[5/7] nss_files: Add generic code for set*ent, end*ent and file open
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Patch applied to master at the time it was sent
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Commit Message
This reduces RSS usage if nss_files is not actually used, and can
be used later to make NSS data thread-specific. It also results in
a small code size reduction.
Before:
text data bss dec hex filename
2288 0 72 2360 938 nss/files-alias.os
1807 0 72 1879 757 nss/files-ethers.os
1371 0 72 1443 5a3 nss/files-grp.os
6246 0 72 6318 18ae nss/files-hosts.os
869 0 0 869 365 nss/files-initgroups.os
666 0 0 666 29a nss/files-init.os
1934 0 0 1934 78e nss/files-netgrp.os
2353 0 72 2425 979 nss/files-network.os
2130 0 72 2202 89a nss/files-proto.os
1372 0 72 1444 5a4 nss/files-pwd.os
2124 0 72 2196 894 nss/files-rpc.os
2265 0 72 2337 921 nss/files-service.os
1125 0 72 1197 4ad nss/files-sgrp.os
1124 0 72 1196 4ac nss/files-spwd.os
After:
text data bss dec hex filename
2040 0 0 2040 7f8 nss/files-alias.os
1599 0 0 1599 63f nss/files-ethers.os
1155 0 0 1155 483 nss/files-grp.os
6010 0 0 6010 177a nss/files-hosts.os
869 0 0 869 365 nss/files-initgroups.os
666 0 0 666 29a nss/files-init.os
1934 0 0 1934 78e nss/files-netgrp.os
2129 0 0 2129 851 nss/files-network.os
1914 0 0 1914 77a nss/files-proto.os
1156 0 0 1156 484 nss/files-pwd.os
1908 0 0 1908 774 nss/files-rpc.os
2057 0 0 2057 809 nss/files-service.os
909 0 0 909 38d nss/files-sgrp.os
908 0 0 908 38c nss/files-spwd.os
1090 0 8 1098 44a nss/nss_files_data.os
27674 code bytes before, 26344 code bytes after, so it is an overall
win despite the extra initialization code.
---
include/nss_files.h | 60 ++++++++++++++
nss/Makefile | 2 +-
nss/Versions | 4 +
nss/nss_files/files-XXX.c | 67 ++++-----------
nss/nss_files/files-alias.c | 69 ++++------------
nss/nss_files/files-hosts.c | 4 +-
nss/nss_files_data.c | 159 ++++++++++++++++++++++++++++++++++++
7 files changed, 257 insertions(+), 108 deletions(-)
create mode 100644 nss/nss_files_data.c
Comments
On 29/06/2021 07:11, Florian Weimer via Libc-alpha wrote:
> This reduces RSS usage if nss_files is not actually used, and can
> be used later to make NSS data thread-specific. It also results in
> a small code size reduction.
>
> Before:
>
> text data bss dec hex filename
> 2288 0 72 2360 938 nss/files-alias.os
> 1807 0 72 1879 757 nss/files-ethers.os
> 1371 0 72 1443 5a3 nss/files-grp.os
> 6246 0 72 6318 18ae nss/files-hosts.os
> 869 0 0 869 365 nss/files-initgroups.os
> 666 0 0 666 29a nss/files-init.os
> 1934 0 0 1934 78e nss/files-netgrp.os
> 2353 0 72 2425 979 nss/files-network.os
> 2130 0 72 2202 89a nss/files-proto.os
> 1372 0 72 1444 5a4 nss/files-pwd.os
> 2124 0 72 2196 894 nss/files-rpc.os
> 2265 0 72 2337 921 nss/files-service.os
> 1125 0 72 1197 4ad nss/files-sgrp.os
> 1124 0 72 1196 4ac nss/files-spwd.os
>
>
>
> After:
>
> text data bss dec hex filename
> 2040 0 0 2040 7f8 nss/files-alias.os
> 1599 0 0 1599 63f nss/files-ethers.os
> 1155 0 0 1155 483 nss/files-grp.os
> 6010 0 0 6010 177a nss/files-hosts.os
> 869 0 0 869 365 nss/files-initgroups.os
> 666 0 0 666 29a nss/files-init.os
> 1934 0 0 1934 78e nss/files-netgrp.os
> 2129 0 0 2129 851 nss/files-network.os
> 1914 0 0 1914 77a nss/files-proto.os
> 1156 0 0 1156 484 nss/files-pwd.os
> 1908 0 0 1908 774 nss/files-rpc.os
> 2057 0 0 2057 809 nss/files-service.os
> 909 0 0 909 38d nss/files-sgrp.os
> 908 0 0 908 38c nss/files-spwd.os
> 1090 0 8 1098 44a nss/nss_files_data.os
>
> 27674 code bytes before, 26344 code bytes after, so it is an overall
> win despite the extra initialization code.
