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common: Improve waiting for processes on POSIX.

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* common/exechelp-posix.c (struct terminated_child): New definition.
(terminated_children): New variable.
(store_result): New function.
(get_result): Likewise.
(gnupg_wait_process): Store results that were not requested and
consider previously stored results.

waitpid(2) may return information about terminated children that we
did not yet request, and there is no portable way to wait for a
specific set of children.  As a workaround, we store the results of
children for later use.

Signed-off-by: Justus Winter <justus@g10code.com>
This commit is contained in:
Justus Winter 2016-09-05 13:50:17 +02:00
parent c39be0add8
commit e33111fcda
1 changed files with 114 additions and 32 deletions
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118
common/exechelp-posix.c
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@ -583,6 +583,66 @@ gnupg_spawn_process_fd (const char *pgmname, const char *argv[],
}
/* Waiting for child processes.
waitpid(2) may return information about terminated children that we
did not yet request, and there is no portable way to wait for a
specific set of children.
As a workaround, we store the results of children for later use.
XXX: This assumes that PIDs are not reused too quickly. */
struct terminated_child
{
pid_t pid;
int exitcode;
struct terminated_child *next;
};
struct terminated_child *terminated_children;
static gpg_error_t
store_result (pid_t pid, int exitcode)
{
struct terminated_child *c;
c = xmalloc (sizeof *c);
if (c == NULL)
return gpg_err_code_from_syserror ();
c->pid = pid;
c->exitcode = exitcode;
c->next = terminated_children;
terminated_children = c;
return 0;
}
static int
get_result (pid_t pid, int *r_exitcode)
{
struct terminated_child *c, **prevp;
for (prevp = &terminated_children, c = terminated_children;
c;
prevp = &c->next, c = c->next)
if (c->pid == pid)
{
*prevp = c->next;
*r_exitcode = c->exitcode;
xfree (c);
return 1;
}
return 0;
}
/* See exechelp.h for a description. */
gpg_error_t
gnupg_wait_process (const char *pgmname, pid_t pid, int hang, int *r_exitcode)
@ -597,17 +657,25 @@ gnupg_wait_processes (const char **pgmnames, pid_t *pids, size_t count,
{
gpg_err_code_t ec = 0;
size_t i, left;
int *dummy = NULL;
for (i = 0; i < count; i++)
if (r_exitcodes == NULL)
dummy = r_exitcodes = xmalloc (sizeof *r_exitcodes * count);
for (i = 0, left = count; i < count; i++)
{
if (r_exitcodes)
r_exitcodes[i] = -1;
int status = -1;
if (pids[i] == (pid_t)(-1))
return my_error (GPG_ERR_INV_VALUE);
/* See if there was a previously stored result for this pid. */
if (get_result (pids[i], &status))
left -= 1;
r_exitcodes[i] = status;
}
left = count;
while (left > 0)
{
pid_t pid;
@ -639,43 +707,57 @@ gnupg_wait_processes (const char **pgmnames, pid_t *pids, size_t count,
break;
if (i == count)
/* No match, ignore this pid. */
{
/* No match, store this result. */
ec = store_result (pid, status);
if (ec)
break;
continue;
}
/* Process PIDS[i] died. */
left -= 1;
if (r_exitcodes[i] != (pid_t) -1)
{
log_error ("PID %d was reused", pid);
ec = GPG_ERR_GENERAL;
break;
}
if (WIFEXITED (status) && WEXITSTATUS (status) == 127)
left -= 1;
r_exitcodes[i] = status;
}
}
if (ec == 0)
for (i = 0; i < count; i++)
{
if (WIFEXITED (r_exitcodes[i]) && WEXITSTATUS (r_exitcodes[i]) == 127)
{
log_error (_("error running '%s': probably not installed\n"),
pgmnames[i]);
ec = GPG_ERR_CONFIGURATION;
}
else if (WIFEXITED (status) && WEXITSTATUS (status))
else if (WIFEXITED (r_exitcodes[i]) && WEXITSTATUS (r_exitcodes[i]))
{
if (!r_exitcodes)
if (dummy)
log_error (_("error running '%s': exit status %d\n"),
pgmnames[i], WEXITSTATUS (status));
pgmnames[i], WEXITSTATUS (r_exitcodes[i]));
else
r_exitcodes[i] = WEXITSTATUS (status);
r_exitcodes[i] = WEXITSTATUS (r_exitcodes[i]);
ec = GPG_ERR_GENERAL;
}
else if (!WIFEXITED (status))
else if (!WIFEXITED (r_exitcodes[i]))
{
log_error (_("error running '%s': terminated\n"), pgmnames[i]);
ec = GPG_ERR_GENERAL;
}
else
{
if (r_exitcodes)
r_exitcodes[i] = 0;
}
}
}
xfree (dummy);
return gpg_err_make (GPG_ERR_SOURCE_DEFAULT, ec);
}
void
gnupg_release_process (pid_t pid)