-
Simon McVittie authored
To work around older versions of GLib having a potential deadlock in their fd-closing code due to use of non-async-signal-safe functions in the forked child process, the Flatpak-derived code we're using here uses a simple, naive implementation of closing fds: it iterates through every possible fd, up to the rlimit. Unfortunately, Wine users sometimes set their fd rlimit very high (typically around a million), because the "esync" mechanism in Proton's Wine needs a lot of fds. The time taken by each individual syscall is not significant, but when we do a million of them, it adds up. This is arguably a misconfiguration - the recommendation is now to have a soft rlimit of 1024 and a hard rlimit of about a million, so that only processes that opt-in to dealing with a million fds have to be aware of them - but a significant number of misconfigured systems probably still exist. We don't actually *need* to close all the fds here: there's no security boundary, so giving the child access to unnecessary fds isn't a privilage gain; the parent process outlives the child, so leaking fds won't result in them never being closed; and in any case we're reasonably careful to set CLOEXEC on all our fds. So let's just not close them. In particular, this can save literally a million syscalls per helper subprocess invocation (it's not often I get to say that!), reducing pressure-vessel-wrap launch time by 90% on a system with the high fd limit (about 70 seconds down to 7). With the recommended soft limit of 1024, the speedup is less dramatic, but it still takes off nearly 10% (about 6 down to 5.5). Resolves: https://github.com/ValveSoftware/steam-runtime/issues/323 Signed-off-by:
Simon McVittie <smcv@collabora.com>
Simon McVittie authoredTo work around older versions of GLib having a potential deadlock in their fd-closing code due to use of non-async-signal-safe functions in the forked child process, the Flatpak-derived code we're using here uses a simple, naive implementation of closing fds: it iterates through every possible fd, up to the rlimit. Unfortunately, Wine users sometimes set their fd rlimit very high (typically around a million), because the "esync" mechanism in Proton's Wine needs a lot of fds. The time taken by each individual syscall is not significant, but when we do a million of them, it adds up. This is arguably a misconfiguration - the recommendation is now to have a soft rlimit of 1024 and a hard rlimit of about a million, so that only processes that opt-in to dealing with a million fds have to be aware of them - but a significant number of misconfigured systems probably still exist. We don't actually *need* to close all the fds here: there's no security boundary, so giving the child access to unnecessary fds isn't a privilage gain; the parent process outlives the child, so leaking fds won't result in them never being closed; and in any case we're reasonably careful to set CLOEXEC on all our fds. So let's just not close them. In particular, this can save literally a million syscalls per helper subprocess invocation (it's not often I get to say that!), reducing pressure-vessel-wrap launch time by 90% on a system with the high fd limit (about 70 seconds down to 7). With the recommended soft limit of 1024, the speedup is less dramatic, but it still takes off nearly 10% (about 6 down to 5.5). Resolves: https://github.com/ValveSoftware/steam-runtime/issues/323 Signed-off-by:
Simon McVittie <smcv@collabora.com>
utils.c 25.29 KiB
/*
* Contains code taken from Flatpak.
*
* Copyright © 2014-2019 Red Hat, Inc
* Copyright © 2017-2019 Collabora Ltd.
*
* SPDX-License-Identifier: LGPL-2.1-or-later
*
* This program 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.
*
* This 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 this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "utils.h"
#include <ftw.h>
#include <sys/prctl.h>
#include <sys/signalfd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <glib.h>
#include <glib-unix.h>
#include <glib/gstdio.h>
#include <gio/gio.h>
#include "libglnx/libglnx.h"
#include "steam-runtime-tools/glib-backports-internal.h"
#include "steam-runtime-tools/resolve-in-sysroot-internal.h"
#include "steam-runtime-tools/utils-internal.h"
#include "flatpak-bwrap-private.h"
#include "flatpak-utils-base-private.h"
#include "flatpak-utils-private.h"
/**
* pv_envp_cmp:
* @p1: a `const char * const *`
* @p2: a `const char * const *`
*
* Compare two environment variables, given as pointers to pointers
* to the actual `KEY=value` string.
