mirror of
https://gitlab.freedesktop.org/NetworkManager/NetworkManager
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88071abb43
Our coding style recommends C style comments (/* */) instead of C++ (//). Also, systemd (which we partly fork) uses C style comments for the SPDX-License-Identifier. Unify the style. $ sed -i '1 s#// SPDX-License-Identifier: \([^ ]\+\)$#/* SPDX-License-Identifier: \1 */#' -- $(git ls-files -- '*.[hc]' '*.[hc]pp')
481 lines
17 KiB
C
481 lines
17 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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/*
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* Copyright (C) 2018 Red Hat, Inc.
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*/
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#include "nm-default.h"
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#include "nm-io-utils.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include "nm-str-buf.h"
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#include "nm-shared-utils.h"
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#include "nm-secret-utils.h"
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#include "nm-errno.h"
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/*****************************************************************************/
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_nm_printf(4, 5) static int _get_contents_error(GError ** error,
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int errsv,
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int * out_errsv,
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const char *format,
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...)
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{
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nm_assert(NM_ERRNO_NATIVE(errsv));
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if (error) {
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gs_free char *msg = NULL;
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va_list args;
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char bstrerr[NM_STRERROR_BUFSIZE];
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va_start(args, format);
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msg = g_strdup_vprintf(format, args);
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va_end(args);
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g_set_error(error,
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G_FILE_ERROR,
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g_file_error_from_errno(errsv),
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"%s: %s",
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msg,
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nm_strerror_native_r(errsv, bstrerr, sizeof(bstrerr)));
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}
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nm_assert(errsv > 0);
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NM_SET_OUT(out_errsv, errsv);
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return FALSE;
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}
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#define _get_contents_error_errno(error, out_errsv, ...) \
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({ \
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int _errsv = (errno); \
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\
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_get_contents_error(error, _errsv, out_errsv, __VA_ARGS__); \
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})
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/**
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* nm_utils_fd_get_contents:
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* @fd: open file descriptor to read. The fd will not be closed,
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* but don't rely on its state afterwards.
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* @close_fd: if %TRUE, @fd will be closed by the function.
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* Passing %TRUE here might safe a syscall for dup().
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* @max_length: allocate at most @max_length bytes. If the
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* file is larger, reading will fail. Set to zero to use
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* a very large default.
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* WARNING: @max_length is here to avoid a crash for huge/unlimited files.
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* For example, stat(/sys/class/net/enp0s25/ifindex) gives a filesize of
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* 4K, although the actual real is small. @max_length is the memory
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* allocated in the process of reading the file, thus it must be at least
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* the size reported by fstat.
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* If you set it to 1K, read will fail because fstat() claims the
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* file is larger.
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* @flags: %NMUtilsFileGetContentsFlags for reading the file.
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* @contents: the output buffer with the file read. It is always
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* NUL terminated. The buffer is at most @max_length long, including
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* the NUL byte. That is, it reads only files up to a length of
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* @max_length - 1 bytes.
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* @length: optional output argument of the read file size.
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* @out_errsv: (allow-none) (out): on error, a positive errno. or zero.
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* @error:
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*
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*
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* A reimplementation of g_file_get_contents() with a few differences:
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* - accepts an open fd, instead of a path name. This allows you to
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* use openat().
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* - limits the maximum filesize to max_length.
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*
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* Returns: TRUE on success.
