fragments: handle sysroot dir munging directly in a smarter way

Previously we just let the tuple system handle it, but pkg-config modules which do not define
variables were able to get by the checks.  While here, check to ensure we do not duplicate the
sysroot dir twice if it is already defined in the pkg-config module file.

Downstream bug: https://bugs.busybox.net/show_bug.cgi?id=5750

fragment.c

@@ -16,8 +16,29 @@
 #include "pkg.h"
 #include "bsdstubs.h"
 
+static inline char *
+pkg_fragment_copy_munged(const char *source, unsigned int flags)
+{
+	char mungebuf[PKG_BUFSIZE];
+	char *sysroot_dir;
+
+	if (!(flags & PKGF_MUNGE_SYSROOT_PREFIX))
+		return strdup(source);
+
+	sysroot_dir = pkg_tuple_find_global("pc_sysrootdir");
+
+	if (*source != '/' ||
+		(sysroot_dir != NULL && !strncmp(sysroot_dir, source, strlen(sysroot_dir))))
+		return strdup(source);
+
+	strlcpy(mungebuf, sysroot_dir, sizeof mungebuf);
+	strlcat(mungebuf, source, sizeof mungebuf);
+
+	return strdup(mungebuf);
+}
+
 void
-pkg_fragment_add(pkg_list_t *list, const char *string)
+pkg_fragment_add(pkg_list_t *list, const char *string, unsigned int flags)
 {
 	pkg_fragment_t *frag;
 
@@ -26,7 +47,7 @@ pkg_fragment_add(pkg_list_t *list, const char *string)
 		frag = calloc(sizeof(pkg_fragment_t), 1);
 
 		frag->type = *(string + 1);
-		frag->data = strdup(string + 2);
+		frag->data = pkg_fragment_copy_munged(string + 2, flags);
 	}
 	else
 	{
@@ -156,7 +177,7 @@ pkg_fragment_free(pkg_list_t *list)
 }
 
 void
-pkg_fragment_parse(pkg_list_t *list, pkg_list_t *vars, const char *value)
+pkg_fragment_parse(pkg_list_t *list, pkg_list_t *vars, const char *value, unsigned int flags)
 {
 	int i, argc;
 	char **argv;
@@ -165,7 +186,7 @@ pkg_fragment_parse(pkg_list_t *list, pkg_list_t *vars, const char *value)
 	pkg_argv_split(repstr, &argc, &argv);
 
 	for (i = 0; i < argc; i++)
-		pkg_fragment_add(list, argv[i]);
+		pkg_fragment_add(list, argv[i], flags);
 
 	pkg_argv_free(argv);
 	free(repstr);

main.c

@@ -290,11 +290,20 @@ print_variable(pkg_t *pkg, void *data, unsigned int flags)
 	{
 		if (*(req->buf) == '\0')
 		{
-			strlcpy(req->buf, var, sizeof(req->buf));
+			memset(req->buf, 0, sizeof(req->buf));
+
+			if (*var == '/' && (flags & PKGF_MUNGE_SYSROOT_PREFIX))
+				strlcat(req->buf, sysroot_dir, sizeof(req->buf));
+
+			strlcat(req->buf, var, sizeof(req->buf));
 			return;
 		}
 
 		strlcat(req->buf, " ", sizeof(req->buf));
+
+		if (*var == '/' && (flags & PKGF_MUNGE_SYSROOT_PREFIX))
+			strlcat(req->buf, sysroot_dir, sizeof(req->buf));
+
 		strlcat(req->buf, var, sizeof(req->buf));
 	}
 }

