From fd1b8ccca68abe52e1158aa3e5ef42267d952b74 Mon Sep 17 00:00:00 2001
From: Ariadne Conill <ariadne@dereferenced.org>
Date: Thu, 18 Mar 2021 06:22:11 -0600
Subject: [PATCH] main: if PKG_CONFIG_FDO_SYSROOT_RULES is set, or DESTDIR
 matches PKG_CONFIG_SYSROOT_DIRS, disable the automatic sysroot rewriting

Closes #205.
---
 cli/main.c              | 13 +++++++++++++
 libpkgconf/libpkgconf.h |  1 +
 libpkgconf/tuple.c      |  7 +++++--
 man/pkgconf.1           |  4 ++++
 4 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/cli/main.c b/cli/main.c
index f32b06c..11b8898 100644
--- a/cli/main.c
+++ b/cli/main.c
@@ -1015,6 +1015,9 @@ main(int argc, char *argv[])
 		return EXIT_SUCCESS;
 	}
 
+	if (getenv("PKG_CONFIG_FDO_SYSROOT_RULES"))
+		want_client_flags |= PKGCONF_PKG_PKGF_FDO_SYSROOT_RULES;
+
 	if ((want_flags & PKG_SHORT_ERRORS) == PKG_SHORT_ERRORS)
 		want_client_flags |= PKGCONF_PKG_PKGF_SIMPLIFY_ERRORS;
 
@@ -1101,8 +1104,18 @@ main(int argc, char *argv[])
 		pkgconf_client_set_buildroot_dir(&pkg_client, builddir);
 
 	if ((sysroot_dir = getenv("PKG_CONFIG_SYSROOT_DIR")) != NULL)
+	{
+		const char *destdir;
+
 		pkgconf_client_set_sysroot_dir(&pkg_client, sysroot_dir);
 
+		if ((destdir = getenv("DESTDIR")) != NULL)
+		{
+			if (!strcmp(destdir, sysroot_dir))
+				want_client_flags |= PKGCONF_PKG_PKGF_FDO_SYSROOT_RULES;
+		}
+	}
+
 	/* we have determined what features we want most likely.  in some cases, we override later. */
 	pkgconf_client_set_flags(&pkg_client, want_client_flags);
 
diff --git a/libpkgconf/libpkgconf.h b/libpkgconf/libpkgconf.h
index 6f188de..8715789 100644
--- a/libpkgconf/libpkgconf.h
+++ b/libpkgconf/libpkgconf.h
@@ -251,6 +251,7 @@ PKGCONF_API pkgconf_cross_personality_t *pkgconf_cross_personality_find(const ch
 #define PKGCONF_PKG_PKGF_SIMPLIFY_ERRORS		0x1000
 #define PKGCONF_PKG_PKGF_DONT_FILTER_INTERNAL_CFLAGS	0x2000
 #define PKGCONF_PKG_PKGF_DONT_MERGE_SPECIAL_FRAGMENTS	0x4000
+#define PKGCONF_PKG_PKGF_FDO_SYSROOT_RULES		0x8000
 
 #define PKGCONF_PKG_DEPF_INTERNAL		0x1
 
diff --git a/libpkgconf/tuple.c b/libpkgconf/tuple.c
index 0d9946d..2d550d8 100644
--- a/libpkgconf/tuple.c
+++ b/libpkgconf/tuple.c
@@ -254,8 +254,11 @@ pkgconf_tuple_parse(const pkgconf_client_t *client, pkgconf_list_t *vars, const
 	const char *ptr;
 	char *bptr = buf;
 
-	if (*value == '/' && client->sysroot_dir != NULL && strncmp(value, client->sysroot_dir, strlen(client->sysroot_dir)))
-		bptr += pkgconf_strlcpy(buf, client->sysroot_dir, sizeof buf);
+	if (!(client->flags & PKGCONF_PKG_PKGF_FDO_SYSROOT_RULES))
+	{
+		if (*value == '/' && client->sysroot_dir != NULL && strncmp(value, client->sysroot_dir, strlen(client->sysroot_dir)))
+			bptr += pkgconf_strlcpy(buf, client->sysroot_dir, sizeof buf);
+	}
 
 	for (ptr = value; *ptr != '\0' && bptr - buf < PKGCONF_BUFSIZE; ptr++)
 	{
diff --git a/man/pkgconf.1 b/man/pkgconf.1
index 2df3d6a..ab603f1 100644
--- a/man/pkgconf.1
+++ b/man/pkgconf.1
@@ -213,6 +213,10 @@ The format of the debug log messages is implementation-specific.
 If set, disables the path relocation feature.
 .It Va PKG_CONFIG_MSVC_SYNTAX
 If set, uses MSVC syntax for fragments.
+.It Va PKG_CONFIG_FDO_SYSROOT_RULES
+If set, follow the sysroot prefixing rules that freedesktop.org pkg-config uses.
+.It Va DESTDIR
+If set to PKG_CONFIG_SYSROOT_DIR, assume that PKG_CONFIG_FDO_SYSROOT_RULES is set.
 .El
 .Sh EXAMPLES
 Displaying the CFLAGS of a package: