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/*-------------------------------------------------------------------------
*
* wait_error.c
* Convert a wait/waitpid(2) result code to a human-readable string
*
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/common/wait_error.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include <signal.h>
#include <sys/wait.h>
/*
* Return a human-readable string explaining the reason a child process
* terminated. The argument is a return code returned by wait(2) or
* waitpid(2), which also applies to pclose(3) and system(3). The result is a
* translated, palloc'd or malloc'd string.
*/
char *
wait_result_to_str(int exitstatus)
{
char str[512];
/*
* To simplify using this after pclose() and system(), handle status -1
* first. In that case, there is no wait result but some error indicated
* by errno.
*/
if (exitstatus == -1)
{
snprintf(str, sizeof(str), "%m");
}
else if (WIFEXITED(exitstatus))
{
/*
* Give more specific error message for some common exit codes that
* have a special meaning in shells.
*/
switch (WEXITSTATUS(exitstatus))
{
case 126:
snprintf(str, sizeof(str), _("command not executable"));
break;
case 127:
snprintf(str, sizeof(str), _("command not found"));
break;
default:
snprintf(str, sizeof(str),
_("child process exited with exit code %d"),
WEXITSTATUS(exitstatus));
}
}
else if (WIFSIGNALED(exitstatus))
{
#if defined(WIN32)
snprintf(str, sizeof(str),
_("child process was terminated by exception 0x%X"),
WTERMSIG(exitstatus));
#else
snprintf(str, sizeof(str),
_("child process was terminated by signal %d: %s"),
WTERMSIG(exitstatus), pg_strsignal(WTERMSIG(exitstatus)));
#endif
}
else
snprintf(str, sizeof(str),
_("child process exited with unrecognized status %d"),
exitstatus);
return pstrdup(str);
}
/*
* Return true if a wait(2) result indicates that the child process
* died due to the specified signal.
*
* The reason this is worth having a wrapper function for is that
* there are two cases: the signal might have been received by our
* immediate child process, or there might've been a shell process
* between us and the child that died. The shell will, per POSIX,
* report the child death using exit code 128 + signal number.
*
* If there is no possibility of an intermediate shell, this function
* need not (and probably should not) be used.
*/
bool
wait_result_is_signal(int exit_status, int signum)
{
if (WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum)
return true;
if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 128 + signum)
return true;
return false;
}
/*
* Return true if a wait(2) result indicates that the child process
* died due to any signal. We consider either direct child death
* or a shell report of child process death as matching the condition.
*
* If include_command_not_found is true, also return true for shell
* exit codes indicating "command not found" and the like
* (specifically, exit codes 126 and 127; see above).
*/
bool
wait_result_is_any_signal(int exit_status, bool include_command_not_found)
{
if (WIFSIGNALED(exit_status))
return true;
if (WIFEXITED(exit_status) &&
WEXITSTATUS(exit_status) > (include_command_not_found ? 125 : 128))
return true;
return false;
}
/*
* Return the shell exit code (normally 0 to 255) that corresponds to the
* given wait status. The argument is a wait status as returned by wait(2)
* or waitpid(2), which also applies to pclose(3) and system(3). To support
* the latter two cases, we pass through "-1" unchanged.
*/
int
wait_result_to_exit_code(int exit_status)
{
if (exit_status == -1)
return -1; /* failure of pclose() or system() */
if (WIFEXITED(exit_status))
return WEXITSTATUS(exit_status);
if (WIFSIGNALED(exit_status))
return 128 + WTERMSIG(exit_status);
/* On many systems, this is unreachable */
return -1;
}
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