Commit a1f79978e8c60720d1b4217d3ada638ceb6593a5
2021-02-08T02:52:50
closefrom: Import some changes from sudo Take most of the changes done in sudo, but preserve the existing local changes and refactoring. In addition, refactor pstat implementation into closefrom_pstat(), so that the code is easier to read, and requires no conditional declarations.
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diff --git a/src/closefrom.c b/src/closefrom.c
index 962af79..be38813 100644
--- a/src/closefrom.c
+++ b/src/closefrom.c
@@ -1,6 +1,8 @@
/*
- * Copyright (c) 2004-2005, 2007, 2010, 2012-2014
- * Todd C. Miller <Todd.Miller@courtesan.com>
+ * SPDX-License-Identifier: ISC
+ *
+ * Copyright (c) 2004-2005, 2007, 2010, 2012-2015, 2017-2018
+ * Todd C. Miller <Todd.Miller@sudo.ws>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@@ -17,19 +19,11 @@
#include <config.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include <stdio.h>
-#ifdef STDC_HEADERS
-# include <stdlib.h>
-# include <stddef.h>
-#else
-# ifdef HAVE_STDLIB_H
-# include <stdlib.h>
-# endif
-#endif /* STDC_HEADERS */
+#include <errno.h>
#include <fcntl.h>
#include <limits.h>
+#include <stdlib.h>
+#include <unistd.h>
#ifdef HAVE_PSTAT_GETPROC
# include <sys/param.h>
# include <sys/pstat.h>
@@ -56,10 +50,6 @@
# define OPEN_MAX 256
#endif
-#if defined(HAVE_FCNTL_CLOSEM) && !defined(HAVE_DIRFD)
-# define closefrom closefrom_fallback
-#endif
-
static inline void
closefrom_close(int fd)
{
@@ -81,46 +71,46 @@ closefrom_fallback(int lowfd)
long fd, maxfd;
/*
- * Fall back on sysconf() or getdtablesize(). We avoid checking
- * resource limits since it is possible to open a file descriptor
- * and then drop the rlimit such that it is below the open fd.
+ * Fall back on sysconf(_SC_OPEN_MAX) or getdtablesize(). This is
+ * equivalent to checking the RLIMIT_NOFILE soft limit. It is
+ * possible for there to be open file descriptors past this limit
+ * but there is not much we can do about that since the hard limit
+ * may be RLIM_INFINITY (LLONG_MAX or ULLONG_MAX on modern systems).
*/
#ifdef HAVE_SYSCONF
maxfd = sysconf(_SC_OPEN_MAX);
#else
maxfd = getdtablesize();
#endif /* HAVE_SYSCONF */
- if (maxfd < 0)
+ if (maxfd < OPEN_MAX)
maxfd = OPEN_MAX;
+ /* Make sure we did not get RLIM_INFINITY as the upper limit. */
+ if (maxfd > INT_MAX)
+ maxfd = INT_MAX;
+
for (fd = lowfd; fd < maxfd; fd++)
closefrom_close(fd);
}
-/*
- * Close all file descriptors greater than or equal to lowfd.
- * We try the fast way first, falling back on the slow method.
- */
-#if defined(HAVE_FCNTL_CLOSEM)
-void
-closefrom(int lowfd)
-{
- if (fcntl(lowfd, F_CLOSEM, 0) == -1)
- closefrom_fallback(lowfd);
-}
-#elif defined(HAVE_PSTAT_GETPROC)
-void
-closefrom(int lowfd)
+#if defined(HAVE_PSTAT_GETPROC)
+static int
+closefrom_pstat(int lowfd)
{
- struct pst_status pstat;
+ struct pst_status pst;
int fd;
- if (pstat_getproc(&pstat, sizeof(pstat), 0, getpid()) != -1) {
- for (fd = lowfd; fd <= pstat.pst_highestfd; fd++)
+ /*
+ * EOVERFLOW is not a fatal error for the fields we use.
+ * See the "EOVERFLOW Error" section of pstat_getvminfo(3).
+ */
+ if (pstat_getproc(&pst, sizeof(pst), 0, getpid()) != -1 ||
+ errno == EOVERFLOW) {
+ for (fd = lowfd; fd <= pst.pst_highestfd; fd++)
(void)close(fd);
- } else {
- closefrom_fallback(lowfd);
+ return 0;
}
+ return -1;
}
#elif defined(HAVE_DIRFD)
static int
@@ -135,8 +125,8 @@ closefrom_procfs(int lowfd)
int ret = 0;
int i;
- /* Use /proc/self/fd (or /dev/fd on FreeBSD) if it exists. */
-# if defined(__FreeBSD__) || defined(__FreeBSD_kernel__) || defined(__APPLE__)
+ /* Use /proc/self/fd (or /dev/fd on macOS) if it exists. */
+# ifdef __APPLE__
path = "/dev/fd";
# else
path = "/proc/self/fd";
@@ -180,13 +170,28 @@ closefrom_procfs(int lowfd)
return ret;
}
+#endif
+/*
+ * Close all file descriptors greater than or equal to lowfd.
+ * We try the fast way first, falling back on the slow method.
+ */
void
closefrom(int lowfd)
{
- if (closefrom_procfs(lowfd) == 0)
+ /* Try the fast method first, if possible. */
+#if defined(HAVE_FCNTL_CLOSEM)
+ if (fcntl(lowfd, F_CLOSEM, 0) != -1)
+ return;
+#endif /* HAVE_FCNTL_CLOSEM */
+#if defined(HAVE_PSTAT_GETPROC)
+ if (closefrom_pstat(lowfd) != -1)
+ return;
+#elif defined(HAVE_DIRFD)
+ if (closefrom_procfs(lowfd) != -1)
return;
+#endif /* HAVE_DIRFD */
+ /* Do things the slow way. */
closefrom_fallback(lowfd);
}
-#endif /* HAVE_FCNTL_CLOSEM */