LGTM, only a minor nit below.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> include/nss_files.h | 60 ++++++++++++++
> nss/Makefile | 2 +-
> nss/Versions | 4 +
> nss/nss_files/files-XXX.c | 67 ++++-----------
> nss/nss_files/files-alias.c | 69 ++++------------
> nss/nss_files/files-hosts.c | 4 +-
> nss/nss_files_data.c | 159 ++++++++++++++++++++++++++++++++++++
> 7 files changed, 257 insertions(+), 108 deletions(-)
> create mode 100644 nss/nss_files_data.c
>
> diff --git a/include/nss_files.h b/include/nss_files.h
> index 6a0dcdb85b..7bf1951496 100644
> --- a/include/nss_files.h
> +++ b/include/nss_files.h
> @@ -20,6 +20,9 @@
> #define _NSS_FILES_H
>
> #include <stdio.h>
> +#if IS_IN (libc)
> +#include <libc-lock.h>
> +#endif
>
> /* Open PATH for reading, as a data source for nss_files. */
> FILE *__nss_files_fopen (const char *path);
> @@ -47,6 +50,63 @@ int __nss_readline_seek (FILE *fp, off64_t offset) attribute_hidden;
> int __nss_parse_line_result (FILE *fp, off64_t offset, int parse_line_result);
> libc_hidden_proto (__nss_parse_line_result)
>
> +/* Per-file data. Used by the *ent functions that need to preserve
> + state across calls. */
> +struct nss_files_per_file_data
> +{
> + FILE *stream;
> +#if IS_IN (libc)
> + /* The size of locks changes between libc and nss_files, so this
> + member must be last and is only available in libc. */
> + __libc_lock_define (, lock);
> +#endif
> +};
> +
> +/* File index for __nss_files_data_get. */
> +enum nss_files_file
> + {
> + nss_file_aliasent,
> + nss_file_etherent,
> + nss_file_grent,
> + nss_file_hostent,
> + nss_file_netent,
> + nss_file_protoent,
> + nss_file_pwent,
> + nss_file_rpcent,
> + nss_file_servent,
> + nss_file_sgent,
> + nss_file_spent,
> +
> + nss_file_count
> + };
> +
> +/* Obtains a pointer to the per-file data for FILE, which is written
> + to *PDATA, and tries to open the file at PATH for it. On success,
> + returns NSS_STATUS_SUCCESS, and the caller must later call
> + __nss_files_data_put. On failure, NSS_STATUS_TRYAGAIN is returned,
> + and *ERRNOP and *HERRNOP are updated if these pointers are not
> + null. */
> +enum nss_status __nss_files_data_open (struct nss_files_per_file_data **pdata,
> + enum nss_files_file file,
> + const char *path,
> + int *errnop, int *herrnop);
> +libc_hidden_proto (__nss_files_data_open)
> +
Ok.
> +/* Unlock the per-file data, previously obtained by
> + __nss_files_data_open. */
> +void __nss_files_data_put (struct nss_files_per_file_data *data);
> +libc_hidden_proto (__nss_files_data_put)
> +
> +/* Performs the set*ent operation for FILE. PATH is the file to
> + open. */
> +enum nss_status __nss_files_data_setent (enum nss_files_file file,
> + const char *path);
> +libc_hidden_proto (__nss_files_data_setent)
> +
> +/* Performs the end*ent operation for FILE. */
> +enum nss_status __nss_files_data_endent (enum nss_files_file file);
> +libc_hidden_proto (__nss_files_data_endent)
> +
> struct parser_data;
>
> /* Instances of the parse_line function from
Ok.
> diff --git a/nss/Makefile b/nss/Makefile
> index 9682a31e20..271a0e7716 100644
> --- a/nss/Makefile
> +++ b/nss/Makefile
> @@ -31,7 +31,7 @@ routines = nsswitch getnssent getnssent_r digits_dots \
> compat-lookup nss_hash nss_files_fopen \
> nss_readline nss_parse_line_result \
> nss_fgetent_r nss_module nss_action \
> - nss_action_parse nss_database
> + nss_action_parse nss_database nss_files_data
>
> # These are the databases that go through nss dispatch.
> # Caution: if you add a database here, you must add its real name
Ok.
> diff --git a/nss/Versions b/nss/Versions
> index fdddea104c..7b040b4786 100644
> --- a/nss/Versions
> +++ b/nss/Versions
> @@ -19,6 +19,10 @@ libc {
> __nss_services_lookup2; __nss_next2; __nss_lookup;
> __nss_hash; __nss_database_get;
> __nss_files_fopen; __nss_readline; __nss_parse_line_result;
> + __nss_files_data_endent;
> + __nss_files_data_open;
> + __nss_files_data_put;
> + __nss_files_data_setent;
> }
> }
>
Ok.