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*/
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gboolean
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nm_utils_fd_get_contents(int fd,
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gboolean close_fd,
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gsize max_length,
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NMUtilsFileGetContentsFlags flags,
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char ** contents,
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gsize * length,
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int * out_errsv,
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GError ** error)
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{
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nm_auto_close int fd_keeper = close_fd ? fd : -1;
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struct stat stat_buf;
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gs_free char * str = NULL;
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const bool do_bzero_mem = NM_FLAGS_HAS(flags, NM_UTILS_FILE_GET_CONTENTS_FLAG_SECRET);
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int errsv;
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g_return_val_if_fail(fd >= 0, FALSE);
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g_return_val_if_fail(contents && !*contents, FALSE);
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g_return_val_if_fail(!error || !*error, FALSE);
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NM_SET_OUT(length, 0);
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if (fstat(fd, &stat_buf) < 0)
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return _get_contents_error_errno(error, out_errsv, "failure during fstat");
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if (!max_length) {
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/* default to a very large size, but not extreme */
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max_length = 2 * 1024 * 1024;
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}
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if (stat_buf.st_size > 0 && S_ISREG(stat_buf.st_mode)) {
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const gsize n_stat = stat_buf.st_size;
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ssize_t n_read;
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if (n_stat > max_length - 1)
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return _get_contents_error(error,
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EMSGSIZE,
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out_errsv,
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"file too large (%zu+1 bytes with maximum %zu bytes)",
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n_stat,
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max_length);
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str = g_try_malloc(n_stat + 1);
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if (!str)
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return _get_contents_error(error,
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ENOMEM,
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out_errsv,
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"failure to allocate buffer of %zu+1 bytes",
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n_stat);
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n_read = nm_utils_fd_read_loop(fd, str, n_stat, TRUE);
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if (n_read < 0) {
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if (do_bzero_mem)
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nm_explicit_bzero(str, n_stat);
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return _get_contents_error(error,
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-n_read,
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out_errsv,
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"error reading %zu bytes from file descriptor",
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n_stat);
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}
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str[n_read] = '\0';
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if (n_read < n_stat) {
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if (!(str = nm_secret_mem_try_realloc_take(str, do_bzero_mem, n_stat + 1, n_read + 1)))
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return _get_contents_error(error,
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ENOMEM,
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out_errsv,
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"failure to reallocate buffer with %zu bytes",
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n_read + 1);
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}
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NM_SET_OUT(length, n_read);
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} else {
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nm_auto_fclose FILE *f = NULL;
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char buf[4096];
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gsize n_have, n_alloc;
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int fd2;
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if (fd_keeper >= 0)
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fd2 = nm_steal_fd(&fd_keeper);
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else {
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fd2 = fcntl(fd, F_DUPFD_CLOEXEC, 0);
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if (fd2 < 0)
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return _get_contents_error_errno(error, out_errsv, "error during dup");
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}
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if (!(f = fdopen(fd2, "r"))) {
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errsv = errno;
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nm_close(fd2);
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return _get_contents_error(error, errsv, out_errsv, "failure during fdopen");
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}
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n_have = 0;
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n_alloc = 0;
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while (!feof(f)) {
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gsize n_read;
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n_read = fread(buf, 1, sizeof(buf), f);
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errsv = errno;
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if (ferror(f)) {
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if (do_bzero_mem)
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nm_explicit_bzero(buf, sizeof(buf));
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return _get_contents_error(error, errsv, out_errsv, "error during fread");
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}
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if (n_have > G_MAXSIZE - 1 - n_read || n_have + n_read + 1 > max_length) {
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if (do_bzero_mem)
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nm_explicit_bzero(buf, sizeof(buf));
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return _get_contents_error(
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error,
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EMSGSIZE,
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out_errsv,
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"file stream too large (%zu+1 bytes with maximum %zu bytes)",
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(n_have > G_MAXSIZE - 1 - n_read) ? G_MAXSIZE : n_have + n_read,
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max_length);
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}
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if (n_have + n_read + 1 >= n_alloc) {
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gsize old_n_alloc = n_alloc;
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if (n_alloc != 0) {
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nm_assert(str);
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if (n_alloc >= max_length / 2)
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n_alloc = max_length;
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else
