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) 1996-2024, 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          34 : 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          34 :     if (exitstatus == -1)
      43             :     {
      44           0 :         snprintf(str, sizeof(str), "%m");
      45             :     }
      46          34 :     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          34 :         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          34 :             default:
      63          34 :                 snprintf(str, sizeof(str),
      64          34 :                          _("child process exited with exit code %d"),
      65          34 :                          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          34 :     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         278 : wait_result_is_signal(int exit_status, int signum)
     103             : {
     104         278 :     if (WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum)
     105           0 :         return true;
     106         278 :     if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 128 + signum)
     107           0 :         return true;
     108         278 :     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         284 : wait_result_is_any_signal(int exit_status, bool include_command_not_found)
     122             : {
     123         284 :     if (WIFSIGNALED(exit_status))
     124           2 :         return true;
     125         564 :     if (WIFEXITED(exit_status) &&
     126         282 :         WEXITSTATUS(exit_status) > (include_command_not_found ? 125 : 128))
     127           0 :         return true;
     128         282 :     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           8 : wait_result_to_exit_code(int exit_status)
     139             : {
     140           8 :     if (exit_status == -1)
     141           0 :         return -1;              /* failure of pclose() or system() */
     142           8 :     if (WIFEXITED(exit_status))
     143           8 :         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             : }