> diff --git a/nss/nss_files/files-XXX.c b/nss/nss_files/files-XXX.c
> index b4b989d9bb..91553d7ca5 100644
> --- a/nss/nss_files/files-XXX.c
> +++ b/nss/nss_files/files-XXX.c
> @@ -45,10 +45,12 @@
> # include <netdb.h>
> # define H_ERRNO_PROTO , int *herrnop
> # define H_ERRNO_ARG , herrnop
> +# define H_ERRNO_ARG_OR_NULL herrnop
> # define H_ERRNO_SET(val) (*herrnop = (val))
> #else
> # define H_ERRNO_PROTO
> # define H_ERRNO_ARG
> +# define H_ERRNO_ARG_OR_NULL NULL
> # define H_ERRNO_SET(val) ((void) 0)
> #endif
>
> @@ -58,15 +60,11 @@
> # define EXTRA_ARGS_VALUE
> #endif
>
> -/* Locks the static variables in this file. */
> -__libc_lock_define_initialized (static, lock)
>
> /* Maintenance of the stream open on the database file. For getXXent
> operations the stream needs to be held open across calls, the other
> getXXbyYY operations all use their own stream. */
>
> -static FILE *stream;
> -
> /* Open database file if not already opened. */
> static enum nss_status
> internal_setent (FILE **stream)
> @@ -91,41 +89,13 @@ internal_setent (FILE **stream)
> enum nss_status
> CONCAT(_nss_files_set,ENTNAME) (int stayopen)
> {
> - enum nss_status status;
> -
> - __libc_lock_lock (lock);
> -
> - status = internal_setent (&stream);
> -
> - __libc_lock_unlock (lock);
> -
> - return status;
> -}
> -
> -
> -/* Close the database file. */
> -static void
> -internal_endent (FILE **stream)
> -{
> - if (*stream != NULL)
> - {
> - fclose (*stream);
> - *stream = NULL;
> - }
> + return __nss_files_data_setent (CONCAT (nss_file_, ENTNAME), DATAFILE);
> }
>
Ok.
> -
> -/* Thread-safe, exported version of that. */
> enum nss_status
> CONCAT(_nss_files_end,ENTNAME) (void)
> {
> - __libc_lock_lock (lock);
> -
> - internal_endent (&stream);
> -
> - __libc_lock_unlock (lock);
> -
> - return NSS_STATUS_SUCCESS;
> + return __nss_files_data_endent (CONCAT (nss_file_, ENTNAME));
> }
>
>
Ok.
> @@ -194,26 +164,19 @@ CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
> size_t buflen, int *errnop H_ERRNO_PROTO)
> {
> /* Return next entry in host file. */
> - enum nss_status status = NSS_STATUS_SUCCESS;
> -
> - __libc_lock_lock (lock);
> -
> - /* Be prepared that the set*ent function was not called before. */
> - if (stream == NULL)
> - {
> - int save_errno = errno;
> -
> - status = internal_setent (&stream);
> -
> - __set_errno (save_errno);
> - }
>
> - if (status == NSS_STATUS_SUCCESS)
> - status = internal_getent (stream, result, buffer, buflen, errnop
> - H_ERRNO_ARG EXTRA_ARGS_VALUE);
> + struct nss_files_per_file_data *data;
> + enum nss_status status = __nss_files_data_open (&data,
> + CONCAT (nss_file_, ENTNAME),
> + DATAFILE,
> + errnop, H_ERRNO_ARG_OR_NULL);
> + if (status != NSS_STATUS_SUCCESS)
> + return status;
>
> - __libc_lock_unlock (lock);
> + status = internal_getent (data->stream, result, buffer, buflen, errnop
> + H_ERRNO_ARG EXTRA_ARGS_VALUE);
>
> + __nss_files_data_put (data);
> return status;
> }
>
Ok.
> @@ -248,7 +211,7 @@ _nss_files_get##name##_r (proto, \
> == NSS_STATUS_SUCCESS) \
> { break_if_match } \
> \
> - internal_endent (&stream); \
> + fclose (stream); \
> } \
> \
> return status;
Ok.