pkg.c

@@ -247,13 +247,13 @@ pkg_new_from_file(const char *filename, FILE *f, unsigned int flags)
 			else if (!strcmp(key, "Version"))
 				pkg->version = pkg_tuple_parse(&pkg->vars, value);
 			else if (!strcasecmp(key, "CFLAGS"))
-				pkg_fragment_parse(&pkg->cflags, &pkg->vars, value);
+				pkg_fragment_parse(&pkg->cflags, &pkg->vars, value, flags);
 			else if (!strcasecmp(key, "CFLAGS.private"))
-				pkg_fragment_parse(&pkg->cflags_private, &pkg->vars, value);
+				pkg_fragment_parse(&pkg->cflags_private, &pkg->vars, value, flags);
 			else if (!strcasecmp(key, "LIBS"))
-				pkg_fragment_parse(&pkg->libs, &pkg->vars, value);
+				pkg_fragment_parse(&pkg->libs, &pkg->vars, value, flags);
 			else if (!strcasecmp(key, "LIBS.private"))
-				pkg_fragment_parse(&pkg->libs_private, &pkg->vars, value);
+				pkg_fragment_parse(&pkg->libs_private, &pkg->vars, value, flags);
 			else if (!strcmp(key, "Requires"))
 				pkg_dependency_parse(pkg, &pkg->requires, value);
 			else if (!strcmp(key, "Requires.private"))
@@ -262,18 +262,7 @@ pkg_new_from_file(const char *filename, FILE *f, unsigned int flags)
 				pkg_dependency_parse(pkg, &pkg->conflicts, value);
 			break;
 		case '=':
-			if (!(flags & PKGF_MUNGE_SYSROOT_PREFIX) || strcasecmp(key, "prefix"))
 			pkg_tuple_add(&pkg->vars, key, value);
-			else
-			{
-				char mungebuf[PKG_BUFSIZE];
-				char *sysroot_dir = pkg_tuple_find_global("pc_sysrootdir");
-
-				strlcpy(mungebuf, sysroot_dir, sizeof mungebuf);
-				strlcat(mungebuf, value, sizeof mungebuf);
-
-				pkg_tuple_add(&pkg->vars, key, mungebuf);
-			}
 			break;
 		default:
 			break;

pkg.h

@@ -157,8 +157,8 @@ int pkg_argv_split(const char *src, int *argc, char ***argv);
 void pkg_argv_free(char **argv);
 
 /* fragment.c */
-void pkg_fragment_parse(pkg_list_t *list, pkg_list_t *vars, const char *value);
-void pkg_fragment_add(pkg_list_t *list, const char *string);
+void pkg_fragment_parse(pkg_list_t *list, pkg_list_t *vars, const char *value, unsigned int flags);
+void pkg_fragment_add(pkg_list_t *list, const char *string, unsigned int flags);
 void pkg_fragment_copy(pkg_list_t *list, pkg_fragment_t *base, unsigned int flags);
 void pkg_fragment_delete(pkg_list_t *list, pkg_fragment_t *node);
 void pkg_fragment_free(pkg_list_t *list);

tests/lib1/sysroot-dir.pc

@@ -0,0 +1,5 @@
+Name: sysroot-dir
+Description: Package for testing whether sysroot dirs are repeated or not
+Version: 1
+CFlags: -I/sysroot/include
+Libs: -L/sysroot/lib -lfoo

tests/run.sh.in

@@ -244,6 +244,11 @@ run_test "PKG_CONFIG_PATH='${selfdir}/lib1' ${1} --variable=foo case-sensitivity
 run_test "PKG_CONFIG_PATH='${selfdir}/lib1' ${1} --variable=Foo case-sensitivity" \
 	"4"
 
+run_test "PKG_CONFIG_PATH='${selfdir}/lib1' PKG_CONFIG_SYSROOT_DIR='/sysroot' ${1} --libs sysroot-dir" \
+	'-L/sysroot/lib -lfoo'
+run_test "PKG_CONFIG_PATH='${selfdir}/lib1' PKG_CONFIG_SYSROOT_DIR='/sysroot2' ${1} --libs sysroot-dir" \
+	'-L/sysroot2/sysroot/lib -lfoo'
+
 # 10) tests for internal getopt implementation with options at the end
 if [ "x@STRICT_MODE@" = "xno" ]; then
 	run_test "PKG_CONFIG_PATH='${selfdir}/lib1' ${1} foo --libs" \