cdd442ebd
Denys Vlasenko
2026-10-05
Subject
ash: waitproc: unobfuscate and explain what the code does
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shell/ash.c+11 -5
| @@ -4349,11 +4349,11 @@ waitproc(int block, int *status) | |
| err = waitpid(-1, status, flags); | |
| while (err < 0 && errno == EINTR); | |
| - | /* Return if error (for example, ECHILD); or if pid found; |
| - | * or if "block" is DOWAIT_NONBLOCK (=0), in this case return -1. |
| - | */ |
| - | if (err || (err = -!block)) |
| - | break; |
| + | if (err) /* waitpid() returned PID or error? */ |
| + | break; /* return it */ |
| + | err = -!block; |
| + | if (err) /* block == DOWAIT_NONBLOCK (0)? */ |
| + | break; /* return -1 */ |
| /* "block" is DOWAIT_CHILD_OR_SIG. All children are running | |
| * (waitpid(WNOHAG) above returned 0), wait for signals: | |
| @@ -4372,6 +4372,12 @@ waitproc(int block, int *status) | |
| } while (gotsigchld); | |
| /* If we fall off the loop, err is 0, which means we got a !SIGCHLD signal */ | |
| + | /* Possible returns: |
| + | * PID of successfully waited-for child. |
| + | * -1 on waitpid() error (can get ECHILD: no one to wait for) |
| + | * -1 if DOWAIT_NONBLOCK |
| + | * 0 if there were no waitable children and got a signal (not SIGCHLD) |
| + | */ |
| return err; | |
| } | |