\
> diff --git a/nss/nss_files/files-alias.c b/nss/nss_files/files-alias.c
> index 30971bfe56..9624b6224c 100644
> --- a/nss/nss_files/files-alias.c
> +++ b/nss/nss_files/files-alias.c
> @@ -33,16 +33,11 @@
>
> NSS_DECLARE_MODULE_FUNCTIONS (files)
>
> -/* Locks the static variables in this file. */
> -__libc_lock_define_initialized (static, lock)
>
> /* Maintenance of the stream open on the database file. For getXXent
> operations the stream needs to be held open across calls, the other
> getXXbyYY operations all use their own stream. */
>
> -static FILE *stream;
> -
> -
> static enum nss_status
> internal_setent (FILE **stream)
> {
> @@ -66,41 +61,13 @@ internal_setent (FILE **stream)
> enum nss_status
> _nss_files_setaliasent (void)
> {
> - enum nss_status status;
> -
> - __libc_lock_lock (lock);
> -
> - status = internal_setent (&stream);
> -
> - __libc_lock_unlock (lock);
> -
> - return status;
> -}
> -
> -
> -/* Close the database file. */
> -static void
> -internal_endent (FILE **stream)
> -{
> - if (*stream != NULL)
> - {
> - fclose (*stream);
> - *stream = NULL;
> - }
> + return __nss_files_data_setent (nss_file_aliasent, "/etc/aliases");
> }
>
Ok.
> -
> -/* Thread-safe, exported version of that. */
> enum nss_status
> _nss_files_endaliasent (void)
> {
> - __libc_lock_lock (lock);
> -
> - internal_endent (&stream);
> -
> - __libc_lock_unlock (lock);
> -
> - return NSS_STATUS_SUCCESS;
> + return __nss_files_data_endent (nss_file_aliasent);
> }
>
> /* Parsing the database file into `struct aliasent' data structures. */
Ok.
> @@ -369,26 +336,22 @@ _nss_files_getaliasent_r (struct aliasent *result, char *buffer, size_t buflen,
> int *errnop)
> {
> /* Return next entry in host file. */
> - enum nss_status status = NSS_STATUS_SUCCESS;
>
> - __libc_lock_lock (lock);
> + struct nss_files_per_file_data *data;
> + enum nss_status status = __nss_files_data_open (&data, nss_file_aliasent,
> + "/etc/aliases", errnop, NULL);
> + if (status != NSS_STATUS_SUCCESS)
> + return status;
>
> - /* Be prepared that the set*ent function was not called before. */
> - if (stream == NULL)
> - status = internal_setent (&stream);
> + result->alias_local = 1;
>
> - if (status == NSS_STATUS_SUCCESS)
> - {
> - result->alias_local = 1;
> -
> - /* Read lines until we get a definite result. */
> - do
> - status = get_next_alias (stream, NULL, result, buffer, buflen, errnop);
> - while (status == NSS_STATUS_RETURN);
> - }
> -
> - __libc_lock_unlock (lock);
> + /* Read lines until we get a definite result. */
> + do
> + status = get_next_alias (data->stream, NULL, result, buffer, buflen,
> + errnop);
> + while (status == NSS_STATUS_RETURN);
>
> + __nss_files_data_put (data);
> return status;
> }
>
Ok.
> @@ -418,9 +381,9 @@ _nss_files_getaliasbyname_r (const char *name, struct aliasent *result,
> do
> status = get_next_alias (stream, name, result, buffer, buflen, errnop);
> while (status == NSS_STATUS_RETURN);
> - }
>
> - internal_endent (&stream);
> + fclose (stream);
> + }
>
> return status;
> }
Ok.
> diff --git a/nss/nss_files/files-hosts.c b/nss/nss_files/files-hosts.c
> index 2b47ec3e53..1dd51d1db9 100644
> --- a/nss/nss_files/files-hosts.c
> +++ b/nss/nss_files/files-hosts.c
> @@ -349,7 +349,7 @@ _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
> status = gethostbyname3_multi
> (stream, name, af, result, buffer, buflen, errnop, herrnop);
>
> - internal_endent (&stream);
> + fclose (stream);
> }
>
> if (canonp && status == NSS_STATUS_SUCCESS)
> @@ -475,7 +475,7 @@ _nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
> status = NSS_STATUS_SUCCESS;
> }
>
> - internal_endent (&stream);
> + fclose (stream);
> }
> else if (status == NSS_STATUS_TRYAGAIN)
> {
Ok.
> diff --git a/nss/nss_files_data.c b/nss/nss_files_data.c
> new file mode 100644
> index 0000000000..7b7662abf1
> --- /dev/null
> +++ b/nss/nss_files_data.c
> @@ -0,0 +1,159 @@
> +/* Returns a pointer to the global nss_files data structure.
> + Copyright (C) 2021 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 <nss_files.h>
> +
> +#include <allocate_once.h>
> +#include <errno.h>
> +#include <netdb.h>
> +#include <nss.h>
> +#include <stdlib.h>
> +
> +/* This collects all per file-data. */
> +struct nss_files_data
> +{
> + struct nss_files_per_file_data files[nss_file_count];
> +};
> +
> +/* For use with allocate_once. */
> +static void *nss_files_global;
> +static void *
> +nss_files_global_allocate (void *closure)
> +{
> + struct nss_files_data *result = malloc (sizeof (*result));
> + if (result != NULL)
Maybe add brackets here?
