1 files changed, 143 insertions, 0 deletions
diff --git a/libblkid/at.c b/libblkid/at.c
new file mode 100644
index 000000000..f8bfe1399
--- /dev/null
+++ b/libblkid/at.c
@@ -0,0 +1,143 @@
+/*
+ * Portable xxxat() functions.
+ *
+ * No copyright is claimed.  This code is in the public domain; do with
+ * it what you wish.
+ *
+ * Written by Karel Zak <kzak@redhat.com>
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+#include "at.h"
+#include "c.h"
+
+#ifdef HAVE_FSTATAT
+int fstat_at(int dir, const char *dirname __attribute__ ((__unused__)),
+	     const char *filename, struct stat *st, int nofollow)
+{
+	return fstatat(dir, filename, st,
+			nofollow ? AT_SYMLINK_NOFOLLOW : 0);
+}
+#else
+int fstat_at(int dir, const char *dirname, const char *filename,
+				struct stat *st, int nofollow)
+{
+
+	if (*filename != '/') {
+		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);
+	}
+
+	return nofollow ? lstat(filename, st) : stat(filename, st);
+}
+#endif
+
+#ifdef HAVE_FSTATAT
+int open_at(int dir, const char *dirname __attribute__ ((__unused__)),
+	    const char *filename, int flags)
+{
+	return openat(dir, filename, flags);
+}
+#else
+int open_at(int dir, const char *dirname, const char *filename, int flags)
+{
+	if (*filename != '/') {
+		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);
+	}
+	return open(filename, 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 HAVE_FSTATAT
+ssize_t readlink_at(int dir, const char *dirname __attribute__ ((__unused__)),
+		    const char *pathname, char *buf, size_t bufsiz)
+{
+	return readlinkat(dir, pathname, buf, bufsiz);
+}
+#else
+ssize_t readlink_at(int dir, const char *dirname, const char *pathname,
+		    char *buf, size_t bufsiz)
+{
+	if (*pathname != '/') {
+		char path[PATH_MAX];
+		int len;
+
+		len = snprintf(path, sizeof(path), "%s/%s", dirname, pathname);
+		if (len < 0 || len + 1 > sizeof(path))
+			return -1;
+
+		return readlink(path, buf, bufsiz);
+	}
+	return readlink(pathname, buf, bufsiz);
+}
+#endif
+
+#ifdef TEST_PROGRAM_AT
+#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, "cannot open %s", 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