*
* In particular this is suitable for sorting a #GStrv using `qsort`.
*
* Returns: negative, 0 or positive if `*p1` compares before, equal to
* or after `*p2`
*/
int
pv_envp_cmp (const void *p1,
const void *p2)
{
const char * const * s1 = p1;
const char * const * s2 = p2;
size_t l1 = strlen (*s1);
size_t l2 = strlen (*s2);
size_t min;
const char *tmp;
int ret;
tmp = strchr (*s1, '=');
if (tmp != NULL)
l1 = tmp - *s1;
tmp = strchr (*s2, '=');
if (tmp != NULL)
l2 = tmp - *s2;
min = MIN (l1, l2);
ret = strncmp (*s1, *s2, min);
/* If they differ before the first '=' (if any) in either s1 or s2,
* then they are certainly different */
if (ret != 0)
return ret;
ret = strcmp (*s1, *s2);
/* If they do not differ at all, then they are equal */
if (ret == 0)
return ret;
/* FOO < FOO=..., and FOO < FOOBAR */
if ((*s1)[min] == '\0')
return -1;
/* FOO=... > FOO, and FOOBAR > FOO */
if ((*s2)[min] == '\0')
return 1;
/* FOO= < FOOBAR */
if ((*s1)[min] == '=' && (*s2)[min] != '=')
return -1;
/* FOOBAR > FOO= */
if ((*s2)[min] == '=' && (*s1)[min] != '=')
return 1;
/* Fall back to plain string comparison */
return ret;
}
/**
* pv_get_current_dirs:
* @cwd_p: (out) (transfer full) (optional): Used to return the
* current physical working directory, equivalent to `$(pwd -P)`
* in a shell
* @cwd_l: (out) (transfer full) (optional): Used to return the
* current logical working directory, equivalent to `$(pwd -L)`
* in a shell
*
* Return the physical and/or logical working directory.
*
* Equivalent to `$(pwd -L)` in a shell.
*/
void
pv_get_current_dirs (gchar **cwd_p,
gchar **cwd_l)
{
g_autofree gchar *cwd = NULL;
const gchar *pwd;
g_return_if_fail (cwd_p == NULL || *cwd_p == NULL);
g_return_if_fail (cwd_l == NULL || *cwd_l == NULL);
cwd = g_get_current_dir ();
if (cwd_p != NULL)
*cwd_p = flatpak_canonicalize_filename (cwd);
if (cwd_l != NULL)
{
pwd = g_getenv ("PWD");
if (pwd != NULL && _srt_is_same_file (pwd, cwd))
*cwd_l = g_strdup (pwd);
else
*cwd_l = g_strdup (cwd);
}
}
void
pv_search_path_append (GString *search_path,
const gchar *item)
{
g_return_if_fail (search_path != NULL);
if (item == NULL || item[0] == '\0')
return;
if (search_path->len != 0)
g_string_append (search_path, ":");
g_string_append (search_path, item);
}
gchar *
pv_capture_output (const char * const * argv,
GError **error)
{
gsize len;
gint wait_status;
g_autofree gchar *output = NULL;
g_autofree gchar *errors = NULL;
gsize i;
g_autoptr(GString) command = g_string_new ("");
g_return_val_if_fail (argv != NULL, NULL);
g_return_val_if_fail (argv[0] != NULL, NULL);
g_return_val_if_fail (error == NULL || *error == NULL, FALSE);
for (i = 0; argv[i] != NULL; i++)
{
g_autofree gchar *quoted = g_shell_quote (argv[i]);
g_string_append_printf (command, " %s", quoted);
}
g_debug ("run:%s", command->str);
/* We use LEAVE_DESCRIPTORS_OPEN to work around a deadlock in older GLib,
* and to avoid wasting a lot of time closing fds if the rlimit for
* maximum open file descriptors is high. Because we're waiting for the
* subprocess to finish anyway, it doesn't really matter that any fds
* that are not close-on-execute will get leaked into the child. */
if (!g_spawn_sync (NULL, /* cwd */
(char **) argv,
NULL, /* env */
(G_SPAWN_SEARCH_PATH |
G_SPAWN_LEAVE_DESCRIPTORS_OPEN),
NULL, NULL,
&output,
&errors,
&wait_status,
error))
return NULL;
g_printerr ("%s", errors);
if (!g_spawn_check_exit_status (wait_status, error))
return NULL;
len = strlen (output);
/* Emulate shell $() */
if (len > 0 && output[len - 1] == '\n')
output[len - 1] = '\0';
g_debug ("-> %s", output);
return g_steal_pointer (&output);
}
/*
* Returns: (transfer none): The first key in @table in iteration order,
* or %NULL if @table is empty.