> + for (int i = 0; i < nss_file_count; ++i)
> + {
> + result->files[i].stream = NULL;
> + __libc_lock_init (result->files[i].lock);
> + }
> + return result;
> +}
Ok.
> +/* Like __nss_files_data_open, but does not perform the open call. */
> +static enum nss_status
> +__nss_files_data_get (struct nss_files_per_file_data **pdata,
> + enum nss_files_file file, int *errnop, int *herrnop)
> +{
> + struct nss_files_data *data = allocate_once (&nss_files_global,
> + nss_files_global_allocate,
> + NULL, NULL);
> + if (data == NULL)
> + {
> + if (errnop != NULL)
> + *errnop = errno;
> + if (herrnop != NULL)
> + {
> + __set_h_errno (NETDB_INTERNAL);
> + *herrnop = NETDB_INTERNAL;
> + }
> + return NSS_STATUS_TRYAGAIN;
> + }
> +
> + *pdata = &data->files[file];
> + __libc_lock_lock ((*pdata)->lock);
> + return NSS_STATUS_SUCCESS;
> +}
> +
Ok.
> +/* Helper function for opening the backing file at PATH. */
> +static enum nss_status
> +__nss_files_data_internal_open (struct nss_files_per_file_data *data,
> + const char *path)
> +{
> + enum nss_status status = NSS_STATUS_SUCCESS;
> +
> + if (data->stream == NULL)
> + {
> + data->stream = __nss_files_fopen (path);
> +
> + if (data->stream == NULL)
> + status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
> + }
> +
> + return status;
> +}
> +
> +
Ok.
> +enum nss_status
> +__nss_files_data_open (struct nss_files_per_file_data **pdata,
> + enum nss_files_file file, const char *path,
> + int *errnop, int *herrnop)
> +{
> + enum nss_status status = __nss_files_data_get (pdata, file, errnop, herrnop);
> + if (status != NSS_STATUS_SUCCESS)
> + return status;
> +
> + /* Be prepared that the set*ent function was not called before. */
> + if ((*pdata)->stream == NULL)
> + {
> + int saved_errno = errno;
> + status = __nss_files_data_internal_open (*pdata, path);
> + __set_errno (saved_errno);
> + if (status != NSS_STATUS_SUCCESS)
> + __nss_files_data_put (*pdata);
> + }
> +
> + return status;
> +}
> +
> +libc_hidden_def (__nss_files_data_open)
> +
Ok.
> +void
> +__nss_files_data_put (struct nss_files_per_file_data *data)
> +{
> + __libc_lock_unlock (data->lock);
> +}
> +libc_hidden_def (__nss_files_data_put)
> +
Ok.
> +enum nss_status
> +__nss_files_data_setent (enum nss_files_file file, const char *path)
> +{
> + struct nss_files_per_file_data *data;
> + enum nss_status status = __nss_files_data_get (&data, file, NULL, NULL);
> + if (status != NSS_STATUS_SUCCESS)
> + return status;
> +
> + if (data->stream == NULL)
> + status = __nss_files_data_internal_open (data, path);
> + else
> + rewind (data->stream);
> +
> + __nss_files_data_put (data);
> + return status;
> +}
> +libc_hidden_def (__nss_files_data_setent)
> +
Ok.
> +enum nss_status
> +__nss_files_data_endent (enum nss_files_file file)
> +{
> + /* No cleanup is necessary if not initialized. */
> + struct nss_files_data *data = atomic_load_acquire (&nss_files_global);
> + if (data == NULL)
> + return NSS_STATUS_SUCCESS;
> +
> + struct nss_files_per_file_data *fdata = &data->files[file];
> + __libc_lock_lock (fdata->lock);
> + if (fdata->stream != NULL)
> + {
> + fclose (fdata->stream);
> + fdata->stream = NULL;
> + }
> + __libc_lock_unlock (fdata->lock);
> +
> + return NSS_STATUS_SUCCESS;
> +}
> +libc_hidden_def (__nss_files_data_endent)
>
Ok.
