lib: add wrappers for "at" functions

Signed-off-by: Karel Zak <kzak@redhat.com>

2 files changed, 102 insertions, 1 deletions

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 9a3bf35bd..36396a385 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -3,7 +3,7 @@ include $(top_srcdir)/config/include-Makefile.am
 AM_CPPFLAGS += -DTEST_PROGRAM
 
 noinst_PROGRAMS = test_blkdev test_ismounted test_wholedisk test_mangle \
-		  test_tt test_canonicalize
+		  test_tt test_canonicalize test_at
 if LINUX
 if HAVE_CPU_SET_T
 noinst_PROGRAMS += test_cpuset
@@ -14,6 +14,7 @@ test_blkdev_SOURCES = blkdev.c
 test_ismounted_SOURCES = ismounted.c
 test_wholedisk_SOURCES = wholedisk.c
 test_mangle_SOURCES = mangle.c
+test_at_SOURCES = at.c
 if LINUX
 test_cpuset_SOURCES = cpuset.c
 endif
diff --git a/lib/at.c b/lib/at.c
new file mode 100644
index 000000000..1993f9983
--- /dev/null
+++ b/lib/at.c
@@ -0,0 +1,100 @@
+/*
+ * Portable xxxat() functions.
+ *
+ * Copyright (C) 2010 Karel Zak <kzak@redhat.com>
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#include "at.h"
+
+int fstat_at(int dir, const char *dirname, const char *filename,
+				struct stat *st, int nofollow)
+{
+#ifdef HAVE_FSTATAT
+	return fstatat(dir, filename, st,
+			nofollow ? AT_SYMLINK_NOFOLLOW : 0);
+#else
+	char path[PATH_MAX];
+	int len;
+
+	len = snprintf(path, sizeof(path), "%s/%s", dirname, filename);
+	if (len < 0 || len + 1 > sizeof(path))
+		return -1;
+
+	return nofollow ? lstat(path, st) : stat(path, st);
+#endif
+}
+
+int open_at(int dir, const char *dirname, const char *filename, int flags)
+{
+#ifdef HAVE_FSTATAT
+	return openat(dir, filename, flags);
+#else
+	char path[PATH_MAX];
+	int len;
+
+	len = snprintf(path, sizeof(path), "%s/%s", dirname, filename);
+	if (len < 0 || len + 1 > sizeof(path))
+		return -1;
+
+	return open(path, flags);
+#endif
+}
+
+FILE *fopen_at(int dir, const char *dirname, const char *filename, int flags,
+			const char *mode)
+{
+	int fd = open_at(dir, dirname, filename, flags);
+
+	if (fd < 0)
+		return NULL;
+
+	return fdopen(fd, mode);
+}
+
+#ifdef TEST_PROGRAM
+#include <err.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <string.h>
+
+int main(int argc, char *argv[])
+{
+	DIR *dir;
+	struct dirent *d;
+	char *dirname;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s <directory>\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+	dirname = argv[1];
+
+	dir = opendir(dirname);
+	if (!dir)
+		err(EXIT_FAILURE, "%s: open failed", dirname);
+
+	while ((d = readdir(dir))) {
+		struct stat st;
+		FILE *f;
+
+		printf("%32s ", d->d_name);
+
+		if (fstat_at(dirfd(dir), dirname, d->d_name, &st, 0) == 0)
+			printf("%16jd bytes ", st.st_size);
+		else
+			printf("%16s bytes ", "???");
+
+		f = fopen_at(dirfd(dir), dirname, d->d_name, O_RDONLY, "r");
+		printf("   %s\n", f ? "OK" : strerror(errno));
+		if (f)
+			fclose(f);
+	}
+	closedir(dir);
+	return EXIT_SUCCESS;
+}
+#endif