*/
gpointer
pv_hash_table_get_arbitrary_key (GHashTable *table)
{
GHashTableIter iter;
gpointer key = NULL;
g_hash_table_iter_init (&iter, table);
if (g_hash_table_iter_next (&iter, &key, NULL))
return key;
else
return NULL;
}
gboolean
pv_boolean_environment (const gchar *name,
gboolean def)
{
const gchar *value = g_getenv (name);
if (g_strcmp0 (value, "1") == 0)
return TRUE;
if (g_strcmp0 (value, "") == 0 || g_strcmp0 (value, "0") == 0)
return FALSE;
if (value != NULL)
g_warning ("Unrecognised value \"%s\" for $%s", value, name);
return def;
}
/**
* pv_async_signal_safe_error:
* @message: A human-readable message
* @exit_status: Call `_exit` with this status
*
* Exit with a fatal error, like g_error(), but async-signal-safe
* (see signal-safety(7)).
*/
void
pv_async_signal_safe_error (const char *message,
int exit_status)
{
if (write (2, message, strlen (message)) < 0)
{
/* Ignore - there's nothing we can do about it anyway - but
* suppress -Wunused-result. */
}
_exit (exit_status);
}
#define PROC_SYS_KERNEL_RANDOM_UUID "/proc/sys/kernel/random/uuid"
/**
* pv_get_random_uuid:
* @error: Used to raise an error on failure
*
* Return a random UUID (RFC 4122 version 4) as a string.
* It is a 128-bit quantity, with 122 bits of entropy, and 6 fixed bits
* indicating the "variant" (type, 0b10) and "version" (subtype, 0b0100).
*
* Returns: (transfer full): A random UUID, or %NULL on error
*/
gchar *
pv_get_random_uuid (GError **error)
{
g_autofree gchar *contents = NULL;
if (!g_file_get_contents (PROC_SYS_KERNEL_RANDOM_UUID,
&contents, NULL, error))
return NULL;
g_strchomp (contents); /* delete trailing newline */
/* Format: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx */
if (strlen (contents) != 36)
return glnx_null_throw (error, "%s not in expected format",
PROC_SYS_KERNEL_RANDOM_UUID);
return g_steal_pointer (&contents);
}
/**
* pv_wait_for_child_processes:
* @main_process: process for which we will report wait-status;
* zero or negative if there is no main process
* @wait_status_out: (out): Used to store the wait status of `@main_process`,
* as if from `wait()`, on success
* @error: Used to raise an error on failure
*
* Wait for child processes of this process to exit, until the @main_process
* has exited. If there is no main process, wait until there are no child
* processes at all.
*
* If the process is a subreaper (`PR_SET_CHILD_SUBREAPER`),
* indirect child processes whose parents have exited will be reparented
* to it, so this will have the effect of waiting for all descendants.
*
* If @main_process is positive, return when @main_process has exited.
* Child processes that exited before @main_process will also have been
* "reaped", but child processes that exit after @main_process will not
* (use `pv_wait_for_child_processes (0, &error)` to resume waiting).