@@ -20,6 +20,9 @@
#define _NSS_FILES_H
#include <stdio.h>
+#if IS_IN (libc)
+#include <libc-lock.h>
+#endif
/* Open PATH for reading, as a data source for nss_files. */
FILE *__nss_files_fopen (const char *path);
@@ -47,6 +50,63 @@ int __nss_readline_seek (FILE *fp, off64_t offset) attribute_hidden;
int __nss_parse_line_result (FILE *fp, off64_t offset, int parse_line_result);
libc_hidden_proto (__nss_parse_line_result)
+/* Per-file data. Used by the *ent functions that need to preserve
+ state across calls. */
+struct nss_files_per_file_data
+{
+ FILE *stream;
+#if IS_IN (libc)
+ /* The size of locks changes between libc and nss_files, so this
+ member must be last and is only available in libc. */
+ __libc_lock_define (, lock);
+#endif
+};
+
+/* File index for __nss_files_data_get. */
+enum nss_files_file
+ {
+ nss_file_aliasent,
+ nss_file_etherent,
+ nss_file_grent,
+ nss_file_hostent,
+ nss_file_netent,
+ nss_file_protoent,
+ nss_file_pwent,
+ nss_file_rpcent,
+ nss_file_servent,
+ nss_file_sgent,
+ nss_file_spent,
+
+ nss_file_count
+ };
+
+/* Obtains a pointer to the per-file data for FILE, which is written
+ to *PDATA, and tries to open the file at PATH for it. On success,
+ returns NSS_STATUS_SUCCESS, and the caller must later call
+ __nss_files_data_put. On failure, NSS_STATUS_TRYAGAIN is returned,
+ and *ERRNOP and *HERRNOP are updated if these pointers are not
+ null. */
+enum nss_status __nss_files_data_open (struct nss_files_per_file_data **pdata,
+ enum nss_files_file file,
+ const char *path,
+ int *errnop, int *herrnop);
+libc_hidden_proto (__nss_files_data_open)
+
+/* Unlock the per-file data, previously obtained by
+ __nss_files_data_open. */
+void __nss_files_data_put (struct nss_files_per_file_data *data);
+libc_hidden_proto (__nss_files_data_put)
+
+/* Performs the set*ent operation for FILE. PATH is the file to
+ open. */
+enum nss_status __nss_files_data_setent (enum nss_files_file file,
+ const char *path);
+libc_hidden_proto (__nss_files_data_setent)
+
+/* Performs the end*ent operation for FILE. */
+enum nss_status __nss_files_data_endent (enum nss_files_file file);
+libc_hidden_proto (__nss_files_data_endent)
+
struct parser_data;
/* Instances of the parse_line function from
@@ -31,7 +31,7 @@ routines = nsswitch getnssent getnssent_r digits_dots \
compat-lookup nss_hash nss_files_fopen \
nss_readline nss_parse_line_result \
nss_fgetent_r nss_module nss_action \
- nss_action_parse nss_database
+ nss_action_parse nss_database nss_files_data
# These are the databases that go through nss dispatch.
# Caution: if you add a database here, you must add its real name
@@ -19,6 +19,10 @@ libc {
__nss_services_lookup2; __nss_next2; __nss_lookup;
__nss_hash; __nss_database_get;
__nss_files_fopen; __nss_readline; __nss_parse_line_result;
+ __nss_files_data_endent;
+ __nss_files_data_open;
+ __nss_files_data_put;
+ __nss_files_data_setent;
}
}
@@ -45,10 +45,12 @@
# include <netdb.h>
# define H_ERRNO_PROTO , int *herrnop
# define H_ERRNO_ARG , herrnop
+# define H_ERRNO_ARG_OR_NULL herrnop
# define H_ERRNO_SET(val) (*herrnop = (val))
#else
# define H_ERRNO_PROTO
# define H_ERRNO_ARG
+# define H_ERRNO_ARG_OR_NULL NULL
# define H_ERRNO_SET(val) ((void) 0)
#endif
@@ -58,15 +60,11 @@
# define EXTRA_ARGS_VALUE
#endif
-/* Locks the static variables in this file. */
-__libc_lock_define_initialized (static, lock)
/* Maintenance of the stream open on the database file. For getXXent
operations the stream needs to be held open across calls, the other
getXXbyYY operations all use their own stream. */
-static FILE *stream;
-
/* Open database file if not already opened. */
static enum nss_status
internal_setent (FILE **stream)
@@ -91,41 +89,13 @@ internal_setent (FILE **stream)
enum nss_status
CONCAT(_nss_files_set,ENTNAME) (int stayopen)
{
- enum nss_status status;
-
- __libc_lock_lock (lock);
-
- status = internal_setent (&stream);
-
- __libc_lock_unlock (lock);
-
- return status;
-}
-
-
-/* Close the database file. */
-static void
-internal_endent (FILE **stream)
-{
- if (*stream != NULL)
- {
- fclose (*stream);
- *stream = NULL;
- }
+ return __nss_files_data_setent (CONCAT (nss_file_, ENTNAME), DATAFILE);
}
-
-/* Thread-safe, exported version of that. */
enum nss_status
CONCAT(_nss_files_end,ENTNAME) (void)
{
- __libc_lock_lock (lock);
-
- internal_endent (&stream);
-
- __libc_lock_unlock (lock);
-
- return NSS_STATUS_SUCCESS;
