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wait_error.c
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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 *
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
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
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 }
#define WTERMSIG(w)
Definition: win32_port.h:141
char * pstrdup(const char *in)
Definition: mcxt.c:1186
char * wait_result_to_str(int exitstatus)
Definition: wait_error.c:32
bool wait_result_is_signal(int exit_status, int signum)
Definition: wait_error.c:92
#define WIFEXITED(w)
Definition: win32_port.h:138
const char * pg_strsignal(int signum)
Definition: pgstrsignal.c:42
bool wait_result_is_any_signal(int exit_status, bool include_command_not_found)
Definition: wait_error.c:111
#define WIFSIGNALED(w)
Definition: win32_port.h:139
#define snprintf
Definition: port.h:192
#define _(x)
Definition: elog.c:87
#define WEXITSTATUS(w)
Definition: win32_port.h:140