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n_alloc *= 2;
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} else {
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nm_assert(!str);
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n_alloc = NM_MIN(n_read + 1, sizeof(buf));
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}
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if (!(str = nm_secret_mem_try_realloc_take(str,
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do_bzero_mem,
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old_n_alloc,
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n_alloc))) {
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if (do_bzero_mem)
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nm_explicit_bzero(buf, sizeof(buf));
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return _get_contents_error(error,
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ENOMEM,
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out_errsv,
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"failure to allocate buffer of %zu bytes",
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n_alloc);
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}
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}
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memcpy(str + n_have, buf, n_read);
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n_have += n_read;
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}
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if (do_bzero_mem)
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nm_explicit_bzero(buf, sizeof(buf));
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if (n_alloc == 0)
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str = g_new0(char, 1);
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else {
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str[n_have] = '\0';
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if (n_have + 1 < n_alloc) {
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if (!(str = nm_secret_mem_try_realloc_take(str, do_bzero_mem, n_alloc, n_have + 1)))
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return _get_contents_error(error,
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ENOMEM,
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out_errsv,
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"failure to truncate buffer to %zu bytes",
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n_have + 1);
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}
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}
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NM_SET_OUT(length, n_have);
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}
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*contents = g_steal_pointer(&str);
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NM_SET_OUT(out_errsv, 0);
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return TRUE;
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}
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/**
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* nm_utils_file_get_contents:
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* @dirfd: optional file descriptor to use openat(). If negative, use plain open().
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* @filename: the filename to open. Possibly relative to @dirfd.
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* @max_length: allocate at most @max_length bytes.
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* WARNING: see nm_utils_fd_get_contents() hint about @max_length.
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* @flags: %NMUtilsFileGetContentsFlags for reading the file.
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* @contents: the output buffer with the file read. It is always
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* NUL terminated. The buffer is at most @max_length long, including
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* the NUL byte. That is, it reads only files up to a length of
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* @max_length - 1 bytes.
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* @length: optional output argument of the read file size.
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* @out_errsv: (allow-none) (out): on error, a positive errno. or zero.
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* @error:
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*
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* A reimplementation of g_file_get_contents() with a few differences:
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* - accepts an @dirfd to open @filename relative to that path via openat().
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* - limits the maximum filesize to max_length.
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* - uses O_CLOEXEC on internal file descriptor
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* - optionally returns the native errno on failure.
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*
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* Returns: TRUE on success.
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*/
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gboolean
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nm_utils_file_get_contents(int dirfd,
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const char * filename,
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gsize max_length,
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NMUtilsFileGetContentsFlags flags,
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char ** contents,
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gsize * length,
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int * out_errsv,
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GError ** error)
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{
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int fd;
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g_return_val_if_fail(filename && filename[0], FALSE);
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g_return_val_if_fail(contents && !*contents, FALSE);
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NM_SET_OUT(length, 0);
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if (dirfd >= 0) {
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fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC);
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if (fd < 0) {
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return _get_contents_error_errno(error,
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out_errsv,
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"Failed to open file \"%s\" with openat",
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filename);
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}
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} else {
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fd = open(filename, O_RDONLY | O_CLOEXEC);
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if (fd < 0) {
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return _get_contents_error_errno(error,
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out_errsv,
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"Failed to open file \"%s\"",
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filename);
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}
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}
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return nm_utils_fd_get_contents(fd,
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TRUE,
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max_length,
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flags,
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contents,
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length,
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out_errsv,
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error);
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}
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/*****************************************************************************/
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/*
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* Copied from GLib's g_file_set_contents() et al., but allows
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* specifying a mode for the new file.