*
* If @main_process is zero or negative, wait for all child processes
* to exit.
*
* This function cannot be called in a process that is using
* g_child_watch_source_new() or similar functions, because it waits
* for all child processes regardless of their process IDs, and that is
* incompatible with waiting for individual child processes.
*
* Returns: %TRUE when @main_process has exited, or if @main_process
* is zero or negative and all child processes have exited
*/
gboolean
pv_wait_for_child_processes (pid_t main_process,
int *wait_status_out,
GError **error)
{
if (wait_status_out != NULL)
*wait_status_out = -1;
while (1)
{
int wait_status = -1;
pid_t died = wait (&wait_status);
if (died < 0)
{
if (errno == EINTR)
{
continue;
}
else if (errno == ECHILD)
{
g_debug ("No more child processes");
break;
}
else
{
return glnx_throw_errno_prefix (error, "wait");
}
}
g_debug ("Child %lld exited with wait status %d",
(long long) died, wait_status);
if (died == main_process)
{
if (wait_status_out != NULL)
*wait_status_out = wait_status;
return TRUE;
}
}
if (main_process > 0)
{
g_set_error (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND,
"Process %lld was not seen to exit",
(long long) main_process);
return FALSE;
}
return TRUE;
}
typedef struct
{
GError *error;
GMainContext *context;
GSource *wait_source;
GSource *kill_source;
GSource *sigchld_source;
gchar *children_file;
/* GINT_TO_POINTER (pid) => arbitrary */
GHashTable *sent_sigterm;
/* GINT_TO_POINTER (pid) => arbitrary */
GHashTable *sent_sigkill;
/* Scratch space to build temporary strings */
GString *buffer;
/* 0, SIGTERM or SIGKILL */
int sending_signal;
/* Nonzero if wait_source has been attached to context */
guint wait_source_id;
guint kill_source_id;
guint sigchld_source_id;
/* TRUE if we reach a point where we have no more child processes. */
gboolean finished;
} TerminationData;
/*
* Free everything in @data.
*/
static void
termination_data_clear (TerminationData *data)
{
if (data->wait_source_id != 0)
{
g_source_destroy (data->wait_source);
data->wait_source_id = 0;
}
if (data->kill_source_id != 0)
{
g_source_destroy (data->kill_source);
data->kill_source_id = 0;
}
if (data->sigchld_source_id != 0)
{
g_source_destroy (data->sigchld_source);
data->sigchld_source_id = 0;
}
if (data->wait_source != NULL)
g_source_unref (g_steal_pointer (&data->wait_source));
if (data->kill_source != NULL)
g_source_unref (g_steal_pointer (&data->kill_source));
if (data->sigchld_source != NULL)
g_source_unref (g_steal_pointer (&data->sigchld_source));
g_clear_pointer (&data->children_file, g_free);
g_clear_pointer (&data->context, g_main_context_unref);
g_clear_error (&data->error);
g_clear_pointer (&data->sent_sigterm, g_hash_table_unref);
g_clear_pointer (&data->sent_sigkill, g_hash_table_unref);
if (data->buffer != NULL)
g_string_free (g_steal_pointer (&data->buffer), TRUE);
}
G_DEFINE_AUTO_CLEANUP_CLEAR_FUNC (TerminationData, termination_data_clear)
/*
* Do whatever the next step for pv_terminate_all_child_processes() is.
*
* First, reap child processes that already exited, without blocking.
