From: Michael Tremer <michael.tremer@ipfire.org>
Date: Fri, 6 Oct 2023 14:55:55 +0000 (+0000)
Subject: archive: read: Add option to follow symlinks
X-Git-Tag: 0.9.30~1529
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=695e76f492bb7a1e96c823ec595149bd0c8778ff;p=pakfire.git

archive: read: Add option to follow symlinks

This is useful when we want to read some data from an archive which
requires us to follow a symlink.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/_pakfire/archive.c b/src/_pakfire/archive.c
index 236c05f6e..f3a34dea9 100644
--- a/src/_pakfire/archive.c
+++ b/src/_pakfire/archive.c
@@ -92,7 +92,7 @@ static PyObject* Archive_read(ArchiveObject* self, PyObject* args) {
 	Py_BEGIN_ALLOW_THREADS
 
 	// Try to open the file
-	f = pakfire_archive_read(self->archive, filename);
+	f = pakfire_archive_read(self->archive, filename, PAKFIRE_ARCHIVE_READ_FOLLOW_SYMLINKS);
 	if (!f) {
 		Py_BLOCK_THREADS
 		PyErr_SetFromErrno(PyExc_OSError);
diff --git a/src/libpakfire/archive.c b/src/libpakfire/archive.c
index 68c6d4d51..85c5c228b 100644
--- a/src/libpakfire/archive.c
+++ b/src/libpakfire/archive.c
@@ -44,6 +44,7 @@
 #include <pakfire/logging.h>
 #include <pakfire/package.h>
 #include <pakfire/pakfire.h>
+#include <pakfire/path.h>
 #include <pakfire/private.h>
 #include <pakfire/repo.h>
 #include <pakfire/scriptlet.h>
@@ -581,6 +582,9 @@ struct pakfire_archive_read_cookie {
 
 	// File handle opened by the cookie
 	FILE* __f;
+
+	// Some flags
+	int flags;
 };
 
 static ssize_t __pakfire_archive_cookie_read(void* c, char* buffer, size_t size) {
@@ -615,6 +619,8 @@ static cookie_io_functions_t pakfire_archive_read_functions = {
 static int __pakfire_archive_read_filter(struct pakfire* pakfire, struct archive* a,
 		struct archive_entry* e, void* data) {
 	struct pakfire_archive_read_cookie* cookie = (struct pakfire_archive_read_cookie*)data;
+	const char* symlink = NULL;
+	int r;
 
 	// Fetch path
 	const char* p = archive_entry_pathname(e);
@@ -622,8 +628,31 @@ static int __pakfire_archive_read_filter(struct pakfire* pakfire, struct archive
 		return PAKFIRE_WALK_ERROR;
 
 	// We found a match
-	if (strcmp(cookie->path + 1, p) == 0)
+	if (strcmp(cookie->path + 1, p) == 0) {
+		if (cookie->flags & PAKFIRE_ARCHIVE_READ_FOLLOW_SYMLINKS) {
+			switch (archive_entry_filetype(e)) {
+				case AE_IFLNK:
+					break;
+
+				default:
+					return PAKFIRE_WALK_DONE;
+			}
+
+			// Resolve the destination of the symlink
+			symlink = archive_entry_symlink(e);
+			if (!symlink)
+				return PAKFIRE_WALK_ERROR;
+
+			// Update path
+			r = pakfire_path_merge(cookie->path, cookie->path, symlink);
+			if (r)
+				return PAKFIRE_WALK_ERROR;
+
+			return PAKFIRE_WALK_AGAIN;
+		}
+
 		return PAKFIRE_WALK_DONE;
+	}
 
 	// Otherwise we skip the file
 	return PAKFIRE_WALK_SKIP;
@@ -644,7 +673,7 @@ static int __pakfire_archive_read(struct pakfire* pakfire, struct archive* a,
 	return PAKFIRE_WALK_DONE;
 }
 
-PAKFIRE_EXPORT FILE* pakfire_archive_read(struct pakfire_archive* archive, const char* path) {
+PAKFIRE_EXPORT FILE* pakfire_archive_read(struct pakfire_archive* archive, const char* path, int flags) {
 	struct pakfire_archive_read_cookie* cookie = NULL;
 	int r;
 
@@ -664,6 +693,9 @@ PAKFIRE_EXPORT FILE* pakfire_archive_read(struct pakfire_archive* archive, const
 	// Store a reference to the archive
 	cookie->archive = pakfire_archive_ref(archive);
 
+	// Store flags
+	cookie->flags = flags;
+
 	// Store the path
 	r = pakfire_string_set(cookie->path, path);
 	if (r) {
@@ -680,6 +712,7 @@ PAKFIRE_EXPORT FILE* pakfire_archive_read(struct pakfire_archive* archive, const
 	}
 
 	// Open the archive
+AGAIN:
 	cookie->a = open_archive(archive, cookie->f);
 	if (!cookie->a)
 		goto ERROR;
@@ -687,8 +720,19 @@ PAKFIRE_EXPORT FILE* pakfire_archive_read(struct pakfire_archive* archive, const
 	// Walk through the archive
 	r = pakfire_walk(archive->pakfire, cookie->a,
 		__pakfire_archive_read, __pakfire_archive_read_filter, cookie);
-	if (r)
-		goto ERROR;
+	if (r) {
+		switch (-r) {
+			case EAGAIN:
+				if (cookie->a)
+					archive_read_free(cookie->a);
+				if (cookie->f)
+					rewind(cookie->f);
+				goto AGAIN;
+
+			default:
+				goto ERROR;
+		}
+	}
 
 	// Nothing found
 	if (!cookie->__f) {
diff --git a/src/libpakfire/include/pakfire/archive.h b/src/libpakfire/include/pakfire/archive.h
index aa4c674ae..bf75bdc78 100644
--- a/src/libpakfire/include/pakfire/archive.h
+++ b/src/libpakfire/include/pakfire/archive.h
@@ -35,7 +35,11 @@ int pakfire_archive_open(struct pakfire_archive** archive, struct pakfire* pakfi
 struct pakfire_archive* pakfire_archive_ref(struct pakfire_archive* archive);
 struct pakfire_archive* pakfire_archive_unref(struct pakfire_archive* archive);
 
-FILE* pakfire_archive_read(struct pakfire_archive* archive, const char* filename);
+enum pakfire_archive_read_flags {
+	PAKFIRE_ARCHIVE_READ_FOLLOW_SYMLINKS = (1 << 0),
+};
+
+FILE* pakfire_archive_read(struct pakfire_archive* archive, const char* filename, int flags);
 int pakfire_archive_extract(struct pakfire_archive* archive,
 	const char* path, const int flags);