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*/
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gboolean
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nm_utils_file_set_contents(const char *filename,
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const char *contents,
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gssize length,
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mode_t mode,
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int * out_errsv,
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GError ** error)
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{
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gs_free char *tmp_name = NULL;
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struct stat statbuf;
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int errsv;
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gssize s;
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int fd;
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g_return_val_if_fail(filename, FALSE);
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g_return_val_if_fail(contents || !length, FALSE);
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g_return_val_if_fail(!error || !*error, FALSE);
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g_return_val_if_fail(length >= -1, FALSE);
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if (length == -1)
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length = strlen(contents);
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tmp_name = g_strdup_printf("%s.XXXXXX", filename);
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fd = g_mkstemp_full(tmp_name, O_RDWR | O_CLOEXEC, mode);
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if (fd < 0) {
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return _get_contents_error_errno(error, out_errsv, "failed to create file %s", tmp_name);
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}
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while (length > 0) {
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s = write(fd, contents, length);
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if (s < 0) {
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errsv = NM_ERRNO_NATIVE(errno);
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if (errsv == EINTR)
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continue;
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nm_close(fd);
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unlink(tmp_name);
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return _get_contents_error(error,
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errsv,
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out_errsv,
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"failed to write to file %s",
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tmp_name);
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}
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g_assert(s <= length);
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contents += s;
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length -= s;
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}
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/* If the final destination exists and is > 0 bytes, we want to sync the
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* newly written file to ensure the data is on disk when we rename over
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* the destination. Otherwise, if we get a system crash we can lose both
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* the new and the old file on some filesystems. (I.E. those that don't
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* guarantee the data is written to the disk before the metadata.)
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*/
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if (lstat(filename, &statbuf) == 0 && statbuf.st_size > 0) {
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if (fsync(fd) != 0) {
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errsv = NM_ERRNO_NATIVE(errno);
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nm_close(fd);
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unlink(tmp_name);
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return _get_contents_error(error, errsv, out_errsv, "failed to fsync %s", tmp_name);
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}
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}
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nm_close(fd);
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if (rename(tmp_name, filename)) {
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errsv = NM_ERRNO_NATIVE(errno);
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unlink(tmp_name);
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return _get_contents_error(error,
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errsv,
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out_errsv,
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"failed rename %s to %s",
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tmp_name,
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filename);
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}
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return TRUE;
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}
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/**
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* nm_utils_file_stat:
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* @filename: the filename to stat.
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* @out_st: (allow-none) (out): if given, this will be passed to stat().
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*
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* Just wraps stat() and gives the errno number as function result instead
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* of setting the errno (though, errno is also set). It's only for convenience
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* with
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*
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* if (nm_utils_file_stat (filename, NULL) == -ENOENT) {
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* }
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*
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* Returns: 0 on success a negative errno on failure. */
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int
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nm_utils_file_stat(const char *filename, struct stat *out_st)
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{
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struct stat st;
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if (stat(filename, out_st ?: &st) != 0)
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return -NM_ERRNO_NATIVE(errno);
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return 0;
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}
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/**
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* nm_utils_fd_read:
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* @fd: the fd to read from.
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* @out_string: (out): output string where read bytes will be stored.
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*
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* Returns: <0 on failure, which is -(errno).
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* 0 on EOF.
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* >0 on success, which is the number of bytes read. */
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gssize
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nm_utils_fd_read(int fd, NMStrBuf *out_string)
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{
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gsize buf_available;
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gssize n_read;
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int errsv;
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g_return_val_if_fail(fd >= 0, -1);
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g_return_val_if_fail(out_string, -1);
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/* If the buffer size is 0, we allocate NM_UTILS_GET_NEXT_REALLOC_SIZE_1000 (1000 bytes)
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* the first time. Afterwards, the buffer grows exponentially.
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*
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* Note that with @buf_available, we always would read as much buffer as we actually
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* have reserved. */
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nm_str_buf_maybe_expand(out_string, NM_UTILS_GET_NEXT_REALLOC_SIZE_1000, FALSE);
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buf_available = out_string->allocated - out_string->len;
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n_read = read(fd, &((nm_str_buf_get_str_unsafe(out_string))[out_string->len]), buf_available);
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if (n_read < 0) {
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errsv = errno;
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return -NM_ERRNO_NATIVE(errsv);
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}
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if (n_read > 0) {
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nm_assert((gsize) n_read <= buf_available);
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nm_str_buf_set_size(out_string, out_string->len + (gsize) n_read, TRUE, FALSE);
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}
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return n_read;
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}
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