*
* Then, act according to the phase we are in:
* - before wait_period: do nothing
* - after wait_period but before grace_period: send SIGTERM
* - after wait_period and grace_period: send SIGKILL
*/
static void
termination_data_refresh (TerminationData *data)
{
g_autofree gchar *contents = NULL;
gboolean has_child = FALSE;
const char *p;
char *endptr;
if (data->error != NULL)
return;
g_debug ("Checking for child processes");
while (1)
{
int wait_status = -1;
pid_t died = waitpid (-1, &wait_status, WNOHANG);
if (died < 0)
{
if (errno == EINTR)
{
continue;
}
else if (errno == ECHILD)
{
/* No child processes at all. We'll double-check this
* a bit later. */
break;
}
else
{
glnx_throw_errno_prefix (&data->error, "wait");
return;
}
}
else if (died == 0)
{
/* No more child processes have exited, but at least one is
* still running. */
break;
}
/* This process has gone away, so remove any record that we have
* sent it signals. If the pid is reused, we'll want to send
* the same signals again. */
g_debug ("Process %d exited", died);
g_hash_table_remove (data->sent_sigkill, GINT_TO_POINTER (died));
g_hash_table_remove (data->sent_sigterm, GINT_TO_POINTER (died));
}
/* See whether we have any remaining children. These could be direct
* child processes, or they could be children we adopted because
* their parent was one of our descendants and has exited, leaving the
* child to be reparented to us (their (great)*grandparent) because we
* are a subreaper. */
if (!g_file_get_contents (data->children_file, &contents, NULL, &data->error))
return;
g_debug ("Child tasks: %s", contents);
for (p = contents;
p != NULL && *p != '\0';
p = endptr)
{
guint64 maybe_child;
int child;
GHashTable *already;
while (*p != '\0' && g_ascii_isspace (*p))
p++;
if (*p == '\0')
break;
maybe_child = g_ascii_strtoull (p, &endptr, 10);
if (*endptr != '\0' && !g_ascii_isspace (*endptr))
{
glnx_throw (&data->error, "Non-numeric string found in %s: %s",
data->children_file, p);
return;
}
if (maybe_child > G_MAXINT)
{
glnx_throw (&data->error, "Out-of-range number found in %s: %s",
data->children_file, p);
return;
}
child = (int) maybe_child;
g_string_printf (data->buffer, "/proc/%d", child);
/* If the task is just a thread, it won't have a /proc/%d directory
* in its own right. We don't kill threads, only processes. */
if (!g_file_test (data->buffer->str, G_FILE_TEST_IS_DIR))
{
g_debug ("Task %d is a thread, not a process", child);
continue;
}
has_child = TRUE;
if (data->sending_signal == 0)
break;
else if (data->sending_signal == SIGKILL)
already = data->sent_sigkill;
else
already = data->sent_sigterm;
if (!g_hash_table_contains (already, GINT_TO_POINTER (child)))
{
g_debug ("Sending signal %d to process %d",
data->sending_signal, child);
g_hash_table_add (already, GINT_TO_POINTER (child));
if (kill (child, data->sending_signal) < 0)
g_warning ("Unable to send signal %d to process %d: %s",
data->sending_signal, child, g_strerror (errno));
/* In case the child is stopped, wake it up to receive the signal */
if (kill (child, SIGCONT) < 0)
g_warning ("Unable to send SIGCONT to process %d: %s",
child, g_strerror (errno));
/* When the child terminates, we will get SIGCHLD and come
* back to here. */
}
}
if (!has_child)
data->finished = TRUE;
}
/*
* Move from wait period to grace period: start sending SIGTERM to
* child processes.
*/
static gboolean
start_sending_sigterm (gpointer user_data)
{
TerminationData *data = user_data;
g_debug ("Wait period finished, starting to send SIGTERM...");
if (data->sending_signal == 0)
data->sending_signal = SIGTERM;
termination_data_refresh (data);
data->wait_source_id = 0;
return G_SOURCE_REMOVE;
}
/*
* End of grace period: start sending SIGKILL to child processes.
*/
static gboolean
start_sending_sigkill (gpointer user_data)
{
TerminationData *data = user_data;
g_debug ("Grace period finished, starting to send SIGKILL...");
data->sending_signal = SIGKILL;
termination_data_refresh (data);
data->kill_source_id = 0;
return G_SOURCE_REMOVE;
}
/*
* Called when at least one child process has exited, resulting in
* SIGCHLD to this process.
