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From: Florian Weimer <fw@sourceware.org> To: glibc-cvs@sourceware.org Subject: [glibc] elf: Implement _dl_write Date: Wed, 7 Oct 2020 15:35:29 +0000 (GMT) [thread overview] Message-ID: <20201007153529.7DC47384242A@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b31d4355ae817aa3caf9414f842cc07465bca028 commit b31d4355ae817aa3caf9414f842cc07465bca028 Author: Florian Weimer <fweimer@redhat.com> Date: Wed Oct 7 16:39:50 2020 +0200 elf: Implement _dl_write The generic version is parallel to _dl_writev. It cannot use _dl_writev directly because the errno value needs to be obtained under a lock. Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Diff: --- elf/Makefile | 2 +- elf/dl-write.c | 56 ++++++++++++++++++++++++++++++++++++++ sysdeps/generic/ldsodefs.h | 6 ++++ sysdeps/unix/sysv/linux/dl-write.c | 30 ++++++++++++++++++++ 4 files changed, 93 insertions(+), 1 deletion(-) diff --git a/elf/Makefile b/elf/Makefile index e0a8bf2998..ab792d45c2 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -34,7 +34,7 @@ dl-routines = $(addprefix dl-,load lookup object reloc deps \ version profile tls origin scope \ execstack open close trampoline \ exception sort-maps lookup-direct \ - call-libc-early-init) + call-libc-early-init write) ifeq (yes,$(use-ldconfig)) dl-routines += dl-cache endif diff --git a/elf/dl-write.c b/elf/dl-write.c new file mode 100644 index 0000000000..7350aff003 --- /dev/null +++ b/elf/dl-write.c @@ -0,0 +1,56 @@ +/* Implementation of the _dl_write function. Generic version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <ldsodefs.h> +#include <libc-lock.h> +#include <sys/uio.h> + +ssize_t +_dl_write (int fd, const void *buffer, size_t length) +{ + struct iovec iov = { .iov_base = (void *) buffer, .iov_len = length }; + ssize_t ret; + +#if RTLD_PRIVATE_ERRNO + /* We have to take this lock just to be sure we don't clobber the private + errno when it's being used by another thread that cares about it. + Yet we must be sure not to try calling the lock functions before + the thread library is fully initialized. */ + if (__glibc_unlikely (_dl_starting_up)) + { + ret = __writev (fd, &iov, 1); + if (ret < 0) + ret = -errno; + } + else + { + __rtld_lock_lock_recursive (GL(dl_load_lock)); + __writev (fd, &iov, 1); + if (ret < 0) + ret = -errno; + __rtld_lock_unlock_recursive (GL(dl_load_lock)); + } +#else + ret = __writev (fd, &iov, 1); + if (ret < 0) + ret = -errno; +#endif + + return ret; +} diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index ba114ab4b1..7cb1fccc80 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -757,6 +757,12 @@ _dl_dprintf (int fd, const char *fmt, ...) } #endif +/* Write LENGTH bytes at BUFFER to FD, like write. Returns the number + of bytes written on success, or a negative error constant on + failure. */ +ssize_t _dl_write (int fd, const void *buffer, size_t length) + attribute_hidden; + /* Write a message on the specified descriptor standard output. The parameters are interpreted as for a `printf' call. */ void _dl_printf (const char *fmt, ...) diff --git a/sysdeps/unix/sysv/linux/dl-write.c b/sysdeps/unix/sysv/linux/dl-write.c new file mode 100644 index 0000000000..1c6298fb41 --- /dev/null +++ b/sysdeps/unix/sysv/linux/dl-write.c @@ -0,0 +1,30 @@ +/* Implementation of the _dl_write function. Linux version. + Copyright (C) 2020 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#include <sysdep.h> +#include <unistd.h> +#include <ldsodefs.h> + +ssize_t +_dl_write (int fd, const void *buffer, size_t length) +{ + long int r = INTERNAL_SYSCALL_CALL (write, fd, buffer, length); + if (INTERNAL_SYSCALL_ERROR_P (r)) + r = - INTERNAL_SYSCALL_ERRNO (r); + return r; +}
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