1 /*-------------------------------------------------------------------------
2 *
3 * wait_error.c
4 * Convert a wait/waitpid(2) result code to a human-readable string
5 *
6 *
7 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
9 *
10 *
11 * IDENTIFICATION
12 * src/common/wait_error.c
13 *
14 *-------------------------------------------------------------------------
15 */
16
17 #ifndef FRONTEND
18 #include "postgres.h"
19 #else
20 #include "postgres_fe.h"
21 #endif
22
23 #include <signal.h>
24 #include <sys/wait.h>
25
26 /*
27 * Return a human-readable string explaining the reason a child process
28 * terminated. The argument is a return code returned by wait(2) or
29 * waitpid(2). The result is a translated, palloc'd or malloc'd string.
30 */
31 char *
wait_result_to_str(int exitstatus)32 wait_result_to_str(int exitstatus)
33 {
34 char str[512];
35
36 if (WIFEXITED(exitstatus))
37 {
38 /*
39 * Give more specific error message for some common exit codes that
40 * have a special meaning in shells.
41 */
42 switch (WEXITSTATUS(exitstatus))
43 {
44 case 126:
45 snprintf(str, sizeof(str), _("command not executable"));
46 break;
47
48 case 127:
49 snprintf(str, sizeof(str), _("command not found"));
50 break;
51
52 default:
53 snprintf(str, sizeof(str),
54 _("child process exited with exit code %d"),
55 WEXITSTATUS(exitstatus));
56 }
57 }
58 else if (WIFSIGNALED(exitstatus))
59 {
60 #if defined(WIN32)
61 snprintf(str, sizeof(str),
62 _("child process was terminated by exception 0x%X"),
63 WTERMSIG(exitstatus));
64 #else
65 snprintf(str, sizeof(str),
66 _("child process was terminated by signal %d: %s"),
67 WTERMSIG(exitstatus), pg_strsignal(WTERMSIG(exitstatus)));
68 #endif
69 }
70 else
71 snprintf(str, sizeof(str),
72 _("child process exited with unrecognized status %d"),
73 exitstatus);
74
75 return pstrdup(str);
76 }
77
78 /*
79 * Return true if a wait(2) result indicates that the child process
80 * died due to the specified signal.
81 *
82 * The reason this is worth having a wrapper function for is that
83 * there are two cases: the signal might have been received by our
84 * immediate child process, or there might've been a shell process
85 * between us and the child that died. The shell will, per POSIX,
86 * report the child death using exit code 128 + signal number.
87 *
88 * If there is no possibility of an intermediate shell, this function
89 * need not (and probably should not) be used.
90 */
91 bool
wait_result_is_signal(int exit_status,int signum)92 wait_result_is_signal(int exit_status, int signum)
93 {
94 if (WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum)
95 return true;
96 if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 128 + signum)
97 return true;
98 return false;
99 }
100
101 /*
102 * Return true if a wait(2) result indicates that the child process
103 * died due to any signal. We consider either direct child death
104 * or a shell report of child process death as matching the condition.
105 *
106 * If include_command_not_found is true, also return true for shell
107 * exit codes indicating "command not found" and the like
108 * (specifically, exit codes 126 and 127; see above).
109 */
110 bool
wait_result_is_any_signal(int exit_status,bool include_command_not_found)111 wait_result_is_any_signal(int exit_status, bool include_command_not_found)
112 {
113 if (WIFSIGNALED(exit_status))
114 return true;
115 if (WIFEXITED(exit_status) &&
116 WEXITSTATUS(exit_status) > (include_command_not_found ? 125 : 128))
117 return true;
118 return false;
119 }
120