Clean up the synopsis section & fix mandoc warnings

[pw-darwin.git] / libutil / flopen.c

diff --git a/libutil/flopen.c b/libutil/flopen.c
index 92254cc1c3cf51b577e925f561532721d635b091..485eee4c1109b00b179acd3daeadd9bc6d0f6049 100644 (file)
--- a/libutil/flopen.c
+++ b/libutil/flopen.c
@@ -1,5 +1,7 @@
 /*-
- * Copyright (c) 2007 Dag-Erling Coïdan Smørgrav
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2007-2009 Dag-Erling Coïdan Smørgrav
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -32,16 +34,23 @@ __FBSDID("$FreeBSD$");
 #include <sys/stat.h>
 
 #include <errno.h>
-#include <fcntl.h>
 #include <stdarg.h>
 #include <unistd.h>
 
 #include <libutil.h>
 
-int
-flopen(const char *path, int flags, ...)
+/*
+ * Reliably open and lock a file.
+ *
+ * Please do not modify this code without first reading the revision history
+ * and discussing your changes with <des@freebsd.org>.  Don't be fooled by the
+ * code's apparent simplicity; there would be no need for this function if it
+ * was easy to get right.
+ */
+static int
+vflopenat(int dirfd, const char *path, int flags, va_list ap)
 {
-       int fd, operation, serrno, truncate;
+       int fd, operation, serrno, trunc;
        struct stat sb, fsb;
        mode_t mode;
 
@@ -51,56 +60,88 @@ flopen(const char *path, int flags, ...)
 
        mode = 0;
        if (flags & O_CREAT) {
-               va_list ap;
-
-               va_start(ap, flags);
-               mode = va_arg(ap, int); /* mode_t promoted to int */
-               va_end(ap);
+               mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
        }
 
-       operation = LOCK_EX;
-       if (flags & O_NONBLOCK)
-               operation |= LOCK_NB;
+        operation = LOCK_EX;
+        if (flags & O_NONBLOCK)
+                operation |= LOCK_NB;
 
-       truncate = (flags & O_TRUNC);
-       flags |= ~O_TRUNC;
+       trunc = (flags & O_TRUNC);
+       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) {
                        /* unsupported or interrupted */
                        serrno = errno;
-                       close(fd);
+                       (void)close(fd);
                        errno = serrno;
                        return (-1);
                }
-               if (stat(path, &sb) == -1) {
+               if (fstatat(dirfd, path, &sb, 0) == -1) {
                        /* disappeared from under our feet */
-                       close(fd);
+                       (void)close(fd);
                        continue;
                }
                if (fstat(fd, &fsb) == -1) {
                        /* can't happen [tm] */
                        serrno = errno;
-                       close(fd);
+                       (void)close(fd);
                        errno = serrno;
                        return (-1);
                }
                if (sb.st_dev != fsb.st_dev ||
                    sb.st_ino != fsb.st_ino) {
                        /* changed under our feet */
-                       close(fd);
+                       (void)close(fd);
                        continue;
                }
-               if (truncate && ftruncate(fd, 0) != 0) {
+               if (trunc && ftruncate(fd, 0) != 0) {
                        /* can't happen [tm] */
                        serrno = errno;
-                       close(fd);
+                       (void)close(fd);
                        errno = serrno;
                        return (-1);
                }
+               /*
+                * The following change is provided as a specific example to
+                * avoid.
+                */
+#if 0
+               if (fcntl(fd, F_SETFD, FD_CLOEXEC) != 0) {
+                       serrno = errno;
+                       (void)close(fd);
+                       errno = serrno;
+                       return (-1);
+               }
+#endif
                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);
+}