+ return __nss_files_data_endent (CONCAT (nss_file_, ENTNAME));
}
@@ -194,26 +164,19 @@ CONCAT(_nss_files_get,ENTNAME_r) (struct STRUCTURE *result, char *buffer,
size_t buflen, int *errnop H_ERRNO_PROTO)
{
/* Return next entry in host file. */
- enum nss_status status = NSS_STATUS_SUCCESS;
-
- __libc_lock_lock (lock);
-
- /* Be prepared that the set*ent function was not called before. */
- if (stream == NULL)
- {
- int save_errno = errno;
-
- status = internal_setent (&stream);
-
- __set_errno (save_errno);
- }
- if (status == NSS_STATUS_SUCCESS)
- status = internal_getent (stream, result, buffer, buflen, errnop
- H_ERRNO_ARG EXTRA_ARGS_VALUE);
+ struct nss_files_per_file_data *data;
+ enum nss_status status = __nss_files_data_open (&data,
+ CONCAT (nss_file_, ENTNAME),
+ DATAFILE,
+ errnop, H_ERRNO_ARG_OR_NULL);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
- __libc_lock_unlock (lock);
+ status = internal_getent (data->stream, result, buffer, buflen, errnop
+ H_ERRNO_ARG EXTRA_ARGS_VALUE);
+ __nss_files_data_put (data);
return status;
}
@@ -248,7 +211,7 @@ _nss_files_get##name##_r (proto, \
== NSS_STATUS_SUCCESS) \
{ break_if_match } \
\
- internal_endent (&stream); \
+ fclose (stream); \
} \
\
return status; \
@@ -33,16 +33,11 @@
NSS_DECLARE_MODULE_FUNCTIONS (files)
-/* Locks the static variables in this file. */
-__libc_lock_define_initialized (static, lock)
/* Maintenance of the stream open on the database file. For getXXent
operations the stream needs to be held open across calls, the other
getXXbyYY operations all use their own stream. */
-static FILE *stream;
-
-
static enum nss_status
internal_setent (FILE **stream)
{
@@ -66,41 +61,13 @@ internal_setent (FILE **stream)
enum nss_status
_nss_files_setaliasent (void)
{
- enum nss_status status;
-
- __libc_lock_lock (lock);
-
- status = internal_setent (&stream);
-
- __libc_lock_unlock (lock);
-
- return status;
-}
-
-
-/* Close the database file. */
-static void
-internal_endent (FILE **stream)
-{
- if (*stream != NULL)
- {
- fclose (*stream);
- *stream = NULL;
- }
+ return __nss_files_data_setent (nss_file_aliasent, "/etc/aliases");
}
-
-/* Thread-safe, exported version of that. */
enum nss_status
_nss_files_endaliasent (void)
{
- __libc_lock_lock (lock);
-
- internal_endent (&stream);
-
- __libc_lock_unlock (lock);
-
- return NSS_STATUS_SUCCESS;
+ return __nss_files_data_endent (nss_file_aliasent);
}
/* Parsing the database file into `struct aliasent' data structures. */
@@ -369,26 +336,22 @@ _nss_files_getaliasent_r (struct aliasent *result, char *buffer, size_t buflen,
int *errnop)
{
/* Return next entry in host file. */
- enum nss_status status = NSS_STATUS_SUCCESS;
- __libc_lock_lock (lock);
+ struct nss_files_per_file_data *data;
+ enum nss_status status = __nss_files_data_open (&data, nss_file_aliasent,
+ "/etc/aliases", errnop, NULL);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
- /* Be prepared that the set*ent function was not called before. */
- if (stream == NULL)
- status = internal_setent (&stream);
+ result->alias_local = 1;
- if (status == NSS_STATUS_SUCCESS)
- {
- result->alias_local = 1;
-
- /* Read lines until we get a definite result. */
- do
- status = get_next_alias (stream, NULL, result, buffer, buflen, errnop);
- while (status == NSS_STATUS_RETURN);
- }
-
- __libc_lock_unlock (lock);
+ /* Read lines until we get a definite result. */
+ do
+ status = get_next_alias (data->stream, NULL, result, buffer, buflen,
+ errnop);
+ while (status == NSS_STATUS_RETURN);
+ __nss_files_data_put (data);
return status;
}
@@ -418,9 +381,9 @@ _nss_files_getaliasbyname_r (const char *name, struct aliasent *result,
do
status = get_next_alias (stream, name, result, buffer, buflen, errnop);
while (status == NSS_STATUS_RETURN);
- }
- internal_endent (&stream);
+ fclose (stream);
+ }
return status;
}
@@ -349,7 +349,7 @@ _nss_files_gethostbyname3_r (const char *name, int af, struct hostent *result,
status = gethostbyname3_multi
(stream, name, af, result, buffer, buflen, errnop, herrnop);
- internal_endent (&stream);
+ fclose (stream);
}
if (canonp && status == NSS_STATUS_SUCCESS)
@@ -475,7 +475,7 @@ _nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
status = NSS_STATUS_SUCCESS;
}
- internal_endent (&stream);
+ fclose (stream);
}
else if (status == NSS_STATUS_TRYAGAIN)
{
new file mode 100644
@@ -0,0 +1,159 @@
+/* Returns a pointer to the global nss_files data structure.
