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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) 1996-2026, 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 : 0 : wait_result_to_str(int exitstatus)
34 : : {
35 : 0 : 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 [ # # ]: 0 : if (exitstatus == -1)
43 : : {
44 : 0 : snprintf(str, sizeof(str), "%m");
45 : 0 : }
46 [ # # ]: 0 : 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 [ # # # ]: 0 : switch (WEXITSTATUS(exitstatus))
53 : : {
54 : : case 126:
55 : 0 : snprintf(str, sizeof(str), _("command not executable"));
56 : 0 : break;
57 : :
58 : : case 127:
59 : 0 : snprintf(str, sizeof(str), _("command not found"));
60 : 0 : break;
61 : :
62 : : default:
63 : 0 : snprintf(str, sizeof(str),
64 : 0 : _("child process exited with exit code %d"),
65 : 0 : WEXITSTATUS(exitstatus));
66 : 0 : }
67 : 0 : }
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 : 0 : WTERMSIG(exitstatus), pg_strsignal(WTERMSIG(exitstatus)));
78 : : #endif
79 : 0 : }
80 : : else
81 : 0 : snprintf(str, sizeof(str),
82 : 0 : _("child process exited with unrecognized status %d"),
83 : 0 : exitstatus);
84 : :
85 : 0 : return pstrdup(str);
86 : 0 : }
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 : 0 : wait_result_is_signal(int exit_status, int signum)
103 : : {
104 [ # # # # : 0 : if (WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum)
# # ]
105 : 0 : return true;
106 [ # # # # ]: 0 : if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 128 + signum)
107 : 0 : return true;
108 : 0 : return false;
109 : 0 : }
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 : 0 : wait_result_is_any_signal(int exit_status, bool include_command_not_found)
122 : : {
123 [ # # # # ]: 0 : if (WIFSIGNALED(exit_status))
124 : 0 : return true;
125 [ # # # # ]: 0 : if (WIFEXITED(exit_status) &&
126 : 0 : WEXITSTATUS(exit_status) > (include_command_not_found ? 125 : 128))
127 : 0 : return true;
128 : 0 : return false;
129 : 0 : }
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 : 0 : wait_result_to_exit_code(int exit_status)
139 : : {
140 [ # # ]: 0 : if (exit_status == -1)
141 : 0 : return -1; /* failure of pclose() or system() */
142 [ # # ]: 0 : if (WIFEXITED(exit_status))
143 : 0 : 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 : 0 : }
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