pseudo insists on dereferencing /proc/*/fd/* filenames which means that /dev/fd/62 or /proc/$$/fd/62 or /proc/self/fd/62 don't work.

This means the pseudo environment can break any program or script that depends on /dev/fd/* working

I think the easiest fix is to attempt to open the last symlink where lstat worked, not the one where it doesn't work.

This example works under normal system or with fakeroot, but fails under pseudo:

bash -c 'cat <( echo hello )'

strace shows what is going on:

bash -c 'strace -f cat <( echo hello )'

without pseudo (or even just using fakeroot), it's as simple as:

openat(AT_FDCWD, "/dev/fd/63", O_RDONLY) = 3


but with pseudo we get this link de-referencing and failure:


lstat("/dev", {st_mode=S_IFDIR|0755, st_size=4040, ...}) = 0

lstat("/dev/fd", {st_mode=S_IFLNK|0777, st_size=13, ...}) = 0

rt_sigprocmask(SIG_BLOCK, [HUP USR1 USR2 ALRM TERM CHLD], [HUP USR1 USR2 ALRM TERM CHLD], 8) = 0

readlink("/dev/fd", "/proc/self/fd", 4096) = 13

rt_sigprocmask(SIG_SETMASK, [HUP USR1 USR2 ALRM TERM CHLD], NULL, 8) = 0

lstat("/proc", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0

lstat("/proc/self", {st_mode=S_IFLNK|0777, st_size=0, ...}) = 0

rt_sigprocmask(SIG_BLOCK, [HUP USR1 USR2 ALRM TERM CHLD], [HUP USR1 USR2 ALRM TERM CHLD], 8) = 0

readlink("/proc/self", "6724", 4096)    = 4

rt_sigprocmask(SIG_SETMASK, [HUP USR1 USR2 ALRM TERM CHLD], NULL, 8) = 0

lstat("/proc/6724", {st_mode=S_IFDIR|0555, st_size=0, ...}) = 0

lstat("/proc/6724/fd", {st_mode=S_IFDIR|0500, st_size=0, ...}) = 0

lstat("/proc/6724/fd/63", {st_mode=S_IFLNK|0500, st_size=64, ...}) = 0

rt_sigprocmask(SIG_BLOCK, [HUP USR1 USR2 ALRM TERM CHLD], [HUP USR1 USR2 ALRM TERM CHLD], 8) = 0

readlink("/proc/6724/fd/63", "pipe:[21346885]", 4096) = 15

rt_sigprocmask(SIG_SETMASK, [HUP USR1 USR2 ALRM TERM CHLD], NULL, 8) = 0

lstat("/proc/6724/fd/pipe:[21346885]", 0x7ffe0f16e040) = -1 ENOENT (No such file or directory)

newfstatat(AT_FDCWD, "/proc/6724/fd/pipe:[21346885]", 0x7ffe0f16e080, 0) = -1 ENOENT (No such file or directory)

openat(AT_FDCWD, "/proc/6724/fd/pipe:[21346885]", O_RDONLY) = -1 ENOENT (No such file or directory)