*/
static gboolean
sigchld_cb (int sfd,
G_GNUC_UNUSED GIOCondition condition,
gpointer user_data)
{
TerminationData *data = user_data;
struct signalfd_siginfo info;
ssize_t size;
size = read (sfd, &info, sizeof (info));
if (size < 0)
{
if (errno != EINTR && errno != EAGAIN)
g_warning ("Unable to read struct signalfd_siginfo: %s",
g_strerror (errno));
}
else if (size != sizeof (info))
{
g_warning ("Expected struct signalfd_siginfo of size %"
G_GSIZE_FORMAT ", got %" G_GSSIZE_FORMAT,
sizeof (info), size);
}
g_debug ("One or more child processes exited");
termination_data_refresh (data);
return G_SOURCE_CONTINUE;
}
/**
* pv_terminate_all_child_processes:
* @wait_period: If greater than 0, wait this many microseconds before
* sending `SIGTERM`
* @grace_period: If greater than 0, after @wait_period plus this many
* microseconds, use `SIGKILL` instead of `SIGTERM`. If 0, proceed
* directly to sending `SIGKILL`.
* @error: Used to raise an error on failure
*
* Make sure all child processes are terminated.
*
* If a child process catches `SIGTERM` but does not exit promptly and
* does not pass the signal on to its descendants, note that its
* descendant processes are not guaranteed to be terminated gracefully
* with `SIGTERM`; they might only receive `SIGKILL`.
*
* Return when all child processes have exited or when an error has
* occurred.
*
* This function cannot be called in a process that is using
* g_child_watch_source_new() or similar functions.
*
* The process must be a subreaper, and must have `SIGCHLD` blocked.
*
* Returns: %TRUE on success.
*/
gboolean
pv_terminate_all_child_processes (GTimeSpan wait_period,
GTimeSpan grace_period,
GError **error)
{
g_auto(TerminationData) data = {};
sigset_t mask;
int is_subreaper = -1;
glnx_autofd int sfd = -1;
if (prctl (PR_GET_CHILD_SUBREAPER, (unsigned long) &is_subreaper, 0, 0, 0) != 0)
return glnx_throw_errno_prefix (error, "prctl PR_GET_CHILD_SUBREAPER");
if (is_subreaper != 1)
return glnx_throw (error, "Process is not a subreaper");
sigemptyset (&mask);
if (pthread_sigmask (SIG_BLOCK, NULL, &mask) != 0)
return glnx_throw_errno_prefix (error, "pthread_sigmask");
if (!sigismember (&mask, SIGCHLD))
return glnx_throw (error, "Process has not blocked SIGCHLD");
data.children_file = g_strdup_printf ("/proc/%d/task/%d/children",
getpid (), getpid ());
data.context = g_main_context_new ();
data.sent_sigterm = g_hash_table_new (NULL, NULL);
data.sent_sigkill = g_hash_table_new (NULL, NULL);
data.buffer = g_string_new ("/proc/2345678901");
if (wait_period > 0 && grace_period > 0)
{
data.wait_source = g_timeout_source_new (wait_period / G_TIME_SPAN_MILLISECOND);
g_source_set_callback (data.wait_source, start_sending_sigterm,
&data, NULL);
data.wait_source_id = g_source_attach (data.wait_source, data.context);
}
else if (grace_period > 0)
{
start_sending_sigterm (&data);
}
if (wait_period + grace_period > 0)
{
data.kill_source = g_timeout_source_new ((wait_period + grace_period) / G_TIME_SPAN_MILLISECOND);
g_source_set_callback (data.kill_source, start_sending_sigkill,
&data, NULL);
data.kill_source_id = g_source_attach (data.kill_source, data.context);
}
else
{
start_sending_sigkill (&data);
}
sigemptyset (&mask);
sigaddset (&mask, SIGCHLD);
sfd = signalfd (-1, &mask, SFD_NONBLOCK | SFD_CLOEXEC);
if (sfd < 0)
return glnx_throw_errno_prefix (error, "signalfd");
data.sigchld_source = g_unix_fd_source_new (sfd, G_IO_IN);
g_source_set_callback (data.sigchld_source,
(GSourceFunc) G_CALLBACK (sigchld_cb), &data, NULL);
data.sigchld_source_id = g_source_attach (data.sigchld_source, data.context);
termination_data_refresh (&data);
while (data.error == NULL
&& !data.finished
&& (data.wait_source_id != 0
|| data.kill_source_id != 0
|| data.sigchld_source_id != 0))
g_main_context_iteration (data.context, TRUE);
if (data.error != NULL)
{
g_propagate_error (error, g_steal_pointer (&data.error));
return FALSE;
}
return TRUE;
}
/*
* @str: A path
* @prefix: A possible prefix
*
* The same as flatpak_has_path_prefix(), but instead of a boolean,
* return the part of @str after @prefix (non-%NULL but possibly empty)
* if @str has prefix @prefix, or %NULL if it does not.
