glibc/posix/Versions
Adhemerval Zanella 882d6e17bc posix: Add posix_spawn_file_actions_addclosefrom_np
This patch adds a way to close a range of file descriptors on
posix_spawn as a new file action.  The API is similar to the one
provided by Solaris 11 [1], where the file action causes the all open
file descriptors greater than or equal to input on to be closed when
the new process is spawned.

The function posix_spawn_file_actions_addclosefrom_np is safe to be
implemented by iterating over /proc/self/fd, since the Linux spawni.c
helper process does not use CLONE_FILES, so its has own file descriptor
table and any failure (in /proc operation) aborts the process creation
and returns an error to the caller.

I am aware that this file action might be redundant to the current
approach of POSIX in promoting O_CLOEXEC in more interfaces. However
O_CLOEXEC is still not the default and for some specific usages, the
caller needs to close all possible file descriptors to avoid them
leaking.  Some examples are CPython (discussed in BZ#10353) and OpenJDK
jspawnhelper [2] (where OpenJDK spawns a helper process to exactly
closes all file descriptors).  Most likely any environment which calls
functions that might open file descriptor under the hood and aim to use
posix_spawn might face the same requirement.

Checked on x86_64-linux-gnu and i686-linux-gnu on kernel 5.11 and 4.15.

[1] https://docs.oracle.com/cd/E36784_01/html/E36874/posix-spawn-file-actions-addclosefrom-np-3c.html
[2] https://github.com/openjdk/jdk/blob/master/src/java.base/unix/native/libjava/childproc.c#L82
2021-07-08 14:08:15 -03:00

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libc {
GLIBC_2.0 {
# functions with special/multiple interfaces
__bsd_getpgrp; __getpgid; __setpgid;
# functions with required interface outside normal name space
_exit;
# functions used in other libraries
__sched_get_priority_max; __sched_get_priority_min;
__sched_getparam; __sched_getscheduler; __sched_setscheduler;
__sched_yield; __fork; __getpid; __wait;
# functions used by libstdc++ 2.7.2
__waitpid;
# global variables
__environ; _environ;
# variables in normal name space
environ; optarg; opterr; optind; optopt;
re_max_failures; re_syntax_options;
# a*
alarm;
# c*
confstr;
# e*
execl; execle; execlp; execv; execve; execvp; fexecve;
# f*
fnmatch; fork; fpathconf; freeaddrinfo;
# g*
getaddrinfo; getdtablesize; getegid; geteuid; getgid; getopt; getopt_long;
getopt_long_only; getpgid; getpgrp; getpid; getppid; getsid; getuid; glob;
glob_pattern_p; globfree; group_member;
# n*
nanosleep;
# p*
pathconf; pause; pselect;
# r*
re_comp; re_compile_fastmap; re_compile_pattern; re_exec; re_match;
re_match_2; re_search; re_search_2; re_set_registers; re_set_syntax;
regcomp; regerror; regexec; regfree;
# s*
sched_get_priority_max; sched_get_priority_min; sched_getparam;
sched_getscheduler; sched_rr_get_interval; sched_setparam;
sched_setscheduler; sched_yield; setegid; seteuid; setgid;
setpgid; setpgrp; setsid; setuid; sleep; sysconf;
# t*
times;
# u*
uname;
# v*
vfork;
# w*
wait; wait3; wait4; waitpid;
}
GLIBC_2.1 {
# functions used in other libraries
__pread64; __pwrite64;
# g*
gai_strerror; getnameinfo; glob64; globfree64;
# p*
pread; pread64; pwrite; pwrite64;
# w*
waitid; wordexp; wordfree;
}
GLIBC_2.1 {
# Compat symbols for the obsolete, unimplemented XSI streams extension.
fattach; fdetach; getmsg; getpmsg; isastream; putmsg; putpmsg;
}
GLIBC_2.1.2 {
# functions used in other libraries
__vfork;
}
GLIBC_2.2 {
# p*
posix_spawn_file_actions_init; posix_spawn_file_actions_destroy;
posix_spawn_file_actions_addclose; posix_spawn_file_actions_addopen;
posix_spawn_file_actions_adddup2;
posix_spawnattr_init; posix_spawnattr_destroy;
posix_spawnattr_getsigdefault; posix_spawnattr_setsigdefault;
posix_spawnattr_getflags; posix_spawnattr_setflags;
posix_spawnattr_getpgroup; posix_spawnattr_setpgroup;
posix_spawnattr_setsigmask; posix_spawnattr_getsigmask;
posix_spawn; posix_spawnp; posix_spawnattr_getschedpolicy;
posix_spawnattr_setschedpolicy; posix_spawnattr_getschedparam;
posix_spawnattr_setschedparam;
# Used in macros.
__sysconf;
}
GLIBC_2.2.3 {
# Extended Interface.
fnmatch;
}
GLIBC_2.2.6 {
# For syscall wrapper
__nanosleep;
}
GLIBC_2.3.2 {
# Note that these symbols appear in sysdeps/unix/sysv/linux/Versions
# under GLIBC_2.0; the first instance in the script is taken as the
# default, so linux configurations put them in GLIBC_2.0 while other
# configuration put them in GLIBC_2.3.2.
getresgid; getresuid; setresgid; setresuid;
}
GLIBC_2.3.3 {
sched_getaffinity; sched_setaffinity;
}
GLIBC_2.3.4 {
regexec;
}
GLIBC_2.6 {
__sched_cpucount;
}
GLIBC_2.7 {
__sched_cpualloc; __sched_cpufree;
}
GLIBC_2.10 {
__posix_getopt;
}
GLIBC_2.11 {
execvpe;
}
GLIBC_2.15 {
posix_spawn;
posix_spawnp;
}
GLIBC_2.27 {
glob; glob64;
}
GLIBC_2.29 {
posix_spawn_file_actions_addchdir_np;
posix_spawn_file_actions_addfchdir_np;
}
GLIBC_2.30 {
}
GLIBC_2.34 {
_Fork;
execveat;
posix_spawn_file_actions_addclosefrom_np;
}
GLIBC_PRIVATE {
__libc_fork; __libc_pread; __libc_pwrite;
__nanosleep_nocancel; __pause_nocancel;
__shm_get_name;
}
}