+ Copyright (C) 2021 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 <nss_files.h>
+
+#include <allocate_once.h>
+#include <errno.h>
+#include <netdb.h>
+#include <nss.h>
+#include <stdlib.h>
+
+/* This collects all per file-data. */
+struct nss_files_data
+{
+ struct nss_files_per_file_data files[nss_file_count];
+};
+
+/* For use with allocate_once. */
+static void *nss_files_global;
+static void *
+nss_files_global_allocate (void *closure)
+{
+ struct nss_files_data *result = malloc (sizeof (*result));
+ if (result != NULL)
+ for (int i = 0; i < nss_file_count; ++i)
+ {
+ result->files[i].stream = NULL;
+ __libc_lock_init (result->files[i].lock);
+ }
+ return result;
+}
+/* Like __nss_files_data_open, but does not perform the open call. */
+static enum nss_status
+__nss_files_data_get (struct nss_files_per_file_data **pdata,
+ enum nss_files_file file, int *errnop, int *herrnop)
+{
+ struct nss_files_data *data = allocate_once (&nss_files_global,
+ nss_files_global_allocate,
+ NULL, NULL);
+ if (data == NULL)
+ {
+ if (errnop != NULL)
+ *errnop = errno;
+ if (herrnop != NULL)
+ {
+ __set_h_errno (NETDB_INTERNAL);
+ *herrnop = NETDB_INTERNAL;
+ }
+ return NSS_STATUS_TRYAGAIN;
+ }
+
+ *pdata = &data->files[file];
+ __libc_lock_lock ((*pdata)->lock);
+ return NSS_STATUS_SUCCESS;
+}
+
+/* Helper function for opening the backing file at PATH. */
+static enum nss_status
+__nss_files_data_internal_open (struct nss_files_per_file_data *data,
+ const char *path)
+{
+ enum nss_status status = NSS_STATUS_SUCCESS;
+
+ if (data->stream == NULL)
+ {
+ data->stream = __nss_files_fopen (path);
+
+ if (data->stream == NULL)
+ status = errno == EAGAIN ? NSS_STATUS_TRYAGAIN : NSS_STATUS_UNAVAIL;
+ }
+
+ return status;
+}
+
+
+enum nss_status
+__nss_files_data_open (struct nss_files_per_file_data **pdata,
+ enum nss_files_file file, const char *path,
+ int *errnop, int *herrnop)
+{
+ enum nss_status status = __nss_files_data_get (pdata, file, errnop, herrnop);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
+
+ /* Be prepared that the set*ent function was not called before. */
+ if ((*pdata)->stream == NULL)
+ {
+ int saved_errno = errno;
+ status = __nss_files_data_internal_open (*pdata, path);
+ __set_errno (saved_errno);
+ if (status != NSS_STATUS_SUCCESS)
+ __nss_files_data_put (*pdata);
+ }
+
+ return status;
+}
+
+libc_hidden_def (__nss_files_data_open)
+
+void
+__nss_files_data_put (struct nss_files_per_file_data *data)
+{
+ __libc_lock_unlock (data->lock);
+}
+libc_hidden_def (__nss_files_data_put)
+
+enum nss_status
+__nss_files_data_setent (enum nss_files_file file, const char *path)
+{
+ struct nss_files_per_file_data *data;
+ enum nss_status status = __nss_files_data_get (&data, file, NULL, NULL);
+ if (status != NSS_STATUS_SUCCESS)
+ return status;
+
+ if (data->stream == NULL)
+ status = __nss_files_data_internal_open (data, path);
+ else
+ rewind (data->stream);
+
+ __nss_files_data_put (data);
+ return status;
+}
+libc_hidden_def (__nss_files_data_setent)
+
+enum nss_status
+__nss_files_data_endent (enum nss_files_file file)
+{
+ /* No cleanup is necessary if not initialized. */
+ struct nss_files_data *data = atomic_load_acquire (&nss_files_global);
+ if (data == NULL)
+ return NSS_STATUS_SUCCESS;
+
+ struct nss_files_per_file_data *fdata = &data->files[file];
+ __libc_lock_lock (fdata->lock);
+ if (fdata->stream != NULL)
+ {
+ fclose (fdata->stream);
+ fdata->stream = NULL;
+ }
+ __libc_lock_unlock (fdata->lock);
+
+ return NSS_STATUS_SUCCESS;
+}
+libc_hidden_def (__nss_files_data_endent)