Line data Source code
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) 1996-2026, 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), which also applies to pclose(3) and system(3). The result is a
30 : * translated, palloc'd or malloc'd string.
31 : */
32 : char *
33 17 : wait_result_to_str(int exitstatus)
34 : {
35 : char str[512];
36 :
37 : /*
38 : * To simplify using this after pclose() and system(), handle status -1
39 : * first. In that case, there is no wait result but some error indicated
40 : * by errno.
41 : */
42 17 : if (exitstatus == -1)
43 : {
44 0 : snprintf(str, sizeof(str), "%m");
45 : }
46 17 : else if (WIFEXITED(exitstatus))
47 : {
48 : /*
49 : * Give more specific error message for some common exit codes that
50 : * have a special meaning in shells.
51 : */
52 17 : switch (WEXITSTATUS(exitstatus))
53 : {
54 0 : case 126:
55 0 : snprintf(str, sizeof(str), _("command not executable"));
56 0 : break;
57 :
58 0 : case 127:
59 0 : snprintf(str, sizeof(str), _("command not found"));
60 0 : break;
61 :
62 17 : default:
63 17 : snprintf(str, sizeof(str),
64 17 : _("child process exited with exit code %d"),
65 17 : WEXITSTATUS(exitstatus));
66 : }
67 : }
68 0 : else if (WIFSIGNALED(exitstatus))
69 : {
70 : #if defined(WIN32)
71 : snprintf(str, sizeof(str),
72 : _("child process was terminated by exception 0x%X"),
73 : WTERMSIG(exitstatus));
74 : #else
75 0 : snprintf(str, sizeof(str),
76 0 : _("child process was terminated by signal %d: %s"),
77 : WTERMSIG(exitstatus), pg_strsignal(WTERMSIG(exitstatus)));
78 : #endif
79 : }
80 : else
81 0 : snprintf(str, sizeof(str),
82 0 : _("child process exited with unrecognized status %d"),
83 : exitstatus);
84 :
85 17 : return pstrdup(str);
86 : }
87 :
88 : /*
89 : * Return true if a wait(2) result indicates that the child process
90 : * died due to the specified signal.
91 : *
92 : * The reason this is worth having a wrapper function for is that
93 : * there are two cases: the signal might have been received by our
94 : * immediate child process, or there might've been a shell process
95 : * between us and the child that died. The shell will, per POSIX,
96 : * report the child death using exit code 128 + signal number.
97 : *
98 : * If there is no possibility of an intermediate shell, this function
99 : * need not (and probably should not) be used.
100 : */
101 : bool
102 138 : wait_result_is_signal(int exit_status, int signum)
103 : {
104 138 : if (WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum)
105 0 : return true;
106 138 : if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 128 + signum)
107 0 : return true;
108 138 : return false;
109 : }
110 :
111 : /*
112 : * Return true if a wait(2) result indicates that the child process
113 : * died due to any signal. We consider either direct child death
114 : * or a shell report of child process death as matching the condition.
115 : *
116 : * If include_command_not_found is true, also return true for shell
117 : * exit codes indicating "command not found" and the like
118 : * (specifically, exit codes 126 and 127; see above).
119 : */
120 : bool
121 146 : wait_result_is_any_signal(int exit_status, bool include_command_not_found)
122 : {
123 146 : if (WIFSIGNALED(exit_status))
124 0 : return true;
125 292 : if (WIFEXITED(exit_status) &&
126 146 : WEXITSTATUS(exit_status) > (include_command_not_found ? 125 : 128))
127 0 : return true;
128 146 : return false;
129 : }
130 :
131 : /*
132 : * Return the shell exit code (normally 0 to 255) that corresponds to the
133 : * given wait status. The argument is a wait status as returned by wait(2)
134 : * or waitpid(2), which also applies to pclose(3) and system(3). To support
135 : * the latter two cases, we pass through "-1" unchanged.
136 : */
137 : int
138 4 : wait_result_to_exit_code(int exit_status)
139 : {
140 4 : if (exit_status == -1)
141 0 : return -1; /* failure of pclose() or system() */
142 4 : if (WIFEXITED(exit_status))
143 4 : return WEXITSTATUS(exit_status);
144 0 : if (WIFSIGNALED(exit_status))
145 0 : return 128 + WTERMSIG(exit_status);
146 : /* On many systems, this is unreachable */
147 0 : return -1;
148 : }
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