*
* Returns: (nullable) (transfer none): the part of @str after @prefix,
* or %NULL if @str is not below @prefix
*/
const char *
pv_get_path_after (const char *str,
const char *prefix)
{
while (TRUE)
{
/* Skip consecutive slashes to reach next path
element */
while (*str == '/')
str++;
while (*prefix == '/')
prefix++;
/* No more prefix path elements? Done! */
if (*prefix == 0)
return str;
/* Compare path element */
while (*prefix != 0 && *prefix != '/')
{
if (*str != *prefix)
return NULL;
str++;
prefix++;
}
/* Matched prefix path element,
must be entire str path element */
if (*str != '/' && *str != 0)
return NULL;
}
}
/**
* pv_current_namespace_path_to_host_path:
* @current_env_path: a path in the current environment
*
* Returns: (transfer full): The @current_env_path converted to the host
* system, or a copy of @current_env_path if we are not in a Flatpak
* environment or it's unknown how to convert the given path.
*/
gchar *
pv_current_namespace_path_to_host_path (const gchar *current_env_path)
{
gchar *path_on_host = NULL;
g_return_val_if_fail (g_path_is_absolute (current_env_path),
g_strdup (current_env_path));
if (g_file_test ("/.flatpak-info", G_FILE_TEST_IS_REGULAR))
{
struct stat via_current_env_stat;
struct stat via_persist_stat;
const gchar *home = g_getenv ("HOME");
const gchar *after = NULL;
if (home == NULL)
home = g_get_home_dir ();
if (home != NULL)
after = pv_get_path_after (current_env_path, home);
/* If we are inside a Flatpak container, usually, the home
* folder is '${HOME}/.var/app/${FLATPAK_ID}' on the host system */
if (after != NULL)
{
path_on_host = g_build_filename (home,
".var",
"app",
g_getenv ("FLATPAK_ID"),
after,
NULL);
if (lstat (path_on_host, &via_persist_stat) < 0)
{
/* The file doesn't exist in ~/.var/app, so assume it was
* exposed via --filesystem */
g_clear_pointer (&path_on_host, g_free);
}
else if (lstat (current_env_path, &via_current_env_stat) == 0
&& (via_persist_stat.st_dev != via_current_env_stat.st_dev
|| via_persist_stat.st_ino != via_current_env_stat.st_ino))
{
/* The file exists in ~/.var/app, but is not the same there -
* presumably a different version was mounted over the top via
* --filesystem */
g_clear_pointer (&path_on_host, g_free);
}
}
after = pv_get_path_after (current_env_path, "/run/host");
/* In a Flatpak container, usually, '/run/host' is the root of the
* host system */
if (after != NULL && path_on_host == NULL)
path_on_host = g_build_filename ("/", after, NULL);
}
/* Either we are not in a Flatpak container or it's not obvious how the
* container to host translation should happen. Just keep the same path. */
if (path_on_host == NULL)
path_on_host = g_strdup (current_env_path);
return path_on_host;
}