mirror of
https://github.com/flatpak/flatpak.git
synced 2026-03-28 03:45:10 -04:00
fdio: New APIs to read/write on fds, fd-relative
We don't have this really in GLib, unfortunately. We do want GCancellable, but we also want to operate on raw fds where possible. The "read a file and validate as UTF-8" is a common use case of mine, and this combines that with openat().
This commit is contained in:
Colin Walters
@@ -28,6 +28,8 @@ libglnx_la_SOURCES = \
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$(libglnx_srcpath)/glnx-console.c \
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$(libglnx_srcpath)/glnx-dirfd.h \
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$(libglnx_srcpath)/glnx-dirfd.c \
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$(libglnx_srcpath)/glnx-fdio.h \
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$(libglnx_srcpath)/glnx-fdio.c \
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$(libglnx_srcpath)/glnx-xattrs.h \
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$(libglnx_srcpath)/glnx-xattrs.c \
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$(libglnx_srcpath)/glnx-shutil.h \
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225
glnx-fdio.c
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225
glnx-fdio.c
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@@ -0,0 +1,225 @@
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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
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*
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* Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include "config.h"
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#include <string.h>
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#include <stdio.h>
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#include <glnx-fdio.h>
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#include <glnx-errors.h>
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#include <glnx-local-alloc.h>
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static guint8*
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glnx_fd_readall_malloc (int fd,
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gsize *out_len,
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gboolean nul_terminate,
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GCancellable *cancellable,
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GError **error)
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{
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gboolean success = FALSE;
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const guint maxreadlen = 4096;
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int res;
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struct stat stbuf;
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guint8* buf = NULL;
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gsize buf_allocated;
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gsize buf_size = 0;
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gssize bytes_read;
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do
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res = fstat (fd, &stbuf);
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while (G_UNLIKELY (res == -1 && errno == EINTR));
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if (res == -1)
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{
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glnx_set_error_from_errno (error);
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goto out;
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}
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if (S_ISREG (stbuf.st_mode) && stbuf.st_size > 0)
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buf_allocated = stbuf.st_size;
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else
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buf_allocated = 16;
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buf = g_malloc (buf_allocated);
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while (TRUE)
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{
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gsize readlen = MIN (buf_allocated - buf_size, maxreadlen);
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if (g_cancellable_set_error_if_cancelled (cancellable, error))
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goto out;
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do
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bytes_read = read (fd, buf + buf_size, readlen);
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while (G_UNLIKELY (bytes_read == -1 && errno == EINTR));
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if (G_UNLIKELY (bytes_read == -1))
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{
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glnx_set_error_from_errno (error);
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goto out;
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}
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if (bytes_read == 0)
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break;
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buf_size += bytes_read;
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if (buf_allocated - buf_size < maxreadlen)
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buf = g_realloc (buf, buf_allocated *= 2);
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}
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if (nul_terminate)
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{
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if (buf_allocated - buf_size == 0)
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buf = g_realloc (buf, buf_allocated + 1);
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buf[buf_size] = '\0';
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}
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success = TRUE;
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out:
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if (success)
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{
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*out_len = buf_size;
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return buf;
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}
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g_free (buf);
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return NULL;
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}
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/**
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* glnx_fd_readall_bytes:
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* @fd: A file descriptor
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* @cancellable: Cancellable:
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* @error: Error
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*
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* Read all data from file descriptor @fd into a #GBytes. It's
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* recommended to only use this for small files.
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*
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* Returns: (transfer full): A newly allocated #GBytes
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*/
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GBytes *
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glnx_fd_readall_bytes (int fd,
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GCancellable *cancellable,
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GError **error)
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{
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guint8 *buf;
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gsize len;
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buf = glnx_fd_readall_malloc (fd, &len, FALSE, cancellable, error);
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if (!buf)
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return NULL;
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return g_bytes_new_take (buf, len);
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}
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/**
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* glnx_fd_readall_utf8:
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* @fd: A file descriptor
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* @out_len: (out): Returned length
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* @cancellable: Cancellable:
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* @error: Error
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*
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* Read all data from file descriptor @fd, validating
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* the result as UTF-8.
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*
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* Returns: (transfer full): A string validated as UTF-8, or %NULL on error.
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*/
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char *
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glnx_fd_readall_utf8 (int fd,
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gsize *out_len,
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GCancellable *cancellable,
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GError **error)
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{
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gboolean success = FALSE;
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guint8 *buf;
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gsize len;
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buf = glnx_fd_readall_malloc (fd, &len, TRUE, cancellable, error);
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if (!buf)
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goto out;
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if (!g_utf8_validate ((char*)buf, len, NULL))
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{
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g_set_error (error,
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G_IO_ERROR,
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G_IO_ERROR_INVALID_DATA,
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"Invalid UTF-8");
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goto out;
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}
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success = TRUE;
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out:
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if (success)
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{
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if (out_len)
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*out_len = len;
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return (char*)buf;
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}
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g_free (buf);
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return NULL;
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}
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/**
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* glnx_file_get_contents_utf8_at:
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* @dfd: Directory file descriptor
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* @subpath: Path relative to @dfd
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* @out_len: (out) (allow-none): Optional length
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* @cancellable: Cancellable
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* @error: Error
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*
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* Read the entire contents of the file referred
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* to by @dfd and @subpath, validate the result as UTF-8.
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* The length is optionally stored in @out_len.
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*
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* Returns: (transfer full): UTF-8 validated text, or %NULL on error
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*/
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char *
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glnx_file_get_contents_utf8_at (int dfd,
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const char *subpath,
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gsize *out_len,
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GCancellable *cancellable,
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GError **error)
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{
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gboolean success = FALSE;
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glnx_fd_close int fd = -1;
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char *buf;
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gsize len;
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do
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fd = openat (dfd, subpath, O_RDONLY | O_NOCTTY | O_CLOEXEC);
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while (G_UNLIKELY (fd == -1 && errno == EINTR));
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if (G_UNLIKELY (fd == -1))
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{
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glnx_set_error_from_errno (error);
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goto out;
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}
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buf = glnx_fd_readall_utf8 (fd, &len, cancellable, error);
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if (G_UNLIKELY(!buf))
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goto out;
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success = TRUE;
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out:
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if (success)
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{
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if (out_len)
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*out_len = len;
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return buf;
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}
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g_free (buf);
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return NULL;
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}
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50
glnx-fdio.h
Normal file
50
glnx-fdio.h
Normal file
@@ -0,0 +1,50 @@
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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*-
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*
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* Copyright (C) 2014,2015 Colin Walters <walters@verbum.org>.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#pragma once
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#include <glnx-backport-autocleanups.h>
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#include <limits.h>
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#include <dirent.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <attr/xattr.h>
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G_BEGIN_DECLS
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GBytes *
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glnx_fd_readall_bytes (int fd,
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GCancellable *cancellable,
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GError **error);
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char *
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glnx_fd_readall_utf8 (int fd,
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gsize *out_len,
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GCancellable *cancellable,
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GError **error);
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char *
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glnx_file_get_contents_utf8_at (int dfd,
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const char *subpath,
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gsize *out_len,
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GCancellable *cancellable,
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GError **error);
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G_END_DECLS
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