diff options
Diffstat (limited to 'gnulib-m4/getcwd-path-max.m4')
| -rw-r--r-- | gnulib-m4/getcwd-path-max.m4 | 254 |
1 files changed, 254 insertions, 0 deletions
diff --git a/gnulib-m4/getcwd-path-max.m4 b/gnulib-m4/getcwd-path-max.m4 new file mode 100644 index 00000000..e9c52d90 --- /dev/null +++ b/gnulib-m4/getcwd-path-max.m4 @@ -0,0 +1,254 @@ +# getcwd-path-max.m4 +# serial 26 +dnl Copyright (C) 2003-2007, 2009-2024 Free Software Foundation, Inc. +dnl This file is free software; the Free Software Foundation +dnl gives unlimited permission to copy and/or distribute it, +dnl with or without modifications, as long as this notice is preserved. + +# Check for several getcwd bugs with long file names. +# If so, arrange to compile the wrapper function. + +# This is necessary for at least GNU libc on linux-2.4.19 and 2.4.20. +# I've heard that this is due to a Linux kernel bug, and that it has +# been fixed between 2.4.21-pre3 and 2.4.21-pre4. + +# From Jim Meyering + +AC_DEFUN([gl_FUNC_GETCWD_PATH_MAX], +[ + AC_CHECK_DECLS_ONCE([getcwd, alarm]) + AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles + AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) + AC_CHECK_HEADERS_ONCE([unistd.h]) + AC_REQUIRE([gl_PATHMAX_SNIPPET_PREREQ]) + AC_CACHE_CHECK([whether getcwd handles long file names properly], + [gl_cv_func_getcwd_path_max], + [# Arrange for deletion of the temporary directory this test creates. + ac_clean_files="$ac_clean_files confdir3" + dnl Please keep this in sync with tests/test-getcwd.c. + AC_RUN_IFELSE( + [AC_LANG_SOURCE( + [[ +#include <errno.h> +#include <stdlib.h> +#if HAVE_UNISTD_H +# include <unistd.h> +#else +# include <direct.h> +#endif +#if HAVE_DECL_ALARM +# include <signal.h> +#endif +#include <string.h> +#include <limits.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <fcntl.h> + +]gl_PATHMAX_SNIPPET[ + +#ifndef AT_FDCWD +# define AT_FDCWD 0 +#endif +#ifdef ENAMETOOLONG +# define is_ENAMETOOLONG(x) ((x) == ENAMETOOLONG) +#else +# define is_ENAMETOOLONG(x) 0 +#endif + +/* Use the getcwd function, not any macro. */ +#undef getcwd + +]GL_MDA_DEFINES[ + +#ifndef S_IRWXU +# define S_IRWXU 0700 +#endif + +/* The length of this name must be 8. */ +#define DIR_NAME "confdir3" +#define DIR_NAME_LEN 8 +#define DIR_NAME_SIZE (DIR_NAME_LEN + 1) + +/* The length of "../". */ +#define DOTDOTSLASH_LEN 3 + +/* Leftover bytes in the buffer, to work around library or OS bugs. */ +#define BUF_SLOP 20 + +int +main () +{ +#ifndef PATH_MAX + /* The Hurd doesn't define this, so getcwd can't exhibit the bug -- + at least not on a local file system. And if we were to start worrying + about remote file systems, we'd have to enable the wrapper function + all of the time, just to be safe. That's not worth the cost. */ + exit (0); +#elif ((INT_MAX / (DIR_NAME_SIZE / DOTDOTSLASH_LEN + 1) \ + - DIR_NAME_SIZE - BUF_SLOP) \ + <= PATH_MAX) + /* FIXME: Assuming there's a system for which this is true, + this should be done in a compile test. */ + exit (0); +#else + char buf[PATH_MAX * (DIR_NAME_SIZE / DOTDOTSLASH_LEN + 1) + + DIR_NAME_SIZE + BUF_SLOP]; + char *cwd; + size_t initial_cwd_len; + size_t cwd_len; + int fail; + size_t n_chdirs; + +# if HAVE_DECL_ALARM + /* This test makes some buggy getcwd implementations take a long time, e.g. + on NAS devices + <https://lists.gnu.org/archive/html/bug-gnulib/2024-03/msg00444.html> + and in sandboxed environments <https://bugs.gentoo.org/447970>. + Give up after 5 seconds; a getcwd slower than that isn't worth using + anyway. */ + signal (SIGALRM, SIG_DFL); + alarm (5); +# endif + + cwd = getcwd (buf, PATH_MAX); + if (cwd == NULL) + exit (10); + + cwd_len = initial_cwd_len = strlen (cwd); + fail = 0; + n_chdirs = 0; + + while (1) + { + size_t dotdot_max = PATH_MAX * (DIR_NAME_SIZE / DOTDOTSLASH_LEN); + char *c = NULL; + + cwd_len += DIR_NAME_SIZE; + /* If mkdir or chdir fails, it could be that this system cannot create + any file with an absolute name longer than PATH_MAX, such as cygwin. + If so, leave fail as 0, because the current working directory can't + be too long for getcwd if it can't even be created. On Linux with + the 9p file system, mkdir fails with error EINVAL when cwd_len gets + too long; ignore this failure because the getcwd() system call + produces good results whereas the gnulib substitute calls getdents64 + which fails with error EPROTO. + For other errors, be pessimistic and consider that as a failure, + too. */ + if (mkdir (DIR_NAME, S_IRWXU) < 0 || chdir (DIR_NAME) < 0) + { + if (! (errno == ERANGE || is_ENAMETOOLONG (errno))) + #ifdef __linux__ + if (! (errno == EINVAL)) + #endif + fail = 20; + break; + } + + if (PATH_MAX <= cwd_len && cwd_len < PATH_MAX + DIR_NAME_SIZE) + { + struct stat sb; + + c = getcwd (buf, PATH_MAX); + if (!c && errno == ENOENT) + { + fail = 11; + break; + } + if (c) + { + fail = 31; + break; + } + if (! (errno == ERANGE || is_ENAMETOOLONG (errno))) + { + fail = 21; + break; + } + + /* Our replacement needs to be able to stat() long ../../paths, + so generate a path larger than PATH_MAX to check, + avoiding the replacement if we can't stat(). */ + c = getcwd (buf, cwd_len + 1); + if (c && !AT_FDCWD && stat (c, &sb) != 0 && is_ENAMETOOLONG (errno)) + { + fail = 32; + break; + } + } + + if (dotdot_max <= cwd_len - initial_cwd_len) + { + if (dotdot_max + DIR_NAME_SIZE < cwd_len - initial_cwd_len) + break; + c = getcwd (buf, cwd_len + 1); + if (!c) + { + if (! (errno == ERANGE || errno == ENOENT + || is_ENAMETOOLONG (errno))) + { + fail = 22; + break; + } + if (AT_FDCWD || errno == ERANGE || errno == ENOENT) + { + fail = 12; + break; + } + } + } + + if (c && strlen (c) != cwd_len) + { + fail = 23; + break; + } + ++n_chdirs; + } + + /* Leaving behind such a deep directory is not polite. + So clean up here, right away, even though the driving + shell script would also clean up. */ + { + size_t i; + + /* Try rmdir first, in case the chdir failed. */ + rmdir (DIR_NAME); + for (i = 0; i <= n_chdirs; i++) + { + if (chdir ("..") < 0) + break; + if (rmdir (DIR_NAME) != 0) + break; + } + } + + exit (fail); +#endif +} + ]])], + [gl_cv_func_getcwd_path_max=yes], + [case $? in + 10|11|12) gl_cv_func_getcwd_path_max='no, but it is partly working';; + 31) gl_cv_func_getcwd_path_max='no, it has the AIX bug';; + 32) gl_cv_func_getcwd_path_max='yes, but with shorter paths';; + *) gl_cv_func_getcwd_path_max=no;; + esac], + [# Cross-compilation guesses: + case "$host_os" in + aix*) # On AIX, it has the AIX bug. + gl_cv_func_getcwd_path_max='guessing no, it has the AIX bug' ;; + gnu*) # On Hurd, it is 'yes'. + gl_cv_func_getcwd_path_max='guessing yes' ;; + linux* | kfreebsd*) + # On older Linux+glibc it's 'no, but it is partly working', + # on newer Linux+glibc it's 'yes'. + # On Linux+musl libc, it's 'no, but it is partly working'. + # On kFreeBSD+glibc, it's 'no, but it is partly working'. + gl_cv_func_getcwd_path_max='guessing no, but it is partly working' ;; + *) # If we don't know, obey --enable-cross-guesses. + gl_cv_func_getcwd_path_max="$gl_cross_guess_normal" ;; + esac + ]) + ]) +]) |