Introduce the flopenat(3) function.

Reviewed by:	des, emaste
Differential Revision:	https://reviews.freebsd.org/D11690

diff --git a/libutil/flopen.c b/libutil/flopen.c
index 89297290796e32dd7d0381e4172d1eb19c487d31..bb5d99629a3efeb9c6fcf17ce9e2dde25c7ce6f8 100644 (file)
--- a/libutil/flopen.c
+++ b/libutil/flopen.c
@@ -45,8 +45,8 @@ __FBSDID("$FreeBSD$");
  * code's apparent simplicity; there would be no need for this function if it
  * was easy to get right.
  */
-int
-flopen(const char *path, int flags, ...)
+static int
+vflopenat(int dirfd, const char *path, int flags, va_list ap)
 {
        int fd, operation, serrno, trunc;
        struct stat sb, fsb;
@@ -58,11 +58,7 @@ flopen(const char *path, int flags, ...)
 
        mode = 0;
        if (flags & O_CREAT) {
-               va_list ap;
-
-               va_start(ap, flags);
                mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
-               va_end(ap);
        }
 
         operation = LOCK_EX;
@@ -73,7 +69,7 @@ flopen(const char *path, int flags, ...)
        flags &= ~O_TRUNC;
 
        for (;;) {
-               if ((fd = open(path, flags, mode)) == -1)
+               if ((fd = openat(dirfd, path, flags, mode)) == -1)
                        /* non-existent or no access */
                        return (-1);
                if (flock(fd, operation) == -1) {
@@ -83,7 +79,7 @@ flopen(const char *path, int flags, ...)
                        errno = serrno;
                        return (-1);
                }
-               if (stat(path, &sb) == -1) {
+               if (fstatat(dirfd, path, &sb, 0) == -1) {
                        /* disappeared from under our feet */
                        (void)close(fd);
                        continue;
@@ -123,3 +119,27 @@ flopen(const char *path, int flags, ...)
                return (fd);
        }
 }
+
+int
+flopen(const char *path, int flags, ...)
+{
+       va_list ap;
+       int ret;
+
+       va_start(ap, flags);
+       ret = vflopenat(AT_FDCWD, path, flags, ap);
+       va_end(ap);
+       return (ret);
+}
+
+int
+flopenat(int dirfd, const char *path, int flags, ...)
+{
+       va_list ap;
+       int ret;
+
+       va_start(ap, flags);
+       ret = vflopenat(dirfd, path, flags, ap);
+       va_end(ap);
+       return (ret);
+}

diff --git a/libutil/libutil.h b/libutil/libutil.h
index b20ffa291a904d97ddb973ef50ef4d82c060a60a..fa924dbd28be81c97346c9c4ab83024e42043875 100644 (file)
--- a/libutil/libutil.h
+++ b/libutil/libutil.h
@@ -93,6 +93,7 @@ int   expand_number(const char *_buf, uint64_t *_num);
 int    extattr_namespace_to_string(int _attrnamespace, char **_string);
 int    extattr_string_to_namespace(const char *_string, int *_attrnamespace);
 int    flopen(const char *_path, int _flags, ...);
+int    flopenat(int _dirfd, const char *_path, int _flags, ...);
 int    forkpty(int *_amaster, char *_name,
            struct termios *_termp, struct winsize *_winp);
 void   hexdump(const void *_ptr, int _length, const char *_hdr, int _flags);