goto fail;
+			if (errno == 0)
+				break;
+
+			switch (errno) {
+			case EINVAL:
+				error = "error in argument expansion";
+				break;
+			case ELOOP:
+				error = "recursive argument expansion";
+				break;
+			case EILSEQ:
+				error = "missing \"";
+				break;
+			default:
+				error = strerror(errno);
+				break;
 			}
-			break;
+
+			fprintf(stderr, "%s: %zu: %s\n",
+				filename, lineno, error);
+			goto fail;
 		}
 
 		if (splitkv(line, &key, &value)) {
@@ -258,7 +273,7 @@ service_t *rdsvc(int dirfd, const char *filename)
 			goto fail_line;
 		}
 
-		value = strexpand(value, argc, args);
+		value = strdup(value);
 		if (value == NULL) {
 			fputs("out of memory", stderr);
 			goto fail_line;

lib/src/strexpand.c

@@ -1,72 +0,0 @@
-/* SPDX-License-Identifier: GPL-3.0-or-later */
-/*
- * Copyright (C) 2018 - David Oberhollenzer
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-#include <string.h>
-#include <stdlib.h>
-#include <ctype.h>
-
-#include "util.h"
-
-char *strexpand(const char *inp, size_t argc, const char *const *argv)
-{
-	char *out, *dst;
-	const char *ptr;
-	size_t i, len;
-
-	ptr = inp;
-	len = 0;
-
-	while (*ptr != '\0') {
-		if (ptr[0] == '%' && isdigit(ptr[1])) {
-			i = ptr[1] - '0';
-			if (i < argc)
-				len += strlen(argv[i]);
-			ptr += 2;
-		} else if (ptr[0] == '%' && ptr[1] == '%') {
-			ptr += 2;
-			len += 1;
-		} else {
-			++ptr;
-			++len;
-		}
-	}
-
-	out = calloc(1, len + 1);
-	if (out == NULL)
-		return NULL;
-
-	dst = out;
-
-	while (*inp != '\0') {
-		if (inp[0] == '%' && isdigit(inp[1])) {
-			i = inp[1] - '0';
-			if (i < argc) {
-				len = strlen(argv[i]);
-				memcpy(dst, argv[i], len);
-				dst += len;
-			}
-			inp += 2;
-		} else if (inp[0] == '%' && inp[1] == '%') {
-			*(dst++) = '%';
-			inp += 2;
-		} else {
-			*(dst++) = *(inp++);
-		}
-	}
-
-	return out;
-}